SUGGESTED GUIDE

FOR

WEED CONTROL

1969

Ü.S.CE?T. Of AGRICULTURE

NATIONIUGWCUITURAL lllRARy

MAY 12 196y

CURRENT SERIAL RECORDS

Agriculture Handbook No. 332

Agricultural Research Service

UNITED STATES DEPARTMENT OF AGRICULTURE
USDA POLICY ON PESTICIDES

One of the most important responsibilities of

the Department of Agriculture is to develop and

facilitate the use of methods and materials for the

control of pests. The Department's research,

education, and regulatory programs are expected

to make continuing progress in the never-ending

struggle to protect man, his food and fiber supplies, and his forests from the ravages of pests.

Such protection is essential if the American people

are to continue to enjoy their present high standard

of living, and if this abundance of quality food and

relative freedom from the hazards of pests are to be

enjoyed by all mankind.

In protecting man, animals, plants, farm and

forest products, communities, and households

against depredation of pests, the Department has

vital concern for (1) the health and well-being of

people who use pesticides and those who use

products protected by their use; and (2) for the

protection of fish, wildlife, soil, air, and water

from pesticide pollution.

In keeping with this concern, it is the policy of

the Department of Agriculture to practice and to

encourage the use of those means of effective pest

control which provide the least potential hazard

to man and animals. When residual pesticides

must be used to control or eliminate pests, they

shall be used in minimal effective amounts, applied

precisely to the infested area and at minimal

effective frequency. Biological, ecological, or cultural methods or nonpersistent and low-toxicity

pesticides will be used whenever such means are

feasible and will safely and effectively control or

eliminate target pests.

In carrying out these objectives, the Department

will cooperate in the fullest with the other agencies

and departments of government, and will seek to

develop broad areas of collaboration in establishing

the criteria to guide the use and development of

pest-control materials.

Further, the USDA will urge that all users of

pesticides exercise constant vigilance to assure the

protection of human health by avoiding unnecessary exposure of crops, livestock, fish, and wildlife.

The Department commends this policy to

States and local authorities as a guide in their

respective jurisdictions.
^

SUGGESTED GUIDE

FOR

WEED CONTROL

1969

Prepared by Crops Research Division

Agriculture Handbook No. 332

Washington, D.C. ^P^^^^ ^^^^

For sale by the Superintendent of Documents, U.S. Government Printing Office

Washington, D.C. 20402 - Price 70 cents
PREFACE

Research in weed control is conducted by the U.S. Department of Agriculture and certain other Federal agencies, State agricultural experiment

stations, and industrial organizations. Many of the most effective weed-control

practices resulting from this research are summarized in this handbook as a

guide for farm advisory personnel in the various States.

Correct identification of a weed species is helpful in selecting and using

weed-control suggestions. Providing information on weed identification is

outside the scope of this handbook. Descriptive and illustrative guides to the

identification of weeds have been published and are available from the State

agricultural experiment stations in nearly all States.

The successful and safe use of weed-control methods depends on strict

adherence to the appropriate treatment procedures. These details may vary

between localities because of differences in soil, climate, crop varieties, cultural

methods, and weed species. The weed-control methods described here may be

considered as a general guide. Specific information may be obtained from

State agricultural experiment station and extension service personnel and other

local agricultural authorities.

All suggested uses of herbicides were registered prior to July 15, 1968,

under the provisions of the Federal Insecticide, Fungicide, and Rodenticide

Act. The registration of herbicides changes frequently as new information on

uses and residues becomes available. New uses are frequently added to labels

and old uses are sometimes cancelled. In order to use herbicides effectively

and safely, up-to-date labels and instructions must be followed.

Because new herbicides and new uses for older ones are being developed

constantly, it is important to obtain the latest information from the U.S.

Department of Agriculture, State agricultural experiment stations and extension

services, and manufacturers of specific products.

FOLLOW THB LABEL

U.S. »ErAHTMENT OF AGmCULTUKE

If herbicides are handled or applied improperly, or if unused portions are not disposed of safely, they may be injurious to humans,

domestic animals, desirable plants, and fish or other wildlife, and

may contaminate water supplies. Use herbicides only when needed

and handle them with care. Follow the directions and heed all

precautions on the container label.
A

CONTENTS

Page

Basic principles and methods of weed control 1

Growth cycles and propagation of weeds 1

Plant competition 1

Hand and mechanical methods 2

Flame 2

Herbicides 2

Biological agents 2

Impact of weed control on crop production 2

Precautions for safe use of herbicides 3

Properties of herbicides ^-- 4

General considerations in use of herbicides 4

Purchasing herbicides _-__ 4

Calculations for herbicide applications 13

Mixing spray materials 14

Application equipment _ 14

Calibration of application equipment 15

How to determine per-acre output of sprayers 15

How to determine output of spreaders ^— 17

Effect of weather conditions on herbicide applications 17

Weed control in field crops 1^

Weed control in horticultural crops 36

Vegetables ^7

Deciduous tree fruits and nuts 40

Citrus and subtropical fruits and nuts 42

Small fruits 43

Ornamental plants 45

Weed control in horticultural plant beds and nurseries 4b

Weed control in greenhouses 47

Weed control in forage crops, pastures, and rangelands_ _ _ 47

Weed control in lawns and other turf areas___ 52

Weed control in noncropland 54

Construction aids 54

Cultural, biological, and mechanical control 54

Control with herbicides 55

Control of aquatic weeds ^

Construction aids ^J:

Management practices ^

Hand and mechanical control ^

Biological control ^1

Chemical control ^1

Appendix—Herbicide tolerances for crops ^5

Crop index ^*

Weed index ^^
LIST OF TABLES

Table

1 Chemical, physical, and biological properties of herbicides 5

2 Weed control in field row crops 1§

3 Weed control in close-drilled field crops 27

4 Control of perennial weeds in cropland in fallow periods or by spot

treatment 3^

5 Weed control in vegetables 37

6 Weed control in deciduous tree fruits and nuts llllllllll I 40

7 Weed control in citrus and subtropical fruits and nuts ' 42

8 Weed control in small fruits 44

9 Weed control in ornamental plants 45

10 Weed control with soil fumigant herbicides in horticultural' plant

beds and nurseries 4*7

11 Weed control in forage crops, pastures, and rangelands ~_ ~ ' " 48

12 Weed control in lawns and other turf areas 53

13 Weed control in noncropland (ditchbanks, fence rows, "floodways^

mdustrial sites, and railroad, highway, and utihty fine rights-ofway) rß

14 Control of aquatic weeds (irrigation canals, drainage ditches,

streams, lakes, ponds, reservoirs, marshes) .' 62
SUGGESTED GUIDE FOR WEED CONTROL 1969

Prepared by CROPS RESEARCH DIVISION, Agricultural Research Service ^

BASIC PRINCIPLES AND METHODS OF WEED CONTROL

Weed control is an integral part of the overall

management program for crop production, grazing

land, lawns, gardens, irrigation and drainage

systems, and other crop and noncrop areas. For

greatest effectiveness and economy, weed-control

methods must be based on the basic principles of

plant ecology and physiology, soil fertihty, soilwater relations, and plant growth. Effective

weed-control methods and materials include crop

rotation, grazing, cultivation, mowing, flame, and

the use of herbicides, surfactants, and biological

agents. The effects of chemicals and biological

agents on human beings, livestock, fish, and wildlife must be considered. All these principles and

phases of vegetation control are considered in the

preparation of this handbook.

GROWTH CYCLES AND PROPAGATION OF

WEEDS

A weed is any plant that grows where it is not

desired. Weeds, like other plants, are classified

by growth cycle as annuals, biennials,, and

perennials. Algae and some other aquatic plants

have a shorter life cycle. Annuals mature in

one season and are nearly always propagated by

seeds. Examples are pigweed, crabgrass, and

common ragweed.^ A variation of the true annual

is the winter annual that germinates in the fall

and matures seed the next season. Examples

are cheat, pennycress, shepherdspurse, and wild

barley. Most annuals are prolific seed producers,

and seeds of many remain viable in the soil for

many years. Even though most annual weeds

are easily killed by mechanical or chemical means,

the enormous accumulation of seeds in the soil

makes their control difficult.

Biennials require two growing seasons to

complete the reproduction cycle and are propagated by seeds only. Common examples are

1 The technical information in this publication was

compiled and reviewed by L. L. Danielson, W. B, Ennis,

Jr., W. A. Gentner, J. T. Holstun, Jr., D. L. Klingman,

W. C. Shaw, F. L. Timmons, and associated personnel of

the Crops Protection Research Branch, Crops Research

Division. Helpful suggestions were made by reviewers

in the Pesticides Regulation Division and the Federal

Extension Service of the U.S. Department of Agriculture.

2 Source for common names of weeds is 1966 list of

Weed Society of America (Weeds 14, No. 4, pp. 347-386).

burdock, wild carrot, and mullein. They often

can be controlled by cultivation or timely mowing.

Perennials Uve more than 2 years. Many have

several methods of reproduction in addition to

seeds. These include bulbs, tubers, corms, lateral

roots, rhizomes, and stolons. Most of these

organs have buds and store food for overwintering

and reproduction. Several provide means of

vegetative spread. Many perennial weeds are

difficult to control and require intensive and

persistent effort. Common examples are Canada

thistle, cattail, field bindweed, johnsongrass, and

nutsedge. Unlike most annual plants, killing the

top growth of a perennial once does not usually

prevent it from surviving and producing a new

top growth from food in the storage or reproductive organs. To prevent this vegetative reproduction, the supply of stored food must be greatly

depleted by repeatedly destroying the top growth,

roots, and reproductive organs or greatly altering

the physiological processes with herbicides.

PLANT COMPETITION

Competition of desirable crops or plants with

undesirable plants frequently provides effective

and economical weed control. Careful selection

of adapted and desirable species or varieties and

maintenance of optimum soil fertility and cultural

conditions for their maximum growth are important. Mowing, pasturing with Hvestock, spraying

with selective herbicides, liming, fertihzing, or

other means of altering the environment to favor

the desired species over weeds may be necessary

for the most satisfactory results. Usually the

desired competitive crop must be planted.

Occasionally a mixture of desirable and undesirable vegetation already established on native

ranges, ditchbanks, fence rows, or other noncultivated areas can be favorably altered by repeated

apphcations of selective herbicides. Under such

treatment the resistant desirable species become

dominant and the susceptible undesirable species

are gradually eliminated. The elimination of

deep-rooted perennial weeds or other aggressive

species often necessitates the use of drastic and

frequently expensive chemical or mechanical

methods. Thereafter, desirable species can be

planted and suitable conditions provided for their

effective competition with surviving or reinvading

weeds.
AGRICULTURE HANDBOOK 332, U.S. DEPT. OF AGRICULTURE

HAND AND MECHANICAL METHODS

Numerous effective herbicides and improved

methods of appUcation have replaced many less

effective hand and mechanical methods of weed

control. However, hand and mechanical methods

are still necessary or advantageous in many situations. Hand weeding of flowerbeds, small vegetable gardens, and other small-area plantings

sensitive to herbicides is often the safest and most

satisfactory method. Mulches also aid in weed

control. Improvements in tools used for cultivating, mowing, burning, and ditch cleaning and in

other machinery needed for vegetation control

have coincided with improvements in chemical

methods. Judicious use of such equipment in

seedbed preparation, cultivation of crops, and

mowing in noncultivated areas may cause weed

seeds to germinate, destroys successive crops of

weeds, and prevents weeds from producing mature seeds. Even the most effective chemical

methods frequently must be supplemented by

hand or mechanical weeding to remove surviving

weeds and to prevent future spread by seed or

other plant parts.

FLAME

Flame is used effectively for weed control in

some situations. Several types of burners are

available. Those used for nonselective control of

weeds as on ditchbanks produce a relatively large,

varying flame pattern. Those used for selective

control of weeds as in cotton and corn produce a

relatively small constant flame pattern that can

be confined to definite areas in or between the

rows. Some specialized burners are designed to

trap and retain the generated heat momentarily

in the weed area.

Fuels most commonly used are propane, butane,

and mixtures of these two petroleum gases.

Either a vaporizer or self-energizing design of the

burner usually increases the efficiency of the

combustion. Fuel oil, kerosene, and other petroleum liquids are also used.

HERBICIDES

Since 1950 thousands of chemicals have been

evaluated for effectiveness as herbicides and more

than 100 of these have been recommended for controlling one or more weeds. The effectiveness of

herbicides on susceptible species is affected by

stage of growth, soil organic matter and pH, fertiUty, and texture; rainfall and irrigation; water

pH and chemical content; temperature of air and

water; light intensity; and other soil, water, and

climatic factors. Crop and weed plants vary

widely in their responses to different herbicides.

Some herbicides may kill fish, some may injure

livestock and wildlife, and a few may affect

humans. However, safe and effective herbicides

are available for controlling many weeds growing

in various environments, including cropland,

rangeland, gardens, lawns, ditchbanks, and other

noncrop areas, and in irrigation, drainage, navigable, and potable waters. Because of the many

factors and principles involved and the dynamic

nature of research on herbicides, information about

chemical weed control is rapidly increasing and

new recommendations are continually replacing

old ones.

Suggestions for apphcation rates of herbicides

are based on the active ingredient or acid equivalent contained, and not on the total weight of the

product.

BIOLOGICAL AGENTS

Only limited attention has been given to controlling undesirable plants by using insects, plant

disease organisms, and other natural enemies.

Research is now underway to discover and develop effective and safe biological agents to control such weedy species as alligatorweed, waterhyacinth, submersed aquatic weeds, Scotch broom,

halogeton, cactus, tansy ragwort, puncturevine,

gorse, and St. Johnswort. One noticeably successful biological control agent in the Northwestern

States is the beetle Chrysolina spp. This insect

is native to Europe but was introduced from

Australia to the United States to control St.

Johnswort. Research on biological control of

weeds is being increased and probably will be

emphasized considerably in the future.

IMPACT OF WEED CONTROL ON CROP

PRODUCTION

Weed-control principles, methods, and practices

have an important impact on all phases of crop

production. New chemical, cultural, mechanical,

biological, and combination methods of weed

control affect crop choice; the variety to use;

seedbed preparation; method of seeding; seeding

rates; row spacing; plant spacing in the row;

plant populations; fertilizer practices, including

type, time of application, and placement; cultivation; irrigation practices; harvesting; seedcleaning operations; erosion control; fallow practices for weed control; disease- and insect-control

practices; pasture renovation; pasture and range

management; clearing new lands for crops or

pasture; forest management; the utilization of

farm water resources for irrigation and recreation ;

and the maintenance of drainage ditches, ditchbanks, irrigation canals, and farm roadsides.

Equally important are the significant effects crop

manageraent and production practices have on

the choice and effectiveness of weed-control

methods.
SUGGESTED GUIDE FOR WEED CONTROL 19 69

PRECAUTIONS FOR SAFE USE OF HERBICIDES

All chemicals described in this handbook,

especially when used on raw agricultural crops

as defined under Public Law 518, should be appUed

in accordance with the directions on the manufacturer's label, as registered under the Federal

Insecticide, Fungicide, and Rodenticide Act.

Specifications with respect to crop, amount of

chemical, and time of application should be

strictly observed.

Many herbicides are irritating or potentially

dangerous, but they are not hazardous if used

properly and if recommended precautions are

observed. Most herbicides have a low acute oral

toxicity, but a few are highly toxic to humans,

livestock, and wildlife, and some are toxic to

fish. The relative degree of acute toxicity to

warmblooded animals is given for most herbicides

listed for weed control in table 1. In the following

data the LD50 ratings (lethal dosage that kills

50 percent of the experimental animals) are classified as to acute oral toxicity:

Acute oral toxicity LD50, mg. Lethal dosage for

Class per kg. 150-lb. man

Highly toxic 50 and below___ Few drops to 1 teaspoon.

Moderately toxic. 50-500 1 teaspoon to 1 oz.

Mildly toxic 500-5,000 1 oz. to 1 pt. or 1 lb.

Nontoxic Above 5,000_ _.- 1 pt. to over 1 qt.

All LD50 values in table 1 are based on a single

dose of material orally administered to animals,

followed by observation of the treated animals for

a definite period. However, these findings do not

indicate the possible hazards that may arise from

skin contact or inhalation of the substances.

Likewise, these data do not accurately predict the

toxicity of a formulation that may differ according to the solvent or diluent used.

The following general precautions should be

observed in applying herbicides:

For humans—

1. Read the label on each container before

using the contents. Follow instructions; heed all

cautions and warnings. Store in closed, welllabeled containers out of the reach of children and

pets, and where the herbicides cannot contaminate

food or water.

2. Avoid inhaling vapors, dusts, or spray mists.

Use a mask when specified on the container label.

3. Avoid repeated or prolonged contact of

herbicides by the skin. Some individuals are

hypersensitive to certain chemicals and must be

especially careful to avoid allergic reactions.

4. Wash hands and face thoroughly with soap

and water after each use of an herbicide. Do not

eat, drink, or smoke until you have washed your

h^i^^s and face. Wear synthetic rubber gloves and

wear goggles where label instructions specify.

5. Avoid spilling herbicide concentrate on your

skin and keep it out of your eyes, nose, and

mouth. If you spill any on your skin, wash it off

immediately with soap and water. If you spill it

on your clothing, launder the clothing before

wearing it again.

6. Handle flammable chemicals with care to

avoid ignition from friction, sparks, or contact

with combustible materials.

7. Avoid contaminating potable water supplies

with herbicides.

8. Dispose of empty containers and surplus

herbicide solutions by burial at least 18 inches

deep in a level, isolated area where they will not

contaminate water supplies.

For livestock—

1. Prevent Hvestock from grazing in areas

where herbicide sprays may have increased the

palatabiUty of poisonous plants or increased the

amounts of nitrate or other chemicals of certain

plants to a toxic level.

2. Prevent livestock from drinking water that

has been treated with an herbicide during the

time after treatment prescribed on the label.

For wildlife and fish—

1. Avoid overdoses and spillage of herbicides in

or near streams, ponds, and lakes or in areas

frequented by wildlife.

2. A few herbicides are toxic to fish and wildlife.

Do not apply herbicides that do not have an approved label for such use to canals, lakes, ponds,

or streams.

3. Consult Federal or State game and fish

departments for advice if a proposed herbicide

application might endanger wildlife or fish.

For desirable plants—

1. Avoid spraying when and where drift of fine

spray or volatiHzed fumes is likely to contact

nearby sensitive crop or ornamental plants. Use

spot treatment control of weeds in lawns if they

are not too numerous.

2. Reduce drift hazards by using low dritt

formulations, amine or low-volatile esters of

phenoxy herbicides, low spraying pressures, and

large volumes of coarse sprays and by spraying

when wind is low in velocity and blowing away

from nearby sensitive plants. Do not spray when

temperatures exceed 90° F. i • • j

3. Avoid applying a soil sterilant herbicide to

the foHage or over the root zone of a tree, shrub,

or other desirable plant where leaching the chemical into the soil may result in death or injury of the

plant.

4. Avoid applying herbicides or cleaning out

appHcation equipment on sloping bare ground,
AGRICULTURE HANDBOOK 3 32, U.S. DEPT. OF AGRICULTURE

pavement, or other areas where the herbicide may

be carried by surface runoflF to valuable plants

downslope.

5. Avoid using herbicide sprayers for other

purposes on crop or ornamental plants that are

sensitive to herbicides until the equipment is

thoroughly cleaned. Clean the equipment with

warm water and detergent, followed by 12 to 24

hours of soaking with a solution of one part of

household ammonia in 100 parts of water, or rinse

the sprayer for 2 minutes with a 0.25-percent

suspension of activated charcoal (one-fourth pound

of activated charcoal in 10 gallons of water containing household detergent), followed by a rinse

of clean water.

No matter how well it has been cleaned, a

sprayer that previously has been used for applying

phenoxy herbicides should not be used to spray

cotton, tomatoes, grapes, and many ornamentals

highly sensitive to 2,4-D and other phenoxy or

similar growth-regulator herbicides.

6. Do not store herbicides near seeds, bulbs,

fertilizers, insecticides, fungicides, or other farm

chemicals and supplies.

PROPERTIES OF HERBICIDES

Descriptions of the chemical, physical, and

biological properties of herbicides mentioned in

this handbook are given in table 1. The herbicides

are designated by their common and chemical

names. Their acute oral toxicity to warmblooded

animals is indicated by the LD50 rating given in

terms of milligrams of herbicide per kilogram of

body weight of rats, except where other animals

are specifically named. The basic chemical reference material used to calculate application rates

is shown for each herbicide. The kinds of commercial formulations are given as a convenience

in determining the kinds of application equipment

needed in using the herbicides. Brief reference is

made to certain important weeds controlled by

each herbicide, some of the practical uses in crops,

specialized methods of application, and specific

toxic or persistence characteristics. Specialized,

accepted uses of the herbicides in various crops

and in noncrop weed situations are described in

detail under the appropriate headings on pages

18-64.

GENERAL CONSIDERATIONS IN USE OF HERBICIDES

PURCHASING HERBICIDES

Formulations

Most herbicides are usually purchased as a

commercial formulation that contains the herbicide and can be (1) dissolved, emulsified, or

suspended in a liquid carrier, (2) distributed dry

by a spreader or by hand, or (3) injected into soil

for vaporization and fumigation. Often an emulsifier, spreader, sticker, or other surfactant is

added to facilitate dilution and adhering capacity

or to increase wetting of plants. Many formulations contain inactive fillers that serve as diluents

only. For example, there may be 2, 3, 4, or 6

pounds of active herbicide in a gallon of liquid

formulation weighing as much as 10 pounds or 4,

10, 20, 50, or 80 percent of active chemical in a

granule, pellet, or powder formulation.

Active Chemical Content

Although the carrier components contained in

herbicides, such as emulsifiers, solvents, and other

adjuvants, often affect problems encountered in

mixing and spraying and on weed-control results,

the economic value of an herbicide is largely

dependent on the relative amount of phytotoxic

chemical that is contained per gallon or pound.

One of the best guides to use in purchasing a

commercial herbicide is the price per pound of

active chemical. The containers for all commercial

herbicides have labels that state the amount of

active chemicals contained in the particular

product. This is expressed in percentage of active

ingredient, acid equivalent, or phenol equivalent

for solids and in pounds per gallon for liquids.

Where a formulation contains a mixture of herbicides, the amount of each herbicide is given on

the label and should be considered in determining

the relative value of the mixture.

Acid equivalent is commonly used to express

the active chemical in dalapon and the phenoxy,

benzoic, and picolinic acid herbicides, such as

2,4-p, silvex, 2,3,6-TBA, and picloram. Phenol

equivalent is used to express the active chemical

in dinitrophenol and pentachlorophenol derivatives. For most other compounds the active

chemical content is expressed as active ingredient.

Usually the concentrated formulations are more

economical to use than diluted concentrations

when the herbicide is applied in a spray. For

example, 2,4-D formulations that contain 4

pounds of acid equivalent per gallon nearly always

cost less per pound of 2,4-D than formulations

containing only 1 or 2 pounds of 2,4-D acid

equivalent per gallon. On the other hand, herbicides to be broadcast dry in granules or pellets

may require diluted concentrations as low as 4,

10, or 20 percent to permit precise and uniform

application.
SUGGESTED GUIDE FOR WEED CONTROL 19 69

^ tí

"S .2

¡i

ig

T3

-^ O 03

O-TH tí •tí tí o

0) 03 03

ptí ü O

C3 -^

«^i^ tí

lis

•S 03 o

tí oT^ ^:tí S o3 '-4-S Vp

Tí -Tí +5

fc-i ^ .tí

o; >^ ^

asb X2 bß a;

g2>

OX2 <D

+^^ tí

O ^

tí M ^ 5^

O û^ «3 03

^ o g a¿ c^

03 í^üS-o 02 tí

o

^ O) o

o 03 Q.

g =3 >

O

O

C7'

>. c^ b ^ ar;tí

•r; œ ;tí _5^ o Oí

g g ^0 «2 bc

;H tí o3 tí g

fe

« 3

§^^^

. ipil a 03 s ^ tí

^-tí^a-a^

m ^ o3

03

oc o

gtí

bßcr^ ^:tí 9-'

03 tí ^ Ö <l^

P 03 4^ ;^ ^

S^ ^^ 2

ce

03

_ o3 O)

Ç0 'œ ."tí

)¿ 02 ^ ^

> œ <D

^ œ 'tí

o

tí

c3

ü •

^ ^ tí §^a

o

o3 O) *-^ cß

o bß _p ^

'^ 22 a?

pq

o3

tí^

<D O

O ^

O

o

tí

a;

a

03

tí

O

ü

o

o

o

o

O}

o

o

o

o

tí tí -rj .2^ tí

w '+^ la o3

? £a2|

^ CD ^' ^ tíí^

^^ bß^ öii

Ä 2 -^ rtí (í3

:^§§§-2

"5^¿ 21 g 2

^ O "^ O

tí

c3

s^g

+3 .ÍH -^

+^ , ^ <D 33 '^

O k

tí O'

Oí fH « "tí

é§

03 _

03 ^

^MX3tíco¿oa)co

2 a o o; ^, o3 ^

03 o

^

^

^§a

PHO

«2 o3 "S)? bß tí tí ..

igsjl g^ œ„ ö3._

> ^ 03 tín û) tí ^

a tí bí^. . dg bßbß ^. 25

tí .B^ o ^

fH ü

O

Oí C^ 03 .tírtí +^ 5::;

O

O

PH

o r/}

'ß S

^ <!

tí'^ tí

o ü <u ü .^ c? ss ;H

o

a^ tí.

o ü o

o o

"tí '-^ tíT3

„ _. (D P_H

-§ «^ Ö g tíi

o3 ^ -PH ^ o3 a

í-i o3 w ,

O ;H >i íH CO

rv bß 03 a; -t¿ J

O ü «'^ Oc

a == O í^ 2.

o o .a ^ ce '

,^ 02 rv o

bßÖ § p^¿

tí "0-2 fH tí,

•tí ü T3 ü g

O

o

o

o

tí

03

-O

03

O -^^ o

tí o t^

a

03tí

tí

O

a

a

o

o

t

CO

-Û^

CD

>>o3

aa

CO P^

^§§

^ o3 oo

I

O

.tíT3

a «

03 "^

o; 1 tí 1 >>;H Ü

-M X5 <D

a a

< <CÍ

o

o

LO

a; o3

o >^

a s

c3 '^

CO

i

a

o

o

tí

o

a

a

03

O

00

o

6

tí

a

ce

03 tí

Si a ^ ci

O >, ^ F o;

A o

tí ^ N

o ^

o f^

O

lO

CO

tí ^

-I

22o o

isI

X2

tí

o3

03
AGRICULTURE HANDBOOK 3 3,2, U.S. DEPT. OF AGRICULTURE

Ö

o

o

1^

>

§^

Pi

O-^ tí

•tí í3 O

^ cS 03

03

PQ

O.tí g

ige

o

a03tí

tí

O

a

ao

o

tí W)

o3 di

tí Oí

a^;H Tí

^H a;

o '^

O

T3

03

O

tí ^H 'S tí ^g

.tí !?• «2

.a tí S

a ^S^

bD (D -73

o; .tí

111

O

o

tí

ctí

o

tí

o;

tí

O) Ü

«^

o

o

OH

o

o

Ä"S I

X5 ÍH C<ï o

^ tí típq

tí c3 OLJ

tí ^ fl'^'^

.2 '^ tí CD

03 tíV3 ?3

a ëSs

a3 ?í bC o

73^^x3 > a

ortí aí;rj tí

Ä g ^ o OQ

pH

o

o

!ítí

T3 O

03 -, I T3 O tí bc .jH ^ ^ tí ^

T3'^ (D O

¿ tí ^

O O) O

«3 >;»'^

'0^ tí

-p tí «tí

•tí o g-^

i2 tí gnö

œ O o3 ü

o; 02 >^ CO OTS

1^ tí 'S 5R ^ ^ tí

^ § « S r9 tí §

bC Ü tí '^Tr ^ P i2

í o "^ o 5 i^ "2 H -

bß^ü t+H 'sr ^ O iS ¿g ítí bD Ö o -o

f^ . .^ r<^ O Oí

T3

Oí

O

o

T3

tí

O

tí rt --3 fH.ST3

•tí 2 tí 02 Ö *t3 tí 4J 'S 0 ^ « 03

Tí S^ a tí ©z: ^^

T3tí

Kr2 '^.tí Tr^H T3 ^C oä W)aí.

o; Ö 03 bDAT-jTi

03 •^j «2 CÍH S ®

^ tí 03 S 03 03 g

W)a2 ^ ^ tí i5c.-+^

.tí í>. ^ • " ^ tí X5 _r3 r^ 02 -^ .tí Tí

„ o3

03

O

Tití

2 ^ 03 03 § 5*4:.

-^^ g S^ «2 ü _, ^

tí S ^ 2S H S S^ o CO 'ÓQ Ö ^ OAJ

K5

PLH

s tí

-1-3 ^

tí 03

03 tí

O

o

03

, tí o e o. ^S'-B^-S^

'í:» títí'^j'd^ .

?^ Ortí § >.^

¿'f.-ei^ití^

o

o

tí p—1

Xí 'o

1 o3 ^ ;-l ?

tí

có1 %ptí o +3

so

03

a

¿ é

1 03

1 T3 tí

03 3oo tí tí 03 03

PP PQ

3 .. O 03^ 2

5 X ^ 73 a tí

a o tí 0-5 T3 2^03•£: o tí

Q^-^ Í-U-M oo c3

PQ m
SUGGESTED GUIDE FOR WEED CONTROL 19 69

o Oí .^X5

*^ 9 fc <^'°

Snot a^

O 25 03 *-)

^ «5*^ JL S

,-H -t^ o3 Ö rv tí

O O i?, ^ 'T o

O^ o Ors,-.2

tí

•^ O

T3tí

c3

02

O)

OO ü S

03 c3 'S tí

o

Qí o ^ ë Tlií

ft _, O o3'-3 03 •^.S _Ä gffi

o °3 ü ¿-0 tí

^ s tí^ 2œ

'o g o3 c3X2^^

O

1^

Ig.

tí a; • c3

03 -t¿ ft :3

« =3 o tí tí ^ í^tí'

t-i O t-,

¿ tí t-^ >; 03 -S

«r^-5 S tí tí ^

tí rí -ÍH tí bD 5 S tí O °~

O c3- O 03

|12| ^ O^ ^

02 ftCtí 5

O

tí o;

o; bß

I ,tí c3

03 o3 '^•^

bC ^^ ^ M ^

tí œ -if ^ ft rj

-Tí tí ^5^^ 03-2

OO ftcD w_^ 7'-^

OoT -U303g^tí

î^ Oí

S o; g

|J1 ^^ tí

--H 02 03

^•Jbc-^^

o.S o.S ^^tí

•^ ;^ o; 03 tí «2

: ü

^Sí ^_H 0 tí tí

3 g

rtí:^ c3^ 03 ^

03 ^

03 TO «r;

»4-1 bC ^ tí

||*N03

XS câ^ o;

bC tí'O tí tí 03 tí

...ft

tí.s

s > ft o3

^^

03 o3

<1^ ^

bC

03 tí

0^ tí S

03^ 03 o

^«+-í tí ;H

bCT3 o tí tí

tí 03^ O-*^

o; 'T3

bß 03

03

03ftft

O

Io 03

O

g o ^ ft > í>,^ qií

O

bO?

0 0

Ö w

; T5

a0

o ft

t^ t^

03ft

O

O

ft"—" tí 'tí ""o Tí w

^^S g ir.2 g^ ^

--^ fll'rí o, n ^ tí

g 03

03 ., C3 tí 03^

' bC ^T3 <ií Oí^tí

03 JO «j^ 'ü JO ^ J

^ -7^ -g -tí 'n riaá _

„ . .S tí 4^ -^

.03^-*:^ ^ tí g

\tí ^ S - tí

+3 0; tí 02 tí

o 03 'tí T3 \%nës

tío jl^'tí ^^' C3.r=^ ft tí

03

>

'tí

PM

PM

O

Q

03ft

O

o

«Li ^ T3 '^ ÍU M

03 ^ '^p 'ü ^ ^ !o

« ^ 03 -tí ^.2 2

ftg ^^ g üctí

O o

tí 03 "^ >

03 ü

^03

9^S p 5 ü t'^

•2 tí S^ ^ tí.s o 03 .Û

.ll^tí-S o g 03 g.^ 03

tí "^ --- o? s íR -P

Si bc;

44 ft I

tí '^ Ö g

'r:<3O'-=fa203a303

^ ^ O

bCfe bCctí

02

03 4-»tí

-0 03

-|j 03 tí >

f. tí

u cr

03 03 ft T3

0

0 .^

o

p 5 -

;H tí V^

*^ r ft-+^ Ö s tí s o ^ '^ o

o O

o

o

o

^o

PH

3 i

-tí 0-S-Í3

S oS 2 03

ft^ft ft^ft

o 'S o T3

o o

o

o

lO

o

o

o

0 .

tH 03

CO ^

1 g

'?»'>» fttí

O C3

>-• Ä

o ^

o

PH

t—I

O

03 ^

tí 03

P, §4^

S S

^ tí

S3tí X5

02 I—!'

Pi 0

S •c ft^

ft

0

•>

u

o

2 o

^ o

CO (N

>> ft

rl 0

4-3

0 ft

>, 0

y

03 13

03

r1 03 ü

03

T3

0 tí

0

-títí

n0

í>> o T3Ä

4^

^1

o

í^ CO

o

T3

So

ft

O

CO

CO

o

»o

tí

o

'ft

o

u

ft

o

tí

o

ft

o

o

o

A

PH

o

00

o

o

a

k 03

¿

¿^ fe:ë ^

03f-H O ptí

-^ 03 S.2

1â

0

•'S

ÔT3

CO CD fe >» CO Ü

<N 03 Jtí 0

1 03

^.2 ^P -í 0 0

5o

032

T3 0

^'^ tí ^:tí tí 2 §

CQ

03

a03

O

1—I

co"

A

o

o

2o

''S

é

O

o

tí

-L P

^. tí

o o*

fe p

-5'S

•Ä ^

^3 c3

tí

03

O

O

o

o

o

o

10

CO

A

(M CS tí I 4^ tí ^-M O) O

03 í>i^ I Si

<'^ ft

P

'Ü

a

tí

o 03

2o'Sft

03tí

03

ft

Q Q
AGRICULTURE HANDBOOK 332, U.S. DEPT. OF AGRICULTURE

Oí

tí

o

o

5^

"^

t

^

^

Ö

'-es

6

1^

<

tí

^ tí

O)

-^ 0 03

-^ +^ ^-1

03 c3 ^

2 03 03

03 '^

c3

Ö

tí

O

S

so

o

4J (^ I

O.íí ü

ce o œ c3

G;

T3tí

03

0)

S ^ ^

ÍR o3 02

2T3 -jf bß a;

^3 ü <3^ o tí o

;H ü tí

;3 ü <D

•^O bC

a «. fe O)

^-.a-^ 3

^3 .

