SUGGESTED GUIDE

FOR

WEED CONTROL

1967

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 cul-^^

tural 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.

¿^'Z^^t^i^'t^è^^l^

Secretary's Memorandum 1565,

issued December 23, 1964.
SUGGESTED GUIDE

FOR

WEED CONTROL

1967

Prepared by Crops Research Division

Agriculture Handbook No. 332

Washington, D.C. Issued July 1967

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

Washington, D.C. 20402 - Price 40 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 January 1, 1967,

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.

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.

FOLLOW THE LABEL

U.S. DEPAÍTMENT Of AGRICUl
CONTENTS

Pago

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 15

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 18

Weed control in horticultural crops 33

Vegetables 34

Deciduous tree fruits and nuts 36

Citrus and subtropical fruits and nuts 38

Small fruits 38

Ornamental plants 40

Weed control in horticultural plant beds and nurseries 41

Weed control in greenhouses 41

Weed control in forage crops, pastures, and rangelands 42

Weed control in lawns and other turf areas 47

Weed control in noncropland 49

Construction aids 49

Cultural, biological, and mechanical control 49

Control with herbicides 49

Control of aquatic weeds 55

Construction aids 55

Management practices 55

Hand and mechanical control 55

Biological control 56

Chemical control 56

Crop, site, and topic index 60

Weed index by crops or sites 62
LIST OF TABLES

Table Page

1 Chemical, physical, and biological properties of herbicides 5

2 Amounts of herbicide liquid formulation or wettable powder to use

per acre in various concentrations and for various application

rates ^^

3 Weed control in field row crops 18

4 Weed control in close-drilled field crops 26

5 Control of perennial weeds in cropland 32

6 Weed control in vegetables 34

7 Weed control in deciduous tree fruits and nuts 37

8 Weed control in citrus and subtropical fruits and nuts 38

9 Weed control in small fruits 39

10 Weed control in ornamental plants 40

11 Weed control with soil fumigant herbicides in horticultural plant

beds and nurseries 42

12 Weed control in forage crops, pastures, and rangelands 43

13 Weed control in lawns and other turf areas 47

14 Weed control in noncropland (ditchbanks, fence rows, floodways,

industrial sites, and railroad, highway, and utility line rights-ofway) 52

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

streams, lakes, ponds, reservoirs, marshes) 57
SUGGESTED GUIDE FOR WEED CONTROL 1967

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 fertility, 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 Avildlife 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, shepherds-purse, 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 F. L. Timmons, L. L. Danielson,

J. T. Holstun, Jr., D. L. Klingman, H. L. Morton, W. C.

Shaw, W. B. Ennis, Jr., 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.

burdock, wild carrot, and mullein. They often

can be controlled by cultivation or timely mowing.

Perennials live 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 livestock, spraying

with selective herbicides, liming, fertilizing, or

other means of altering the environment to favor

the desired species over w^eeds 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

applications 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
AGRICULTURE HANDBOOK 3 32; U.S. DEPT. OF AGRICULTURE

methods. Thereafter, desirable species can be

planted and suitable conditions provided for their

effective competition with surviving or reinvading

weeds.

HAND AND MECHANICAL METHODS

Numerous effective herbicides and improved

methods of application 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. Improvements in tools used

for cultivating, mowing, burning, and ditch clean>

ing 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 w^eed 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, fertility, 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 application 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

management and production practices have on

the choice and effectiveness of weed-control

methods.
SUGGESTED GUIDE FOR WEED CONTROL 1967

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 applied

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

heeded. 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. 160-pound man

Highly toxic 50 and below. __ Few drops to 1

teaspoon.

Moderately toxic _ 50-500 1 teaspoon to 1

ounce.

Mildly toxic 500-5,000 1 ounce to 1 pint

or 1 pound.

Nontoxic Above 5,000 1 pint to over 1

quart.

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 original labeled

containers.

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 yoiuhands 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 livestock from grazing in areas

where herbicide sprays may have increased the

palatibility 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 wUdlife.