- ^ ü '5

-^^ tí

OH^^

oo o;

o3 O

3 2 2 =^ ^ =3

;i^ rtí f> ^ O

o3^ä ü o O?^ S5o3 '^

bß.

o3 í-i CL

a o;

ai OH ^H

MBH:

a;9i^!^Wo3SC!bßo

CO bß«4- K. fH t>i*;3 -r^

03 ^7i 03'^

tí

03

bß

•g O ^ o

S ö ti)o

4H " ""^

gi*3^rs

Jo-eOotí^o^al^a^í=^ ". O m ftí

' 03 _( d

! tí í o; O ^ H tí ^ 4S ;H

§ b£0.tí > g

o o

r» c3

O O

^ g 03

c3

02

tí

'-+3

03

O

o

o

o:tí T5n3

CO

tí

er

03 a g ^'5 -S a 'S

g.0.2 a^ o3c^ Ö » 5 -^ .tí 02 4^ rtí .tí

Q

bß :

tí

o

;-( tí

''S

Oí

OH

O

O

I o

o

tí

'tí

cr

P

o

CD

^ tí ¿

-^.^^ .

3^00

03

• Í5 tí í

©•3 ¿o,

fO TíH"

tí

S

PLH

pq

03

tí

O Ö .. .„

ü S '^-=' -^^

.— tí ^ <^

03 fH ^ ^ o

OH tí í; 03 tí

CO <D 4J o o

.a .2 ^ «r £

03-^^^^^ s

t^ ^ > 03

-g ;H OH o; rtí ^

H -^^ O S bßti

ë ^:tí¿

• 72 CO I I,

Pin•^ /i^ ^ OH

o-^ g a >-.

03*^0^-^

O grtí 03 f;^

¿a

Pi

03

Ü c3 tí tí

O'tí tí a

PH''

OH

O tí

' O

o

2 bß .-'-^í .tí '-¡3 Ö f» .2 lîilï il- --^ o 03 ^ M'^,

ü bß tí 03^

c:? O "^ ü g

© Ö g SH®

bß

bß- tí

o ^

d bß

Ti

T3 tí

03 S

1.a ^3

.a (^

03

m

>

tí '73 tí c3

fe s feo

OH "^ OH^ jtí tí

O üO 03

O O

1-H

7,000

38-51

¿ . ¿ 03 .4. tí tí H c3 •

O

i is (t

hept

acid

tí -^ .^.2

03

a

e glycol

a

oacetate)

cyclo[2.2.

icarboxyl

tí SëS-V

T3 -r^-^ o3co

o >,^ X ^-

CO ^ o oc^

c3

^ H o

Ti

í/2 O tí Q H W

O

o

o

H

PH

o

o

o

CO

CO

OH

O

^3 a;

I +3

> 03

:$; i

.o

>^ 03

O

PH

.tí í^ aj

tn 03 í>i

» o; ;-i

3H,^ <^ o-tí '

03 ^ tí t; 4^ tí

o tí g

O

°3 03 O tí tí

O «+H «+M ;ÍÍ ^ P-J

02 o3 _ T' S2 tí

d 03 :tí ÍTÍ ^ c^

*"" o d :tí *^-t ^

^•^ o o ^

02 bßX2 „. „

d ^ 4^ .r, 03 ^

T3 tí M^ o g

> 03 tí f-t T3 o; i3

03 d ^ ^ OH d

«2 § OH§ 03 g

•g 03 g ^ tí 03

c3 O

O

03 4^

<-¿ CO

^OH tí ^

o3 ;H

O

'Ö (X)

tí ü

03 tí

03

«+-( bß

<^ 5rí o; 03

ÍOH^

CO

>^03

tí t»

03-0

a 03

03

03 bß o

03 03

tí^'^^

'^?, tí*^

03—I 9^03 stí ,-H^

.tí ^ 03T3 tí ^

(1^ Ö tí_o bßo3-5-°

03 í>> 03 -tí

- tí o g

CO

TJ£|

.S5|fe^-3§^S

o2o;^OHot»^o'^

O

03

O^

02 PH

O

tí

o

o

o

IgOH O

r2-2

o

o

o

CO

I o

o

03

ü

03

tí

03

OH

O

•r (M . -73

O

43ci¿|

- >;í tí -^f T3 S^5-2¿'S £3, 03 Oncvf 03

Oí (M

O o

PH

O

o

CO

tí

03

OH

tí Ü f^

o c3 tí

X2 tí tí

U 03 03 W ^ fe

PH

tí tí

03 O

^ (-1

03 43

OH 03

oao

"^ ^ ^ '„ ..

i li

§ g^ g-g

o O

PM

d"

o o

fe fe

g PH

tí^ tí

03 ü 03

;H tí ^

03 tí 03

^^ ^

O ÜO

o o

o o o

o CO o

o CO o

sa

o^tí A

sí rtí ;-!

^ Ontí

c^

03

;H

I 03

g»l

'^ T* OH

OH ^ I

fH <13'^

oí" .22

fe

o

PL,
SUGGESTED GUIDE FOR WEED CONTROL 19 619

-Sog

^ S 03 03 Ö S

111 o3 Ü

Ö

t» . ^

d <D 0

bC '^

^ ^ iXi ^

'O'Ö'OTJ O

U '^ U Q^ U

O

o

O

O

o

o

ü tí ü o

tí "^ tí tí

o «DO)

bC bßbß

(D -g O) O)

S O) S S

(D d (X) O)

Q tí O) -^^ . „ ,^. .

^'t;^L,aQtí^2tí

^ ^ao^-^ g

. ¿ .tí 03 O +3

O) ü «i (K f-( !> c3

CO tí C)4^'Ö_Q,-H ^

;3 S "^ 2 ^tt^ •-

>. OQ!) tí 2 oís

"^ ^^ .-^'^ 5b Ä^

^ ^ M ^ O) tí

bbo o ü o g ^O

o

tí ^

I—t ^

ft o

Oí »r

Cl bß

tí ^1

m cù

u ^

o3 O ^

*-* -.4.

tí 04

O) ü

a ^-^

c3

c3 ^3 O

PH 02 f^

&: ^ ^

O

o

o

s o

CO f2

2 .^

o o ^

CO tí çH

o Oí CO

^ tí 03

ÍL ® lO ft

o

o

tí

ptí

A 0)

o Ö

ë T-H

^ >.

ü X

T3 o

Ttl

4^

a;

SO

o

o

o3

oT

tí

O

O

ó "^

I 03

2rtí

I

O

CD

» O) "^ es I ^

^ tí--;3 ce ^«-^

o tí -( ?á •- 02 -

t> r^ o '=^ o3

>^ ft g Ö. g o;

tí ft ^ SS-^ ^

^ c3 O Ö 5í ^

tí .^^'^ Ö 2

^^ ^H I- '^ tí O Ü <D Si'^.tí

^H O ¿^ Ä o ^

tí œ =3.^^^

:tí ^ âg g g.a o

o

o

F—( ^

0

=3 .^

c3tí ^

tí 03 tí ^

tí 0

^'tí Ö ^

T3

03

O

I 4^ O

fe tí Í-I ¿Jig

ü ÇH (D T3

tí g O tí

-^ .tí tí 03 CO P.. jD O) CO

. „ CO o3

bC œ _

tí O3T3

•'^ '-I tí

. tí T3 CO

œ "tí "1^ a

-+^ tí 0 n

gS^2s^-ft

j c3 tí o ?H ^

'sja %^ •^ 0 tí

bC

tí ¡

Cuùl -M 4-3 ' t^ .tí ^"^

fe^ t^ &<j CO CO c3 tí '-I

bCrJ

O tí

bcS

03,

rtí

tí' 0

Oí T3

a

a

PH o

il

OX5

O

I V

o o3

O

tí O

<M

PLH

O

>.

Ä

02 í^iSítí

^ tí tí ^

o O

bC tí^O

tí Ö ^ :

tí o '^ w

le

tí ^

j 4J CO

LaS?. '7^ ^ ^;tí bc '*'

?3 _H ^ ^ tí è^ tí «^ ST3

>^. ^^a i

c3

&1 O

§ a

O

O

2lí ^ tí tí a;

O

PM

O

o

o

tí tí

S ^

w

;5 o m

£,ja t^ O _Í3 -3 T3

< O

I*

•=1

2ií 2

03 c3

2 02

^^ c»

g bC

bC^

O tí

s| CD tí

<D c3

O

.a 'S -r '^

o tí »^ ""^ t-i tí O) I

>^<D^.a

-a í^ ^^

o

O

CO

03

O

o

o

o

o

>^ .

TD

tí c3 ü

CD 0 03

ptí ^

^^ a

2^ .a^ Ortí T3 c3

V a

O tí

CO o

O m

0^ 5 03

PL, PH

tí

O

tí

tí

o

o

&

O

O

o

o

¿ o

o o

"^ o

CO (N

bC

tí

%O

I Go , i-H

¿ 2<¿ ^

0^(M O

4 a^g^

CO'rH 3 >

^•—^ I CO "^

coíJT^o

I t>5_tí ;H

T3

03

O

bC

.a ^ 43 CD

bß

• ;:H CO

bfití.tí g

K-iT3 bß O

.ÏÏ bßiS >.

O fe O

gigi

o o

o

o

o

o

CO

tí

O

rH 00

A a

Q^ tí rH 'd

^. tí

Tti c3

2.a T3 O

>>tí

_^ 03

03 03 rtí

tísa

CO

c3 ^

CD^

U -)J tí^

a

0

03

bß tí

ü

O

CO o 02 -4^

'D CO T3 . ^

"^ bß.S-S

g tí cr 03

S'a <^ CO

P§a tí

m i=ß tí '-^S cH

•2 0 O.^ctí

4-= o; CO C -.

rtí '3^

«D tí

^§

o3 tí

O CQ

^ fe

O CO

II

co^

PH

w o

tí :tí

<u o

tí

0

< íí

02

tí

*tí

cr

tí

03

O

o o

o o

(N O

=3" I '^

^ 03 «2

-tí-fe Ö

-t^ -tí (Dq3

^ ' ü

rH 'T' 03

-tí^

^ 03-tí

9 Ö

a-s

ft

tí-^ « tí tí ^

¿ o

ft

A CO

ai

?:a

tí

^ ^

o PL,

03tí

cr

03u

03

PH
10 AGRICULTURE HANDBOOK 33,2, U.S. DEPT. OF AGRICULTURE

50 ,

o3 0) o3 O

03 ^ c3 .^

O CT' O OQ

?H QQ ^ ^

^^ 'S «2 bß g bßg bß g

03 TJ o3 bß o3n3

.S s .s .2 .S $

bß Ö bß g bß tí

.2 g-ö 2^ 2-^

tí g ö ^ g g

o o^ tí

o i; 2 «

tí °'^ Oí

"^ «2.2 o

tí S^ X tí •^ '^ o . ^

a O- a Ä

-o

«2 TO CO

03,+H 52 «

(H (H o3 X

bß tí ^ ^

^ M % o

>H tí ¡^ 02

^ 02-^ 03

-^^ s '^ bß

2^ 2 S tí o ^ "^

"•^ tí-^

O

ü S¿

O) ^

a

T3 O

Oí'O

>..b a

c3 03 o

02 CO

CU O tí tí OJ

fl ¿1 g o«+-i

g tí b

bßOTJ

o tí S] 0

03 o3 N

a a a 03

0 0 0 f-l

;« M ui >i

PH On PM PL,

'-•35.

«4-1 (D ^ 02

o ^ ^ fH

^TJTS Oí

^ 03 a;t! S O <1^ ÎS o3 ^H > "^

;H_Q > tí

-2 -^ O^ 'o W) 0 00

tí 02 'S "^

03

02

Pu

tí

T3

O

O

O

O

O

O

tí OJ

(M

tí

T3

o

o

03

>

'tí

O

o

^^T-T

I

i>

CO

o

tí

Oí

10 «tí

^ O

I
SUGGESTED GUIDE FOR WEED CONTROL 19 619 11

c3

1°

öS«

S=3

o3x3

oß pj o "3

PH

^

d'

o o

^ Ö

—.^ ^

ü ^ 0)

co^ o

ü ^ oj

t! O bß

> >iÍH

^

o

T3tí bjD'

O O

o ;-4 O c; 0)

Vi a ÍH o

tío

tí a >.tí tí tí 4-^ cr

o

rtí O rtí Oí

2

o

r/2 bD 02 CO

tí œ >< rtí ^ .s

'-'. fi-^ •!-" +3 ^ _LO

o

o

o

A

tí ^c3

§ ^ S S ^

as—« oj u"A

o ^j . -x5 ^ tí

^ ce d Cu rrl

> Ä

T5 Ö

^ ¿ O

'^ . ^ ^ (-1 is ^ «l-H

^ 02 « § ü ^Xi

tí ^ 7, .¿ bc a3

tí sg ^ ^ ir. ^ ^ s o3 "tS ü 1^ o

^bß'öS'^;^-^ o

^ ^ tí OH OJ ÍH >

g ^ 03 «2 - 0^;

tí bC tí 1=^ d CL"^. ^ -rH

coa22tí'=3tH'r3oo

s tí'bbtí m b^ fe^ ir

r5 •!-• t- t>. ^ ^ fe- ^^ ^ c3 bc'

. f. >^

O

o

o

lO

I o

o

o

1 O

>> . 4^

t^tí -ö

>»

.2 § rC r^u

/T 03

S.S BZ 2 s .2 fe

9 03 -0 o

ri O

o

t:^ CO (D -H-" 02

tí c3 bO'* típ-H Q.T3 03 ;H *+H 9

l'Stí tí §.^ 03 03 .tí o--^ -^

bC_ rt

Oí tí M^'ü

^ ^J OH tí O M œ tí tí

PL,

Cß

(U 1

tí

tS3 o

03 Q ü

§ §

GQ 02 Sí

•+3tí

<u

o

Ui

OJ a

o

o

tí

g

o

o

1^S.2

o

o

o

o

o

o

o

flí O

-üq

o ^

-».3 tí

4-3 i

tí T!

CO §

ë -£§

CO tí

o, <u

03 bí)

O

c5

3

T3

o

O}

o3

Ti

O

tí

03

tí

as

tí tí

.2 o

>^

«2

H çç^ ^ tí 03

i t»ií^ © tí

D^^ ^ > S

^T3 > o g o

tí gS-^T^

oi|-3^^tí"

g o o 03 ga; o '^

tí ö3 .p -^ --^ ° ^ î^«^ i -^ _ Ö tí

tí

>.è tí

bJD oB

— a; " 03

o

Jß

«2

tí

o

p.-

o o

o

o

CO

Ti

O

03

^ 03

0 tía)'^í-'^^>^

^ ^ I

tí'tí Oí tí tí a

§T32

tí o; I

tí>3 Q,

2 ^ a

tíítí bC

O 5 tí

O

s .s

tí^ bp

-S.S.S

o3 Tí '-+3

Oí-^ 03

r^ to 'tí Ou

P « ^ £ 2

-r3 $H '^^

^ ä -

03

+3 ^

?> 03

O tí

Q. O

O

>

'tí

:=; <ii

o

CO

o

X5

O

2 2

o

o

o

03

O

a o

'2 2

O

O

o

T3

tí

o

o

o

a 03

§.2

öSo, CÙ

o ü

o

03

bC—! ^

» í7p CO tí

tí tí tí ^ fH

23 a; O d ^

^ g ü § >

PH

CO

I

o

í>>tí

I«

I

CO

o

o

bß

tí o

03 t„

03

O c3

¿ O

r< ^

Í-^

O

o

o'

Oí f3

tí

Ctí

Oí

o

o

o »^ o

(£) i> o

^•^ ^. o

CO T-l rH

T3

o

. o

^^

-^^ 03

ois

o3 S^ tí ^_2 tí

^ O QL,

Ä ^ 03 o

^ S o:tí

tít^S >>

t^gco o^

2o^ fe

*C 'S

-52 •>-; 13

^.a'3

O ^

tí

O(-1

•73 o3

>>o3

OHX5

O ^3

H H
12 AGRICULTURE HANDBOOK 33 2, U.S. DEPT. OF AGRICULTURE

T3

.S

tí

o

O

» o

GO

•S

§^

5ïi

m

03

a

Pi

2 Ö

,-9 s

^ 0 03

2 03 03

pq

PÔ

Q

o

O

'-^ S § tí

^ 02 ^ ^

âï

(D ^

g.S

02 ^

tí bß 03

ö tí o3 -tS O 53 ^ ,2

a ^ ^ -^

g ^ tí _

fin

03 m

OS

Ö

>

^ Î3 tí ta ^ g ä §

if CO .2 03

tí I -í3 o

a ^.a-^

Stíeg ^ o bCg

ES 2 tí—

J œ 02

m '^ ^

-2 --' 3 '-'

-O o a^^

^ OH^;tí

t> t-i d 02 ^ ü g 0

^ >

&^

So

bß.-

tíT3

o bß

tí

03

a bf) ^

3 £

4^ O)

0) o

7) ctí tí O

W í-i

O 03

f

4J a O) O o

tí Ü4^

T3tí

al

ses.tile

03 tí ^ 03

o;

g So

o vr^T3 O

^ bß 0) m

tí 0^ tí

0)

minati

and

w

0 not

T3

03

O U ^r.'^

£

tí S tí l> O

03

a i

a

a^ ^

'o'a --H T3 o;

o «3 ^^

^H <D

1^ ^.^ 03

§ ^2

«D tí

O ^

U o PQ

rn (7^

^-j^

tí tí

c3 OJ

a a

0

03tí

X2 o

+3

a rr

o; CI) ft

tí f-i

!^

tí ..

tí

o

3

03

O

H

CO

.s c3

o

o

o

I o

o

X

o

tí

o

-«rH 03

Q

4

W W H

o

o

o

I O

o

CO

O o

lO o

00 CO

o

tí

o

tí o

M.^ o 02 p .

;3 o3'g^^-3

7^.^-5-I

OXi ce O) ^"^ c3

I 'C %,

-^ ^ (M

: PLH

PQ H H

n 9 ^^

c<r of oí"

Oí bß

02 (M

^^-^ tí

43

hi

^

ft

>% ;_, T3 O

O

X5

o

O Q

a

^

ci

JM 73

bßo;

O 7J

JiïÎ

;H tí

cu ft

a

CI) «D

Ti >

(•") ^^tí

Xi f-i

^H 03

<v ft

a ^

.-tí^-H c3

leH 03 f-( S tí bß

tí O

" tí--^

c3^

^ 03 tí

0) 0) 02

oPn ^:tí

d^tí^^ o o"*^ o

03 ,^i ¿1

hn 03 O) LT

..^ cS ft

-^^ ..V .^ tí

tí 73 o Tí

^ O 73 03

lili 73 bß S

tí oœ •-

d^ií o tí

^ ^ i> tí

o 2 o 73 ft ü
SUGGESTED GUIDE FOR WEED CONTROL 19 6'9 13

Volatility

Another important consideration in purchasing

2,4-D, 2,4,5-T, or other phenoxy herbicides for

certain weeds and special situations is the type of

herbicide formulation—amine or high-volatile or

low-volatile ester. When vapors from the herbicide are likely to injure adjacent crops or plants,

an emulsifiable acid, amine salt formulation, or a

low-volatile ester should be used. Esters of

2,4-D and 2,4,5-T are classified as high or low

volatile according to the degree of vaporization

that occurs. In general, methyl, ethyl, isopropyl,

butyl, and amyl esters are considered highly

volatile. The butoxyethyl, butoxyethoxypropyl,

ethoxyethoxypropyl, propyleneglycolbutylether,

isooctyl, and other high molecular weight esters are

low volatile.

Granular Herbicides

Granular herbicides are formulated for application as dry granules. They are applied with

specialized granular pesticide spreading equipment

or modified fertilizer spreaders.

Granules are prepared in several ways. Some

herbicides are impregnated on granules of clay,

vermiculite, or crop residues, such as corncobs, by

spraying, dipping, or exposing the granules to

herbicide vapors. Granules are also prepared by

mixing an herbicide with finely ground clay or

fertilizer salts, and particles are formed by

extrusion or prilling.

One of the most important properties of granular

herbicides is physical selectivity or the tendency

for particles to bounce off foliage and other plant

parts to the soil or to settle to the bottom of ponds,

lakes, and other bodies of water. This physical

selectivity enhances the chemical selectivity of

herbicides used on growing crops or on submersed

aquatic weeds. Sprays are often intercepted by

crop foliage and their effectiveness in killing

germinating weed seeds in the soil is reduced.

Granules tend to bounce off and sift down through

the foliage to the soil where they are needed.

Granular herbicides are of special interest in the

growing of horticultural crops, because their

physical selectivity helps to broaden the use of a

few effective herbicides to cover a relatively large

number of crops. They have therefore been used

rather extensively in horticultural crops after clean

cultivation. Granules also fill a specific need in

transplanted crops, where preemergence herbicide

treatments cannot be used. As a matter of convenience, granular herbicides have also been

extensively used in preplant soil-incorporated and

preemergence treatments of horticultural crops.

Because of the scarcity in many areas of clean

water supplies for spraying and the need for extra

labor and equipment for water hauling, granular

herbicides have been used in several field row

crops and in ranges and pastures. Granular forms

of some herbicides are also useful in controlling

aquatic weeds and weeds in noncropland areas,

including ditchbanks, rights-of-way, and industrial

sites.

Numerous experiments have shown that granules and sprays of many herbicides are equally

effective in controlling germinating weed seed in

the soil. Each herbicide, whether used in spray

or granular form, requires certain specific conditions of climate, soil, and application technique

for best results. Recommendations prepared by

weed research specialists in State agricultural

experiment stations and by the individual manufacturers of granular herbicides outline these

necessary conditions.

CALCULATIONS FOR HERBICIDE

APPLICATIONS

Recommended rates of herbicide applications

are stated in ounces or pounds per square rod,

1,000 square feet, or acre where the area to be

treated can be measured. Where spot spraying of

individual or small clumps of plants is necessary

or where dense foliage of certain aquatic plants,

brush, or trees is to be thoroughly wet, the concentration of spray is usually recommended in

pounds of active chemical per 100 gallons of water

or oil. To control submersed aquatic weeds, the

rate is usually expressed as pounds of active

chemical per acre-foot of water or as parts per

million by weight of water (p.p.m.w.) in the area

treated.

1. To determine the amount of herbicide required for submersed aquatic weeds, use the

following data and calculations:

1 acre-foot of water weighs 2,722,500 pounds

1 p.p.m.w. =2.7 pounds of active herbicide in 1

acre-foot of water

(1) Pounds of herbicide = pounds per acre-foot

(area in acres X average depth in feet)

Example :

Rate=4 pounds per acre-foot

Area=2.5 acres

Depth=3 feet (average), or 7.5 acre-feet

Then pounds of herbicide=4X7.5=30 pounds

required

(2) Pounds of herbicide=p.p.m.w. X acre-feetX

2.7

Example :

Rate=1.5 p.p.m.w.

Volume=2 acres, 3 feet deep (average), or 6

acre-feet

Then pounds of herbicide= 1.5X6X2.7 =24.3

pounds required

2. To determine the amount of herbicide formulation required per acre, per acre-foot, per

100 gallons, or for a total area, use the following

calculations :

320-446 O - 69 -
14 AGRICULTURE HANDBOOK 33.2, U.S. DEPT. OF AGRICULTURE

12.15 gallons

(1) For liquid formulations—

Rate or amountrequired in pounds ^ . ,

-ñ Í 7-i—1 . . 1 —Î1—=gallonsreq uired rounds oí herbicide per gallon

Examples:

Rate, 2 pounds per acre ^ _ „

T-^ ^ *^-^n =0.5 gallon 4 pounds per gallon

Concentration, 4 pounds per 100 gallons , ^ —f *Vi ^ =1 gallon 4 pounds per gallon

Amount required, 24.3 pounds

2 pounds per gallon

(2) For granule, dust, or pellet formulations—

Use the same calculations as for liquid formulations, except use pounds of active herbicide per

pound of formulation (percent-î-100) instead of

pounds per gallon.

Examples:

Rate, 2 pounds per acre _ ,

0.5 pound (50-percent material) ^

Concentration, 4 pounds per 100 gallons

0.5 pound (50-percent material)

Amount required, 24.3 pounds _.(y. ^ i

0.20 pound (20-percent material) ~" * P

= 8 pounds

MIXING SPRAY MATERIALS

When the capacity of a spray tank is not known

or adequately marked to indicate the number of

gallons at different levels of liquid in the tank,

the best procedure is to set the sprayer or tank

on a level base and gradually fill the tank with

known quantities of water. As the water is added,

the level of water should be marked in number of

gallons or fractions of a gallon on the side of the

tank or on a calibration rod or stick held perpendicularly in the center of the tank. Carefully

measured markings are very useful in determining

the volume in partially filled tanks.

To approximate quickly the capacity of a

sprayer tank (all measurements in inches), use

the following calculations:

Rectangular tanks: Capacity in gallons=lengthX

widthXdepthX 0.00439

Example:

60X36X30X0.00439=284.47 gallons

Cylindrical tanks: Capacity in gallons=lengthX

square of diameterX 0.0034

Example:

60X (36X36)X0.0034=264.38 gallons

Tanks with elliptical cross section: Capacity in

gallons=lengthX square of (short diameter+

long diameter)-î-2X0.0034

Example :

60x(^^y^Yx0.0034=::183.6 gallons

Never pour the liquid concentrate or dry herbicide formulation into an empty tank. Either fill

the tank half full with water, add the herbicide,

agitate, and complete the filling or start filling

and add the herbicide gradually as the filling is

continued. Agitate or stir until all solid material

is dissolved. If a water-soluble powdered or crystalline form of herbicide is to be used with a

liquid herbicide, dissolve the solid material in

water first and then add and mix the liquid. If

0Ü is to be used in an oil-water or invert emulsion,

premix the emulsifier and the oil-soluble herbicide

with the oil in a separate container and then add

slowly to a partially filled tank of water with

constant stirring or agitation. Circulate the mixture until it is uniformly white before using.

Agitate suspensions of water-dispersible powders

and oil-water emulsions constantly or frequently

during spraying to maintain a uniform spray

mixiture. Use the spray mixture within 1 or 2

days, because some herbicides lose strength or the

mixtures deteriorate on standing.

APPLICATION EQUIPMENT

Results from using herbicides depend largely

on how well or how poorly they are applied.

This, in turn, depends on the suitability of the

equipment for the particular situation and the

care and skill with which the operator utilizes the

equipment. Suitable equipment has been devised

for nearly every situation requiring herbicide

applications.

Ground sprayers include (1) hand sprayers of

various types suitable for treating small patches,

inaccessible areas, fence rows, and spot spraying;

(2) boomless power sprayers—nozzle-cluster

type—adapted for spraying roadsides and ditchbanks, under utility lines, and along fence rows;

(3) power sprayers with tractor or truck-mounted

solid or sectional booms suitable for spraying

field, pasture, range, and turf areas or for roadside

and ditchbank spraying; (4) power row-crop

sprayers with various single and multiple nozzle

arrangements or other devices for placement

spraying; (5) power sprayers equipped with hoses,

hand booms, or adjustable spray guns for application of foliage, basal, and stump treatments for

brush control, spot treatments, and spraying

around structures; and (6) power-driven mist

blowers, ranging from hand-carried to truckmounted equipment, designed for dispersing concentrated sprays in finely atomized form at low

volumes per acre and adapted for covering vegetation rapidly with a minimum of solution in

inaccessible areas where wind drift can be utilized

to advantage and where a hazard to desirable

vegetation does not exist.

Aerial sprayers of many types have been

developed on fixed-wing aircraft and helicopters.

They have several advantages for application of
SUGGESTED GUIDE FOR WEED CONTROL 1969 15

herbicides at low volumes for many large field,

rangeland, aquatic, and right-of-way areas when

and where spray drift is not a hazard.

Suitable spreaders, ranging from hand-operated

to power-driven and tractor-, truck-, or boatrQounted types, have been developed for most

situations requiring application of granular or

pellet herbicide formulations.

See U.S. Department of Agriculture Handbook

269, ^'Herbicide Manual for Noncropland Weeds,''

or publications of the State agricultural experiment stations or extension service for.more detailed

information on herbicide application equipment,

including tanks, pumps, booms, nozzles, hoses and

fittings, power sources, pressure regulation, droplet

size, specialized accessories, and other features of

selection, adaptation, and use of application

equipment.

For information on aerial equipment, see U.S.

Department of Agriculture Handbook 287, ''Aerial

Application of Agricultural Chemicals.''

CALIBRATION OF APPLICATION

EQUIPMENT

The type and operating condition of application

equipment for herbicides are important for

efficient chemical weed control. This is especially

true of sprayers. Accurate appUcation of the

desired rate and uniform distribution of spray

solution or dry material are essential requirements

for good results. A sprayer must uniformly

distribute any quantity from 5 to 100 gallons or

more per acre, since various weeds and locations

may require a wide range of dilution for proper

plant coverage. Sprayer or spreader output should

be determined for each particular treatment

operation.

A good method of calibration is to make initial

adjustments to suit the machine and job requirements, and then make a trial run to determine the

actual output of the machine. The herbicide

spray mixture then should be prepared accordingly. The calibration should be repeated frequently to check nozzle orifice wear and other

factors affecting performance. This is especially

important when wettable powders or abrasive

sprays are used.

HOW TO DETERMINE PER-ACRE OUTPUT

OF SPRAYERS

There are many methods of calibrating a

sprayer. One method is given for caHbrating

each of the following types of ground and aerial

sprayers.

Power Sprayers—Boom Type

1. Check to see whether all nozzles are discharging uniformly by spraying water through

them at a uniform pressure and catching the

discharge from each nozzle in a separate container,

such as a calibrated baby bottle. If the discharge

varies widely, replace all worn nozzle tips that

give a much larger discharge.

2. Place the sprayer on level ground and fill

the spray tank completely with water. Adjust

the spraying pressure as you will use it in the field.

3. Drive exactly one-eighth mile (66Ó feet) in

a field or along a road, ditchbank, or other area

to be sprayed at the speed you will use when

spraying—usually 3 to 5 miles an hour. Measure

from where the spraying begins. Mark the notch

in which the throttle is set and keep it there

when spraying.

4. Shut off the spray, return to the original

spraying position on level ground, and measure

the water required to refill the tank (a quart jar

is satisfactory).

5. Calculate the output as follows:

Number of quarts used X16.5 ^

^f'-jTT—£-^ TTr~'—Í—7= gallons per acre Width 01 spray swath m leet ° ^

Example:

Water used=6 quarts

Spray swath width=20 feet

Then — =^4.95 gallons per acre

6. Divide the number of gallons the tank holds

by the number of gallons your sprayer applies per

acre (approximately 5). Multiply the number of

acres one tankful will spray by the amount of

herbicide to be used per acre. This gives the

amount of herbicide to be used for each tankful.

Example :

Tank capacity=55 gallons

Outputs 5 gallons per acre

Desired rate of herbicide=2 pints per acre

55 Then—X2=:22 pints, or 2.75 gallons, of

o

herbicide

In some row crops only narrow bands are

sprayed, centered over each row, such as in preemergence treatments of cotton or soybeans.

When treatments are made in this manner, the

rate of treatment is in terms of the area treated

and not per acre of actual crop. Thus in cotton

with 36-inch row spacing, if a 12-inch band is

treated at 1.5 pounds per acre (based on the area

actually treated), the amount of chemical per acre

. 12 of cotton is —XI.5=0.5 pound,

oo

Hand-Type Boom Sprayers

1. Fill knapsack or other hand sprayer to a

marked point with water and spray while walking

at a steady pace, maintaining a constant tank

pressure for a distance of 330 feet. Multiply 330

by the width of swath in feet and divide by

43,560 to obtain the fraction of an acre sprayed.
16 AGRICULTURE HANDBOOK 3 3 2, U.S. DEPT. OF AGRICULTURE

2. Refill to the marked point in the tank.

Change the number of pints or quarts required to

gallons by dividing by 8 or 4 and divide by the

fraction of an acre sprayed.

Example:

Swath width=4 feet

Water required to refill=5.5 pints, or 0.69

gallon

=0.030 acre sprayed

4o, OOU

-^7^ =23 gallons (approximately) per acre

U.Uo

3. If too much spray is applied, walk faster or

use a lower spraying pressure until the desired

volume is achieved. Use the reverse procedure to

obtain more volume. For larger volumes, change

the orifice size of the nozzle.

4. Determine the amount of herbicide for each

tankful by dividing the capacity of the tank in

gallons by the number of gallons applied per acre

to obtain the fraction of an acre each tankful will

spray. Multiply that fraction by the desired rate

of application per acre.

Example :

Capacity of tank=3 gallons

Output per acre=23 gallons

Rate per acre=2 pints

3

Then — =0.13 acre per tank

2X0.13=0.26 pint per tank

1 pint=16 fluid ounces=2 cups=32 tablespoons

Then 0.26X32=8.3 tablespoons, or 0.5 cup,

per tank, or 2.8 tablespoons per gallon

Single-Nozzle Hand Sprayers

1. Use the same procedure as for hand-type

boom sprayers, except measure off an area

10X43.6 (436 square feet) to obtain the basic

data for determining sprayer output and calculate

as follows:

436 ^ ^, , —^-—^ = 0.01 acre sprayed

If 2 pints, or 0.25 gallon, is used, then

0.25 gallon ^_ „

^ ^^^ =25 gallons per acre. 0.01 acre ^ ^

2. Determine the amount of herbicide for each

tankful as follows :

Capacity of tank=3 gallons

Output of sprayer=25 gallons per acre

Desired rate per acre=2 pints

3

Then — =0.12 acre per tankful ^o

2 pintsX 0.12 acre=0.24 pint per tankful

0.24 pintX32 tablespoons=7.7 tablespoons,

or about 0.5 cup

Aerial Sprayers

1. To determine the rate of flow per acre and

per minute, put a measured amount of spray in

the tank or fill the tank with water to a definite

level. Instruct the pilot to turn on the spray for a

timed interval, for example 60 seconds, while flying

level and straight at the speed to be used for

spraying. Subtract the velocity of headwind from

the airspeed to obtain the groundspeed. When the

plane lands, drain and measure the liquid remaining in the tank; or with the plane in the location

where the tank was filled, measure the amount

required to refill the tank to the same level. Compute the flow rate in gallons per minute as follows :

S=groundspeed of plane per hour (assume 80 m.p.h. airspeed—5 m.p.h. headwind=75 m.p.h.)

Ti^= width of effective swath (not total swath) in feet (assume 40 feet)

r=time sprayed in seconds (assume 60 seconds, or -^) or 0.017 hour) 60

0=gallons used (assume 12.5)

Th n ^ C^^ m.p.h.)X5,280 feet per hourX^T (40 feet)XT (0.017 hour)

43,560 square feet -6.18 acres

Gallons per minute=^=—p-= :12.5

12 5 Gallons per acre=7r^=2.02 6.18

2. To determine the amount of herbicide required for each filling of the tank, divide the

capacity of the tank by gallons per acre applied

and multiply by the desired rate per acre.

Example :

If 120 gallons is the capacity of the tank and

2 pints per acre is the desired rate, then

120 —— r=.60 acres sprayed per tank and

60X2 pints=120 pints (15 gallons) of

herbicide required.
SUGGESTED GUIDE FOR WEED CONTROL 19 6-9 17

HOW TO DETERMINE OUTPUT OF

SPREADERS

For acceptable accuracy, calibration of raechanical broadcasters or spreaders for applying dry

herbicide formulations must be done with the

actual material under the conditions to be encountered in the field. Where calibration pans

are available for spreaders to catch the material

during trial runs and retain it for weighing,

calibration is a simple procedure. Determining

and maintaining a desired rate of application by

hand or mechanical blowers, broadcasters, and

other devices not equipped for catching the

material applied require a more comphcated and

wasteful procedure.

Mechanical Spreaders With Calibration Pans

1. Fill the spreader at least half full of the

material to be applied. With the calibration pan

in place, push or pull the spreader by hand or

power-driven vehicle over terrain typical of that

to be treated for a sufficient distance to cover

0.01 acre, or 435.6 square feet. For a spreader 3

435.6 feet wide, the distance should be —^:= 145.2

feet. For a spreader 8 feet wide, the distance

would be —-^ = 54.45 feet.

o

2. Weigh the material from the calibration pan

and multiply by 100 to give the amount applied

per acre.

3. Continue this procedure with adjustments

of the feed mechanism until the desired rate is

achieved.

Hand Broadcasting and Mechanical Devices

Not Equipped To Catch Herbicide

Begin with a weighed amount of herbicide

formulation. Apply the material to a measured

area, preferably 435.6 square feet, or 0.01 acre.

Weigh the remaining material and subtract from

the initial weight to determine how much was

applied. Continue the procedure with appropriate adjustments until the desired rate can be

approximated in repeated trials. If the treatment

period extends over several hours or days, occasionally check the rate being applied by weighing

the amount applied to a measured area and make

any necessary corrective adjustments.

EFFECT OF WEATHER CONDITIONS ON

HERBICIDE APPLICATIONS

Wind

Winds cause improper distribution of herbicides

and greatly increase the hazard of damage from

drift to sensitive crops in nearby fields or gardens.

Ground applications of herbicides seldom should

be made during winds of more than 10 to 15 miles

per hour. Applications by airplane should stop

when winds become stronger than 6 to 8 miles

per hour.

The herbicide 2,4-D and other phenoxy herbicides should never be applied when wind of any

velocity is blowing across the area to be sprayed

toward nearby valuable sensitive plants.

Humidity

High or moderate humidity increases the

effectiveness of most herbicide applications to

foliage, because it reduces losses of spray from

evaporation and aids absorption of the chemicals

by weed foliage. Low humidity, on the other

hand, reduces the effectiveness of herbicide sprays

by increasing the rate of evaporation. The disadvantages of low humidity can be overcome

partially by using oil or oil-water emulsions instead

of water as spray diluents.

Temperature

Moderate temperatures, ranging from 70° to

85° F., are favorable for spray applications of most

herbicides. Low temperatures during the week

before spraying often slow plant growth and retard

herbicidal activity. High temperatures increase

losses of herbicides that are volatile and increase

the possibility of injury to crops from selective

herbicides. The carbamates, dinitro compounds,

and high-volatile esters of phenoxy compounds

volatilize rapidly at temperatures above 80°. At

temperatures above 90°, even the low-volatile

esters of 2,4-D and other phenoxy compounds

become significantly volatile. In general, do not

use herbicidal sprays when the temperature is

above 90°.

Rainfall

Rainfallimmediately after postemergence foliage

applications of herbicides may reduce thé effectiveness of the amine salt formulations of 2,4-D, watersoluble dinitro compounds, and some other foUage

toxicants. Usually effectiveness is not reduced if a

moderate rain occurs several hours after postemergence application. The effectiveness of preemergence herbicide treatments may be increased

by moderate rain occurring shortly after application. In low-rainfall areas sprinkler irrigation is

often used with good results when the water is

applied immediately after preemergence herbicide

applications. However, if heavy rains occur soon

after preemergence treatments, control of weeds

may be reduced or crop damage increased.
18 AGRICULTURE HANDBOOK 332, U.S. DEPT. OF AGRICULTURE

WEED CONTROL IN FIELD CROPS

The treatments described for weed control in

field crops (tables 2-4) are, in many cases, components of a program involving two or more

treatments. Because problems and conditions vary

widely, it would be impractical to attempt to list

the hundreds of différent combined practices that

would be necessary to cover all localized problems.

Local recommendations of State agricultural experiment stations and extension service weed

specialists, herbicide labels provided by the manufacturer, and local conditions must be considered

in developing programs that include several

treatments.

TABLE 2.—Weed control infield row crops

[Numbers in parentheses=pounds of active ingredient per acre unless otherwise indicated: for herbicide tolerances, see Appendix]

Treatment Time of application Weeds controlled Remarks

Rotary hoe in and

between rows.

Shallow cultivation (2

in. deep or less)

between rows.

Flame

Atrazine (2-4) _

Atrazine (2-4) or

simazine (2-4).

CDAA (3.5) plus

TCBC (7).

After 2 in. tall but

before stalks stiffen.

From emergence to layby.

Before corn is 2 in. tall

and after 12 in. tall.

In fall preceding year of

corn production, in

spring before planting

corn, or half in fall plus

half in spring.

After planting but before

emergence.

_do_

All seedling weeds that

are uprooted.

All weeds

Kills tops of most weeds

up to 4 in. tall.

Quackgrass, many small

seeded annual weeds.

Most small-seeded

annual weeds.

_do_

CDAA (4)

Propachlor (4).

_do_

_do_

Most annual grasses,

do

Diuron (0.4-0.8).

2,4-D (1-2)

-do_

-do_

Most small-seeded

annual weeds.

do

Atrazine (2-4). Before weeds are more

than 1 in. tall; do not

apply later than 3

weeks after planting.

Most annual weeds less

than 1 in. tall.

Effective only on shallow-rooted

seedling weeds.

Use often enough to control weeds

while young; this practice will

control but seldom eradicates deeprooted perennial weeds.

If less than 2 in. tall, corn will be

burned to ground but will recover;

if 12 in. tall, is tolerant; if 3-10 in.

tall, may be severely injured if

flamed; do not repeat flaming of

2-in. stage.

Incorporate 2-4 in. deep; may persist

for more than one crop season in

amounts toxic to sensitive crops.

Atrazine works effectively with less

soil moisture than simazine; simazine

controls broadleaf signalgrass better

than atrazine; may persist for more

than one season in amounts toxic to

sensitive crops.

Planting corn deeper than 1 in. will

increase safety margin. TCBC may

persist for more than one season in

amounts toxic to sensitive crops.

Primarily for use on dark soils high

in organic matter; do not use on

coarse-textured soils.

More satisfactory on fine-textured

soils but can be used on coarsetextured soil.

May cause serious injury if corn is

planted less than !}{ in. deep.

Planting corn deeper than 1 in. increases safety margin; low-volatile

esters are preferred formulations in

most States; in some States amine

formulations cause injury, particularly in sandy soils; use only amine

or low-volatile esters where such

susceptible crops as cotton, grapes,

tobacco, or tomatoes are nearby;

follow precautions to avoid drift of

any formulation.

Apply as foliage spray to corn and

weeds.
SUGGESTED GUIDE FOR WEED CONTROL 1969

TABLE 2.—Weed control in field row crops—Continued

19

Treatment Time of application Weeds controlled Remarks

CORN—continued

Atrazine (1).

DNBP (1-2).

Linuron (1.5) plus 0.5-

percent surfactant.

2,4-D (0.25-0.5) or dicamba (0.25).

Nitrogen solution (80-

120) N plus one of

following additives:

Atrazine (1), linuron

(0.6), diuron (0.6),

2,4-D (0.3) ; add 0.5-

percent surfactant to

mixture.

2,4-D (0.5) in drill

row and (1.5) between rows.

EPTC (2)_

When corn is 20-30 in.

tall and weeds not

over 1 in. tall.

After corn emergence

but before 2-leaf

stage.

After corn is 15 in. tall

and weeds are less

than 4-6 in. tall.

When corn is 4-18 in.

tall and weeds are

smaller than corn.

_do_

When corn is 20-30 in.

tall.

After last cultivationMost small-seeded annual weeds small

enough to be covered

by spray.

Most annual weeds

covered by spray.

Most broadleaf annual

weeds; control or

stunting of perennial

broadleaf weeds.

Immediately before

planting.

Most annual weeds less

than 1 in. tall; some

annual weeds up to

3-4 in. tall.

Most small-seeded annual weeds from after

last cultivation until

harvest.

Annual grasses, wild

cane, some annual

broadleaf weeds.

Apply as basally directed spray to

minimize contact with corn; normally add 1 pt. surfactant to each

25 gal. field spray mixture.

Apply as foliage spray to weeds and

corn.

Direct spray so as to cover only

weeds, soil, and lower 3-6 in. of

corn.

Apply as foliage spray to corn and

weeds until corn is 12 in. tall;

thereafter use in basally directed

spray to avoid spraying into corn

whorl; inbred lines of corn may be

injured if treated; low-volatile ester

or amine formulations less likely to

damage nearby susceptible crops;

avoid applications when temperatures are high and corn is growing

rapidly; seed set may be reduced if

2,4-D is applied 2 weeks before silking until after silks are dry; dicamba not registered for use after

corn is 36 in. tall; avoid drift of

either herbicide from area of

application.

Apply as basally directed spray contacting only weeds, soil, and lower

3-4 in. of stalk; need spray equipment, such as stainless steel or

fiberglass not corroded by nitrogen ;

agitation required; clean field of

weeds when corn is 12 in. tall.

Apply with drop nozzles of 2 volume

capacities (small nozzles for drill

row, large nozzles for between

rows) ; direct spray to contact only

weeds, soil, and lower 3-4 in. of

corn.

Incorporate 1-2 in. deep; corn

planted deeper than 2 in. may be

severely injured.

Seedbed preparation

and fungicide treatment of seed.

Hand hoeing and spot

spraying.

Before and at planting.

Usually when cotton is

6-18 in. tall where

other control measures

are used.

Helpful in controlling

all weeds.

All weeds resistant to

other control

measures.

Locally proper techniques of seedbed

preparation and planting procedures,

including use of fungicides, that

lead to quick emergence of healthy

uniform stands on uniform seedbeds

are essential to optimum results from

weed-control practices.

Apply as needed, normally on spot

basis, to remove weeds escaping

other control practices; spot removal, by hoeing or chemicals, of

resistant weeds may be necessary to

prevent their increase over several

years.
20 AGRICULTURE HANDBOOK 3 32, U.S. DEPT. OF AGRICULTURE

TABLE 2.—Weed control infield row crops—Continued

Treatment Time of application Weeds controlled Remarks

COTTON—continued

Cultivate with tools

such as sweeps set

to cultivate 1-2 in.

deep.

Cross-cultivate with

tools such as shieldtype sweeps, sweeps,

or disk hillers and

sweeps set to

cultivate 1-2 in.

deep; distance

between inside tools

determines cotton

stand left.

Flame in rows and

between rows.

Incorporate trifluralin

(0.5-1), nitralin

(0.5-1), or DCPA

(8-10.5) in soil.

Apply EPTC (1-1.5)

1 in. subsurface in

two 6-in.-wide

bands centered 7

in. from drill row.

CIPC (4-10), DCPA

(8), diuron (0.4-1.6),

monuron (1.6),

norea (0.75-2.5), or

prometryne (2-2.4).

Naphtha, 20 gal. per

acre of band actually

treated (5 gal. per

13,068 row-ft. of

10-in. band).

From cotton emergence

to approximately 18

in. tall.

From cotton emergence

to approximately 15

in. tall; cultivate

first in direction of

planting, then at

right angles to

direction of planting.

Flame directed into

row at base of cotton

plants can be used

after cotton is 10-12

in. high until it is

so large it is damaged

mechanically by

equipment; flame

between rows can be

started any time.

From several weeks to

immediately before

planting.

In conjunction with

planting only.

After planting but

before emergence.

1-3 applications after

smallest cotton is 2 in.

tall and before bark

cracks appear (about

1 week after emergence

until 4 weeks after

emergence).

Generally all weeds

growing between

rows.

Generally all weeds

growing between rows

and most weeds in

Most small plants

enveloped by flame

will be topkilled;

large grass plants

can be slowly burned

back by series of

light flamings.

Most grasses from seed;

some small-seeded

annual broadleaf

weeds such as pigweed

and purslane.

Johnsongrass from

seed, nutsedge, most

annual weeds.

Most small-seeded

annual weeds.

Most annual weeds in

seedling stage; perennial grasses and nutsedge will be topkilled

if treated in early

emergence stages; few

perennial broadleaf

weeds will be topkilled when small

enough to be covered

by spray.

More effective if used before weeds

are more than 2 in. tall; cultivation

too close to row or too deep may

damage cotton; select type of

cultivation with regard to other

operations that may precede or

follow cultivation.

Used in check-planted or drilled

cotton in lieu of check planting;

cross-cultivation generally

restricted to relatively level fields;

one of most effective controls for

chemical-resistant weeds such as

Johnsongrass, nutsedge, and

perennial vines; effectively used

in combination with other control

measures.

Best used on small weeds to keep

clean field clean; may be of value

in carefully planned salvage

programs; greatest hazard arises

from burning vegetation killed

by previous flaming; this hazard

can be avoided with several light

flamings where weed growth is

heavy; for in-row flaming, direct

burners so as to keep high heat

zone in drill row near soil surface;

use hooded burners for flaming

between rows.

Incorporate immediately after

application; mix uniformly 1-2

in. deep; incorporate after seedbeds

are formed, or prepare seedbeds

after incorporation by method that

keeps herbicide in position no

deeper than 1 in. below point at

which cottonseeds are to be planted.

Use in combination with preplanting

trifluralin or preemergence diuron;

follow with postemergence naphtha,

postemergence DSMA, and possibly

other postemergence treatments;

special instructions for triband

weed control are essential to this

practice.

Normally apply in conjunction with

planting; usually restrict to band

treatment; apply CIPC as spray

or granules; incorporate granular

CIPC Y2 in. deep; in general, only

use DCPA on very fine soils and

monuron on very coarse soils.

Apply as laterally directed spray to

drill area at less than 1 in. above

soil; diseased or mechanically

damaged cotton may be severely

injured; naphthas not developed

specifically for cotton may not be

satisfactory.
SUGGESTED GUIDE FOR WEED CONTROL 19 69

TABLE 2.—Weed control in field row crops—Continued

21

Treatment Time of application Weeds controlled Remarks

COTTON—continued

Trifluralin (0.75) _

DSMA(3) orMSMA(2)

MSMA (2) or DSMA

(3) plus norea (0.8).

MSMA (2) or DSMA

(3) plus diuron (0.2).

MSMA (2) or DSMA

(3) plus fluometuron

(0.8).

Diuron (0.2-0.4) _

Before first irrigation

after cotton emergence.

1-2 applications after

smallest cotton is at

least 3 in. tall but

before first bloom

opens.

1-2 applications after

smallest cotton is at

least 3 in. tall but

before first bloom

opens.

1-2 applications after

smallest cotton is at

least 6 in. tall but

before first bloom

opens.

1-2 applications after

smallest cotton is at

least 3 in. tall but

before first bloom

opens.

1-2 applications after

cotton is 6 in. tall.

For lay-by purposes,

split application;

diuron (0.3-0.75) per

application.

For lay-by purposes,

single application ;

CIPC (8), diuron

(0.5-1.5), linuron

(0.5-1.5), monuron

(0.5-1.2), or

prometryne (1).

For spot spraying;

dalapon, 0.74 lb. per

5 gal. water, or TCA

ester, 1 lb. per 5 gal.

diesel fuel.

Once when cotton is 12

in. tall; again when

14-25 in.

When cotton is 15-24

in. tall.

Before johnsongrass

flowers for best control.

Most small-seeded annual

weeds and johnsongrass from seed

between rows.

Most annual grasses,

seedling cocklebur,

few other broadleaf

weeds; nutsedge and

small johnsongrass

will be topkilled.

Most annual weeds ; nutsedge and small

johnsongrass will be

topkilled.

_do_

_do_

Most annual weeds if

treated when less than

3 in. tall, young, and

actively growing.

Most small-seeded annual

weeds germinating

after treatment;

young actively growing

weeds less than 3 in.

tall.

Most small-seeded

annual weeds germinating after treatment;

young actively growing weeds less than

3 in. tall if surfactant is

added.

Established and seedling

johnsongrass.

For western irrigated Cotton Belt

only; apply to soil between rows

and incorporate immediately to

depth of 1-2 in.; control of annual

groundcherry is temporary.

Apply as basally directed spray; 2 applications are frequently necessary

for good control; normally use 1 pt.

surfactant for each 25 gal. spray

mixture; DSMA and MSMA appear

more effective during hot, dry periods.

Apply as basally directed spray;

normally use 1 pt. surfactant for

each 25 gal. spray mixture; DSMA

or MSMA plus norea is less dependent on weather conditions than

either herbicide used alone.

Apply as basally directed spray ; normally use 1 pt. surfactant for each

25 gal. spray mixture; DSMA or

MSMA plus diuron is less dependent

on weather conditions than either

herbicide used alone.

Apply as basally directed spray ; normally use 1 pt. surfactant for each

25 gal. spray mixture; DSMA or

MSMA plus fluometuron is less

dependent on weather conditions

than either herbicide used alone.

Apply as basally directed spray; add

1 pt. surfactant for each 25 gal.

spray mixture; poor control should

be expected under droughty

conditions.

Apply as basally directed spray ; add

1 pt. surfactant for each 25 gal.

spray mix; normally do not cultivate

after first application ; for this

reason split-application technique is

not suggested where resistant weeds

are present.

Apply as basally directed spray; add

1 pt. surfactant for each 25 gal.

spray mix if emerged weeds are

present; in irrigated areas, water

management is essential to insure

thorough wetting of beds after

application.

Dalapon should be applied to wet all

foliage ; apply TCA ester to wet

lower 4-6 in. of all johnsongrass

stems in clump; half rate of TCA

ester is adequate on johnsongrass up

to 12 in. tall if applied to wet all

leaves ; spot treatments seldom economical if infestation exceeds 5

percent.
22 AGRICULTURE HANDBOOK 3 32, U.S. DEPT. OF AGRICULTURE

TABLE 2.—Weed control infield row crops—Continued

Treatment Time of application Weeds controlled Remarks

PEANUTS

Seedbed preparation

and cultivation; bury

litter at least 3 in.

deep with moldboard

plow in preparing flat

seedbed; shallowrunning, nondirting,

flat sweeps are most

satisfactory for cultivation.

Vernolate (2-2.5)

Before planting and

after emergence.

Benenn (1.1-1.5)

Benefin (0.7-1.1) plus

vernolate (1.5-2).

Sesone (2.7), 2,4-DEP

(3), NPA (2-4), or

DNBP (9-12).

DNBP (6) alone or

DNBP (1.5) plus one

of following additives:

2,4-DEP (2), sesone

(2-2.7), diphenamid

(2-3), or NPA (3).

Postemergence DNBP

(3).

Postemergence DNBP

(1.5).

From 2 weeks to immediately before planting.

From 2-3 weeks to

immediately before

planting.

do

After planting but before

emergence.

When peanuts are cracking soil unless weeds

become visible first; in

this case apply herbicides before peanuts

start to crack soil.

Before peanuts are more

than 13^-2 in. in diameter (3- to 5-leaf

stage).

Within 1 month after

peanuts first crack soil ;

use 1-2 applications.

Control of all weeds is

affected by seedbed

preparation; cultivation between rows

controls all weeds.

Most annual weeds;

suppresses nutsedge.

Most grasses from seeds;

many annual broadleaf

weeds.

Most annual weeds;

suppresses nutsedge.

Most small-seeded

annual weeds.

-do_

.do_

.do_

Improper land preparation and cultivation often increase incidence of

southern blight, which may drastically reduce peanut yields and

quality; broken stands intensify

weed problems; rough seedbeds complicate use of herbicides.

Incorporate about 3 in. deep; usually

temporary stunting and leaf fusion

of peanuts; do not use seed of poor

vitality.

Incorporate 2-3 in. deep immediately

after application.

Incorporate 2-3 in. deep immediately

after application ; satisfactory lateseason control of grasses.

All these herbicides may cause injury,

especially in cold, rainy periods

during crop emergence; crop injury

usually temporary; do not use seed

of poor vitality.

Mixtures usually perform better than

single herbicides; timing is critical;

emergent sprays are most effective if

applied when weeds are first visible;

treatment after oldest peanuts have

more than 2 leaves is very hazardous;

peanuts from seed of poor vitality are

likely to be severely injured.

Less effective than emergent mixtures;

peanut foliage will be injured, especially in hot weather or hot, wet

weather.

Can be used if needed as foUowup treatment after emergent mixtures; apply

when weeds first become visible; protect peanuts from spray with shields

or similar devices.

SAFFLOWER

EPTC (3) Several weeks to imme- Winter annual weeds indiately before planting. eluding volunteer

cereals.

IPC (2-3) do Barley, wild oats

Barban (0.38) When wild oats have 1-2 Wild oats

true leaves (approximately 4 in. high).

Incorporate in top inch of soil immediately after application.

Do.

Apply as broadcast spray.

SORGHUM

Cultivation. Before planting to destroy All weeds.

several weed crops and

after crop emergence

until lay-by.

Preplanting cultivation should generally be shallow to reduce moisture

loss; postemergence cultivation

should be often enough to control

weeds in young stages of growth ; set

row widths to facilitate cultivation.
SUGGESTED GUIDE FOR WEED CONTROL 1969

TABLE 2.—Weed control in field row crops—Continued

23

Treatment Time of application Weeds controlled Remarks

SORGHUM—continued

Rotary hoe in and between rows.

After sorghum is 2 in.

tall until stalk begins to

stiffen.

Atrazine (1-2) After planting but before crop emergence.

All seedling weeds young

enough to be uprooted.

Most small-seeded annual weeds.

Norea (1.6-2.4), norea do Norea alone kills most

(1.6-2) plus propazine annual grasses;

(0.8-1), or atrazine mixtures increase con-

(0.8-1). trol of annual broadleaf weeds.

Propachlor (4-5) do Most small-seeded

annual grasses, some

broadleaf weeds.

Propazine (1.5-4) do Most small-seeded

annual broadleaf

weeds, some annual

grasses.

Atrazine (2-3) After crop emergence Most annual weeds less

than 1 in. tall.

Effective only on shallow-rooted seedling weeds.

Some injury to sorghum may occur;

plant sorghum 1 in. deep or deeper to

increase safety margin; do not use

atrazine on sorghum grown in coarsetextured soil or soils low in organic

matter.

Plant sorghum 1 in. deep or deeper to

increase safety margin.

Do.

2,4-D (0.25-0.5) When crop is 4-12 in.

tall.

Most broadleaf annual

weeds.

Flame _ After sorghum is 12 in.

tall.

Kills tops of most small

weeds.

Do.

Apply as broadcast spray in sorghum;

or if necessary to cover weeds, use

directed basal spray.

Apply as foliage spray to crop and

weeds while sorghum is 4-12 in. tall;

basally directed spray in sorghum

6-12 in. tall presents less danger to

crop and may be used if weeds are

shorter than crop; some injury to

sorghum by 2,4-D may occur regardless of growth stage at application.

Direct flame basally; balance speed

and pressure to kill tops of small

weeds without causing more than

slight damage to lower leaves of

sorghum; flame few rows day before

ñeld is to be flamed; adjust equipment

according to appearance of trial rows

1 day after flaming.

SOYBEANS

6-10 cultivations to

depths of 2-4 in.

2-3 shallow cultivations

at depths no greater

than 2 in.

Cultivate in and between rows with

rotary hoe at high

speed.

6-8 weeks before planting.

2-4 weeks before planting.

From unifoliate stage of

beans until first trifoliate leaf has fully

expanded.

Perennial grasses such as

Johnsongrass and

quackgrass, most

annual weeds.

Most annual weeds;

some control of perennial grasses such as

Johnsongrass and

nutsedge.

Most shallow-rooted

annual weeds in

emerging stage.

Alternating disk with field cultivator

is as effective and more economical

than using 1 implement; cultivate

twice in 1 day if wet weather delays

schedule; most effective in dry

weather; may reduce soil moisture

to critical levels, making it advisable

to wait for rain before planting.

Less likely to reduce soil moisture to

critical levels than intensive cultivations at greater depths; use only

where weeds have emerged or are

emerging.

Best results obtained when soil is loose

or lightly crusted; safety to soybeans

increases if rotary hoeing is done

only when beans have lost some

turgidity; chance of yield reductions

increases markedly if soybeans are

rotary hoed after full expansion of

first trifoliate.
24 AGRICULTURE HANDBOOK 33 2, U.S. DEPT. OF AGRICULTURE

TABLE 2.—Weed control infield row crops—Continued

Treatment Time of application Weeds controlled Remarks

SOYBEANS—continued

Cultivate between rows

with tools such as

sweeps.

Dalapon (3.7-7.4) ; use

0.5-percent surfactant

in spray.

Amiben (2-3), linuron

(1-3), CDAA (4-5),

NPA (3-4), or NPA

(3) plus CIPC (2-

2.7).

Nitralin (0.5-1.1), trifluralin (0.5-1), or

vernolate (2-3).

DNBP (1.5) plus NPA

(2-3).

Nonfortified naphthas

(same as for cotton)

at approximately 20

gal. per acre of land

actually treated.

As needed after emergence and until beans

become too large.

In spring when johnsongrass is approximately

1 ft. high (at least 4

weeks before planting

soybeans).

All weeds.

2,4-DB (0.2).

Chloroxuron (1-1.5)

After planting but before

emergence.

From several weeks to

immediately before

planting.

After planting but before

crop emergence.

1 application when beans

are 12-19 days old; if

needed, second application may be made

no sooner than 5 days

after first application.

1 application 2 weeks

before early bloom

until midbloom when

cocklebur plants are

growing above soybeans.

Postemergence when soybeans are over 4 in.

tall and weeds are less

than 2 in. tall.

JohnsongrassMost small-seeded annual grasses, some

broadleaf weeds.

Most annual grasses,

some broadleaf weeds;

some control of nutsedge with vernolate.

Most small-seeded annual grasses, some

broadleaf weeds.

Most small-seeded annual weeds in seedling

stage; kills tops of

most small perennial

weeds.

Cocklebur

Most actively growing

annual broadleaf

weeds less than 2 in.

tall; very little control

of annual grasses.

Cultivation is effective and usually

most economical method of controlling weeds growing between

rows.

Disk treated fields 4-7 days after

treatment; plant soybeans no sooner

than 3 weeks after disking; fall

plowing delays emergence of johnsongrass in northern areas; spring plowing after dalapon treatment is advisable so soybeans can be planted

earlier; use trifluralin or nitralin

incorporated in soil before planting

or amiben preemergence to control

seedling Johnsongrass not affected

by dalapon treatment.

Preemergence herbicides likely to cause

injury on very coarse-textured soils;

soybeans may be injured severely by

linuron on soils low in organic

matter.

Incorporate herbicides 1-2 in. deep in

soil; these preplanting treatments

may cause injury on very coarsetextured soils; nitralin (1.1) frequently fails to control weeds

adequately on dark high-organic

soils of North Central States.

For sandy soils of Coastal Plain,

application 2-3 days after planting

reduces chances of crop injury.

Apply as laterally directed spray to

10-in. band centered over row at

less than 1 in. above soil (5 gal. per

13,068 row-ft.) ; do not treat beans

more than 4 weeks old.

Apply as broadcast foliage spray;

normally use amine formulation;

treatment often injures soybeans

but symptoms (stem curvature and

drooping leaves) generally disappear

within 1 week after treatment; injury is more severe if treatment is

made when soil is very dry; timing

and rate very critical.

Apply as broadcast foliage spray or as

laterally directed spray at base of

soybean plants; use 0.3-0.5 percent

surfactant in spray; agitate spray

mixture; treatment often injures

soybeans, but stunting and leaf

necrosis usually disappear within

2-3 weeks; injury usually does not

reduce soybean yield.
SUGGESTED GUIDE FOR WEED CONTROL 19 69

TABLE 2.—Weed control infield rom crops—Continued

25

Treatment Time of application Weeds controlled Remarks

SOYBEANS—continued

2,4-D wax bars C6 bars

for 4 rows).

After most sesbania

plants have grown

above soybeans.

Sesbania. Wax bars are suspended from booms

or rod attached to rear of tractor so

as to travel 2-3 in. above soybean

plants; sesbania stems rub 2,4-D

wax formulation off bars; speed

should not exceed 4 m.p.h. and

should be slower in extremely heavy

infestations; handle wax bars carefully and remove from tractor when

not in actual weed-control operation;

apply no more than 0.5 lb. per acre

of 2,4-D.

SUGAR BEETS

Cultivation Postemergence (variable) _

Incorporate preplanting

diallate (1.5-2) in

soil.

IPC (3-5) do

Immediately before

planting.

Small weeds in rows, all

weeds between rows.

Wild oats_

Pebulate (4-5), cycloate do-

(3-4),orEPTC (1-2.5).

Pyrazon (4-4.8)-_--- do_

Preemergence endothall After planting but be-

(5.5). fore crop emergence.

Preemergence pyrazon do

(3-4).

Preemergence TCA do

(5-7).

Wild oats, volunteer

cereals, some other

annual grasses.

Most annual grasses,

many annual broadleaf weeds.

Many annual broadleaf

weeds.

Many annual weeds _

Weeds between rows easily controlled

by cultivation ; mechanical thinners

provide some weed control in rows;

various devices such as harrows with

flexible tines used successfully for

weed control in row if beets big

enough to withstand operation and

weeds small enough to be killed.

Incorporate in soil right after application; does not control foxtail.

Incorporate in soil immediately after

application; margin of safety for

EPTC is narrow; use no higher rate

than local experience has shown to

be safe.

Incorporate in soil immediately after

application; crop injury may occur

on coarse-textured soils in Pacific

Northwest.

Postemergence barban

(0.6-0.75).

Postemergence dalapon

(2-3).

Postemergence endothall

(0.75-1.46).

Postemergence pyrazon

(4).

Pyrazon (4) plus

dalapon (2).

When wild oats in 2-leaf

stage.