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 volatilized 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 drift

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.

3. Avoid applying a soil sterilant herbicide 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 runoff 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 1 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,

fertihzers, 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,

frheir acute oral toxicity to warmblooded animals

is indicated by the LD50 rating, or lethal dosage

that kills 50 percent of the experimental animals,

and is 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 apphcation,

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 18-59.

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 forn;iulations 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 tue

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-D, 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 1967

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Preemergence and postemergence

treatments for control of bindweed,

quackgrass, wild garlic, some perennial broadleaved herbaceous weeds; brush treatment may preventcrop production for 1-3 years. Controls many germinating and

established annual broadleavedweeds including lambsquarters, mustard, pigweed; do not use volatile esters near susceptible plants such as cotton, flowers,

grapes, ornamentals, tomatoes. Controls many broadleaved weeds and weed grasses.

Controls many germinating annual broadleaved weeds and weed grasses. Broadleaved weeds; do not use volatile

esters near such susceptible plants as

cotton, flowers, grapes, ornamentals,

tomatoes.

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Basic chemical vised

to calculate

application rate

Acid equivalent

do

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SUGGESTED GUIDE FOR WEED CONTROL 1967 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 appHcation as dry granules. They are appUed with

specialized granular pesticide spreading equipment

or modified fertilizer spreaders.

Granules are prepared in several ways. Some

herbicides are impregnated on granules of clay,

vermicuhte, 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 fohage 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 fohage and their effectiveness in killing

germinating weed seeds in the soil is reduced.

Granules tend to bounce off and sift down through

the fohage 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 controlHng

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 chmate, soil, and appUcation technique

for best results. Recommendations prepared by

weed research specialists in State agricultural

experiment stations and by the individual manufacturers of granular herbicides outhne 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 fohage 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.Xacre-feet

X2.7

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:

(1) For liquid formulations—

-763 O - 67 - 3
14 AGRICULTURE HANDBOOK 3 32, U.S. DEPT. OF AGRICULTURE

=gallonsrequired

=0.5 gallon

= 1 gallon

= 12.15 gallons

Rate or amountrequired in pounds

Pounds of herbicide per gallon

Examples:

Rate, 2 pounds per acre

4 pounds per gallon

Concentration, 4 pounds per 100 gallons

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-^ 100) instead of

pounds per gallon.

Examples:

Rate, 2 pounds per acre _

0.5 pound (50-percent material) P^^nds

Concentration, 4 pounds per 100 gallons

0.5 pound (50-percent material)

Amount required, 24.3 pounds _

0.20 pound (20-percent material) -121.5 pounds

The amounts of herbicide Uquid formulation

or dry product to use per acre in various concentrations and for various appUcation rates are

given in table 2.

-=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 Hquid 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=lengthXsquare of (short diameterslong diameter)-^2X0.0034

TABLE 2.—Amounts of herbicide liquidformulation or wettable powder to use per acre in various concentrations

and for various application rates

Concentration of

herbicide

Pounds of active ingredient per gallon:

2

3

4

5

6

7

8

9

10

Percentage of active ingredient in dryformulations: 1

10

20

25

30

40

50

75

90

% pound

Pints

1.0

.67

.50

.34

.25

.20

.17

.14

.125

.11

.10

Pounds

1.25

2 10

28.75

27.25

25

24

23

22.25

Amount to use per acre to obtain rate ofK pound

Pints

2.0

1.3

1.0

.67

.50

.40

.34

.30

.25

.22

.20

Pounds

2.5

1.2

2 17.5

2 15

2 10

28

26

24.5

H pound

Pints

4.0

2.6

2.0

1.3

1.0

.80

.67

.60

.50

.45

.40

Pounds

5

2.5

2

1.6

1.2

1

2 11

29

% pound

Pints

6.0

4.0

3.0

2.0

1.5

1.2

1.0

.90

.75

.67

.60

Pounds

7

3.5

3

2.33

1.75

1.4

1

2 12.5

1 pound

Pints

8.0

5.3

4.0

2.7

2.0

1.6

1.3

1.1

1.0

.9

Pounds

10

5

4.16

3.33

2.5

2

1.33

1.11

2 pounds

Pints

16.0

10.6

8.0

5.3

4.0

3.2

2.6

2.3

2.0

1.8

1.6

Pounds

20

10

8.33

6.67

5

4

2.67

2.25

3 pounds

Pints

24.0

16.0

12.0

8.0

6.0

4.8

4.0

3.4

3.0

2.7

2.4

Pounds

30

15

12.5

10

7.5

6

4

3.33

4 pounds

Pints

32.0

21.3

16.0

10.7

8.0

6.4

5.

4.

4.

3.

3.

Pounds

40

20

16.67

13.33

10

33

4

^ To be added to water or other liquid to be sprayed on 1 acre. 2 Ounces.
SUGGESTED GUIDE FOR WEED CONTROL 1967 15

Example:

60x(^^y^) X0.0034=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

oil 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

mixture. 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 apphcation of

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 boatmounted types, have been developed for most

situations requiring apphcation 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, speciaHzed 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 application 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 calibrating

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
16 AORICULTURE HANDBOOK 3 32, U.S. DEFT. OF AGRICULTURE

them at a uniform pressure and catching the

discharge from each nozzle in a separate container,

such as a cahbrated 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 (660 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 ,,

Width of spray swath in feet ~^ ^ ^

Example :

Water used=6 quarts

Spray swath width=20 feet

Then —w?^ =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

Output=5 gallons per acre

Desired rate of herbicide=2 pints per acre

Then Çx2=

o

= 22 pints, or 2.75 gallons, of

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 oj cotton is —XI.5=0.5 pound.

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.

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

4X330 „„_ ,

AQ KAH —0-030 acre sprayed

4O,0DU

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

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 tue 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 :

43 560""^'^^ ^^^® sprayed

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

' ^, =25 siallons 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

2 pintsX0.12 acre=0.24 pint per tankful

0.24 pintX32 tablespoons=7.7 tablespoons,

or about 0.5 cup
SUGGESTED GUIDE FOR WEED CONTROL 19 67 17

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:

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

117=:width of effective swath (not total swath) in feet (assume 40 feet)

T=time sprayed in seconds (assume 60 seconds, or —, or 0.017 hour)

ö=gallons used (assume 12.5)

Then S (75 m.p.h.)X5,280 feet per homXW (40 feet)xy (0.017 hour)_^ ^^ ^^^^^

43,560 square feet

Gallons per minute=-^=—-^ = 12.5

Gallons per acre= 6.18 2.02

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 —— =60 acres sprayed per tank and

60X2 pints=120 pints (15 gallons) of

herbicide required.

HOW TO DETERMINE OUTPUT OF

SPREADERS

For acceptable accuracy, calibration of mechanical 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 complicated and

wasteful procedure.

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

Mechanical Spreaders With Calibration Pans Wind

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 sufBcient distance to cover

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

feet wide, the distance should be 435.6=^145.2

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.
18 AGRICULTURE HANDBOOK 3 32, U.S. DEPT. OF AGRICULTURE

The herbicide 2,4-D and other phenoxy herbicides should never be appUed 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 2,4-D, 2,4,5-T, and other

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

Rainfall immediately after postemergence foliage

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

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.

WEED CONTROL IN FIELD CROPS

The treatments described for weed control in

field crops (tables 3-5) 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 different 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 3.—Weed control infield row crops

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

Treatment Time of application Weeds controlled Remarks

CORN

Rotary hoe in and between rows.

Shallow cultivation (2

When corn is yomig

enough to tolerate

(after 2 inches tall but

before stalks stiffen).

From emergence to layby.

Before corn is 2 inches

tall and after 12 inches

tall.

In fall preceding year of

corn production.

After planting but before

emergence.