When crop has emerged

until it has 4 true

leaves and grassy

weeds are less than

3 in. tall.

When crop has emerged

until it has 6 true

leaves and weeds are

less than 23^ in. tall.

When crop has emerged

but before weeds have

more than 2 true

leaves.

Apply when first 2 true

leaves of crop are pea

size.

Many annual broadleaf

weeds.

Most annual grasses

except wild oats and

volunteer cereals.

Wild oats '-

Most small grassy weeds.

Smartweed, wild buckwheat, some other

broadleaf weeds.

Many annual broadleaf

weeds.

Most annual grasses,

many annual broadleaf

weeds.

Apply as broadcast foliage spray.

Do.

Use lower rate when beets have less

than 2 true leaves; when temperature is above 80° F., endothall may

cause excessive injury, especially to

very small sugar beets.

Apply only as band foliage spray;

adequate soil moisture should be

available for good weed control; do

not use if pyrazon was applied

before planting.
26 AGRICULTURE HANDBOOK 3 32, U.S. DEPT. OF AGRICULTURE

TABLE 2.—Weed control infield row crops—Continued

Treatment Time of application Weeds controlled Remarks

SUGARCANE

Fallow plowing.

Atrazine (2-4), simazine

(2-4),diuron(2-3),or

monuron (2-4) ; for

organic soils of

Florida: CDAA (8)

plus 2,4-D (2) ; for

Hawaii only:

Ametryne (4-8).

Fenac (4-6) ; for

Louisiana only:

Terbacil (3.2).

For Florida primarily:

Atrazine (2-4) ; for

Hawaii only: Diuron

(2-3.2) plus surfactant, PCP (5)

emulsified in naphtha,

or ametryne (2-4).

2,4-D (2) ; for

resistant weeds:

2,4,5-T or silvex (1).

6-8 fallow plowings

during spring and

summer before sugarcane is replanted.

Immediately after planting or ratooning; most

may be repeated and/

or supplemented with

other herbicides

during growing season.

Fenac in fall after planting in Florida; in

Louisiana apply fenac

and terbacil in fall

after planting and in

early spring (split

application) or spring

only.

Young succulent weeds

at any time after crop

emergence and before

cane closes in; 1-3

applications may be

necessary.

Postemergence when

needed to vigorously

growing weeds.

Johnsongrass from seed

and rhizomes.

Most annual grasses,

many small-seeded

annual broadleaf

weeds.

Johnsongrass from seed,

most annual grasses,

many broadleaf weeds.

Most annual grasses,

some small-seeded

broadleaf weeds; in

Hawaii many

perehnial grasses and

broadleaf weeds.

2,4-D controls chickweed, henbit, morningglory, pigweed; other

chemicals control

these weeds plus

dogfennel, groundcherry, koa haole,

nightshade, wild

lettuce.

Apply re-treatments as basally

directed sprays.

Apply fenac (6-8) broadcast in Florida;

apply fenac or terbacil on 24- to

30-in. band in Louisiana.

Apply as basally directed spray,

usually as supplement to preemergence treatment; apply atrazine

when seedling weeds are approximately IH in. tall.

Apply as broadcast foliage spray.

TOBACCO

Commercial urea (1)

plus calcium

cyanamide (0.5)

per sq. yd., or

methyl bromide (1)

per 100 sq. ft.

Diphenamid (4-6).

Urea-cyanamide or

cyanamide in October

in mid-Atlantic States.

Pebulate (3).

Benefin (1.2-1.5).

Immediately after

planting seeded

tobacco or after

transplanting and

before any weed

emergence.

Shortly before transplanting.

After beds are formed

but before tobacco

is set.

All annual weeds in

plant beds.

Most annual grasses,

some small-seeded

broadleaf weeds.

Suppresses nutsedge,

controls many annual

weeds.

Many annual grasses,

some broadleaf weeds.

For plant beds only ; thoroughly

mix urea-cyanamide or calcium

cyanamide with upper 3 in.

of soil by disking or raking;

apply methyl bromide to wellpulverized seedbed under gasproof

cover; methyl bromide is very

poisonous; many users employ

specially trained personnel to

apply it.

Shallow incorporation before

transplanting may improve

effectiveness.

Incorporate 2-3 in. deep with powerdriven rotary hoe; read label

carefully for area and other

restrictions.

Incorporate 2-3 in. deep with

power-driven rotary hoe.
SUGGESTED GUIDE FOR WEED CONTROL 19 69 27

TABLE S.-—]Veed control in close-drilledßeld crops

[Numbers in parentheses=pounds of active ingredient per acre unless otherwise indicated; for herbicide tolerances, see Appendix]

Treatment Time of application Weeds controlled Remarks

ESTABLISHED ALFALFA

FlamingDrying of soil in irrigated areas by increasing interval

between irrigations.

Shading by crop

Twice at 3-day interval

in stubble after

harvest.

Whenever feasible during

growing and harvesting

season.

Frequent, shallow

cultivation.

CIPC (6) (granular

formulation) or

DCPA (10).

Dichlobenil (2) (granular formulation).

Diuron (1.5-3.2);

simazine (0.8-1.6).

DNBP (1.3-2.2)

plus 20-50 gal.

diesel or weed oil

plus 50-100 gal.

water.

EPTC (2-4)

2,4-DB (1-2) _

DNBP (amine salts)

(0.75-1.5).

Dalapon (2-2.2).

EPTC (2-3);

2,4-DB (1-2).

DCPA (10).

CIPC (5) (granular

formulation).

In early spring and

in stubble after

harvest.

To moist soil before

dodder attaches to

host in spring.

Shortly before or after

irrigation and before

dodder attaches to

host.

In fall or winter when

alfalfa is dormant or

semidormant.

After first hay crop is

removed but before

regrowth starts.

Immediately before

planting.

Postemergence when

weeds are less than

3 in. tall.

Postemergence when

weeds are small and

alfalfa has 2 or more

true leaves.

Postemergence when

grasses are less than 3

in. tall.

EPTC immediately

before planting;

2,4-DB postemergence

if broadleaf weeds

occur.

(Immediately before

planting.

Or immediately after

planting.

After alfalfa has first

pair true leaves.

Dodder seedlings,

dodder attached to

stubble.

Dodder seedlings

_do_

-doDodder seedlings, some

annual weeds; DCPA

provides some control

of attached dodder.

Dodder seedlings, most

annual weeds, some

perennials.

Manv annual weedsAnnual broadleaf weeds _.

Annual grasses, many

broadleaf weeds.

Broadleaf weeds

Some broadleaf weedsGrass seedlingsSeedlings of grass and

broadleaf weeds.

Dodder, many annual

grass and broadleaf

weeds.

do

Dodder, some annual

weeds.

Spot flaming can be used also for

isolated patches of dodder in seed

crop.

Alfalfa, through shading after it is 2 ft.

tall, provides important part of fullseason control of dodder if dodder

is controlled by other methods

while alfalfa is less than 2 ft. tall.

Supplement with cultural practices

described previously to obtain fullseason control; use DCPA only on

seed crops.

Supplement with cultural practices

described previously to obtain fullseason control; use only on seed

crops; may be applied twice during

season.

Apply before germination of weeds or

while still seedlings; remove or

burn crop residue before treating;

simazine registered for use only on

at least 1-year-old alfalfa in Pacific

Northwest only.

Do not graze treated areas or feed

treated forage to livestock.

Incorporate in soil by disking or

rotary tiUing; EPTC volatile, lost

if applied to wet soil or left on soil

surface more than 3^ hour.

Alfalfa susceptibility increases with

age.

Stunts alfalfa temporarily; may be

repeated later in season; do not feed

first year's growth to dairy cows or

animals being finished for slaughter.

Use this treatment for spring seeding

and seed harvested during seeding

year.

Incorporate lightly if rainfall not expected or furrow irrigation cannot

follow soon after application.

Sprinkle-irrigate soon after application.

Apply granules to moist soil; stunting

of alfalfa probable; earlier application may cause severe injury; must

be applied before dodder attaches to

host; must plant alfalfa early so it

reaches safe stage before dodder

emergence.
28 AGRICULTURE HANDBOOK 3 32, U.S. DEPT. OF AGRICULTURE

TABLE 3.^—Weed control in close-drilled field crops—Continued

Treatment Time of application Weeds controlled Remarks

ESTABLISHED GRASSES GROWN FOR SEED

Plant in rows and

cultivate between

rows.

Dicamba (2-3) in

eastern Oregon;

prometryne (2-3.2) in

eastern Oregon and

eastern Washington;

IPC (4) in eastern

Washington.

2,4-D, 2,4,5-T, MCPA,

or silvex (0.5-0.75)

or dicamba (0.25-

0.5).

Soon after first postharvest irrigation.

After seedling crop

grasses have 3-5

leaves; established

crop grasses not

treated after boot

stage but can be

re-treated after

harvest.

Summer annuals.

Downy brome

Most broadleaf weeds.

Not satisfactory where heavy winter

rains occur and winter annuals are

primary weeds.

Remove all crop residue by burning

or mechanical means immediately^

after harvest; prometryne registered

for use only on perennial bluegrass

seed fields.

Easier to control small, actively

growing, young weeds than large,

slowly growing, old weeds; use

higher rates only on well-established

stands.

ESTABLISHED LEGUMES ^ GROWN FOR SEED

Mechanical tillage When weeds are seed-

(shallow) or flaming lings before seeding

fields with field weed crop, between hay

burners. and seed crops, and

in dormant stages.

2,4-DB (0.5-2) Any time during growing season before budding of legumes.

Many annual weeds _

DNBP (1.9-2.5) or

PCP (4-6) in 5-10

gal. diesel oil, or

endothall (0.5-0.65) in

5-10 gal. water, or

diquat (0.5-0.75) in

20-40 gal. water.

PreharvestMany annual and perennial broadleaf weeds

that are not legumes

and that are not resistant to 2,4-D.

Desiccation of all weeds

before harvest.

Species present will determine when

tillage can be practiced.

Treat weeds when less than 3 in. tall,

or preferably when less than 1 in.

tall, and growing actively ; use

higher rates only for established

legumes; not registered for use on

lespedeza; may reduce seed production of clovers and trefoil when

applied in spring.

Treatment before legume seeds are

mature may reduce their yield and

quality; legumes as well as

weeds are desiccated by treatment;

DNBP not registered for use on

lespedeza; diquat not registered for

use on lespedeza or birdsfoot trefoil;

do not graze fields or feed treated

forage to livestock.

ESTABLISHED LEGUMES ^ GROWN FOR SEED

IPC (3-4) or CIPC

(3-4).

In winter when legumes

are dormant or semidormant.

Winter annual

chickweed.

Apply before germination of weeds or

while still seedlings; burn or remove

crop residue before treating; use only

after legumes have several true

leaves.

See footnotes at end of table.
SUGGESTED GUIDE FOR WEED CONTROL 19 6'9

TABLE 3.—Weed control in close-drilled field crops—Continued

29

Treatment Time of application Weeds controlled Remarks

ESTABLISHED GRASSES ^ GROWN FOR SEED

Atrazine (1-1.2), CIPC

(2-3), diuron (1-3.2),

IPC (2-4), or simazine (1-2).

Preemergence to weeds

in fall or while weeds

are very small.

Winter annuals, except

CIPC and IPC will

not control many

broadleaf winter

annuals.

Treatments listed may be unsatisfactory in area other than Washington

or Oregon; remove or burn all crop

residue before treating; CIPC or

IPC may reduce seed yields of

grasses if applied after Nov. 1 ;

bluegrass and other grasses may be

severely injured by atrazine or simazine in areas outside Washington

and Oregon; atrazine registered for

use only on perennial ryegrass; diuron not registered for use on creeping red fescue; IPC not registered

for use on orchardgrass, bluegrass,

tall fescue; simazine not registered

for use on bluegrass.

ESTABLISHED TREFOIL GROWN FOR SEED

Diuron ( 1.6) In winter when trefoil

is dormant or semidormant.

Manv annual weeds. Apply before germination of weeds

or while seedlings; burn or remove

crop residue before treating.

Select fields relatively

free of weeds; tillage

of land in late summer and early fall is

helpful.

Spring tillage

Late summer, early fall-__ Perennials, annuals _

Before planting Wild oats_

Diallate (1.5-2) In fall or spring preceding spring seeding.

Barban (0.3-0.37) When wild oats in 2-

leaf stage.

MCPA (amine or so- When flax is 2-6 in. tall

dium salts) (0.1-0.6) and weeds are small,

or 2,4-D (amine salt)

(0.1-0.25).

TCA(5),dalapon(0.75), do_

either one in mixture with MCPA

(0.25).

_do_

Late-summer or fall tillage may not

be desirable in some areas where

wind may seriously erode soil.

Spring tillage delays sowing of flax;

practice is successful in some areas

but may be detrimental to flax

yields; use early varieties where

sowing is delayed.

Incorporate herbicide in soil.

_ do Apply as broadcast foliage spray.

Many broadleaf weeds

Most annual grasses.

Apply as broadcast foliage spray;

higher rates than those listed required only in Southwestern United

States; MCPA less likely to injure

flax than 2,4-D ; do not apply

MCPA or 2,4-D after flax reaches

early bud stage; varieties differ in

tolerance to herbicides.

Apply as broadcast foliage spray;

mixture controls both grasses and

broadleaf weeds.

See footnotes at end of table.
30 AGRICULTURE HANDBOOK 332, U.S. DEPT. OF AGRICULTURE

TABLE 3.—Weed control in close-drilledßeld crops—Continued

Treatment Time of application Weeds controlled Remarks

RICE

Use of weed-free crop

seed.

Rotate with row crops

such as soybeans,

cotton, grain sorghums, safflower.

Rotate with pasture

At plantingPhosphate fertilization

of other crops preceding rice or of rice

just before it is

flooded for ñrst time.

Rotate with other

small grains combined with summer

fallow after harvest

of other small grains.

Thorough seedbed

preparation of adequately dried land to

kill all weed growth

before seeding and

repeated shallow

cultivations at 1- to

3-week intervals in

spring before

planting.

Water management at

seeding.

Flood rice to depth of

4-8 in. just after rice

and grassy weeds

emerge.

Timing of nitrogen

application to rice.

Molinate (3) (granular

or emulsifiable

formulation).

In previous seeding cr

just before first

flooding.

Late summer, fall, and

early spring before

planting.

Barnyardgrass, beakrush, mexicanweed,

northern jointvetch

(curly indigo), red

rice, hemp sesbania

(coffeebean).

Many grasses, broadleaf weeds, sedges,

aquatic weeds.

Reduces infestations of

aquatic weeds, broadleaf weeds, sedges.

Barnyardgrass and most

annual grasses in dry

seeded rice.

Many annual weeds,

perennials such as

bulrush, cattail, knotgrass, perennial spikerush.

Deep-rooted perennials,

aquatic weeds, most

annual weeds.

From several days before

planting to 4 weeks

after seeding rice.

Flood when grass weeds

have 1-3 leaves and

hold for 1-3 weeks.

Variable

Immediately before

flooding and seeding.

Barnyardgrass, northern jointvetch (curly

indigo), hemp sesbania

(coifeebean), signalgrass, sprangletop.

Barnyardgrass, most

annual grasses.

Barnyardgrass, other

annual grasses,

aquatic weeds.

Barnyardgrass in waterseeded rice.

Use weed-free rice seed to prevent or

hold down infestations of listed

weeds.

Reduces infestations of listed weeds;

in some cases can help eradicate

some weeds.

Does not reduce grass infestations.

Reduces competition of listed weeds

with rice ; phosphate applied in

standing water stimulates aquatic

weeds; may be applied preplant to

water-seeded rice without stimulating barnyardgrass but may increase

problems with aquatic weeds.

Reduces infestations of listed weeds;

in some cases can help eradicate

some weeds.

Reduces infestations but does not

eradicate listed weeds.

White barnyardgrass not controlled

unless water is held 6-8 in. deep

for 3-4 weeks; water seeding encourages some aquatic weeds such

as algae, annual flatsedge, annual

spikerush, ducksalad; therefore dry

seeding rice by drilling or broadcasting helps control these aquatic

weeds.

Timely and complete draining of

water helps control many aquatic

weeds including algae and ducksalad.

In absence of effective cultural or

chemical control of listed weeds,

delay nitrogen application until

weeds are flowering to reduce competition with rice (this period of

flowering usually occurs 50-60

days after seeding rice).

Incorporate 3-4 in. deep immediately

after application; cross-disking or

cross-harrowing with implements

going 4-6 in. deep has been satisfactory; safe only on water-seeded

rice.
SUGGESTED GUIDE FOR WEED CONTROL 1960

TABLE 3.—Weed control in close-drüled field crops—Continued

31

Treatment Time of application Weeds controlled Remarks

RICE—continued

Molinate (3) (granular

formulation).

MCPA, silvex, 2,4-D,

or 2,4,5-T (0.5-1.5);

amine salt or lowvolatile ester formulations.

Postemergence after

flooding but before

weeds are 3 in. tall.

When longest internodes are }i-% in.

Propanil (4.5-6)- When grassy weeds are

through water and

oldest grass is 6-8 in.

above water (42-50

days after seeding).

Barnyardgrass, spikerush, yerba-de-tago.

Arrowhead, burhead,

ducksalad, ñmbristylis, flatsedge, gooseweed, mexicanweed,

northern jointvetch

(curly indigo), redstem, hemp sesbania

(coffeebean), smartweed, spikerush, waterhyacinth, waterhyssop, waterplantain,

waterprimrose.

Barnyardgrass, other

annual grasses, broadleaf weeds, sedges.

Flood rice before application and

broadcast aerially; maintain flood

at least 7 days; gives residual

control for 14 days if drained at

7 days; poor weed control on

levees and unflooded areas; safe

only on dry-seeded rice.

Severe injury may occur if rice

is treated in early-tillering, latejointing, booting, or early-heading

stages; for emergency treatments

in early stages of rice growth,

2,4,5-T, MCPA, and silvex will

cause less injury than 2,4-D; rapidly

growing weeds are easier to kill than

slow growing weeds; therefore soil

moisture should be adequate to

promote rapid weed growth; water

levels should be lowered if necessary

to expose weed foliage to sprays;

mixtures may be better than single

herbicides where several species are

present; for example, 2,4-D (0.5)

plus 2,4,5-T (0.5) is more effective

than either one at 1 lb. where both

ducksalad and northern jointvetch

(curly indigo) are present; treat

only when temperature is 70°-90°

F. ; do not mix these herbicides with

other pesticides or any material

other than water; nitrogen applied

to rice before treatment may increase its susceptibility; nitrogen

applied 7-21 days before treatment

has increased susceptibility more

than nitrogen applied 1-6 days

before herbicide application;

nitrogen applied at midseason

within 10 days after herbicide may

reduce rice injury; rain 1-6 hours

after spraying may reduce

effectiveness.

Do not alter water depth immediately

before or after spraying; if before

spraying, deep flood is lost by levee

failure, reflood rice to shallow depth

(2-3 in.) ; treat when grass has

resumed rapid growth and is 5-6 in.

tall (similar to shallow-water

culture) ; spray droplets of 200-400

micron diameter are preferable to

coarser or finer sprays; do not mix

propanil with other pesticides;

insecticides such as carbaryl,

parathion, and methyl parathion

may cause injurious interactions if

used within 15 days before or after

propanil application.
32 AGRICULTURE HANDBOOK. 3 32, U.S. DEPT. OF AGRICULTURE

TABLE 3.—Weed control in close-drilled field crops—Continued

Treatment Time of application Weeds controlled Remarks

RICE—continued

Propanil (4-4.5)-

Propanil (3-5) in 10-15

gal. water for aerial

spraying or in 15-25

gal. water for ground

spraying.

Propanil (5-6) plus

surfactant in 12-15

gal. water; use 0.5-

percent surfactant in

spray.

Propanil (5).

Usually 35-45 days after

seeding when oldest

grass is 5-6 in. above

water and broadleaf

weeds and sedges are

just above water.

Soon after crop and

weed emergence when

grass weeds have 1-3

leaves and broadleaf

weeds or sedges are

1-5 in. tall.

When barnyardgrass is

in tillering to jointing

stage.

Propanil (3) in 10 gal.

water.

3-lb. split application to

sprangletop less than

3 in. tall followed bv

2 lb. 7 days later.

When weeds are less

than 1 in.

Barnyardgrass, other

annual grasses, broadleaf weeds.

Annual flatsedge, annual

spikerush, barnyardgrass, fimbristylis,

gooseweed, hemp

sesbania (coifeebean),

northern jointvetch

(curly indigo), signalgrass, many other

annual weeds.

Barnyardgrass.

Sprangletop.

Ducksalad, flatsedge,

redstem, spikerush,

waterhyssop.

Spray droplets of 200-400 micron

diameter are preferable to finer or

coarser droplets; if grasses are not

prevalent weeds, water may be

lowered but not drained to expose

foliage of nongrassy weeds; in such

case water level may be raised after

spraying as rice develops and

temperature increases; do not mix

propanil with other pesticides;

insecticides such as carbaryl,

parathion, and methyl parathion

may cause injurious interactions if

used within 15 days before or after

propanil application.

May be used in drill-, broadcast-,

or water-seeded rice; if rice is water

seeded, drain or lower water to

expose weed foliage; control is

improved by flushing field 2-3 days

before spraying if soil is dry;

postpone spraying for warmer

temperatures if below 50° F. at

night and below 70° during day;

flooding may begin 24 hours after

application and should be completed

in 2-4 days; spray droplets of

200-400 micron diameter are

preferable to finer or coarser spray ;

do not mix herbicides with other

pesticides; insecticides such as

carbaryl, parathion, and methyl

parathion applied within 15 days

before or after propanil have severely

injured rice.

Most effective on rapidly growing

grass; if grass is growing slowly,

light application of nitrogen in

flood 4-7 days before applying

herbicide stimulates grass growth ;

surfactants not developed specifically for rice may not be satisfactory; see propanil (3-5) for droplet

size instructions and precautions on

temperatures and mixing with other

pesticides.

Apply aerially to water-seeded rice

after draining; cross-apply first

treatment using 10 gal. per acre

total spray; apply second treatment

conventionally; begin flushing 1 day

after first treatment; see propanil

(3-5) for droplet size instructions

and precautions on temperatures

and mixing with other pesticides.

Apply aerially after draining ricefield;

see propanil (3-5) for droplet size

instructions and precautions on temperatures and mixing with other

pesticides.
SUGGESTED GUIDE FOR WEED CONTROL 196i9

TABLE 3.^—Weed control in close-drilled field crops—Continued

33

Treatment Time of application Weeds controlled Remarks

RICE—continued

Propanil (4-6) plus

surfactant in 10 gal.

water; use 0.5-

percent surfactant in

spray.

Propanü (2-3) in 10

gal. water.

When weeds are less

than 6 in.

At midseason to weeds

less than 5 ft.

Ducksalad, flatsedge,

gooseweed, redstem,

spikerush, waterhyssop.

Hemp sesbania (coffeebean) .

Apply aerially after draining ricefield;

surfactants not developed specifically for rice may not be satisfactory; see propanil (3-5) for droplet

size instructions and precautions on

temperatures and mixing with other

pesticides.

Apply aerially to flooded or drained

ricefields; see propanil (3-5) for

droplet size instructions and precautions on temperatures and

mixing with other pesticides.

Diuron (0.8-1.2) Before Apr. 10 while Many annual weeds.

weeds are less than 4

in. tall.

Diuron (1.2-1.6) Immediately after

planting.

.do_

Registered for use in eastern Oregon,

Washington, and Idaho where

annual precipitation is more than

16 in.

Registered for use in western Oregon

and western Washington.

Diallate (1-1.25). Preemergence before

crop sprouts are H

in. long.

Wild oats Incorporate in soil.

BARLEY, OATS, AND WHEAT

2,4-D (0.25-1) After cereals are well

tillered but before

boot stage; wheat may

be treated shortly

before harvest.

MCPA (0.2-0.5) 2-leaf to boot stage

Bromoxynil (0.37-0.5). When weeds are small;

when wheat or barley

is in 2-leaf to boot

stage.

Many annual broadleaf

weeds; topkills

several perennial

weeds.

_do_

Many annual broadleaf

weeds including some

not adequately controlled with 2,4-D or

MCPA.

Wheat most tolerant of these crops

to 2,4-D; oats least tolerant; preharvest spraying of wheat may

help to dry weeds before harvest

but earlier treatment is more

desirable.

Oats more tolerant to MCPA than

to 2,4-D; treatment may be used to

control early germinating weeds

when cereals are small.

Not registered for use on oats;

effective only on small weeds.

BARLEY AND WHEAT UNDERSOWN WITH LEGUMES

Postemergence 2,4-D

or MCPA (0.12-0.25).

After cereals are well

tillered (usually 4-8

in. tall) but before

boot stage.

Mustard, yellow rocket,

other broadleaf weeds.

Use only if weed infestation is serious

enough to result in reduction or

loss of legume stands and reduced

cereal yield; cereal canopy may

help protect legumes from herbicides;

waiting later than early joint stage

is inadvisable; use lowest gallonage

and pressure possible to reduce

penetration of cereal and weed

canopy; these rates are frequently

inadequate for Southern, Northwestern, and Western United States;

check with local authorities for

clearances and safety of higher rates.
34 AGRICULTURE HANDBOOK 3 32, U.S. DEPT. OF AGRICULTURE

TABLE 3.—Weed control in close-drüled field crops—Continued

Treatment Time of application Weeds controlled Remarks

DURUM WHEAT AND HARD RED SPRING WHEAT

Triallate (1) In fall before spring

planting.

Barban (0.25-0.37) When wild oats in 2-leaf do

stage but not after

crop reaches 4-leaf

stage.

Wild oats Incorporate in soil.

FALL-SEEDED BARLEY, OATS, AND WHEAT

Dicamba (0.25) Postemergence in spring

before joint stage.

Corn cockle, cow cockle,

dogfennel, smartweed,

wild buckwheat, most

weeds susceptible to

2,4-D.

Mixtures of 0.12 lb. each of dicamba

and 2,4-D per acre will control

mustards better than dicamba alone.

SPRING-SEEDED OATS AND WHEAT

Dicamba (0.12) for oats Postemergence during

and (0.12-0.25) for 2- to 5-leaf stage of

wheat. crop.

Corn cockle, cow cockle,

dogfennel, smartweed,

wild buckwheat, most

weeds susceptible to

2,4-D.

Mixtures of 0.12 lb. each of dicamba

and 2,4-D per acre will control

mustards better than dicamba alone.

1 Includes alfalfa, birdsfoot trefoil, alsike, ladino, red,

and white clover, and lespedeza.

2 Includes alfalfa, birdsfoot trefoil, and crimson, ladino,

red, subterranean, and white clover.

3 Includes bentgrass, bluegrass, creeping red fescue,

orchardgrass, perennial ryegrass, and tall fescue.

TABLE 4.—Control oj perennial weeds in cropland in fallow periods or by spot treatment

[Numbers in parentheses=pounds of active ingredient per acre unless otherwise indicated]

Treatment Time of application Weeds controlled

ALL KINDS

Methyl bromide fumigation, 1 lb. per 100

sq. ft.

Intensive cultivation

Any time during spring,

summer, or fall.

All weeds, weed seed,

rootstocks.

Frequency depends on

species and climatic

conditions.

Most perennial weeds.

BROADLEAP WEEDS

Amitrole (4)_ After harvest of crop

but before Oct. 1.

Canada thistle, hoary

cress, leafy spurge,

poison ivy.

Remarks

Apply under gasproof cover after

thorough tillage of soil; methyl

bromide is very dangerous to man

and warmblooded animals; most

users employ personnel specially

trained in its use; for control in

small, specialized areas; soil temperature should be above 65° F. for

effective results.

More than one season required to

control some species; system may

be combined with competitive crops

and chemicals; follow local recommendations.

Re-treat as necessary; frequently used

as spot treatment; check labels for

restrictions as to crop species and for

other precautions and instructions.
SUGGESTED GUIDE FOR WEED CONTROL 196'9 35

TABLE 4.—Control oj perennial weeds in cropland injallow periods or by spot treatment—Continued

Treatment Time of application Weeds controlled Remarks

BROADLEAF WEEDS—Continued

Silvex (3) Late fall or early spring. _ Smooth bedstraw.

2,4-D (0.5-2). Actively growing foliage,

usually bud stage.

2,4-D (l-3)_ doCanada thistle, field

bindweed, hoary cress,

sowthistle.

Bur ragweed, dogbane,

leafy spurge, Russian

knapweed.

Usually re-treatment will be necessary;

frequently used as spot treatment;

check labels for restrictions as to crop

species and for other precautions and

instructions.

Usually re-treatment will be necessary; observe treated areas and retreat as required; check labels for

restrictions as to crop species and for

other precautions and instructions.

Do.

Amitrole (4)_

Atrazine or simazine

(2-4) followed by

plowing and

planting of corn.

Dalapon (4-5)

followed by plowing

2 weeks later and

planting of corn 4

weeks after

treatment.

Spot spraying with

dalapon (1) per 5

gal. water; or

aromatic oils.

Dalapon (5-7) followed

by disking after 2

weeks.

EPTC (2-6).

In spring when

quackgrass is 4-10

in. tall.

Fall or spring before

planting corn.

In spring when

quackgrass is 4-10

in. tall.

During growing season

from hand applica-,

tors while weeds are

less than 15 in. tall;

to foliage or stems

of weeds.

In spring when grass is

15 in. tall or after

clipping any time

when grass is this

height.

To freshly tilled soil in

early spring.

Quackgrass.

.do.

.do.

Most grasses; oils will

also kill tops of

broadleaf weeds; will

control but not

eradicate perennial

grasses.

Johnsongrass,

Quackgrass.

MH (4) followed by

plowing in 4-8 days.

To foliage in early spring do.

Till soil thoroughly 2 weeks after

application and before planting

any crop; check labels for restrictions

as to crop species and for other precautions and instructions.

Chemical residues in soil may injure

crops other than corn year after

treatment; check labels for restrictions

and other instructions.

Add }i pt. surfactant to each 5 gal.

spray mixture for herbicides mixed

in water; spraying lower 6 in. of

weeds is usually adequate; check

labels for restrictions as to crop

species and for other precautions and

instructions.

Use followup program for seedling control ; check labels for restrictions as to

crop species and for other precautions

and instructions.

Thoroughly work soil before and after

application; check labels for restrictions as to crop species and for other

precautions and instructions.

Corn or sugar beets may be planted as

soon as soil preparation is completed;

not registered for use on other

agronomic crops; check labels for restrictions and other instructions.

Amitrole (4). When weeds are 12-

in. tall.

18 Horsetail rush. Spray foliage; check labels for restrictions as to crop species and for other

precautions and instructions.
36 AGRICULTURE HANDBOOK 332, U.S. DEPT. OF AGRICULTURE

TABLE 4.—Control of perennial weeds in cropland in fallow periods or by spot treatment—^Continued

Treatment Time of application Weeds controlled Remarks

Amitrole (4) followed

by disking after 2

weeks.

Incorporate EPTC or

vernolate (3) in soil.

2,4-D (1-2)

In spring; repeat as Purple nutsedge.

needed for 2-3 years.

In spring Purple and yellow nutsedge.

4-5 applications during

growing season for 2

years.

Purple nutsedge_

Check labels for restrictions as to crop

species and for other precautions and

instructions.

Check labels for restrictions as to crop

species and for other precautions and

instructions.

Most effective where heavily fertilized

grasses can be grown in conjunction

with herbicide treatment; check labels

for restrictions as to crop species and

for other precautions and instructions.

WEED CONTROL IN HORTICULTURAL CROPS

Weed control in horticultural crops is a highly

complex problem because of the large number of

different types of crops and their specific cultural,

climatic, and soil requirements plus the many

species of weeds associated with these environmental and cultural conditions. Horticultural

crops include vegetables, deciduous tree fruits and

nuts, citrus and subtropical fruits and nuts, small

fruits, and ornamental plants.

Several methods of weed control are used

separately and in various combinations in horticultural crops because of the complexity of the

weed problem. Mechanical cultivation is usually

effective in controlling weeds between the rows but

does not efficiently control weeds within the row

because of the proximity of weed and crop plants.

In periods of continued or excessive rainfall,

mechanical cultivation is impossible and the weeds

normally controlled by this method overgrow the

crop. Hand hoeing and hand pulling of weeds

have been used to supplement mechanical cultivation in many crops in the past. The scarcity and

cost of labor in recent years, however, have made

hand weeding impractical in many instances and

impossible in others.

Cultural practices involving suitable rotation of

broadcast and row crops and crops of differing

growth habits can be used to limit the vigor and

spread of certain weeds. For example, sweetpotatoes are very strong competitors and can be

used effectively in rotations to suppress weeds.

Broadcast-planted soybeans and sorghum are also

effective smother crops for use in rotation.

The inefficiency of mechanical cultivation, the

scarcity of hand labor, and the limitations of croprotation practices have stimulated intensive research in chemical weed control. The development of effective herbicides is providing the

farmer with new technological tools of great

potential for use in combination with cultural and

mechanical methods of weed control in horticultural crops.

Examples of herbicides presently in commercial

use for horticultural crops are given in tables 5-10.

This information is intended to show the broad

general areas of herbicidal effectiveness on these

crops. Rate ranges are given, because specific

rates vary with locality and depend on climate,

soil composition, and cultural practices. Excellent weed-control recommendations based on local

research have been prepared by many weed

specialists in State agricultural experiment stations. These recommendations are revised annually to keep abreast of current research. These

sources provide specific herbicide and rate recommendations for each locality. The reader should

consult these specialists for specific rates and

methods for safe and effective use on specific

crops for local areas.

Herbicides are selected on the basis of their

weed specificities. For example, one herbicide

may be highly effective on germinating annual

weed grasses and ineffective on germinating broadleaf weeds. Conversely, others may be effective

on only broadleaf weeds. The grower must

therefore identify the weed and know its time

of emergence and growth as a basis for selecting the

correct herbicide and time of application.

The formulation to be used, whether granules

or spray, will depend on the weed problem. In

general, granules should be used in postemergence

or posttransplanting treatments after clean cultivation to take advantage of the physical selectivity

of this form as a means of minimizing injury to the
SUGGESTED GUIDE FOR WEED CONTROL 196'9 37

crop. Granules may also be used as preplanting

and preemergence treatments as a matter of

convenience.

DNBP, paraquat, PCP, and petroleum solvents are very effective as directed sprays on

young rapidly growing weeds in many fruit and

nut crops and ornamentals. Specific directions for

use under local conditions and a list of approved

crop uses can be obtained from State experiment

station specialists.

Calcium cyanamide is useful in controlling

germinating weeds and young emerged weeds in

plantings of many vegetable, fruit, and nut crops.

It is also a source of readily available nitrogen for

crops. Uses are specialized and local recommendations should be obtained from State experiment

station specialists.

VEGETABLES

More than 50 vegetable crops are grown commercially in the United States. Chemical weedcontrol methods can fill a critical need in their

production. Examples of effective chemical

methods are given in table 5.

TABLE 5.—Weed control in vegetables

[For herbicide tolerances, see Appendix]

TABLE 5.—Weed control in vegetables—Continued

Pounds of

Crop and herbicide active Time of application

ingredient

per acre

Beans, lima:

Amiben 2 Preemergence.

CDAA 4 Do.

CDEC 6 Do.

CIPC 2-6 Do.

Dalapon 6 Spring preplanting

soil treatment

4-5 weeks before

planting.

DNBP (alkanola- 3-9 Preemergence.

mine salt).

Trifluralin

Beans, pole:

CIPC

0.75 -- Preplant, soil incorporated.

Crop and herbicide

Pounds of

active

ingredient

per acre

Time of application

2-6 Preemergence.

Dalapon 6 Spring preplanting

soil treatment

4-5 weeks before

planting.

EPTC 3 Preplant, preemergence, postemergence, soil

incorporated.

Beans, snap:

CDAA 4 Preemergence.

CDEC 6 Do.

CIPC 2-6 Do.

Dalapon 6 Spring preplanting

soil treatment

4-5 weeks before

planting.

DCPA 6-10.5 Preemergence.

DNBP (alkanola- 3-9 Do.

Artichokes, diuron 3.2 Apply in fall or mine salt).

early winter EPTC . 3-4 ._ Preplant, preafter final culti- emergence, postvation. emergence, soil

Asparagus: incorporated.

Amiben 3 Preemergence. Trifluralin . 0.75 ._ Preplant, soil

Dalapon 7-14 Preharvest, postharvest. Beets:

incorporated.

Diuron 3.2 During winter dor- Endothall . 6.5 ._ Preemergence.

mancy, early pre- Pyrazon - 4 __ Preemergence, postemergence (at emergence; see

least 4 weeks area restrictions

before emergence), on label.

or after harvest. Sodium chloride. _.. 200-300__ __ Postemergence.

Monuron l-3.2_._ Preharvest, postharvest.

TCA (sodium

salt).

6-9 __ Preemergence.

Sesone 2-5.5_-_ Do. Broccoli:

Simazine 2-4 Do. CDEC . 4-8 __ Preplant, pretrans2 Preemergence after

disking in early

plant, posttransplant.

spring on estab- DCPA . 10.5 __ Preemergence, postlished bed or transplant.

after postharvest FW-925 . 6 __ Preemergence, postdisking. emergence, post2,4-D (sodium 1 Postemergence on transplant.

salt). seedlings. Trifluralin _ 0.75-l__- __ Preplant, pretrans2.5 During harvest 2

applications 1

month apart; Brussels sprouts:

plant, soil incorporated.

postharvest in CDEC _ 6-8 __ Preemergence, postestablished ferns; emergence, preuse drop nozzles transplant, postfor directed spray. transplant.
38 AGRICULTURE HANDBOOK 3 3 2, U.S. DEPT. OF AGRICULTURE

TABLE 5.~Weed control in vegetables—Contmned TABLE 5.—Weed control in vegetables—Continued

Pounds of

Crop and herbicide active

ingredient

per acre

Time of application

DCPA 10.5_-.

Trifluralin 0.75-1-

Cabbage:

CDAA 4-6_

CDEC 4-8_.

DCPA 10.5_

FW-925 6-__.

Trifluralin 0.75-1.

Cantaloup :

CDEC 4

DCPA 1Ö.5"

NPA (sodium 2-6_

salt).

Caraway, Stoddard (0-

solvent.

Carrots:

CIPC 2-6

DCPA 10.5

Preemergence, posttransplant.

Preplant, pretransplant, soil incorporated.

Preemergence, posttransplant.

Preplant, preemergence, pretransplant, posttransplant.

Preemergence, posttransplant.

Preemergence, postemergence,

posttransplant.

Preplant or pretransplant, soil

incorporated.

Preemergence.

Do.

Do.

Preemergence, postemergence.

Linuron_

Stoddard solvent (0

Cauliflower:

CDEC 4-8

Do.

— Seed crop only at

planting or

transplanting.

1-2 Preemergence, postemergence.

Do.

DCPA 6-10.5_

FW-925 6

Trifluralin 0.75-1 _

Celery :

CDAA___ 4

CDEC 4-6_

Preplant, preemergence, pretransplant, posttransplant.

Preemergence,

posttransplant.

Preemergence,

postemergence,

posttransplant.

Preplant, soil incorporated for transplants.

___ Posttransplant.

Preemergence,

posttransplant.

^^^^ 7 Posttransplant.

Stoddard solvent-- (i) Preemergence, postai • ^^^^ emergence.

Chicory, CDEC 4 Preemergence.

Collards:

CDEC 4 Do.

CIPC 1-2 " Do.

DCPA 10.5 Do.

Crop and herbicide

Pounds of

active Time of application

ingredient

per acre

Corn, sweet:

Atrazine. _

CDAA

CDAA plus

TCBC.

CDEC

Cypromid- _

3-4 Preemergence at

planting time; do

not plant atrazinesensitive crops in

rotation.

4 Preemergence.

1.25 + 2.5_-_ Do.

Dalapon 1.5-

DNBP (alkanolamine salt).

Linuron

Propachlor

6 Do.

1.5 __ Postemergence

directed spray

when crop is 8 in.

tall to lay-by; do

not feed foliage or

stalks.

Postemergence as

directed spray

when corn is 8-20

in. tall; do not use

on corn grown for

seed.

7.5-9 Preemergence.

Simazine2,4-D_

2,4-DEP_

Cress, upland, CIPC.

Cucumbers:

CDEC

NPA (sodium

salt).

Dill, Stoddard

solvent.

Eggplant, DCPA

Endive, CDEC

Escarole, CDEC

Garlic :

CIPC

DCPA

Hanover salad:

CDEC

CIPC

Kale:

CDEC

CIPC

DCPA

Lentils:

Barban

1-2.5 Do.

5 Preemergence; do

not feed treated

forage.

2-4 Preplant, preemergence, soil incorporated.

[1.5 Preemergence on clay

I soils.

\0.25-0.75— Postemergence before corn reaches

24 in. tall.

6 Immediately after

planting.

2 Preemergence.

4 Do.

2-6 Preemergence, posttransplant.

(0 Preemergence, postemergence.

10.5 Transplant, lay-by.

4 Preemergence.

4 Do.

2-4 Preemergence, postemergence.

6-10.5 Preemergence,

transplant.

4 Preemergence.

1-2 Do.

4___.

1-2..

10.5-

Do.

Do.

Do.

0.4 Postemergence for

wild oats control;

do not graze pea

stubble.

See footnote at end of table. See footnote at end of table.
SUGGESTED GUIDE FOR WEED CONTROL 196'9 39

TABLE 5.—Weed control in vegetables—Continued TABLE 5.—Weed control in vegetables—Continued

Pounds of

Crop and herbicide active Time of application

ingredient

per acre

Pounds of

Crop and herbicide active Time of application

ingredient

per acre

Diallate_

IPC___

Lettuce:

Benefin_

1.5 Preplant, preemergence, soil incorporated.

4 Preplant.

CDEC_

CIPC

IPC

Lettuce, head,

DCPA.

Lettuce, leaf, DCPA.

Mint:

Diuron

DNBP (alkanolamine salt).

Mustard greens:

CDEC

DCPA

Okra:

CDEC

Diphenamid

1.1 Preplant, soil incorporated ^-3 weeks

before planting

seed; observe label

precautions on

feeding to livestock

and on crop

rotation.

2-4 Preemergence, pretransplant.

3 Preemergence.

3-4.5 Do.

10.5 Apply 1-6 weeks

after seeding.

10.5 Apply 1-3 weeks

after emergence.

1-2 Preemergence.

3-4.5 Do.

4___.

10.5_

Do.

Do.

Trifluralin_

Onions:

CDAA

CIPC__

DCPA.

KOCN_

Monuron

Parsley, Stoddard

solvent.

Parsnips:

Linuron

Stoddard solvent.

Peas:

Barban

4 Do.

5 Preemergence at

planting.

1 Preplant, soil

incorporated.

6 Preemergence, postemergence.

4-8 Do.

10.5 Preemergence, posttransplant.

16-20 Preemergence, postemergence.

1.6 Do.

(0 Preemergence.

1.5 Postemergence.

(0 Preemergence, postemergence.

0.4.

CDAA_

CIPC._

4___

4-6_

Dalapon 0.7.

Postemergence for

wild oats control;

do not graze pea

stubble.

Preemergence.

Preplant, preemergence, soil incorporated.

Apply after peas are

2-6 in. tall and

have 4-6 nodes;

do not apply within

25 days of harvest;

do not feed vines

to livestock.

DNBP (alkanolamine salt).

IPC

MCPA (amine or

sodium salt).

Diallate 1.3 Preplant, soil incorporated or

preemergence,

soil incorporated;

do not graze unharvested crop.

Í6-9 Preemergence.

11.5-2 Postemergence.

- 4-8 Preplant, postemergence.

0.75 Postemergence as

prebloom.

MCPB 0.25-0.75. _. Early postemergence.

2,4-DB 1.5 Apply when peas

have 4-6 nodes of

growth before

blooming; do not

graze or feed

forage within 30

days.

Peas, southern:

DCPA 6-10.5 Preemergence.

Trifluralin 0.25-1 Preplant, soil incorporated.

Peppermint :

Diuron 2.4 Last cultivation

before emergence.

Terbacil 0.8-1.6 Single preemergence

application in

spring after last

cultivation.

Peppers:

Amiben 3-4 At transplanting or

lay-by.

CIPC 6 Preemergence.

DCPA 6-10.5 Posttransplant.

Diphenamid 5 Immediately after

seeding or within

1 month after

transplanting.

Trifluralin 1 Pretransplant.

Potatoes:

CDAA 3-4 Preemergence, layby.

CDEC 3 Preemergence at

planting.

Dalapon 3-11 Preplant, preemergence, lay-by.

DCPA 6-10.5 At planting.

Diallate 2 Preplant, soil incorporated.

Diphenamid 4-6 Immediately after

planting.

DNBP (alkanol- 3-6 Preemergence.

amine salt).

EPTC 3-6 Preplant, soil incorporated, drag-off,

lay-by incorporated.

Linuron 1 Preemergence.

Sesone 3.6 Premergence, postemergence, lay-by.

2,4-D 2 Preemergence.

2,4-DEP 4 After clean cultivation at lay-by.

See footnote at end of table.
40 AGRICULTURE HANDBOOK 332, U.S. DEPT. OF AGRICULTURE

TABLE 5.—Weed control in vegetables—Continued

Pounds of

Crop and herbicide active Time of application

ingredient

per acre

Pumpkins:

Amiben

NPA (sodium

salt).

Radish, CIPC__

Spinach:

CDEC

3-4 Preemergence.

4 Do.

2 Do.

CIPC.

IPC__

Squash, summer and

winter:

Amiben

DCPA

Sweetpotatoes :

Amiben

CDAA

DCPA

Diphenamid_

EPTC

Tomatoes:

Amiben,

CDAA_

CDEC_

CIPC__

DCPA

Diphenamid_

PebulateTrifluralin_

Turnip greens:

CDEC__

CIPC

DCPA

Turnips:

CDEC

DCPA

Watermelons, NPA

(sodium salt).

2-4 Preemergence,

postemergence.

1-2 Preemergence.

3-6 Preemergence, postemergence.

3-4 Preemergence.

10.5-_ Apply 4-6 weeks

after seeding

preceded by clean

cultivation.

3 At transplanting.

4 Posttransplant.

6-10.5- Do.

4-6 At transplanting.

7.5 Do.

3-5 Postemergence after

clean cultivation.

3 Preemergence to

direct seeded.

6 Within 2 days after

transplanting.

4-6 Preemergence, posttransplant.

4 Postemergence at

lay-by; granular

formulation only.

10.5 Preemergence.

4-6 Immediately after

seeding or within

1 month after

transplanting.

4 Pretransplant or

posttransplant,

soil incorporated.

1 Preplant, soil incorporated for

transplants or

postemergence on

direct seeding.

4 Preemergence.

1-2 Do.

10.5 Do.

4 Do.

10.5-. Postemergence.

2-6 Preemergence, posttransplant.

50-100 gal. per acre.

DECIDUOUS TREE FRUITS AND NUTS

Many different cultural methods and combinations of methods are used in deciduous tree

fruit and nut crop production. Principal among

these are sod culture, strip sod and cultivation,

and clean cultivation.

Herbicides are being used effectively on several

of these crops. In certain of the nut crops, bare

soil culture is maintained with herbicida] oils. Sod

culture is often combined with the use of herbicides

to control perennial woody and annual herbaceous

weeds not controlled by mowing. Clean cultivation

may be conveniently combined with herbicide

treatments to control germinating weed seed and

sprouting perennial weeds so as to extend the

periods between cultivations and thereby minimize

root and trunk injury.

Examples of herbicides that have proved useful

on deciduous tree fruit and nut crop plantings in

some regions are presented in table 6. They indicate the general areas of usefulness of herbicides

for these crops. Specific rates and methods for

safe and effective local use are available from

weed research specialists in State agricultural

experiment stations.

TABLE 6.—Weed control in deciduous tree fruits and

nuts

[For herbicide tolerances, see Appendix]

Pounds of

Crop and herbicide active Time of application

ingredient

per acre

TREE FRUITS

Apples :

AMS 154 In wetting spray to

poison ivy in full

leaf.

Dalapon 11 As spot spray around

base of trees over

4 years old to

control grass.

Dichlobenil 4-6 Early spring or after

clean cultivation.

Diphenamid 6 After clean cultivation but not within

90 days of harvest.

Diuron 3.2 Winter or spring.

DNBP (butyl- 1.9 Coarse spray to

phenol). ground cover when

weeds are small.

Simazine 2-4 In spring before

weeds emerge.

Terbacil 1-3.2 Single directed spring

application before

weeds emerge in

orchards established at least 3

years.

2,4-D (acid or 2 Directed spray on

oil-soluble young weeds,

amine).

See footnotes at end of table.
SUGGESTED GUIDE FOR WEED CONTROL 196'9 41

TABLE 6.—Weed control in deciduous tree fruits and TABLE 6.—Weed control in deciduous tree fruits and

nuts—Continued nuts—Continued

Crop and herbicide

Pounds of

active

ingredient

per acre

Time of application

TREE FRUITS—Continued

Apricots:

Aromatic oil P) Directed spray on

emulsion. young growing

weeds.

Dalapon___ 11 As spot spray around

base of trees when

weeds are small.

Cherries :

Dichlobenil 4-6 Granules preemergence to weeds.

Simazine 2-4 Soil treatment in

late fall or early

spring on dormant

crop more than 1

year old.

Olives:

Aromatic oil (2) Directed spray on

emulsion. young growing

weeds.

Diuron 1.6 Split application fall

and spring.

Simazine 2-4 Broadcast single

directed application to soil before

weeds emerge;

apply in late fall

or midwinter.

Peaches:

Aromatic oil (2) Directed spray on

emulsion. young growing

weeds.

Dalapon 11 Spot spray on growing grass when

weeds are small.

Dichlobenil 4-6 Granules in early

spring.

Diphenamid 6 After clean cultivation, not within 90

days of harvest.

DNBP (butyl- 1.9 Directed coarse

phenol). spray to ground

cover when weeds

are small.

Simazine 4 As soil application

around established

trees before weeds

emerge; after harvest to early spring.

Terbacil 1-3.2 Single directed

spring application

before weeds

emerge in orchards

established at

least 3 years.

Pears:

AMS .-- 1 54 In wetting spray to

poison ivy in full

leaf.

Aromatic oil (2) Directed spray on

emulsion. young weeds.

Crop and herbicide

Pounds of

active

ingredient

per acre

Time of application

TREE FRUITS—Continued

Dalapon 11 Spot spray on growing grass when

weeds are small.

Dichlobenil 4-6 Granules in early

spring.

Diuron 3.2 Directed spray in

winter or spring or

as split application at 3/2 rate in

fall and spring.

DNBP 1.9 Directed coarse

spray on ground

cover.

Simazine 4 Directed spray during dormancy on

well-established

trees.

2,4-D (acid or oil- 2 Directed spray on

soluble amine). young weeds.

Plums:

Aromatic oil (2) Directed spray on

emulsion. young growing

weeds.

Dalapon 11 Spot spray on growing grass when

weeds are small.

Dichlobenil 6 Granules in early

spring.

DNBP 1.9 Directed coarse spray

on ground when

weeds are small.

Simazine (prunes) _ 4-6 For annual broadleaf

and grass weeds

apply preemergence or on clean

cultivated soil in

early spring; for

perennials apply

granule formulation only from

Nov. 15 to Jan. 1.

TREE NUTS

Almonds, aromatic (2) Directed spray on

oil emulsion. young growing

weeds.

Walnuts, English:

Aromatic oil (2) Directed spray on

emulsion. young growing

weeds.

Diuron 4 Late fall or early

spring in wellestablished plantings or as split

applications in

late fall and early

spring.

See footnotes at end of tabli'

1 In 100 gal. water.

2 40-100 gal. per acre.
42 AGRICULTURE HANDBOOK 3 32, U.S. DEPT. OF AGRICULTURE

CITRUS AND SUBTROPICAL FRUITS AND

NUTS

Citrus and subtropical fruit and nut crops

include all citrus crops, avocados, dates, macadamia nuts, pineapples, and many other crops.

Weed problems are many and varied because of

the wide distribution of these crops, their perennial

nature, and the variety of cultural practices used.

Weeds waste irrigation water in plantings of many

of these crops. Weeds also harbor insects, diseases, nematodes, and rodents that cause severe

economic losses.

Herbicides used in combination with mechanical

cultivation are economical, effective, and convenient to use. In many instances damage caused by

close cultivation can be avoided and the periods between cultivations lengthened by using herbicides.

Aromatic oil emulsions have been used effectively for more than 20 years in many citrus

orchards in the West without reducing fruit yield

and quality or visibly injuring the groves with

respect to tree physiology or soil structure. Newer

organic chemical herbicides have been developed and are proving useful in areas where oils

cannot be used and on weeds not controlled by

oils. Many additional promising new herbicides

are being investigated for use on these crops.

Examples of herbicides that have proved useful

on citrus and subtropical fruit and nut crops in

some regions are presented in table 7. They show

the general areas of usefulness of herbicides for

these crops. Specific rates and methods for safe

and effective local use are available from weed

research specialists in State agricultural experiment stations.

TABLE 7.—Weed control in citrus and subtropical

fruits and nuts

[For herbicide tolerances, see Appendix]

Crop and herbicide

Pounds of

active

ingredient

per acre

Time of application

Avocados:

Aromatic oil (i) Directed spray on

emulsion. young growing

weeds.

Dichlobenil 6 Directed spray after

clean cultivation

in early spring.

Monuron 1.6 Soil treatment in

spring and fall

under well-established trees in

California (selected areas only).

See footnote at end of table.

TABLE 7.—Weed control in citrus and subtropical

fruits and nuts—Continued

Crop and herbicide

Pounds of

active

ingredient

per acre

Time of application

Simazine 2-4_

Bananas, diuron_

2.4 _

4.8_

Citrus (grapefruit,

lemons, oranges) :

Aromatic oil (0_

emulsion.

8_

Bromacil (grapefruit, oranges). 6.4_

Dalapon (grapefruit, limes,

oranges, tangerines) .

Dichlobenil 4-6_

Diuron 1.6_

Apply to orchard

floor before weeds

emerge, following

ñnal preparation

of grove.

Directed spray after

planting.

Directed spray in

established plantings and repeat

once after 6 weeks.

Directed spray on

young growing

weeds.

Restricted to commercial groves

established 2 years

in Texas; use as

single directed

spot spray during

growing season

each year for 2

years only; observe all precautions on reuse and

crop rotation.

Restricted to Arizona

and California; use

as single directed

spot spray from

winter to early

summer in commercial groves

established 2 years;

observe all precautions on reuse and

crop rotation.

Directed spot treatment for grass

control.

Restricted to nursery

and nonbearing

stock only; apply

directed spray to

soil and incorporate around

crop established 1

or more years

after transplanting.

Soil treatment in

fall and spring in

groves established

1 year or more in

Arizona and California (selected

areas only).

See footnote at end of table.
SUGGESTED GUIDE FOR WEED CONTROL 196'9 43

TABLE 7.—Weed control in citrus and subtropical

fruits and nuts—Continued

Pounds of

Crop and herbicide active

ingredient

per acre

Time of application

Simazine_

l9.6_

f4-8_

TerbaciL 3.2_

Dates, aromatic oil (0-

emulsion.

Limes, aromatic oil (0-

emulsion.

Macadamia nuts:

Dalapon 9__

Diuron 2-4_

Simazine or

atrazine.

2-4 _

Mangoes, dichlobeniL 6_

Olives, diuron 1.6_

Pineapples:

Atrazine 6.4 _

During rainy season

on established

plantings of lemons

in Arizona and

California.

Oranges in Texas

and Florida.

Grapefruit and

oranges in Texas

only; single

directed spring

application before

weeds emerge in

groves established

at least 2 years.

Arizona and California only;

single directed

spring application

before weeds

emerge in groves

established at

least 2 years.

Directed spray on

young growing

weeds.

Do.

On established grass

before crop harvest and after

gleaning nuts.

Soil treatment;

directed spray

immediately after

harvest.

Soil treatment before harvest and

after gleaning nuts.

Directed spray in

early spring or

after clean cultivation.

Directed spray in

late fall and repeated in early

spring.

Broadcast treatment

immediately after

planting or split

application at 1-2

month intervals

but not later than

160 days before

harvest; observe

label precautions

on feeding foliage

to livestock.

TABLE 7.—Weed control in citrus and subtropical

fruits and nuts—Continued

Pounds of

Crop and herbicide active

ingredient

per acre

Time of application

Bromacil 4.8 _

r6.4_

1.6_

Diuron.

Monuron 1.6-3.2.

Simazine 3.2-4_

Use restricted to

Hawaii; apply

immediately after

planting; observe

label precautions

on crop rotation.

Immediately after

planting.

Postemergence and

repeat at minimum

of 2-month intervals using not

more than 12.8

lb. per year.

Soil treatment immediately after

planting or after

harvest.

Do.

See footnote at end of table.

140-100 gal. per acre.

SMALL FRUITS

Small fruits include cane fruits, cranberries,

grapes, and strawberries. Highly specialized

weed-control methods are required because of the

different growth habits and stature and the

perennial nature of these crops. Many weed

species must be controlled in summer and winter

in many production areas.

Parts of these crop plants are above ground

at all times. It has therefore become a general

practice to use directed, coarse, low-pressure

sprays that avoid herbicide contact with the

crop wherever possible. In some crops, such

as cranberries and strawberries, the use of directed

sprays is not possible. Here highly selective

herbicides such as granular formulations are

most useful.

Examples of herbicides that have been used

successfully on small fruit crops in some production

areas are given in table 8. Specific rates and

methods of application are not given, because

climate, soil composition, cultural practice, and

crop variety affect performance, selectivity, persistence, and injurious effects of herbicides.

Specific recommendations for safe and effective

local use of herbicides based on local research

are available from weed specialists in State

agricultural experiment stations.
44 AGRICULTURE HANDBOOK 332, U.S. DEPT. OF AGRICULTURE

TABLE 8.—Weed control in small fruits

[For herbicide tolerances, see Appendix]

TABLE 8.—Weed control in smallfruits—Continued

Crop and herbicide

Pounds of

active

ingredient

per acre

Time of application

Blackberries:

CIPC 2-6 Soil treatment in

dormant crop.

Í1-2 Soil treatment in

-p.. I dormant crop 1

Umron year old or more.

[2.4 Directed spray in late

winter or as split

application in late

fall and spring.

Simazine 2-4 During crop dormancy.

Blueberries:

CIPC 6-12 Do.

Diuron 1-2 Soil treatment in

dormant crop 1

year old or more.

2,4-D 3 Before burn during

dormancy.

Boysenberries, 2.4 Directed spray in

diuron. late winter or as

split application in

late fall and spring.

Cranberries:

CIPC 8_

Dalapon 8.'

Dichlobenil 2-6_

Ferrous sulfate 800_

Simazine 2-4_

2,4-D _

/'l-2_

Gooseberries, diuron.^ 2.4_

Grapes :

CIPC_ 10-14_

Dalapon 15_

Postharvest during

dormancy.

Postharvest as directed spot spray

on growing grasses.

Granules, prebloom

or postharvest.

Spring to midsummer.

Soil treatment in

dormant crop in

Massachusetts

only.

During dormancy of

crop; broadcast

before white bud

stage or apply

0.25-percent

water solution on

weeds with swab.

Broadcast during

dormancy after

drawing down

winter flood.

Soil treatment in

dormant crop 1

year old or more

in early winter.

Directed spray in late

winter or as split

application in late

fall and spring.

Directed spray in

early spring on

dormant crop.

Directed spot spray

on growing grass

during vegetative

growth of crop.

Crop and herbicide

Pounds of

active

ingredient

per acre

Time of application

Diuron_

l-2_

4.8_

9.6_

DNBP (alkano- 1.25_

lamine salt).

Simazine 2-4_.

Loganberries,

diuron.

Raspberries:

CIPC

2.4_

Diuron.

2-6 _

1-2 _

2.4_

Simazine 2-4_

Strawberries:

Chloroxuron 4

CIPC l-3_

DCPA 9___

Diphenamid 6

Soil treatment in

dormant crop

established at

least 3 years.

Directed spray in

well-established

plantings or 1.6

lb. per acre as

split application

in late fall and

early spring.

Directed spot spray in

established plantings on heavy soils

once in 4 years.

Dormant application

to ground under

trellis.

Soil treatment from

late fall to early

spring on crop

established at

least 3 years.

Directed spray in

late winter or as

split application

in late fall and

spring.

During crop

dormancy or at

planting.

Soil treatment in

early winter on

dormant crop

established at

least 1 year.

Directed spray in

late winter or as

split application

in late fall and

spring.

During crop

dormancy.

Apply in fall after

renovation of beds

and repeat once in

spring at least 60

days before

harvest.

During dormancy

to control

established and

germinating

chickweed.

Soil treatment after

transplanting or

lay-by cultivation.

After row establishment or 2-6 weeks

after transplanting; 1 year before

harvest only; do

not apply within

60 days after

harvest.
SUGGESTED GUIDE FOR WEED CONTROL 196i9 45

TABLE 8.—Weed control in smallfruits—Continued

Pounds of

Crop and herbicide active Time of application

ingredient

per acre

DNBP (amine 3-4.5 During dormancy in

salts). early spring or

after harvest in

Northwestern

States only.

EPTC 4 New beds—1 month

after planting ;

old beds—following clean

cultivation after

harvest.

Sesone 3-4 Soil treatment after

transplanting and

postharvest avoiding flowering and

fruiting period.

Simazine 1 3-4 weeks after

planting.

2, 4-D 1.5 Spray young growing

weeds after

harvest.

2,4-DEP 4 Preplant or posttransplant in

nonharvest year;

postharvest in

production fields.

ORNAMENTAL PLANTS

Ornamental plants, including shade trees

shrubs, herbaceous annuals and perennials, and

bulb crops, form the bulk of plant species in horticultural crops. Some ornamental genera include

numerous species and many varieties. Weed problems are widely different because of the mdividual

soil, climatic, and cultural requirements of many

of these plants. The number of herbicides available

for home or other landscaped plantings is limited

because many kinds of plants are grown together.

Weeds in commercial plantings of individual

species or varieties are controlled by mechanical

cultivation, hand weeding, herbicides, cultural

practices including rotations, and various combinations of these methods.

Ornamental plant families, genera, species, and

even varieties respond differentially to herbicides.

Great care is therefore necessary in selecting and

using herbicides on them. As a result, soil fumigant herbicides are used in many nurseries. Soil

fumigant herbicides are applied, kill many annual

and perennial weeds, and are dissipated before

planting the crops. Most crops can be planted

within a few days after fumigants have been used.

General use of soil fumigant herbicides is restricted

by the cost of material and time required for treatment. Comparatively low-cost selective herbicides

are therefore often used to control specific groups

of weeds.

Examples of herbicides that are useful on

ornamentals in certain regions are presented in

table 9. These examples indicate the general areas

of herbicide usefulness and their potential value

in these crops. Specific rates and methods for safe

and effective local use are available from weed research specialists in State agricultural experiment

stations.

TABLE 9.^—Weed control in ornamental plants

Herbicide

Pounds of

active

ingredient

per acre

Tolerant plants

CDEC 4-6_

CIPC 6-10_

DCPA 10-15.

- _ Use directed spray or granules

on soil in established ornamental plantings: Azalea,

euonymus, gladiolus, iris,

juniper, Poteniilla, privet,

spirea, yew.

._ Use directed spray or granules

on soil in established

plantings: Arborvitae, aster,

Astilbe, azalea, balsam,

barberry, birch, bluebell,

boxwood, camellia, carnation, cedar, chrysanthemum,

columbine, coralbell, creeping juniper, dahlia,

delphinium, dianthus,

Dutch iris, English ivy,

forget-me-not, forsythia,

fuchsia, gladiolus, honeysuckle, hydrangea, laurel,

lilac, lily, magnolia,

Mahonia, maple, mockorange, narcissus, pachysandra, peony, periwinkle,

poplar, privet, rhododendron,

rose, spirea, tulip, viburnum,

wintercreeper, yew.

. _ Use directed spray or granules

on soil in established ornamental plantings: Ageratum,

alyssum, aster, azalea,

babysbreath, barberry,

bleedingheart, candle larkspur, chrysanthemum,

coleus, columbine, coralbell,

dahlia, euonymus, eveningprimrose, feverfew, forgetme-not, forsythia, gladiolus,

golden marguerite, lantana,

lupine, marigold, moss rose,

mourning bride, mourning

pinks, petunia, pokerplant,

purple coneflower, rose,

salvia, scarlet sage, snapdragon, variegated privet,

verbena, yew, zinnia.
46 AGRICULTURE HANDBOOK 332, U.S. DEPT. OF AGRICULTURE

TABLE 9.—Weed controlin ornamental plants—Con. TABLE 9.—Weed control in ornamental plants—Con.

Pounds of

Herbicide active

ingredient

per acre

Tolerant plants

Pounds of

Herbicide active

ingredient

per acre

Tolerant plants

Dichlobenil 4-6 (annual

weeds) ;

6-8

(perennial

weeds).

Use spray or granules in

nursery or landscape plantings; do not treat within 4

weeks of transplanting:

Amur corktree, arborvitae,

ash, azalea (kurume, mollis,

hardy hybrid types, and

hardy native species only),

barberry, beautybush, birch,

boxelder, boxwood, camellia,

Caragana, Cleyera japónica,

cotoneaster, cottonwood,

crabapple, deutzia, dogwood,

eastern red cedar, elm

(American, Chinese), Elwood cypress, euonymus,

flowering almond, flowering

quince, forsythia, gardenia,

golden-rain-tree, hackberry,

heather, holly (except Ilex

crenata L., rotunda L.,

vomitoria Ait.), honeysuckle,

ivy, juniper, kinnikinnick,

laurel, leucothoe, lilac, linden,

locust, magnolia, maple,

mockorange, mountain-ash,

nandina, Qak, osmanthus

(hoUyolive), pachistima,

photinia, pine, pittosporum,

podocarpus, poplar, privet,

pyracantha, rhododendron,

rockrose, rose, Russian-olive,

spirea, spruce, squawcarpet,

viburnum, weigela, willow,

yew.

Diphenamid-- 4-6 Use directed spray or granules

on soil in established ornamental plantings: Evergreen,

deciduous trees.

DNBP (alka- 10.5 Use directed spray or granules

nolamine on soil in established ornasalt). mental plantings: Dahlia,

Dutch iris, gladiolus, lilac,

lily, narcissus, privet, spirea,

tuHp, yew.

Neburon 4 Use directed spray or granules

on soil in established plantings: Arborvitae, Chamaecyparis, euonymus, firethorn,

forsythia, honeysuckle,

juniper, pine, privet, yew.