All seedling weeds that

are uprooted.

All weeds

Effective only on shallow-rooted seedling weeds.

Use often enough to control weeds

inches deep or less)

between rows.

Flame Kills tops of most weeds

up to 4 inches tall.

Quackgrass, most smallseeded annual weeds.

Most small-seeded annual weeds.

while young; this practice will control but seldom eradicates deeprooted perennial weeds.

If less than 2 inches tall, corn will be

Atrazine (4)

burned to ground but will recover;

if 12 inches tall, is tolerant; if 3-10

inches tall, may be severely injured

if flamed; do not repeat flaming of 2-

inch stage.

Incorporate 2-4 inches deep.

Planting corn deeper than 1 inch will

increase safety margin; works effectively with less soil moisture than

simazine.

Atrazine (2-4)
Treatment

CDAA (3.5) plus

TCBC (7).

Diuron (0.4-0.8) _

Simazine (2-4) _

2,4-D (1-2)__.

Atrazine (2-4) _

DNBP (1-2).

Linuron (1.5) plus

0.5-percent surfactant.

2,4-D (0.25-0.5) or

dicamba (0.25).

SUGGESTED GUIDE FOR WEED CONTROL 19 67

TABLE 3.—Weed control infield row crops—Continued

19

Time of application Weeds controlled Remarks

CORN—continued

Nitrogen solution

(80-120) N plus

one of following

additives: Atrazine

(1), linuron (0.62),

diuron (0.6), 2,4-D

(0.30); add 0.5-

percent surfactant

to mixture.

2,4-D (0.5) in drill

row and (1.5)

between rows.

After planting but before

emergence.

do

_do_

-doBefore weeds are more

than 1 inch tall.

After corn emergence

and before 2-leaf

stage.

After corn is 15 inches

tall and weeds are

less than 4-6 inches

tall.

When corn is 4-18

inches tall and weeds

are smaller than corn.

When corn is 20-30

inches tall.

After last cultivation.

Most small-seeded annual weeds.

do

.do_

_do_

Most annual weeds less

than 1 inch tall.

Most small-seeded

annual weeds small

enough to be covered

by spray.

Most annual weeds

covered by spray.

Most broadleaved

annual weeds; control or stunting of perennial broadleaved

weeds.

Most annual weeds less

than 1 inch tall;

some annual weeds

up to 3-4 inches tall.

Most small-seeded

annual weeds from

after last cultivation

until harvest.

Planting corn deeper than 1 inch will

increase safety margin.

May cause serious injury if corn is

planted less than 1}^ inches deep.

Planting corn deeper than 1 inch will

increase safety margin; more effective on brachiaria than atrazine.

Planting corn deeper than 1 inch 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 until corn is about 6 inches

tall; thereafter use in basally directed spray to minimize contact

with corn.

Apply as basally directed spray; limit

use to inbred corn.

Direct spray so as to cover only weeds,

soil, and lower 3-6 inches of corn.

Apply as foliage spray to corn and

weeds until corn is 12 inches 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 inches tall.

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

3-4 inches 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 inches

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 inches of corn.
20 AGRICULTURE HANDBOOK 332, U.S. DEPT. OF AGRICULTURE

TABLE 3.— Weed control infield row crops—Continued

Treatment Time of application Weeds controlled Remarks

Seedbed preparation

and fungicide treatment of seed.

Hand hoeing and spot

spraying.

Cultivate with tools

such as sweeps set

to cultivate 1-2

inches deep.

Cross-cultivate with

tools such as shieldtype sweeps,

sweeps, or diskhillers and sweeps

set to cultivate 1-2

inches deep; distance between inside tools determines cotton stand

left.

Flame in rows and between rows.

Incorporate trifluralin

(0.5-1) in soil or

DCPA (8-10.5).

Apply EPTC (1-1.5)

1 inch subsurface

in two 6-inch-wide

bands centered 7

inches from drill

row.