WEED CONTROL IN HORTICULTURAL

PLANT BEDS AND NURSERIES

The growing of vegetable and ornamental

transplants in plant beds and nurseries is a major

horticultural industry. Seeds are planted in

open fields in the South and in hotbeds in the

cooler areas. High rates of seeding are used and

weeds that emerge with the crops cannot be removed mechanically. Weed separation and removal by hand are diflBcult and time consuming.

NPA (sodium 4-6.

salt).

Sesone 3-3.6-

Simazine 2-3_

Stoddard (0-

solvent.

Trifluralin 0.5-1.

Use directed spray or granules

on soil in established ornamental plantings: Azalea,

cottonwood, holly, maple,

plum, rhododendron.

Use directed spray or granules on soil in established

plantings: Arborvitae, balsam, barberry, bayberry,

camellia, cedar, crabapple,

daffodil, dahlia, elm, forsythia, gladiolus, heather,

hemlock, honeysuckle, hydrangea, iris, juniper,

laurel, lilac, lily, maple,

mockorange. Picea, pine,

redcedar, rose, spirea,

spruce, viburnum, white

birch, yew.

Use directed spray on soil in

established ornamental

plantings: American elm,

arborvitae, Austrian pine,

barberry, blue spruce, boxelder, boxwood, bushhoneysuckle, Caragana,

cotoneaster, dogwood,

Douglas-fir, Fraser fir, hemlock, honeylocust, juniper,

Mahonia, mugo pine,

multiñora rose, Norway

spruce, redcedar, red oak,

red pine, red spruce, rose,

Russian-olive, Scotch pine,

Siberian elm, white-cedar,

white pine, white spruce,

yew.

In directed spray on emerged

weed seedlings between

rows: Most ornamentals.

In directed spray or granules

on soil in established plantings of gladiolus, many

other ornamentals.

50-100 gal. per acre.

Plants involved include tomatoes, peppers, eggplant, celery, petunias, marigolds, and many other

vegetable and ornamental plants.

Large numbers of ornamental plants are vegetatively propagated from cuttings. Weeds are

difficult and expensive to control in slathouses,

coldframes, and liner plantings in the field.

Plants propagated vegetatively include azaleas,

camellias, rhododendrons, pyracantha, and holly.

Weed seed and the underground parts of

perennial weeds in coldframes, hotframes, and
SUGGESTED GUIDE FOR WEED CONTROL 196i9 47

slathouses are usually controlled by soil fumigation. Field plantings of large populations of plants

often include soil fumigation as a preparatory

measure. Cultural practices, including selected

rotation procedures, should supplement the use of

herbicides.

TABLE 10.—Weed control with sou fumigant herbicides in horticultural plant beds and nurseries

Herbicide

Pounds of

active Method of application after

ingredient preparation of soil for planting

per 100

sq. ft.

Calcium

cyanamide.

9.8_

i6.1_

Methyl l-2_

bromide.

SMDC 0.7-l__.

Plant beds; use split application to newly worked soil

90 days before planting or

60 days before freezing in

fall; work first half of

treatment into top 3 in. of

soil and rake second half of

treatment into surface

layer of soil.

Compost and top soil; mix

thoroughly with moist

screened compost as it is

placed in soil bin or pile;

wait 6 weeks before using.

Cover soil with plastic sheet,

inject methyl bromide

under plastic, allow soil to

remain covered 24-48

hours, remove cover, and

aerate 72 hours or longer

before planting.

Apply with sprinkling can or

hose proportioner; mix

herbicide to depth of 5-6

in. ; sprinkle-irrigate immediately to desired depth

of control; plant 14-30

days after treatment depending on soil composition

and moisture content.

1 Per cubic yard.

Soil fumigant herbicides and their use are described briefly in table 10. Specific details for

effective use of fumigants under local conditions

are available from weed research specialists in

State agricultural experiment stations.

WEED CONTROL IN GREENHOUSES

Weeds in greenhouse bench and potting soils

and under the benches generally can be controlled

with herbicides and by steam sterilization.

Weeds in bench and potting soils can be controlled with soil fumigant herbicides, such as

methyl bromide or SMDC, before the soil is

brought into the greenhouse or potting room.

Rates and methods of using these herbicides are

briefly described in the preceding discussion on

weed control in plant beds and nurseries. Specific

details for use are given by the manufacturers,

and information on techniques for specific problems can be obtained from weed research specialists

in State agricultural experiment stations.

Weeds under the benches and around pots in the

benches can be controlled by using a coarse spray

of Stoddard solvent. The weeds should be small

at the time of treatment. A complete spray

coverage of the weed foliage is necessary. Direct

the spray to avoid contact with the foliage or

stalks of crop plants or move the pots from the

bench area during spraying. Keep fresh air

moving into the greenhouse during treatment and

for 2 to 4 hours thereafter.

Great care must be exercised to avoid crop

injury when herbicides are used in maintenance

programs in greenhouses. Crop injury may result

from using volatile herbicides that produce

generalized effects on all plants or from persistent

herbicides that remain in soils for long periods.

Stoddard solvent is suggested for greenhouse use

because it avoids these hazards. It will kill many

species of young growing broadleaf weeds and

weed grasses within a few hours after application

and does not leave a chemical residue.

WEED CONTROL IN FORAGE CROPS, PASTURES, AND RANGELANDS

Weeds, including brush, are undesirable in

forage crops and grazing lands because they

reduce production of palatable forage, some

injure livestock through needles and thorns,

many are poisonous, others impart undesirable

flavors in milk, and in general they reduce the

quantity and quality of animal products. Improved crop-production practices, including proper

fertilization, drainage of soils where necessary,

judicious mowing and grazing practices, and

disease and insect control, contribute to the

vigor of forage plants, which, in turn, aid in

preventing weed problertis and in some cases will

reduce weed populations. This is particularly

true for many annual weeds developing from

new seedlings each year.

Some weed species, however, are favored by

the same conditions responsible for vigorous

growth of forage plants; for example, curly dock

and chickweed are favored by high fertility in

humid regions. Woody plants tend to dominate

the vegetation and must be removed to achieve

efficient production of forage. Most woody plants

will not yield to ordinary management practices.

In addition, many persistent perennial weeds

will not succumb to the known agronomic practices within a reasonable time. Often mechanical

methods are used to control woody weed species.
48 AGRICULTURE HANDBOOK 3 32, U.S. DEPT. OF AGRICULTURE

Fortunately selective herbicides are now available that will aid in dealing with many of these

problems. By killing unwanted species, they may

hasten the succession to more desirable plants.

By selective control of the undesirable species,

along with improved grazing practices, the recovery of native forage plants and other desirable

species may be greatly speeded. Many pastures

and rangelands are so depleted of desirable

species that a long time would be required for

natural succession to take place if only improved

grazing management is practiced. Here seeding

adapted forage species may be necessary.

The herbicides MCPA, silvex, 2,4-D, and

2,4,5-T are not poisonous to livestock, wildlife,

or man at the application rates used to control

weeds in forage crops, pastures, and rangelands

and do not injure most forage grasses. If no

poisonous plants are present in the treated area,

livestock other than milk cows need not be

removed during or after application. Milk cows

should be removed from the pastures for a week

after spraying because of possible residues in the

milk. If poisonous weeds or poisonous woody

plants are known to occur in pastures or on rangelands, remove the livestock from the area for at

least 3 weeks after treatment. Several herbicides,

including MCPA, 2,4-D, and 2,4,5-T, are known

to produce marked changes in the chemical

composition of treated plants. Some herbicides

aiïect the palatability of certain plants, and

livestock will graze some treated species that they

normally would not eat.

Single applications of foliage sprays will often

control mesquite, sand sagebrush, big sagebrush,

perennial ragweed, and other weeds on permanent

pastures and rangelands. However, repeated

treatments are usually needed for most woody

plants and perennial weeds (table 11). For

satisfactory control of mixed stands of oak species

and buckbrush, for instance, repeated annual

applications for 2 or more years, with not more

than 2 years intervening between treatments, are

normally required. Where native grasses are

present, it is almost always desirable to defer the

grazing during the growing season for 1 or 2 years.

Correct timing of herbicide application in

relation to growth stage of weeds and during

periods of adequate moisture in the soil may

determine whether the treatment will succeed or

fail. This varies with individual weed species.

Check on correct timing with agricultural

specialists.

Annual weeds usually are most easily killed

with herbicide foliage sprays while they are small.

However, more nearly adequate control often

results if spraying is delayed until germination

and emergence of such weeds are mostly completed. Such delays may result in a higher overall

percent control than if the treatments were

applied earlier at the most susceptible stage of

the early germinating weeds, because weeds

germinating after spraying with the phenoxy

herbicides are largely unaffected.

The most susceptible stage for perennial weeds

varies greatly with the species and climatic conditions. Many perennial weeds are most susceptible

when actively growing and at the late vegetative

or early bud stages. However, some species, such

as deathcamas and wild garlic, are most susceptible

much earlier in their life cycle. Also, environmental

conditions critically affect responses of species to

herbicides. Therefore, details for controlling individual species usually should be obtained from

local agricultural authorities.

For further information on the control of many

range weeds, see the handbook on ^'Chemical

Control of Range Weeds,^^ U.S. Department of

Agriculture and U.S. Department of Interior,

issued December 1966. The relative susceptibility

of many common woody species to herbicides is

given in U.S. Department of Agriculture Farmers'

Bulletin 2158, ^^Chemical Control of Brush and

Trees.'' Also, the relative susceptibility of many

weeds to 2,4-D, MCPA, 2,4,5-T, silvex, and

2,4-DB is tabulated in Farmers' Bulletin 2183

''Using Phenoxy Herbicides Effectively."

TABLE 11.—Weed control in forage crops, pastures, and rangelands

[Numbers in parentheses=pounds of active ingredient per acre unless otherwise indicated; for herbicide tolerances, see Appendix]

Crop and treatment Time of application Weeds controlled Remarks

FORAGE CROPS

Alfalfa and birdsfoot

trefoil :

New seedings:

CIPC (2)

Dalapon (2).

Postemergence, late fall

or early winter.

4 weeks after seeding or

when grasses are less

than 3 in. tall.

ChickweedCrabgrass, foxtaiL

Do not use if grass is planted with

legume.

Stunts alfalfa temporarily ; repeat

treatments later in summer; no injury to trefoil; do not feed first

year's growth to dairy cows or

animals being finished for slaughter.
SUGGESTED GUIDE FOR WEED CONTROL 19619

TABLE 11.—Weed control in forage crops, pastures, and rangelands—Continued

49

Crop and treatment Time of application Weeds controlled Remarks

FORAGE CROPS—continucd

DNBP (0.75-1.5)___

DNBP amine salts

(0.75-1.5) in 20-

40 gal. water.

EPTC (2-4)

When weeds are small

and legume seedlings

have 2 or more true

leaves.

After emergence of

alfalfa seedlings when

weeds are small.

Immediately before

planting alfalfa or

birdsfoot trefoil.

Chickweed, henbit,

pepperweed, weed

bromegrass.

Bitterweed, lambsquarters, mustard,

pigweed, ragweed,

sneezeweed, tarweed.

Weed grasses, some

broadleaf weeds.

2.4-DB amine salt Postemergence when Broadleaf weeds

or esters (0.75- weeds are less than 3

1.5) in 5-20 gal. in. tall,

water.

Estabhshed stands:

CIPC (2) In fall when legumes are Ohickweed

dormant and weeds

small.

Diuron (1.6-2) In fall after crop is Annual weeds in Northdormant or early western States,

spring.

Diuron (3) do Downy bromegrass

DNBP amine salts In fall when legumes are Chickweed, henbit, yel-

(2) in 20-40 gal. dormant and weeds low rocket seedlings,

water. small. ^ . . , „ ^

2,4-D or MCPA Early dormant stage of sensitive broadleaf

' (0.1-0.25). legume. weeds.

Alfalfa: ^ ^_,

CIPC (6) (granular) _ _ Before or during dodder Dodder

emergence and/or

after first cutting.

Weed burner Stubble following first do

cutting.

Clovers—alsike, crimson, ladino, red,

and white—new

seedings:

CIPC (2)

Often injures birdsfoot trefoil; use in

alfalfa or alfalfa-grass mixtures only;

do not use forage for livestock for

60 days after treatment.

Injures trefoil.

Mix with soil by disking or vigorous

harrowing; herbicide volatile, lost

if applied on wet soil or allowed to

remain on surface for short time;

highest rate required for nutsedge

control.

Can be applied at later stage of

growth than DNBP; do not graze or

feed treated plants to livestock

within 30 days after application.

Stands must be at least 1 year old.

Do.

Re-treatment in late winter or early

spring necessary for heavy

infestations.

Use only as emergency measure if

weed infestation threatens crop.

Timing critical.^

Kill top growth with light flame; burn

patches clean when vegetation has

dried.

Late fall or early winter. _ Chickweed.

CIPC, EPTC, or

IPC (4).

IPC (4)

Clovers—ladino, red,

and sweet:

New seedings:

DNBP (0.75-1.5)

in 20-40 gal.

water.

DNBP amine salts

(0.75-1.5) in 20-

40 gal. water.

2,4-DB (1-1.5) in

20-40 gal. water.

Immediately before

planting clover.

Postemergence when

clover has at least 3

true leaves.

When weeds are small

and clovers have 2 or

more true leaves.

After emergence of clover

seedlings when weeds

are small.

Postemergence when

weeds are less than 3

in. tall.

Weed grasses, some

broadleaf weeds.

do

Chickweed, henbit,

pepperweed, weed

bromegrass.

Bitterweed, lambsquarters, mustard,

pigweed, ragweed,

sneezeweed, tarweed.

Broadleaf weeds

Do not use if grass is mixed with

clover.

Disk into soil before weed germination.

Do not use if grass is mixed with

clover.

Do not graze treated areas or feed

treated forage to livestock before

first cutting.

Do.

Can apply at later stage of legume

growth than DNBP.

See footnote at end of table.
50 AGRICULTURE HANDBOOK 332, U.S. DEPT. OF AGRICULTURE

TABLE 11.—Weed control in forage crops, pastures, and rangelands—Continued

Crop and treatment Time of application Weeds controlled Remarks

FORAGE CROPS—continued

Established stands:

CIPC (2) In fall when clovers are Chickweed.

dormant and weeds

small.

DNBP amine salts do Chickweed, henbit,

(2) in 20-40 gal.

water.

2,4-D or MCPA

(0.1-0.25).

Early dormant stage of

clover.

yellow rocket seedlings.

Sensitive broadleaf

weeds.

Re-treatment in late winter or early

spring necessary for heavy infestations.

Use only as emergency measure if

weed infestation threatens seed crop.

PASTURES AND GRASS-SEED FIELDS

Grasses:

New seedings:

Summer fallow 1 year before planting

grass.

Thorough tillage in 1-2 years preceding

intertilled crops. planting grass.

Silvex (0.5-0.75) After grass seedlings

have reached 2-4 leaf

stage.

2,4-D amine salts do

or esters (0.75).

Perennial weeds including

bermudagrass, Canada

thistle, Johnsongrass,

quackgrass.

Annual broadleaf weeds,

annual grasses.

Reduce or eradicate these species

before planting grasses.

Chickweed, henbit,

knotweed.

Broadleaf weeds

Sprigged stands of

bermudagrass,

simazine or diuron

(3.2).

Seed fields:

CIPC or IPC (3-4) _ Late fall (before Oct. 15)

Just before or just after

sprigging before weeds

emerge.

Dicamba (0.25-0.75) Single leaf.

Diuron (2-3) Late fall, established

fields.

Pastures:

Renovation on soils Late summer

too hilly or stony

to be plowed,

dalapon (7.4).

Annual broadleaf and

weed grasses.

Winter annual weeds in

Northwestern States.

Most winter and spring

broadleaf weeds.

Winter annual weeds including bromegrass.

Sod, weed grasses

Where winter annual grasses are

problem, delay grass seeding until

after last hard freeze in spring if

rainfall or irrigation is sufficient to

establish seedlings before heat and

summer drought start.

Do not exceed 0.5 lb. per acre until

grasses become well established.

If land is heavily infested with seeds

of annual grasses, delay application

until broadleaf weeds are 12-15 in.

tall to aid in preventing germination

of weedy grasses; do not add

surfactants.

Use 1.5 lb. of herbicide per acre on

sandy soil; delay grazing or hay

harvest at least 5 months after

treatment.

Especially effective on winter annual

grasses; too late application will

reduce seed yields.

Grass may be temporarily injured; use

on seed crop only.

Do not use on light sandy soils.

Graze turf heavily during summer,

then kill undesirable grasses; disk

dead sod 3-5 weeks after treatment

and seed; control broadleaf weeds

by selective herbicides in new seeding with 2,4-D or 2,4,5-T.

PERMANENT PASTURES AND RANGELANDS

Pastures:

Fertilize adequately,

mow when grass

becomes coarse,

graze area intensively.

Broomsedge_ Consult local authorities for recommended rates and times of fertilizer

application.
SUGGESTED GUIDE FOR WEED CONTROL 19 619

TABLE 11.—Weed control in forage crops, pastures, and rangelands—Continued

51

Crop and treatment Time of application Weeds controlled Remarks

PERMANENT PASTURES AND RANGELANDS Continued

2,4-D amine salts or

esters (0.5-1).

2,4-D esters (1-2) _.

2,4,5-T amine salts

or silvex (1-2).

Rangelands:

Silvex low-volatile

esters (0.7).

Silvex low-volatile

esters (3).

Silvex or 2,4,5-T lowvolatile esters

(0.5-1).

Cultivation by disk

harrow or disk

plow.

Usually late spring.

Between February and

May.

Fall, winter, or spring. _

May 15-June 30_

Early bloom

Burdock, Canada thistle,

chicory, common

broomweed, dandelion,

ironweed, pigweed,

ragweed, sneezeweed,

tarweed.

Common broomweed,

curly dock, horehound, wild garlic,

wild onion.

Bedstraw, chickweed,

henbit, knawel.

Spray while weeds are actively growing; in humid area where legumes

are in pasture, delay treatments

until initial rapid growth of legumes

has passed; remove milk cows from

pasture for 7 days after spraying.

If second application is necessary,

treat between October and December; remove milk cows from pasture

for 7 days after spraying.

These herbicides kill lespedeza and

seriously injure true clovers; remove

milk cows from pasture 7 days after

spraying.

Full leaf stage and growing actively.

After emergence of full

stand of weeds in

spring.

2,4-D, undiluted Any time.

2,4-D (1.5-2) in 3-5

gal. oil, water, or

oil-water emulsion.

2,4-D (3) in 5 gal. oil

or oil-water

emulsion.

2,4-D esters (1) in

1-4 gal. water,

diesel oil, or oilwater emulsion.

2,4-D esters (1-2) in

3-4 gal. water,

diesel oil, or oilwater emulsion.

2,4-D esters (1.5-3).

2,4-D esters (2).

After spring growth and

before soil moisture is

depleted in upper

8-10 in.

New twig growth 3 in.

or longer and before

soil moisture is depleted in upper 8-10

in.

In May or early June

with 6-8 in. of new

growth.

After full foliage (usually last part of May).

(Early spring, 3- to 5-

leaf stage.

Fully emerged but before flower stems

appear.

'Bud to early bloom

stage.

Yucca

Dalmatian toadflax Seedlings may require re-treatment in

2-3 years.

Shinnery oak Tops killed with 1 application ; to

reduce stands make 2-3 annual applications; in drought years or if

foliage damaged by frost, defer

spraying until next year.

Downy brome and as- Treatment in preparation for spring

sociated broadleaf seeding or for fallow and fall seeding

weeds, e.g., Russian of perennial grasses, e.g., crested

thistle, tansymustard, and intermediate wheatgrasses;

tumble mustard. seeding in furrows will increase seeding success; spring seeding should

not be attempted after Apr. 15.

Hardwood species more Tree injector or other injecting equipthan 1 in. in diameter. ment; apply in cuts 2 in. apart at

base of tree.

Big sagebrush, low sage- Properly timed mowing also controls

brush. sagebrush; can be done where terrain is not too rough or rocky.

Rabbitbrush.

.Early bolting stage. _

2,4-D esters (3) Prebloom stage

2,4-D low-volatile Early branching, preesters (2). bloom stage.

More difficult to control than sagebrush; do not apply when soil

moisture is critically low.

Sand sagebrush Diesel oil preferred for lowest

gallonage.

Buckbrush Repeated annual sprayings may be

necessary; correct timing important.

Deathcamas Spraying ineffective if treatment is

delayed.

Low larkspur Do not graze sprayed areas for at

least 3 weeks after treatment.

Locoweed, princesplume. Repeated annual applications may be

silvery lupine, two- necessary; do not graze sprayed

grooved milkvetch, areas for at least 3 weeks after

waterhemlock, woody treatment,

aster.

Tansy ragwort

Orange sneezeweed

Halogeton Provides 1-year control ; halogeton

reinfests next year unless other plants

occupy site; near trails and bed

grounds.
52 AGRICULTURE HANDBOOK 3 32, U.S. DEPT. OF AGRICULTURE

TABLE 11.—Weed control in forage crops, pastures, and rangelands—Continued

Crop and treatment Time of application Weeds controlled Remarks

PERMANENT PASTURES AND RANGELANDS Continued

2,4,5-T esters (1)

plus2,4-D (2).

2,4,5-T esters or

silvex (2).

2,4,5-T esters or

silvex (3-4).

2,4,5-T low-volatile

esters (0.3).

2,4,5-T low-volatile

esters (0.5).

2,4,5-T low-volatile

esters (8) in 100 gal.

diesel oil.

2,4,5-T low-volatile

esters (12-20) in

100 gal. diesel oil.

2,4,5-T low-volatile

esters (16) in 100

gal. diesel oil.

2,4,5-T low-volatile

esters (32) in 100

gal. diesel oil or

undiluted.

2,4,5-T or silvex lowvolatile esters (8)

in 100 gal. diesel

oil.

'Full leaf stage after

rapid growth.

Actively growing plants

in late vegetative or

early bud stage.

Full leaf stage after

rapid growth.

Late vegetative growth

but before flower buds

form.

After leaves full size and

terminal elongation

stopped.

50-90 days after first

leaves appear in spring.

When soil is dry

Post oak_

Timberline milkvetch__

Mixture may be used if 2,4,5-T makes

up at least % of mixture and use of

2,4-D is not hazardous; re-treatment

within 2 years is necessary ; re-treat

for 1 or 2 consecutive years.

Basal spray summer or

winter.

Summer or winter.

Any timeWhen plants are growing

rapidly.

Blackjack oak, post oak__ Re-treat for 2-3 consecutive years.

Tall larkspur Repeated annual applications necessary; do not graze sprayed areas for

at least 3 weeks after treatment.

Velvet mesquite Re-treat within 2 years.

Honey mesquite Tops killed ; re-treatment necessary in

5-7 years.

Agarita, catclaw, elbow- Apply to frills, stumps, or basal

bush, huisache, mes- trunks.

quite.

Baccharis, bayberry. Do.

beech, birch, Ceanothus, chestnut, chinkapin, cottonwood, hackberry, honeylocust,

hydrangea, madrone,

manzanita, mescalbean, mulberry, narrowleaf spirea, osageorange, pecan, pricklyash, red haw, retama,

sassafras, silver maple,

spicebush, sumac, treeof-heaven, walnut, wild

chinaberry, willow.

Ash, blackgum, blackjack Do.

oak, bur oak, elm,

hickory, pin oak, post

oak, red maple, red oak,

sweetgum, sycamore,

water oak, white oak,

willow oak.

Hardwood species more Tree injector or other injectmg equipthan 1 in. in diameter. ment; apply in cuts 2 in. apart at

base of tree.

Cholla cactus, prickly- Wetting spray,

pear, tasajillo.

1 See U.S. Department of Agriculture Farmers' Bulletin 2211, ''Controlling Dodder in Alfalfa."

WEED CONTROL IN LAWNS AND OTHER TURF AREAS

Good turf care, including proper liming, fertilization, watering, proper height and time of

cutting, and control of insects and diseases,

should accompany any program of weed control

in lawns and other turf areas. Controlling weeds

without correcting other lawn management problems will usually be disappointing. Vigorous turf

is required to fill in the bare spots remaining after

weeds are controlled. In addition, a vigorous

dense turf will greatly aid in preventing reinfestation.

Table 12 contains information about herbicides
SUGGESTED GUIDE FOR WEED CONTROL 196i9 53

that may be used to control weeds in lawns and

other turf areas. Follow explicitly all directions

on the container label. For further information

on controlling 1-awn weeds with herbicides and

for data on the susceptibility of many lawn weeds

to phenoxy herbicides, see U.S. Department of

Agriculture Home and Garden Bulletin 123,

'iawn Weed Control With Herbicides,'^ and

Farmers' Bulletin 2183, ''Using Phenoxy Herbicides Effectively.''

TABLE 12.—Weed control in lawns and other turf areas

[Numbers in parentheses = pounds of active ingredient]

Crop and treatment Time of application Weeds controlled Remarks

NEW SEEDINGS

Methyl bromide (1)

per 100 sq. ft.

Siduron (0.25) per 1,000

sq. ft.

When soil temperature is

above 65° F.

Before weed-grass germination.

Weed grasses and broadleaf weeds—all plant

parts including seeds

and seedling parts;

also disease organisms,

nematodes, insects.

Crabgrass, other annual

grasses.

Well-prepared, moist seedbed; apply

under gastight cover; follow manufacturer's instructions; seed lawn

2-3 days after application; this soil

fumigant is deadly poison; follow

directions on label.

Treat before, during, or after seeding;

water within 3 days if no rain; use

only on bluegrass and fescue lawns.

ESTABLISHED LAWNS (wiTH WEED GRASSES)

Benefin (1.5) per acre. Before weed emergence

Bensulide, 4-5 oz. per do

1,000 sq. ft.

('Spot treatment when

grasses are actively

Crabgrass _

do____

Dalapon (0.25) in 1 gal

water per 1,000 sq. <

ft.

DCPA (0.25) per 1,000

sq. ft.

DSMA and similar

arsonates (1.5-2.5)

per acre.

Petroleum naphtha, 1

gal. per 1,000 sq. ft.

(use full-strength

coarse spray).

SMDC (0.5-1) per 100

sq. ft.

growmg.

July; repeat 3-4 weeks

later; water between

applications.

Early April before weed

emergence.

After weed-grass emergence; re-treat at 7- to

10-day intervals until

control is obtained.

Spot treatment when

grasses are actively

growing.

Early August; repeat

4-6 weeks later.

Clumps of nimblewill,

orchardgrass, quackgrass,timothy.

Bermudagrass

Crabgrass.

Crabgrass, dallisgrass,

goosegrass, sandbur.

Clumps of nimblewill,

orchardgrass, quackgrass, timothy.

Bermudagrass

Do not overseed within 3 months

after treatment.

Do not overseed within 6 months

after treatment.

Will injure all grasses in treated spot;

carefully treat weeds; if applied in

warm moist soil, possible to reseed

in 3-6 weeks.

Lawn grasses also killed by treatment;

reseed 3 weeks after second application if temperatures are high, 6

weeks if temperatures are low; if

soil is dry, water thoroughly before

seeding.

Follow instructions on label.

Follow instructions on label; may

slightly discolor turf.

Carefully treat weeds; also will kill

lawn grasses.

Follow manufacturer's directions;

reseed 3-4 weeks after second

application.

ESTABLISHED LAWNS (WITH BROADLEAF WEEDS)

Dicamba (0.25) per acre.

Endothall (2) in 50-100

gal. water per acre.

Silvex (1-1.5) per acre

or 0. 4-0. 5 oz. per

1,000 sq. ft.

When weeds are actively

growing.

Chickweed, clover,

henbit, knotweed,

purslane, red sorrel.

When plants are small Burclover, henbit, knotweed, pennywort.

Actively growing weeds. Burclover, chickweed,

ground ivy, henbit,

knotweed, pennywort,

violet, white clover,

woodsorrel.

Do not exceed recommended rate;

stay away from shrubs and other

ornamental plants.

May discolor foliage of ryegrass and

bluegrass; keep children and

animals off sprayed areas until after

first rain or sprinkling.

Spray area overall; or to spot treat,

fasten piece of kitchen sponge to

end of stick or broom handle, dip

sponge into solution, spot treat

broadleaf weeds by pressing moist

sponge against crown of each plant;

delay mowing 24-48 hours.
54 AGRICULTURE HANDBOOK 332, U.S. DEPT. OF AGRICULTURE

TABLE 12.—Weed control in lawns and other turf areas—Continued

Crop and treatment Time of application Weeds controlled Remarks

ESTABLISHED LAWNS (WITH BROADLEAF WEEDS) Continued

2,4-D (0. 5) plus silvex

(0. 5) low-volatile

esters per acre.

2,4-D (1) plus dicamba

(0.25) amine salts per

acre.

2,4-D amine salts or

low-volatile esters

(1) per acre (liquid

or granular).

2,4-D amine salts or

low-volatile esters

(1-2) per acre plus

detergent.

When weeds are small

in cool weather or

early spring.

When weeds are small.

Actively growing weeds.

Late fall ; repeat in late

winter or early spring

each year.

Chickweed, clover,

henbit, knotweed, red

sorrel.

do

Buckhorn plantain,

curly dock, dandelion.

Knotweed, wild garlic,

wild onion.

Do not allow spray to drift onto

trees and shrubs.

Do not exceed recommended rate and

avoid flowers and shrubs; esters and

amines not compatible.

Spray area overall; or to spot treat,

fasten piece of kitchen sponge to

end of stick or broom handle, dip

sponge into solution, spot treat

broadleaf weeds by pressing moist

sponge against crown of each plant;

delay mowing 24-48 hours; fall

treatments allow cool-season lawn

grasses to take over space left by

dead weeds.

Follow directions on label; several

successive fall and spring treatments

necessary for control.

WEED CONTROL IN NONCROPLAND

CONSTRUCTION AIDS

Ditchbanks; fence rows, floodways, road and

utility rights-of-way, and other uncultivated areas

should be designed, constructed, and managed in

a manner to enhance efficient vegetation control.

Ditchbanks should be shaped to provide uniform

crowns and slopes, and a roadway should be

maintained on one bank or each bank for efficient

and economic use of mowers, burners, and spraying

machinery. Shaping ditches, grades, and back

slopes along highways to avoid steep or irregular

contours provides similar advantages. Fencing

ditch rights-of-way and providing suitable livestock guards in lieu of gates greatly facilitate

livestock grazing for weed control on ditchbanks.

The livestock must be managed to avoid overgrazing.

Using metal fenceposts and metal or concrete

structures in or along ditches and highways greatly

facilitates the use of weed burners without damage

to the posts and structures. Set corner posts and

utility line poles in concrete to eliminate brace

rods and wires, which are obstacles to weed-control

treatments.

CULTURAL, BIOLOGICAL, AND

MECHANICAL CONTROL

Seeding ditchbanks, fence rows, and rights-ofway to adapted species of low-growing grasses or

other desirable plants usually provides sufficient

competition to reduce greatly the weed problem

and increase the effectiveness and economy of

grazing, mowing, or selective herbicides used for

vegetation control. Establishment of suitable

stands of the desired competitive vegetation is

much easier on recently constructed ditchbanks or

road rights-of-way than on those already heavily

infested with weeds. Frequently weed growth can

be eliminated by repeated burning or by spraying

with a nonpersistent herbicide and then grass or

other revegetation mixture can be successfully

established.

Grazing by livestock, where practicable and

safe, usually provides effective and often the most

economical means of vegetation control on ditchbanks and floodways. Other than grazing by livestock, only a few biological agents effectively

control weeds on noncropland. Examples are

insects that control Scotch broom, gorse, and

St. Johnswort in fence rows and other uncultivated

areas.

Repeated mowing or burning with a butane,

liquid propane, or petroleum burner tends to

eliminate or reduce tall weed species and encourages the dominance of more desirable low-growing

vegetation. Mowing or burning must be repeated

three to eight times each growing season to maintain effective control of undesirable plants.
SUGGESTED GUIDE FOR WEED CONTROL 19619 55

CONTROL WITH HERBICIDES

Choice of Herbicides and Rates

In choosing an herbicide or a mixture of herbicides and the rate of appHcation for weed control in

a noncrop area, the user should consider several

environmental and site characteristics. They include (1) the dominant kind of vegetation present—annuals, deep-rooted herbaceous perennials,

grasses, broadleaf weeds, mixed vegetation, or

woody plants; (2) the objective—total vegetation

control (soil sterilization—bare soil), selective

control of broadleaf weeds and tall coarse

grasses from short competitive and soil-binding

grasses, or control of tall woody plants; (3) the

type and fertility of soil—medium loam, heavy

clay, or light sandy or gravelly loam with high or

low organic matter content; and (4) the amount

and distribution of precipitation.

Many herbicides that are effective on broadleaf weeds are not effective on weedy grasses

and vice versa, but some herbicides are effective

on both types. Usually the herbicides that are

most soluble in water or oil and are applied in

sprays give the most rapid kill of top growth.

Herbicides that are less soluble in water usually

remain in the soil longer and provide weed control

during a longer time. The minimum amount of

precipitation required to leach soil-applied chemicals into the soil around weed roots to make the

herbicide effective ranges from 2 to 5 inches.

Persistence of an herbicide in soil tends to be

longer under conditions of low precipitation, fine

or tight texture of soil, low organic content, nonsubmergence by water, and low micro-organism

content of the soil. Higher rates of application

are usually required on heavier soils and soils

high in organic matter and in regions of greater

precipitation. More frequent application of herbicides may be required to maintain weed control

on lighter soils and in areas of greater precipitation.

Generally, repeated annual applications of soil

sterilant herbicides at relatively light rates are

more effective and economical than less frequent

applications at heavier rates, especially for control

of annual and shallow-rooted perennial weeds and

seedlings of deep-rooted perennial weeds.

Few chemicals used alone w411 kill all species of

plants under all climatic and soil conditions and

at rates that are economically feasible. Mixtures

of herbicides with different solubilities in water

and different weed specificities are used much

more commonly for complete vegetation control

in noncrop areas than are used for selective weed

control on either cropland or noncrop areas. Mixtures are being widely used for soil sterilization

where the soil is unproductive and remains bare

for varying lengths of time. Usually each herbicide component in a mixture is applied at a rate

lower than the rate that would be required if it

were used alone, and the total rate of the mixture

is usually less than that of the major component

herbicide if used alone. The herbicides most

commonly used in mixtures are the sodium borates, sodium chlorate, simazine, and the phenylurea compounds. However, most of the other

herbicides suitable for weed control on noncrop

areas are available in one or several mixtures.

Soil sterilization is expensive and is practical

only where complete vegetation control is desirable and soil erosion is not an important factor.

Such areas are around signposts, bridge abutments, trestles along highways and railroads,

utility poles, and buildings, under guardrails and

transformer cages, along pipelines, on tank farms,

near structures, above concrete linings along

canals, and in parking lots and other noncultivated land where accessibility, visibility, fire prevention, and other considerations justify the

expense.

Use of Herbicides for Woody Plants in Noncropland

The control of undesirable woody plants with

herbicides along ditchbanks, roadsides, and utility

lines or on flood plains and other noncrop areas

differs from that on pastures and rangelands in

the following respects: (1) The noncrop areas of

woody plants frequently are in narrow strips so

that aerial spraying often is not possible or feasible.

(2) These areas usually are adjacent to or near

crops or ornamentals that are sensitive to phenoxytype herbicides. (3) Much greater care must be

used in spraying woody plants. Dormant basal

spray, frill, or stump treatments frequently must

be substituted for foliage sprays along irrigation

canals, reservoirs, lakes, and ponds to avoid contamination of water with herbicides not registered

for use in water. (4) Noncrop areas generally are

closer to adequate supplies of water so that use of

high-volume drenching sprays is more economical

and feasible than on rangelands. (5) Rapid control or elimination of undesirable woody plants m

noncrop areas frequently is more critical and

economically feasible than it is in rangeland.

Consequently, higher rates of herbicides and more

expensive application methods, such as drenching

foliage sprays, aerial spraying with a helicopter,

basal sprays, and cut-surface treatments, are commonly used on noncrop areas.

Special Precautions in Use of Herbicides in

Noncropland

Despite the absence of food or feed crops and

usually of desirable ornamental plants in noncrop

areas, all general precautions for safe use of herbicides described on page 3 should be followed.

Do not allow livestock to graze ditchbanks, rightsof-way, or similar noncrop areas sprayed with
56 AGRICULTURE HANDBOOK 3 32, U.S. DEPT. OF AGRICULTURE

herbicides not registered for use on pastures and

do not feed hay harvested from such areas.

Avoid contamination of water to be used for

irrigation in canals, ponds, or reservoirs by herbicides not registered for use in aquatic areas or on

irrigated crops. Apply such herbicides on banks

of irrigation and drainage canals, ponds, and reservoirs only when there is no water in the canal.

Use only amine or low-volatile esters of 2,4-D,

silvex, or 2,4,5-T for spray applications in noncrop

areas that are near sensitive crops or other desirable plants and prevent spray drift onto the

desirable plants. Use of low spraying pressure

and higher volumes of water or oil reduces the

danger of spray drift. Additional protection

against spray drift onto desirable plants is provided by using invert emulsions of ester formulations and of particulating or other thickening

agents with water-soluble herbicides.

Suggested Uses of Herbicides in Noncropland

Examples of herbicide treatments that have

been used successfully in noncropland are given

in table 13. These examples show the scope of

herbicide usage in noncropland. They are also

guides for the use of herbicides under local conditions. However, rate ranges rather than specific

rates are given. Times of application are given

in general terms because local climate, soil composition, and slope of land, proximity to canals or

ponds or desirable plants, and other site conditions

affect the performance and persistence of herbicides and methods required for their safe use.

Spot treatments for control of perennial weeds

should be used where possible, especially where

there is likelihood of contaminating water or injuring nearby desirable plants. Specific details

for the safe and effective local use of herbicides

can be obtained from weed specialists in the State

agricultural experiment stations.

TABLE 13.—Weed control in noncropland {ditchbanks^ fence rows,floodways, industrial sites, and railroad,

highway, and utility line rights-of-way) ^

[Numbers in parentheses=pounds of active herbicide per acre]

Weed and treatment Time of application Remarks

BROADLEAF HERBACEOUS WEEDS (SELECTIVE CONTROL IN DESIRABLE GRASSES)

Annuals, shallow-rooted perennials,

and seedling perennials:

Dicamba (0.5-1) Early weed growth in spring.

2,4-D (1-2) Early growth to first bloom__

2,4,5-T (1-2) do_

Deep-rooted and other hard-to-kill

perennials:

PBA (20-60)

Picloram (2-3) _

Spray succulent foliage growth,

preferably during period of

adequate rainfall.

Rapid vegetative growth to early

bloom in spring or summer, vigorous rosette growth in fall, or soil

application in fall.

Picloram plus 2,4-D mixture (follow

instructions on label).

Rapid vegetative growth to early

bloom in spring or summer, vigorous rosette growth in fall.

TBP (8-16) During early growth or in fall when

ground is not frozen.

2,3,6-TBA (10-30) Spray succulent foliage growth,

preferably during period of

adequate rainfall.

2,4-D (2-4) Rapid vegetative growth to early

bloom in spring or summer, vigorous rosette growth in fall.

2,4,5-T (2-4) do

Kills only top growth of most

perennials.

Repeat as necessary to maintain control

during growing season.

Use for weeds difficult to control with

2,4-D, e.g., nightshade.

Some grasses injured by heavier rates.

Use special care to avoid spray drift on

desirable plants or contamination of

water to be used for irrigation; apply

only as thickened spray; picloram

persists for 3 years in some soils.

Do.

Repeat as necessary to eliminate or

reduce stand.

Some grasses injured by heavier rates.

Repeat as necessary to eliminate or

reduce stand.

Use for weeds diflacult to control with

2,4-D, e.g., perennial horsenettle.

See footnotes at end of table.
SUGGESTED GUIDE FOR WEED CONTROL 19619 57

TABLE 13.—Weed control in noncropland (ditchbanks, fence rows, floodways, industrial sites, and railroad,

highway, and utility line rights-of-way) ^—Continued

Weed and treatment Time of application Remarks

WEEDY GRASSES WHERE CONTROL OF BROADLEAF WEEDS NOT NECESSARY

Annuals and seedling perennials:

Aromatic oil, 40-80 gal. per acre Spray young growth

Dalapon (5-10) Spray young growth 4-8 in. tall.

DNBP or PCP fortified fuel oil, Spray young growth

40-80 gal. per acre.

Established perennials (bermudagrass,

Johnsongrass, paragrass, quackgrass, reed canarygrass) :

Aromatic oil (120-160 gal. per acre) do

Dalapon 2 (10-15) Spray young growth 6-18 in. tall

Dalapon 2 (20-30) Early growth to early heading. _ _

DNBP fortified fuel oil, 120-160 gal.

per acre.

DSMA or MSMA, 2.5-5 lb. per

100 gal. water per acre.

Sodium TCA (100-150) On aftermath growth in fall or as

soil treatment.

Spray young growth

When weeds are actively growing.

Established perennials (Phragmites,

reed canarygrass) :

Amitrole (8-12) On young growth before heading.

Amitrole-T (4-6) do_

Repeat as necessary to maintain

control.

Do.

Use 2-3 pt. DNBP or 2-3 qt. PCP

per 100 gal. fuel oil.

Repeat every 3-4 weeks during growing

season to eliminate or reduce stand.

Repeat as necessary to suppress growth.

Repeat every 6-8 weeks or as necessary

to eliminate or reduce stand; lighter

rates repeated more frequently

sometimes more effective.

Same as with aromatic oil; use 2-3

pt. DNBP per 100 gal. fuel oil.

Add 1-2 pt. surfactant and spray

until thoroughly wet.

More effective when adequate precipitation follows; may seed desirable grasses next season.

Repeat 2-3 times each growing season

to eliminate or reduce stand; lighter

rates will suppress growth; use only

in drainage ditches and marshes.

Do.

PERENNIAL SEDGES ON IRRIGATION AND DRAINAGE DITCHBANKS

Tall sedges along irrigation and drainage ditches, around ponds (e.g.,

Nebraska sedge) :

Amitrole or amitrole-T (5-10) On young growth 10-15 in. tall Repeat 2-3 times each growing season

to suppress growth; use only in

. . . _, . drainage ditches and marshes.

Amitrole or amitrole-T (10-20) On young growth before heading Repeat every 6-8 weeks as necessary

to eliminate stand; use only in

drainage ditches and marshes.

Dalapon (15-30) On young growth 10-15 in. tall Repeat as necessary to suppress

growth to desired extent; use only

i^xTüT-» r j.'i2 j, r 1 ., -.^^ in drainage ditches and marshes.

DNBP fortified fuel oil, 120-160 do Repeat every 4-6 weeks as necessary

gal. per acre.

2,4-D (60-80) do_

to eliminate stand; use 2-3 pt.

DNBP per 100 gal. fuel oil; avoid

contamination of irrigation or

potable water.

Repeat as necessary to eliminate

stand; permits survival and spread

of Kentucky bluegrass; avoid contamination of irrigation or potable

water.

MIXED HERBACEOUS BROADLEAF AND GRASS WEEDS

Annuals, biennials, shallow-rooted

perennials, and seedling perennials

(lower rates) ; estabhshed deeprooted and other hard-to-kill

perennials (higher rates) :

See footnotes at end of table.
58 AGRICULTURE HANDBOOK 332, U.S. DEPT. OF AGRICULTURE

TABLE 13.—Weed control in noncropland (ditchbanks, fence rows, floodways, industrial sites, and railroad,

highway, and utility line rights-oj-way) ^—Continued

Weed and treatment Time of application Remarks

MIXED HERBACEOUS BROADLEAF AND GRASS WEEDS continued

Amitrole or amitrole-T (3-5; 6-12)___ Early growth to first bloom Repeat as necessary to maintain control or to eliminate or reduce stand;

do not use along irrigation canals,

reservoirs, lakes, ponds.

Amitrole plus simazine mixture do Gives longer lasting control than

(follow instructions on label). amitrole alone; do not use along

irrigation canals, reservoirs, lakes,

ponds.

AMS (50-100; 400-1,000) do Mix 3^-2 lb. per gal. water and spray

to wet foliage; 1 formulation registered for use adjacent to reservoirs,

lakes, ponds, canals, and streams

including domestic water supplies

at rates up to 200 lb. per acre.

Aromatic oil, 40-80 and 120-160 Spray young growth Repeat as necessary to maintain congal, per acre. trol or every 3-4 weeks to eliminate

or reduce stand.

Borate (sodium), 30-120 lb. per Before period of adequate precipita- Apply broadcast as soil treatment.

1,000 sq. ft.; (1,300-5,200). tion.

Borate mixtures with sodium Soil applications before period of

chlorate and/or other chemicals adequate precipitation; spray ap-

(follow instructions on label). plications on early growth to

first bloom.

Early growth to first bloom or before period of adequate precipita

tion.

Use where soil sterilization (bare soil)

desired.

Bromacil (3-6; 10-25).

Chlorate (sodium) (300-600; 700-

1,300).

Chlorate mixtures with borates or

other chemicals (follow directions

on label).

Dalapon plus 2,4-D or 2,4,5-T or

silvex (5-10 plus 1-2; 15-30 plus

2-4).

Dicamba (1-4; 4-8)

Diuron or monuron (5-20; 20-80) _

DNBP or PCP fortified fuel oil,

40-80 and 120-160 gal. per acre.

Erbon (120-160).

Spray foliage and make soil applications before period of adequate

precipitation.

do

Early growth to early bloom or

heading.

When weeds in active growth stageBefore period of adequate precipitation.

Young growth to first heading

Ethylene glycol bis(trichloroacetate)

(10-20).

Monuron-TCA (20-40; 40-66)

Oil, 40-50 gal. per acre aromatic

or fortified fuel oil, plus 2,4-D

ester (2-3).

Paraquat (cation) (0.5-2)

When weeds are young and succulent or during period of adequate precipitation.

Spray when weeds are about 12 in.

tall.

When weeds are young and succulent or during period of adequate precipitation.

Young growth to first heading

Prometone (10-15; 20-60).

See footnotes at end of table.

Spray young growth

Spray early growth to first headingApply higher rates before period of

greatest precipitation or when

bottom or margins of canals,

ditches, or ponds are not submerged

by water.

Observe all precautions to avoid fire

hazard.

Fire hazard usually less but caution

necessary.

Use 2,4,5-T where broadleaf weeds

resistant to 2,4-D are present.

Higher rates equally effective as soil

application before period of adequate precipitation.

Diuron gives longer soil sterility;

monuron more effective on deeprooted weeds.

Repeat as necessary to maintain control or every 3-4 weeks to eliminate

or reduce stand; use 2-3 pt. DNBP

or 2-3 qt. PCP per 100 gal. fuel

oil.

Make soil applications in late fall or

winter in regions of wet winters and

dry summers.

Apply in fuel oil in sufficient volume

to give complete coverage of all

foliage.

Make soil applications in late fall or

winter in regions of wet winters

and dry summers.

Apply same as for aromatic or fortified fuel oil; more economical and

often more effective than oil alone.

Repeat as necessary to maintain control ; kills top growth only of perennials.

Mix in water or oil; oil spray kills top

growth quicker.
SUGGESTED GUIDE FOR WEED CONTROL 19619 59

TABLE 13.—Weed control in noncropland {ditchbanks, fence rows^floodways, industrial sites, and railroad,

highway, and utility line rights-qf-way) ^—Continued

Weed and treatment Time of application Remarks

MIXED HERBACEOUS BROADLEAF AND GRASS WEEDS Continued

Simazine or atrazine (5-20; 20-40) _ __ Spray early growth to first heading;

soil applications before period of

ample precipitation.

Simazine requires more precipitation

for effective root kill; remains

effective in soil longer.

UNDESIRABLE WOODY PLANTS

Alder, Baccharis, boxelder, cottonwood, poplar, sycamore, willow,

and other species susceptible to

2,4-D, 2,4,5-T (2-4).

Mixed species including some susceptible to 2.4-D, 2,4-D plus

2,4,5-T (brush-killer mixture)

(2-4) of 2:1 or 1:1 mixture.

Species resistant to 2,4-D or in areas

near crops susceptible to 2,4-D:

AMS (7-10) in 2 gal. water

At full leaf in spring or early

summer.

_do_

Spray over freshly cut stump or in

frills or notches cut around base

of tree.

AMS (60) in 100 gal. water At full leaf in spring or summer_

Fenuron (east of Rocky Mountains) (12-25).

Just before or during period of

adequate precipitation in spring

from bud growth to full leaf.

Fenuron TCA (12-25) Spray at full leaf stage or broadcast before or during period of

adequate precipitation in spring.

Picloram (6-8.5) Broadcast granules just before or

during period of adequate

precipitation.

Picloram plus 2,4-D mixture (follow

instructions on label).

Spray at full leaf during vigorous

growth.

Silvex (2-4) Spray at full leaf during active

growth; spring treatments best

for some species (e.g., saltcedar).

2,3,6-TBA (10-20) Spray foliage and soil when conditions suitable for active growth.

2,4,5-T (2-4) Spray at full leaf during active

growth; spring treatments best

for some species (e.g., saltcedar).

Apply in 100-300 gal. water per acre

with ground equipment, or in 5-10

gal. water per acre or oil-water or

invert emulsion by airplane or

helicopter.

Do.

Cut notches every 6 in. around

circumference of tree; crystals may

be sprinkled liberally over cut stumps

or in frills or notches.

Spray to thoroughly wet foUage ; with

airblast mist-spray equipment use

100-400 lb. per 100 gal. water and

apply at lower volume; to apply in

oil-water emulsion follow directions

on label; use mist spray only in

areas far removed from crops.

Apply broadcast or in grid pattern at

1-2 teaspoonfuls 3 ft. apart; apply

same rate around base of individual

trees or clumps of brush for spot

treatments; increase rate 50 percent

for cherry, dogwood, elderberry,

osageorange, persimmon, sassafras.

Available in liquid, granular, and

pelleted formulations for spray or

broadcast applications.

Highest rate is necessary for ash,

blackgum, and oak ; for spot

treatments under individual trees

or clumps of brush broadcast 1-2

tablespoonsful per 30 sq. ft. of soil

surface; picloram persists for 3

years in some soils.

Use extreme care to avoid drift of

spray to nearby desirable plants;

spray solution may be applied to cut

stumps or in frills; apply only in

thickened spray; picloram persists

in some soils for 3 years.

Silvex especially effective on maple,

mulberry, palmetto, redbud, saltcedar (Tamarix sp.), trumpetyine.

Especially effective on woody vines.

Especially effective on brambles,

mesquite, oak, osageorange.

1 All herbicides listed are registered under the Federal

Insecticide, Fungicide, and Rodenticide Act for suggested

uses at time of publication, but some herbicides registered

for use may not be included. Rates are in terms of acid

equivalent or active ingredient of herbicide and not necessarily or usually of commercial formulation.

2 When stand of perennial grass or sedge weakens,

herbicide treatments are less frequent, and broadleaf

weeds begin to invade, add amine or low-volatile ester

formulation of 2,4-D at 1 to 2 lb. per acre.
60 AGRICULTURE HANDBOOK 3 32, U.S. DEPT. OF AGRICULTURE

CONTROL OF AQUATIC WEEDS

CONSTRUCTION AIDS

Deepening the edges of ponds, lakes, and

reservoirs to 2 or more feet and filling in marshy

spots prevent or reduce growth of emersed weeds

such as cattail and waterprimrose. Also, fertilizers

and herbicides control submersed weeds at the

shoreline more effectively when the water is not

shallow. Removal of stumps, logs, and other

obstructions from ponds, lake margins, and access

channels facilitates the use of underwater weed

mowers.

A uniform gradient and absence of high or low

spots in the bottom of an irrigation canal permit

thorough draining of water and effective and

economical control of submersed waterweeds in

3 or 4 days of drying. Deep canals with steep

gradients and rapid waterflow provide less favorable conditions for growth of rooted submersed

weeds.

Lining irrigation and drainage canals with concrete or asphalt usually prevents or reduces the

growth of rooted submersed weeds. However,

filamentous algae may grow on concrete linings

and structures and greatly reduce waterflow capacity. Also, silt deposits on the bottom of lined

canals will support obstructive growth of rooted

submersed weeds in water as deep as 8 or 10 feet.

A few species will grow at depths of 25 or 30 feet.

Careful designing and spacing of checks, weirs,

turnouts, bridges, and other structures along

canals minimize interference with the operation

of equipment for mechanical or chemical control of

aquatic weeds. Shaping ditchbanks to provide

uniform crowns and slopes and maintaining roadways on one or both banks are essential for efficient

chaining, dragging, mowing, or spraying operations

to control aquatic weeds.

MANAGEMENT PRACTICES

As supplements to proper design and construction of canals, ponds, lakes, and reservoirs, a

number of management practices can be utilized

to control aquatic weeds or prevent them from

becoming a problem. These practices include

draining, flooding, fertilization, and livestock

grazing.

Draining.—^For control of submersed weeds in

irrigation canals with uniform bottom gradients,

drain completely and let canals dry for 3 or 4 days.

Repeat as necessary when water is not critically

needed for irrigating crops.

To control cattails and certain other emersed

weeds in ponds, marshes, and wet lands, drain

water off, plow the ground, and let it dry for a

few weeks.

Flooding.—Maintain the water level at a depth

of 3 feet or more for several months to control

cattails and certain other emersed weeds.

Fertilization.—Frequent application of NPK

(nitrogen, phosphorus, potassium) mineral fertilizers in ratios of 8-8-2, 10-10-5, or higher stimulates a dense growth or ''bloom'' of microscopic

algae, which shades the pond bottom and prevents

or reduces the growth of rooted submersed weeds

in the Southern States. To control rooted submersed weeds and waterlilies in ponds with stable

water levels, apply 100 to 200 pounds per acre of

NPK mineral fertilizer (analysis 8-8-2) beginning

in late winter or early spring and at 10-day intervals thereafter until a white disk placed 12 to 14

inches below the water surface is invisible. Subsequently apply fertilizer as necessary to maintain

the algae ''bloom.'' Fertilization does not control

submersed weeds where the outflow or change of

water in a month exceeds the water storage capacity of the canal or pond or in cooler waters of

the Central and Northern States.

Livestock Grazing.—Intensive grazing by livestock, where practicable and safe, provides effective and economical control of most kinds of

emersed and marsh species, including aquatic

grasses, sedges, rushes, reeds, cattails, alligatorweed, watercress, and willows. Avoid grazing

where it causes serious erosion of steep banks or

loose soil. Ducks often effectively control duckweed

in small ponds.

HAND AND MECHANICAL CONTROL

Although the traditional hand and mechanical

methods of controlling aquatic weeds have recently been replaced to a considerable extent

by herbicides, the hand and mechanical methods

are still advantageous in many situations.

Control of submersed weeds by mechanical

methods often is less costly than chemical methods

in canals with flows of water greater than 70 c.f.s.

However, in canals that supply water for sprinkler

irrigation, mechanical methods are undesirable

because fragments of dislodged weeds that remain

in the water often clog sprinkler heads, valves,

screens, and other irrigation equipment.

Hand Pulling.—^Young plants of cattail, buttonbush, willow, and certain other emersed or marsh

species can be eliminated by hand pulling. However, frequent inspection of the channel, pond, or

marsh and pulling when plants are young and few

in number are necessary for effective and economical control.

Underwater Mowing.—Self-propelled and boatmounted mowers that cut off submersed or
SUGGESTED GUIDE FOR WEED CONTROL 19619 61

emersed weeds below the water surface at depths

of 6 inches to 6 feet are available.

To eliminate cattails, cut the stems off below

the water surface during the early heading stage

and again 1 to 2 months later when all regrowth

is emersed. A third cutting is necessary when

regrowth occurs a second time.

For killing small patches of waterlilies and

watershield, cut leaves off below the water surface

at frequent intervals. Five or six cuttings a year

may be necessary.

For temporary control of submersed waterweeds

in large canals, around boat docks, and in fishing

and swimming areas of ponds and lakes, mow off

as deeply as possible and remove dislodged weeds.

In canals the dislodged weeds should be trapped

downstream and removed by dragline or other

device to prevent them from lodging against

structures, clogging the canal, and causing overflows, canal breaks, or washed-out structures.

In ponds and lakes weed debris accumulating in

shallow water along the shoreline because of

wave action can be removed by draglining,

cabling, conveying, or other mechanical means.

Chaining and Dragging.—For removal of submersed waterweeds from irrigation or drainage

canals, pull a heavy chain, drag, or disk upstream

along the bottom of the canal with a tractor on

each bank. Several trips are usually necessary to

dislodge all weed growth. Trap the floating

masses of weeds at strategic places downstream

and remove mechanically or by hand.

BIOLOGICAL CONTROL

A few species of fish (e.g., Israeli carp, Tilapia)

are the only organisms that can be recommended

to control certain species of submersed weeds.

Other organisms under study include certain

insects to control alligatorweed and waterhyacinth ;

a large fresh-water snail to control algae, submersed weeds, waterfern, and possibly waterhyacinth; and several low-growing submersed

species, such as waterplantain and dwarf sagittaria,

as effective competitors with ranker growing, more

troublesome pondweeds in large irrigation canals.

To control branched filamentous algae {Pithophora) in southern ponds, stock with fifty 5-inch

or larger fingerling Israeli carp per acre. Under

these temperature conditions the Israeli carp will

not muddy the water and will not spawn successfully.

CHEMICAL CONTROL

Copper sulfate was first used to control algae in

1904, and sodium arsenite was used to control

waterhyacinth in 1902 and submersed weeds in

1927. However, most of the herbicides now

registered by the U.S. Department of Agriculture

for use in controlling one or more aquatic weeds

were discovered since 1945. Herbicides often give

more effective, longer lasting, and less expensive

control of aquatic weeds than do mechanical or

hand methods.

Special PrecautionsinUse of Aquatic Herbicides

A few aquatic herbicides are poisonous to humans and warmblooded animals and must be

handled and used with great care and according

to special procedures. Some herbicides are toxic

to fish, but several do not injure fish at concentrations required to kill weeds. Most aquatic

herbicides do not injure crops irrigated with water

at concentrations required for weed control, but

a few may injure crops at low concentrations.

Only limited information is available on the

persistence and fate of herbicides in water, aquatic

soil, fish, aquatic plants, and crops irrigated with

treated water. Therefore, in addition to following

all general precautions for the safe use of herbicides

described on page 3 and the special precautions

in table 14, the user of an aquatic herbicide

must follow carefully all label instructions and

restrictions regarding aquatic situations in which

the herbicide should not be used, including treated

water for livestock, potable purposes, and irrigation of crops. He must know how much time

should elapse after herbicide treatment and before

treated water may be used for drinking, fishing,

swimming, and irrigating crops.

Suggested Uses of Herbicides for Control of

Aquatic Weeds

Examples of herbicide treatments that have

been used successfully and safely for control of

aquatic weeds are given in table 14. These examples

show the scope of herbicide usage for aquatic

weed control. They are also guides for the use

of herbicides under local conditions. However,

rate ranges rather than specific rates are given

and times of application are given in general

terms, because local climate, altitude, water

temperature, water uses, and site conditions

affect the performance and persistence of herbicides and procedures required for effective and

safe use. Specific details for the safe and effective

local use of aquatic herbicides can be obtained

from aquatic weed specialists of State and Federal

agencies familiar with the particular local

situation.
62 AGRICULTURE HANDBOOK 332, U.S. DEPT. OF AGRICULTURE

TABLE 14.—Control of aquatic weeds (irrigation canals, drainage ditches, streams, lakes, ponds,

reservoirs, marshes)

Type and kind of aquatic

weed or aquatic site

Herbicide ^ Rate or

concentration 2

Remarks

FLOATING WEEDS (UNATTACHED, TOPS ABOVE WATER)

AUigatorweed (floating

mats), duckweed,

waterfern (Salvinia),

waterhyacinth,

waterlettuce :

General control (all

weeds).

Near crops sensitive to

2,4-D:

Duckweed (nonflowing

water).

2,4-D amine salts or 2-4 lb. per 100 gal.

low-volatile esters. diluent.

Waterhyacinth.

Diquat (cation)-

Amitrole-T

Waterhyacinth and

waterlettuce.

More positive eradication—alligatorweed

floating mats.

Diquat (cation).

Ester of silvex _ _

0.5-1 p.p.m.w

1-1.5 lb. per acre.

1-1.5 lb. per acre.

8 lb. per acre____

Spray to uniformly wet foliage when weeds

actively growing; include 10 gal. fuel oil

and 1 pt. emulsifier for waxy hard-to-wet

foliage or in rainy season; repeat every

4-6 weeks.

._ Inject into water or spray on foliage when

actively growing; much less effective in

muddy water.

._ Apply as surface spray in 150-200 gal. water

or as aerial spray in 7.5 gal. water per acre

when actively growing; add 0.1 lb. fenac

per acre for more rapid foliage kill; use

only in drainage ditches and marshes.

._ Apply as surface spray in 150-200 gal. water

or as aerial spray in 7.5 gal. water per acre

when actively growing.

. _ Apply as spray in 150-200 gal. water per acre

at ñrst bloom; re-treat when regrowth

2-4 in. above water; 2-4 applications required for control; do not use for irrigation or domestic purposes.

EMERSED AND MARGINAL WEEDS (ROOTED UNDER WATER, TOPS ABOVE WATER, OR GROWING ON WET SOIL)

Broadleaf species:

General control Silvex, 2,4-D, or

2,4,5-T.

2-4 lb. per acre_

Arrowhead, lotus,

pickerelweed, smartweed, spatterdock,

spikerush, waterprimrose, white waterlily,

other plants with waxy

leaves.

Rooted, emersed alligator- Ester of silvex

weed. (spray).

Grass and grasslike species:

Perennial grasses and /'Amitrole or

2,4-D (low-volatile 1-4 lb. per acre_

ester).

8 lb. per acre.

sedges, e.g., common

reed (Phragmites), cutgrass, Johnsongrass,

knotgrass, paragrass,

quackgrass, ripgut sedge.

amitrole-T.

8-16 lb. per acre

.Dalapon 20-30 lb. per acre

Apply as spray in 200 gal. water per acre to

uniformly wet foliage when weeds actively

growing; reduce volume but not rate when

foliage wet; repeat as necessary.

Apply in oil or in oil-water emulsion (1:10

or 1:20) in sufficient volume to give

uniform coverage; spray when plants

actively growing.

Apply as spray in 150-200 gal. water per

acre at ñrst bloom; re-treat when regrowth

2-4 inches above water; 2-4 applications

required for elimination.

Apply in 100-400 gal. water per acre as

ground spray or in 10-15 gal. water per

acre as aerial spray when plants 6-18 in.

tall and before heading; some grasses, e.g.,

reed canarygrass, require 50 percent less

amitrole-T than amitrole; use only in

drainage ditches and marshes.

Apply in 100-400 gal. water per acre as

ground spray or in 5-15 gal. water per

acre as aerial spray when grasses 6-18 in.

tall and before heading; add 3-4 pt.

wetting agent per 100 gal. water; repeated

light applications at 5-10 lb. per acre are

more effective on some species, e.g.,

paragrass; use only in drainage ditches

and marshes.

See footnotes at end of table.
SUGGESTED GUIDE FOR WEED CONTROL 19619 63

TABLE 14.—Control oj aquatic weeds {irrigation canals, drainage ditches, streams, lakes, ponds,

reservoirs, marshes)—Continued

Type and kind of aquatic

weed or aquatic site

Herbicide ^ Rate or

concentration ^

Remarks

EMERSED AND MARGINAL WEEDS (ROOTED UNDER WATER, TOPS ABOVE WATER, OR GROWING ON WET SOIL) Continued

Bulrushes and cattails

Amitrole 6-12 lb. per acre.

Dalapon 15-30 lb. per acre.

2,4-D (low-volatile 4-6 lb. per acreesters) .

Apply at fully headed or postheading stage

in late summer or early autumn in sufficient volume of spray to give uniform

coverage by ground or aerial equipment;

apply at earlier growth stage for control

during current season and repeat as

necessary to eradicate regrowth; use only

in drainage ditches and marshes.

Same as for amitrole except include 3-4 pt.

wetting agent or 5-10 gal. diesel oil plus

1 pt. emulsifier per 100 gal. spray.

Apply in 1:20 oil-water emulsion at 150-300

gal. per acre; make initial application at

first heading and repeat on regrowth

before heading; 3-4 applications necessary

for elimination.

SUBMERSED WEEDS (TOPS MOSTLY UNDER WATER, USUALLY ROOTED OR ANCHORED)

Ponds, lakes, and reservoirs:

Algae, blue-greenAlgae, filamentous.

Rooted or anchored

weeds, e.g., bladderwort, cabomba, coontail, Elodea, naiad,

pondweeds, waterchestnut, water crowfoot, watermilfoil,

water pennywort,

waterprimrose, waterstargrass, wild celery.

'Copper sulfate

(pentahydrate,

dark blue).

0.1-0.5 p.p.m.w

Dichlone 0.02-0.05 p.p.m.w.

0.5-1 p.p.m.w

1-2 p.p.m.w

0.05-0.2 p.p.m.w-_

0.5-2.5 p.p.m.w

'Copper sulfate

(pentahydrate,

dark blue).

Endothall (dimethylamine salts).

Endothall (dimethylamine salts).

Endothall (disodium 1-4 p.p.m.w. _

salt).

Fenac 15-20 lb. per acreSame weeds plus algae Dichlobenil ,

and chara.

See footnotes at end of table.

'7-10 lb. per acre.

10-15 lb. per acre.

_ Apply crystals or powder at early stage of

algae growth by any method to give rapid

and uniform dispersion; repeat as necessary to maintain control; safe in potable

water.

_ Same as copper sulfate except not safe in

potable water.

_ In soft water safe on most fish except trout;

safe in potable water.

_ In hard water injurious to most fish; safe in

potable water.

_ Apply uniformly over surface or inject below

water surface.

_ Use only for spot treatments or where some

fish kill is not objectionable.

_ Consult weed specialists in State agricultural

experiment stations or extension service

or fish and wildlife specialists for necessary

use permit and regulations; apply at early

stage of weed growth; use lower concentrations in total area treatments and

higher concentrations for margins, spot

treatments, or cold water; follow label

directions on use of treated water; increase

concentration to 5 p.p.m.w. for spot treatments.

_ Apply to temporarily exposed lake or pond

bottoms and shorelines when soil is not

frozen; keep water down at least 3 weeks;

follow label directions on use of treated

water.

- Apply to temporarily exposed lake or pond

bottoms and shorelines; follow label directions on use of treated water.

_ Broadcast over water surface before or as

soon as new growth begins in spring; increase rates in water deeper than 3 ft. and

for spot treatment.
64 AGRICULTURE HANDBOOK 3 3,2, U.S. DEPT. OF AGRICULTURE

TABLE 14.—Control of aquatic weeds (irrigation canals, drainage ditches, streams, lakes, ponds,

reservoirs, marshes)—Continued

Type and kind of aquatic

weed or aquatic site

Herbicide ^ Rate or

concentration 2

Remarks

SUBMERSED WEEDS (TOPS MOSTLY UNDER WATER, USUALLY ROOTED OR ANCHORED) Continued

Same weeds except

Elodea and wild

celery.

Same weeds except

curlyleaf pondweed,

some other pondweeds, Elodea, wild

celery.

Irrigation and drainage

canals with flowing

water—most submersed

species except waterplantain.

Diquat (cation).

'0.25-0.5 p.p.m.w0.5-1.5 p.p.m.w--

Ester of 2,4-D 20-40 lb. per acre,

(granule or pellet

form).

Potassium salt of 1.5-2 p.p.m.w. or 5

silvex (granule or lb. per acre-ft.

liquid form).

Acrolein.

1-2.5 gal. per c.f.s_

0.1-0.6 p.p.m.vAromatic solvents

(xylene).

^Acrolein.

Drainage and irrigation

canals with flow stopped <

or greatly reduced.

Diquat (cation).

Endothall (dimethylamine

salt).

8-10 gal. per c.f.s.

(600-740 p.p.m.v.

in 30 minutes or

300-370 p.p.m.v.

in 60 minutes).

4-7 p.p.m.v

0.25-1 p.p.m.w

1.5-4 p.p.m.w

Reservoirs and large canals

carrying flowing water

for potable use:

Continuous feed method__- Copper sulfate

(pentahydrate).

0.6-1 p.p.m.WRepeated ^^slug" treatments.

-do___L 0.3-2 lb. per c.f.i

Low concentrations sufficient for some weeds,

e.g., naiad in small ponds.

Apply over surface or inject below water

surface; double rates for spot treatments;

follow label directions on use of treated

water.

Apply uniformly over water surface by boat

or helicopter at early stage of weed growth;

use heavy rates for more resistant species

or extremely acid or alkaline water; esters

of 2,4-D toxic to some species of fish at

these rates.

Apply uniformly oyer surface of water or

inject liquid below surface at early stage

of weed growth; not effective in spot

treatments.

Inject into canal at beginning of weed infestation during 3^-4 hours using especially

adapted equipment; effective kill 6-20

miles downstream depending on weed

density.

Inject in large canals (200-2,000 or more

c.f.s.) at one location during period of

8-48 hours; within this range use lower

concentrations and longer periods of application as size of canal increases; apply

from special cylinders under nitrogen gas

pressure.

Add 1-1.5 percent emulsifier and inject into

canal at one station during 30-60 minutes

before weeds become matted at surface;

add 4-5 gal. per c.f.s. to moving ''zone" of

treated water at intervals of 2-4 miles

down canal depending on weed density;

avoid fire hazard.

Apply below water surface continuously

along canal with specially adapted equipment; toxic to fish.

Apply above or below water surface continuously along canal; allow at least 12

hours' exposure of weeds to treated water.

Same as diquat except toxic to fish.

Begin applications early in season at 1

p.p.m.w.; gradually reduce to 0.6 p.p.m.w.

in late summer as water temperature

rises.

Make initial application early in growing

season and repeat as necessary to maintain control; use light rates for soft water

and heavier rates for water high in salts,

especially carbonates; apply large crystals

on concrete bottom or apron or suspend

in water in burlap bags; crystals dissolve

very slowly.

1 All herbicides listed are registered under Federal

Insecticide, Fungicide, and Rodenticide Act for suggested

uses at time of publication, but some herbicides registered

for use in control of aquatic weeds may not be included.

2 Rates and concentrations are in terms of acid equivalent or active ingredient of herbicide and not necessarily

or usually of commercial formulation.
SUGGESTED GUIDE FOR WEED CONTROL 19 619

APPENDIX

65

HERBICIDE TOLERANCES FOR CROPS

Croy and herbicide P.p.m.

Alfalfa:

Diuron 2. 0

Simazine 15. 0

Apples :

AMS 5.0

Dalapon 3. 0

Dichlobenil . 15

Diuron 1. 0

Terbacil . 1

2,4-D (acid or oil-soluble amine) 5. 0

Apricots, dalapon__ 1. 0

Artichokes, diuron 1. 0

Asparagus:

Dalapon 30. 0

Monuron 7. 0

Sesone 2. 0

2,4-D (sodiura salt) 5. 0

Avocados:

Dichlobenil . 15

Monuron 1. 0

Bananas, diuron . 1

Barley, 2,4-D:

Forage 20. 0

Grain . 5

Beans, lima, trifluralin .05

Beans, snap:

DCPA 2.0

Trifluralin . 05

Bermudagrass, sprigged :

Diuron, grass and hay . 7

Simazine 15. 0

Blackberries, diuron 1. 0

Blueberries, diuron 1. 0

Boysenberries, diuron 1. 0

Broccoli :

DCPA 1.0

FW-925 . 75

Trifluralin . 05

Brussels sprouts:

DCPA 1.0

Trifluralin . 05

Cabbage:

DCPA 1.0

FW-925 . 75

Cantaloup, DCPA 1. 0

Carrots, linuron 1. 0

Cauliflower :

DCPA 1.0

FW-925 J . 75

Trifluralin . 05

Cherries, dichlobenil . 15

Citrus (grapefruit, lemons, oranges) :

Bromacil, grapefruit, lemons, oranges . 1

Dalapon, grapefruit, limes, oranges, tangerines 5. 0

Dichlobenil . 15

Diuron :

Pulp 4. 0

Whole fruit 1. 0

Terbacil . 1

Collards, DCPA 2. 0

Corn:

Atrazine :

Fodder and forage 15. 0

Grain (cobs with husks removed, and

kernels) .25

Dalapon:

Dry ears (cobs and kernels) and grain 10. 0

Fodder and forage 5. 0

Crop and herbicide P.p.m.

Diuron:

Forage 2. 0

Grain 1. 0

Linuron, ears or grain .25

Propachlor, forage 1.5

Corn, sweet:

Atrazine :

Fodder or forage 15. 0

Grain (cobs, with husks removed, and

kernels) .25

Dalapon:

Dry ears (cobs and kernels) and grain 5. 0

Fodder and forage 5. 0

Linuron:

Ears or grain .25

Fodder or forage 1. 0

Propachlor:

Forage 1. 5

Grain (cobs, with husks removed, and

kernels) . 1

Cotton:

Dalapon, cottonseed 35. 0

DCPA, cottonseed . 2

Diuron, cottonseed 1. 0

Linuron, cottonseed . 25

Monuron, cottonseed 1. 0

Prometryne :

Cottonseed .25

Forage 1. 0

Trifluralin, cottonseed .05

Cranberries :

Dalapon 5. 0

Dichlobenil . 15

Eggplant, DCPA \. 0

Flax, dalapon, seed 75. 0

Garlic, DCPA L 0

Gooseberries, diuron 1. 0

Grapes:

Dalapon 3. 0

Diuron 1. 0

Grasses, diuron, seed ñelds 2. 0

Kale, DCPA 2.0

Lettuce:

Benefin .05

DCPA, head and leaf 2. 0

Loganberries, diuron 1.0

Macadamia nuts, diuron .1

Mangoes, dichlobenil . 15

Mint, diuron, hay 2.0

Mustard greens, DCPA 5.0

Oats, 2,4-D:

Forage 20.0

Grain .5

Okra, trifluralin .05

Olives, diuron 1.0

Onions:

DCPA 1.0

Monuron, dry bulbs 1.0

Parsnips, with or without tops, linuron .5

Peaches:

Dalapon 15. 0

Dichlobenil . 15

Terbacil . 1

Peanuts:

Benefin .05

Sesone J6. 0

Vernolate, forage and hay .1

Pears:

AMS 5.0

Dalapon 3.0

Diuron 1. 0

2,4-D (acid or oil-soluble amine) 5. 0
66 AGRICULTURE HANDBOOK 332, U.S. DEPT. OF AGRICULTURE

Crop and herbicide P.p.m.

Peas, dalapon, forage and peas 15.0

Peas, southern:

DCPA 2.0

Trifluralin .05

Peppermint:

Diuron, hay 2. 0

Terbacil, hay .1

Peppers:

DCPA 2.0

Trifluralin . 05

Pineapples:

Bromacil . 1

Diuron 1. 0

Monuron 1.0

Plums:

Dalapon 1. 0

Dichlobenil . 15

Potatoes:

Dalapon 10. 0

DCPA 2.0

Linuron 1. 0

Sesone ^ 6. 0

Raspberries, diuron 1. 0

Rice, molinate, grain and straw .1

Sorghum:

Atrazine:

Fodder and forage 15. 0

Grain . 25

Propachlor:

Forage 3. 0

Grain . 25

Soybeans :

Chloroxuron :

Dry . 15

Hay . 15

Crop and herbicide P.p.m.

Linuron, dry and succulent forage and hay 1. 0

Nitralin . 1

Trifluralin . 05

Squash, summer and winter, DCPA 1.0

Strawberries:

Chloroxuron . 1

DCPA 2. 0

Diphenamid 1. 0

Sesone 2. 0

Sugar beets:

Dalapon, roots and tops 5. 0

Pebulate, roots and tops . 1

Sugarcane:

Diuron 1. 0

Monuron 1. 0

Terbacil . 1

Sweetpotatoes, DCPA 2. 0

Tomatoes:

DCPA 1. 0

Pebulate . 1

Trifluralin . 05

Trefoil, birdsfoot, diuron. forage and hay 2. 0

Turnip greens, DCPA 5. 0

Turnips, DCPA, roots 2. 0

Walnuts, English, diuron . 1

Wheat:

Diuron:

Forage, hay, straw 2. 0

Grain - 1. 0

2,4-D:

Forage 20. 0

Grain • 5
SUGGESTED GUIDE FOR WEED CONTROL 19619

CROP INDEX

67

FIELD, FRUIT, AND VEGETABLE CROPS

Page

Alfalfa 27,34,48,49, 65

Almonds 41

Apples 40, 65

Apricots 41, 65

Artichokes 37, 65

Asparagus 38,' 65

Avocados 42, 65

Bananas 42,' 65

Barley 22, 33, 34^ 65

Beans:

Lima 37, 65

Pole 37

Snap 37, 65

Beets 37

Bentgrass- 34

Bermudagrass 45

Blackberries 44, 65

Blueberries 44, 65

Bluegrass 34

Boysenberries 44, 65

Broccoli 37, 65

Brussels sprouts 37' 65

Cabbage 38, 65

Cantaloup 38, 65

Caraway 38

Carrots 10, 11,38,65

Cauliflower 38, 65

Celery 38', 46

Cherries 41, 65

Chicory 38

Clover :

Alsike 28, 34, 49, 50

Crimson 28, 34,49, 50

Ladino 28, 34, 49, 50

Red 28,34,49,50

Subterranean 28, 34, 49, 50

Sweet 28, 49, 50

White 28, 34, 49, 50

Collards-- 38, 65

Corn 11, 18, 19, 35, 65

Corn, sweet 11, 18, 19, 38, 65

Cotton 10, 15, 18-20, 30, 65

Cranberries 43, 44, 65

Cress, upland 38

Cucumbers 38

Dates 42

Dill 38

Eggplant 38,46,65

Endive 38

Escarole 38

Fescue, creeping red 34

Fescue, tall 34

Flax 29,65

Garhc 38, 65

Gooseberries 44, 65

Grapefruit 42, 43, 65

Grapes 12, 18, 43, 44, 65

Grasses 50,65

Hanover salad 38

Kale 38, 65

Legumes 28, 33, 48, 49, 51

Lemons 42, 43, 65

Lentils 38

Lespedeza 28, 34, 51

Lettuce 39, 65

Limes 43, 65

Loganberries 44, 65

Macadamia nuts 42, 43, 65

Mangoes 43,65

Mint 39, 65

Page

Mustard greens 39, 65

Oats "33, 34^65

Okra 39,65

Olives 41,43,65

Onions 39^65

Oranges 42,43,65

Orchardgrass 29, 34, 52

Parsley 39

Parsnips _ 39,65

Peaches 41, 65

Peanuts "'/_ 22,'65

Pears 41, 65

Peas 39,65

Peas, southern 39, 65

Peppermint 39, 65

Peppers 39,46,65

Pineapples 42, 43, 65

Plums 41,65

Potatoes 39, 65

Pumpkins 40

Radish 40

Raspberries 44, 65

Rice iö, 30-33,65

Ryegrass 29,34

Saflflower 22, 30

Sorghum 22, 23, 30, 36,' 65

Soybeans 10, 15, 23-25, 30, 36

Spinach 40

Squash 40, 65

Strawberries 43, 44, 65

Sugar beets 25, 35^ 65

Sugarcane 26, 65

Sweetpotatoes 36, 40, 65

Tangerines 65

Tobacco ii, 18,26,40,65

Tomatoes 12, 18, 46

Trefoil 28,34,49,65

Trefoil, birdsfoot 48

Turnip greens 40, 65

Turnips 40, 65

Walnuts, English 41,65

Watermelons 40

Wheat 33,34,65

Wheat, durum 33, 34

Wheat, hard red spring 33, 34

ORNAMENTALS AND SHADE TREES

Page

Ageratum 45

Almond, flowering 46

Alyssum 45

Amur corktree 46

Arborvitae 45, 46

Ash 46

Aster 45

Astilbe 45

Azalea 45, 46

Babysbreath 45

Balsam 45, 46

Barberry 45, 46

Bayberry 46

Beautybush 46

Birch 45,46

Birch, white 45, 46

Bleedingheart 45

Bluebell 45

Boxelder ^ 46

Boxwood 45, 46

Bush-honeysuckle 45, 46

Camellia 45,46

Caragana ^ 46
68 AGRICULTURE HANDBOOK

33 2, U.S. DEPT. OF AGRICULTURE

Page

Carnation 45

Cedar 46

Cedar, eastern red45, 46

Chamaecyparis 46

Chrysanthemum 45

Cleyera japónica 46

Coleus 45

Columbine 45

Coneflower, purple 45

Coralbell 45

Cotoneaster 46

Cottonwood 46

Crabapple 46

Cypress, Elwood 46

Daffodil 46

Dahlia45,46

Delphinium.--: 45

Deutzia 46

Dianthus 45

Dogwood 46

Douglas-fir 46

Elm 46

Elm, American 46

Elm, Chinese 46

Elm, Siberian 46

Euonymus45, 46

Evening-primrose 45

Feverfew 45

Fir, Fraser 46

Firethorn 46

Forget-me-not 45

Forsythia45,46

Fuchsia 45

Gardenia 46

Gladiolus45,46

Golden-rain-tree 46

Hackberry 46

Heather 46

Hemlock-- 46

Holly 46

Honeylocust 46

Honeysuckle45, 46

Hydrangea45, 46

Iris__-__45,46

Iris, Dutch45,46

Ivy 46

Ivy, English 45

Juniper45, 46

Juniper, creeping 45, 46

Kinnikinnick 46

Lantana 45

Larkspur, candle 45

Laurel 45, 46

Leucothoe 46

Lilac45,46

Lily45,46

Linden 46

Locust 46

Lupine 45

Magnolia45,46

Mahonia45, 46

Page

Maple45,46

Marguerite, golden 45

Marigold 46

Mockorange45, 46

Moss rose 45

Mountain-ash 46

Mourning bride 45

Nandina 46

Narcissus45, 46

Oak 46

Oak, red 46

Osmanthus (hoUyolive) 46

Pachistima 46

Pachysandra 45

Peony 45

Periwinkle 45

Petunia45, 46

Photinia 46

Picea 46

Pine 46

Pine, Austrian 46

Pine, mugo 46

Pine, red 46

Pine, Scotch 46

Pine, white 46

Pinks, mourning 45

Pittosporum 46

Plum 46

Podocarpus 46

Pokerplant 45

Poplar 45, 46

Potentilla 45

Privet45,46

Privet, variegated 45

Pyracantha 46

Quince, flowering 46

Redcedar 46

Rhododendron45, 46

Rockrose 46

Rose 45, 46

Rose, multiflora45, 46

Russian-olive 46

Sage, scarlet 45

Salvia 45

Snapdragon 45

Spirea45,46

Spruce4 46

Spruce, blueI 46

Spruce, Norway-. 46

Spruce, redi 46

Spruce, whiteI 46

Squawcarpet 46

Tulip45,46

Verbena 45

Viburnum45,46

Weigela 46

White-cedar 46

Willow 46

Wintercreeper 45

Yew-45,46

Zinnia 45
SUGGESTED GUIDE FOR WEED CONTROL 19619

WEED INDEX

69

Page

Agarita {Mahonia trifoliolata (Moric.) Fedde) 52

Alder (Alnus spp.) 57

Algae:

Blue-green (many genera) 5, 30, 61, 63

Filamentous green (many genera) 5, 30, 60, 61, 63

Pithophora spp 5^ 30

Alligatorweed (Alternanthera philoxeroides (Mart.)

Griseb.) 2, 60-62

Arrowhead (Sagittaria spp.) 31, 62

Ash (Frazinus spp.) 52, 59

Ash, white {Fraxinus americana L.) 5, 52, 59

Aster, woody (Aster parryi A. Gray) 51

Baccharis (Baccharis spp.) 52, 57

Barley, wild (Hordeum leporinum Link) 22, 33, 65

Barnyardgrass (Echinochloa crusgalli (L.) Beauv.)__ 5,

7, 10, 30-32

Bayberry (Myrica pensylvanica Loisel.) 52

Beakrush (Rhynchospora spp.) 30

Bedstraw {Galium spp.) 51

Bedstraw, smooth (Galium mollugo L.) 35, 51

Beech (Fagus grandifolia Ehrh.) 52

Bermudagrass (Cynodon dactylon (L.) Pers.) 5,

8, 10, 50, 52, 57

Bindweed (Convolvulus spp.) 8, 10, 12

Bindweed, field (Convolvulus arvensis L.)___ 7, 8, 10, 12, 35

Birch (Betula spp.) 52

Bitterweed (ß'eienmm awarwm (Raf.) Rock) 49

Blackgum (Nyssa sylvatica Marsh.) 52, 59

Bladderwort ( Utricularia spp.) 63

Bluegrass (Poa spp.) 29, 53

Bluegrass, Kentucky (Poa pratensis L.) 10, 53, 57

Boxelder (Acer negundo L.) 57

Brackenfern (Pteridium spp.) 7

Bramble (Rubus sp.) 59

Brome, downy (Promus tectorum L.) 10, 51

Brome, Scotch (Cytisus scoparius (L.) Link) 2, 54

Bromegrass (Promus spp.) 49

Bromegrass, downy (Bri/mus tectorum L.) 49

Broomsedge (Andropogon virginicus L.) 50

Broomweed, common (Gutierrezia dracunculoides

(DC.) Blake) 51

Buckbrush (Symphoricarpos spp.) 48,51

Buckwheat, wild (Polygonum convolvulus L.) 25, 34

Bulrush (Scirpus spp.) 5, 30, 63

Burclover (Medicago polymorpha var. vulgaris

(Benth.) (Shinners) 53

Burdock (Arctium spp.) 1, 51

Burhead (Echinodorus cordifolius (L.) Griseb.) 31

Buttonbush (Cephalanthus occidentalis L.) 60

Cabomba (Cahomba caroliniana Gray) 63

Cactus, cholla (Opuntia spp.) 2, 52

Canarygrass, reed (Phalaris arundinacea L.) 5, 57, 62

Cane, wild (Sorghum bicolor (L.) Moench) 19

Carpetweed (Mollugo verticillata L.) 7

Carrot, wild (Daucus carota L.) 1

Catclaw (Schrankia nuttallii (DC.) Standl.) 52

Cattail (Typha spp.) 1, 5, 7, 30, 60-62

Ceanothus (Ceanothus spp.) 52

Celery, wild (Apium leptophyllum (Pers.) F. Muell.)_ 63,

64

Chara (Chara spp.) 63

Cheat (Promus secalinus L.) 1

Cherry (Prunus spp.) 59

Chestnut (Castanea spp.) 52

Chickweed (Stellaria media (L.) Cyrillo) 6-8,

10, 26, 28, 47-52

Chicory (Cichorium intybus L.) 51

Chinaberry, wild (Melia azedarach L.) 52

Chinkapin (Castanea spp.) 52

Clover (Trifolium spp.) 53, 54

Clover, white (Trifolium repens L.) 53

Cockle, corn (Agrostemma githago L.) 7, 34

Page

Cockle, cow (Saponaria vaccaria L.) 34

Cocklebur (Xanthium spp.) 7, 21, 24

Coffeebean. (See Sesbania.)

Coontail (Ceratophyllum spp.) 63

Cottonwood (Populus spp.) 52, 57

Crabgrass (Digitaria spp.) 1, 5, 7, 9-11, 48, 52

Crabgrass, hairy (Digitaria villosa (Walt.) Pers.) _ 4,

5, 7, 9, 1Ö, 48, 52

Crabgrass, smooth (Digitaria ischaemum (Schreb.)

Muhl.) 1,5,7,9-11,48

Cress, hoary (Cardaria draba (L.) Desv.) 5, 34, 35

Crowfoot, water (Ranunculus spp.) 63

Cutgrass (Leersia spp.) 62

Daisy (Chrysanthemum spp.) 6

Dallisgrass (Paspalum dilatatum Poir.) 9, 53

Dandelion (Taraxacum officinale Weber) 51, 54

Deathcamas (Zigadenus spp.) 48, 51

Dock, curlv (Rumex crispus L.) 5, 10, 47, 51, 54

Dodder (Cuscuta spp.) 49

Dogbane (Apocynum spp.) 35

Dogfennel (Eupatorium capillifolium (Lam.) Small) _ 7,

26,34

Dogwood (Cornus spp.) 59

Ducksalad (Heteranthera limosa (Sw.) Willd.) 30-33

Duckweed (Lemna spp.) 62

Elbowbush (Forestiera pubescens Nutt.) 52

Elderberry (Sambucus spp.) 59

Elm ( Ulmus spp.) 52

Elodea (Elodea spp.) 63, 64

Fescue, red (Festuca rubra L.) 10, 29, 34

Fescue, tall (Festuca spp.) 53

Fimbristylis (Fimbristylis spp.) 31,32

Flatsedge (Cyperus spp.) 30-33

Foxtail, giant (Setaria faberii Herrm.) 7, 10, 25

Foxtail, green (Setaria viridis (L.) Beauv.) 7, 10, 25

Foxtail, yellow (Setaria glauca (L.) Beauv.) 7, 10, 25

Garlic, wild (Allium vineale L.) 10, 12, 48, 51, 54

Goldenrod (Solidago spp.) 6

GoosQgvSiss (Eleusine indica (IJ.) Gaertn.) 53

Gooseweed (Sphenoclea zeylanica Gaertn.) 31-33

Gorse ( JJlex europaeus L.) 2, 54

Groundcherry (Physalis spp.) 26

Hackberry (Celtis spp.) 52

Halogeton (Halogeton glomeratus (M. Bieb.) C. A.

Mey.) 2,51

Haw, red (Crataegus spp.) 52

Henbit (Lamium amplexicaule L.) 10, 26, 49-51, 53, 54

Hickory (Carya spp.) 52

Honeylocust (Gleditsia triacanthos L.) 52

Horehound (Marrubium vulgäre L.) 51

Horsenettle (Solanum carolinense L.) 56

Horsetail rush (Equisetum spp.) 5

Huisache (Acacia farnesiana (L.) Willd.) 52

Hydrangea (Hydrangea spp.) 52

Indigo, curly (Aeschynomene virginica (L.) BSP.)_- 30-32

Ironweed (Vernonia spp.) 51

Ivy, ground (Glechoma hederacea L.) 53

Ivy, poison (Rhus radicans L.) 5, 34, 40

Johnsongrass (Sorghum halepense (L.) Pers.) 1,

7-9, 11, 20, 21, 24, 26, 35, 50, 57, 62

Jointvetch, northern (curly indigo) (Aeschynomene

indica L.) 30-32

Knapweed, Russian (Centaurea repens L.) 5, 7, 35

Knawel (Scleranthus annuus L.) 51

Knotgrass (Paspalum distichum L.) 30, 62

Knotweed (Polygonum spp.) 7, 50, 53, 54

Koa haole (Leucaena leucocephala (Lam.) de Wit.)_- 26

Lambsquarters (Chenopodium spp.) 5, 7, 10, 49

Larkspur, low (Delphinium nelsonii Greene) 51

Larkspur, tall (Delphinium barbeyi Huth) 52

Lettuce, wild (Lactuca spp.) 26

Locoweed (Astragalus spp.) 51
70 AGRICULTURE HANDBOOK 332, U.S. DEPT. OF AGRICULTURE

Page

Lotus, American (Nelumbo lutea (Willd.) Pers.) 62

Lupine, silvery (Lupinus argenteus Pursh) 51

Madrone {Arbutus menziessi Pursh) 52

Manzanita (Arct staphylos spp.) 52

Maple (Acer spp.) 52, 59

Maple, red {Acer ruhrum L.) 52, 59

Maple, silver {Acer saccharinum L.) 52, 59

Mescalbean {Sophora secundiflora (Ort.) Lag.) 52

Mesquite {Prosopis spp.) 48, 59

Mesquite, honey {Prosopis glandulosa var. glandu-

/osa (Torr.) Cockerell) 48,52,59

Mesquite, velvet {Prosopis velutina (Woot.)) 48, 52

Mexicanweed {Caperonia castaneaefolia (L.) St.

Hil.) 30,31

Milkvetch, timberline {Astragalus sp.) 51, 52

Milkvetch, twogrooved {Astragalus bisulcatus

(Hook.) Gray) 51

Morningglory {Ipomoea spp.) 7, 8, 26

Mulberry {Morus spp.) 52, 59

Mullein {Verbascum spp.) 1

Mustard {Brassica spp.) 12, 33, 34, 49

Mustard, tumble {Sisymbrium altissimum L.) 12,

33, 34, 49

Naiad {Najas spp.) 63, 64

Nightshade {Solarium spp.) 26

Nimblewill {Muhlenbergia schreberi J. F. Gmel.) 53

Nutsedge {Cyperus spp.) 1, 7, 20, 21, 24, 36, 49

Nutsedge, purple {Cyperus rotundus L.) .7,

20, 21, 24, 36, 49

Nutsedge, yellow {Cyperus esculentus L.) 7,

20, 21, 24, 36, 49

Oak {Quercus spp.) : 48

Oak, blackjack {Quercus marilandica Muenchh.) 52, 59

Oak, bur {Quercus macrocarpa Michx.) 48, 52, 59

Oak, pin {Quercus palustris Muenchh.) 48, 52, 59

Oak, poison {Rhus toxicodendron L.) 5, 48, 59

Oak, post {Quercus stellata Wangenb.) 48, 52, 59

Oak, red {Quercus rubra L.) 48, 59

Oak, shinnery {Quercus havardii Rydb.) 48, 51, 59

Oak, water {Quercus nigra L.) 48, 52, 59

Oak, white {Quercus alba L.) 48, 52, 59

Oak, willow {Quercus phellos L.) 48, 52, 59

Oats, wild {Avena fatua L.) 5,

7, 11, 22, 25, 29,33,34, 59

Onion, wild {A Ilium canadense L.) 51, 54

Orchardgrass {Dactylis glomerata L.) 29, 34, 52

Osageorange {Madura pomifera (Raf.) Schneid.) __ 52, 59

Palmetto {Serenoa repens (Bartr.) Small) 59

Paragrass {Panicum purpurascens Raddi) 57, 62

Pecan {Carya spp.) 52

Pennycress {Thlaspi spp.) 1

Pennywort {Hydrocotyle spp.) 53

Pennywort, water {Hydrocotyle umbellata L.) 53, 63

Pepperweed (Lepidium spp.) 49

Persimmon {Diospyros spp.) 59

Phragmites (Phragmites communis Trin.) 7

Pickerelweed {Pontederia cordata L.) 62

Pigweed {Amaranthus spp.)___ 1, 5, 7, 10, 12, 20, 26, 49, 51

Plantain, buckhorn {Plantago lanceolata L.) 54

Pondweed {Potamogetón spp.) 61, 63

Pondweed, curlyleaf {Potamogetón crispus L.)__ 61, 63, 64

Poplar {Populus spp.) 57

Pricklyash {Zanthoxylum americanum Mill.) 5, 52

Pricklypear {Opuntia spp.) 52

Princesplume {Polygonum orientale L.) 51

Puncturevine {Tribulus terrestris L.) 2, 8

Purslane {Portulaca olerácea L.) 7, 20, 53

Quackgrass {Agropyron repens CL.). Beauv.) 5,

7-12, 18, 35, 50, 52, 57, 62

Rabbitbrush {Chrysothamnus spp.) 51

Ragweed, bur {Franseria discolor Nutt.) 1,

5, 35, 48, 49, 51

Ragweed, common {Ambrosia artemisiifolia L.)__ 5, 49, 51

Ragwort, tansy {Senecio jacobaea L.) 2, 51

Redbud {Cercis spp.) 59

Page

Redstem {Anmania auriculata Willd.) 31-33

Reed, common {Phragmites communis Trin.) 62

Reeds {Phragmites spp.) 60

Retama {Parkinsonia aculeata L.) 52

Rice, red {Oryza sativa L.) 30

Rocket, yellow {Barbarea vulgaris R. Br.) 33, 49, 50

Rushes {Juncus spp.)_-_ 35, 60

Sagebrush, big {Artemisia tridentata Nutt.) 48, 51

Sagebrush, low {Artemisia arbuscula Nutt.) 48, 51

Sagebrush, sand {Artemisia filifolia Torr.) _' 48, 51

Sagittaria, dwarf {Sagittaria subíala (L.) Buchenau)- 61

Saltcedar (Tamarix pentandra Pall.) 59

Sandbur {Cenchrus spp.) 53

Sassafras (Sassafras spp.) 52,59

Sedge, Nebraska {Carex nebraskensis Dewey) 30,

32, 60, 62

Sedge, ripgut {Carex lacustris Willd.) 30, 32, 60, 62

Sedges {Carex spp.) 30, 32, 60, 62

Sesbania, hemp {Sesbania exáltala (Raf.) Cory)_ 25, 30-33

Shepherdspurse {Capsella bursa-pastoris (L.)

Medic.) 1

Signalgrass, broadleaf {Brachiaria platyphylla

(Griseb.) Nash) 30,32

Smartweed {Polygonum spp.) 2, 5, 7, 31, 34, 62

Sneezeweed {Helenium spp.) - 49, 51

Sneezeweed, orange (western) {Helenium hoopesii

Gray) 49,51

Sorrel, red {Rumex acetosella L.) 7, 53, 54

Sowthistle {Sonchus spp.) 35

Spatterdock {Nuphar advena (Ait.) Ait. f.) 62

Spicebush {Lindera benzoin (L.) Blume) 52

Spikerush {Eleocharis spp.) 30-33, 62

Spirea, narrowleaf {Spiraea alba DuRoi) 52

Sprangletop {Leptochloa spp.) 30, 32

Spurge, leafy {Euphorbia esula L.) 5, 34, 35

St. Johnswort {Hypericum perforatum L.) 2, 54

Strawberry, wild {Fragaria spp.) 7

Sumac {Rhus spp.) 52

Sweetgum (Liquidambar styraciflua L.) 52

Sycamore {Platanus spp.) 52, 57

Tansymustard {Descurainia pinnata (Walt.) Britt.)_ 51

Tarweed {Madia spp.) 49, 51

Tasajillo {Opuntia leptocaulis DC.) 52

Thistle, Canada {Cirsium arvense (L.) Scop.) 1,

5, 7, 9, 34, 35, 50, 51

Thistle, Russian {Salsola kali L. var. tenuifolia

Tausch) 8,51

Timothy (Phleum pratense L.) 52

Toadflax, Dalmatian {Linaria dalmática Mill.) 51

Tree-of-heaven {Ailanthus altissima (Mill.) Swingle). 52

Trumpetvine {Campsis radicans (L.) Seem.) 59

Tules {Scirpus spp.). {See Bulrush.)

Velvetleaf {Abutilón theophrasti Medic.) 7

Violet {Viola spp.) 53

Walnut {Juglans spp.) 52

Waterchestnut ( Trapa natans L.) 63

Watercress {Nasturtium officinale R. Br.) 60

Waterfern {Salvinia spp.) 61, 62

Waterhemlock {Cicuta spp.) 51

Waterhyacinth {Eichhornia crassipes (Mart.)

Solms.) 2,5,31,61,62

Waterhyssop {Bacopa caroliniana (Walt.) Robins.)- 31-33

Waterlettuce {Pistia stratiotes L.) 62

Waterlily {Nymphaea spp.) 61

Waterlily, white {Nymphaea tuberosa Paine) 62

Watermilfoil {Myriophyllum spp.) 63

Waterplantain {Alisma spp.) 31, 61, 64

Waterprimrose {Jussiaea spp.) 31, 60, 62, 63

Watershield {Brasenia schreberi Gmel.) 61

Waterstargrass {Heteranthera dubia (Jacq.) MacM.) _ 63

Wildrye {Elymus spp.) 5

Willow {Salix spp.) 52,57,60

Woodsorrel {Oxalis spp.) 53

Yerba-de-tago {Eclipta alba (L.) Hassk.) 31

Yucca {Yucca spp.) 51

U.S.GOVERNMENT PRINTING OFFICE : 1969—O-320-446