CIPC (4-10), DCPA

(8), diuron (0.4-

1.6), monuron (1.6),

norea (0.75-2.5), or

prometryne (2-3).

Before and at planting

Usually when cotton is

6-18 inches tall where

other control measures

are used.

From cotton emergence

to approximately 18

inches tall.

From cotton emergence

to approximately 15

inches 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

inches 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.

Helpful in controlling all

weeds.

All weeds resistant to

other control measures.

Generally all weeds

growing between rows.

Generally all weeds

growing between rows

and most weeds in

rows.

Most small plants enveloped by flame will

be topkilled; large

grass plants can be

slowly burned back by

series of light fl^mings.

Most grasses from seed;

some small-seeded

annual broadleaved

weeds such as pigweed

and purslane.

Nutsedge, johnsongrass

from seed, most

annual weeds.

Most small-seeded

annual weeds.

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.

More effective if used before weeds

are more than 2 inches 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 J^-l inch

deep.

Use in combination with preplanting

trifluralin or preemergence diuron;

follow with postemergencc 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 5^ inch deep; in general, only

use DCPA on very light soils and

monuron on very heavy soils.
SUGGESTED GUIDE FOR WEED CONTROL 1967

TABLE 3.—Weed control infield row crops—Continued

21

Treatment Weeds controlled Remarks

COTTON—continued

Naphtha, 20 gaL per

acre of band actually treated (5 gal.

per 13,068 row-feet

of 10-inch band).

DSMA (3).

DSMA (3) plus diuron

(0.2).

Diuron (0.2-0.4).

For lay-by purposes,

split application;

diuron, 0.3-0.75 lb.

per application.

For lay-by purposes,

single application;

CIPC (8), diuron

(0.5-1.5), linuron

(0.5-1.6), monuron

(0.5-1.6), or

prometryne (1).

Trifluralin (0.75)

1-3 applications after

smallest cotton is 2

inches tall and before

bark cracks appear

(about 1 week after

emergence until 4

weeks after emergence) .

1-2 applications after

smallest cotton is 3

inches tall but before

first bloom opens.

1-2 applications after

smallest cotton is at

least 6 inches tall but

before first bloom

opens.

1-2 applications after

cotton is 6 inches tall.

Once when cotton is 12

inches tall; again

when 15-24 inches.

When cotton is 15-24

inches tall.

Before first irrigation

after cotton emergence.

Most annual weeds in

seedling stage; perennial grasses and

nutsedge will be topkilled if treated in

early emergence

stages; few perennial

broadleaved weeds

will be topkilled when

small enough to be

covered by spray.

Most annual grasses,

seedling cocklebur, few

other broadleaved

weeds; nutsedge and

small Johnsongrass

will be topkilled.

Most annual weeds;

nutsedge and small

Johnsongrass will be

topkilled.

Most annual weeds if

treated when less than

3 inches tall, young,

and actively growing.

Most small-seeded annual weeds germinating after treatment;

young actively growing weeds less than 3

inches tall.

Most small-seeded

annual weeds germinating after treatment; young, actively

growing weeds less

than 3 inches tall if

surfactant is added.

Most small-seeded

annual weeds and

Johnsongrass from

seed between rows.

Apply as laterally directed spray to

drill area at less than 1 inch above

soil; diseased or mechanically damaged cotton may be severely injured; naphthas not developed

specifically for cotton may not be

satisfactory.

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 appears

more effective during hot, dry

periods.

Apply as basally directed spray;

normally use 1 pt. surfactant for

each 25 gal. spray mixture; DSMA

plus diuron is less dependent on

weather conditions than DSMA or

diuron used alone.

Apply as basally directed spray; add

1 pt. surfactant for each 25 gal.

spray mixture.

Apply as basally directed spray; add

1 pt. surfactant for each 25 gal.

spray mix; normally use no cultivation 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.

For western irrigated Cotton Belt only;

apply to soil between rows and incorporate immediately to depth of 1-2

inches; control of annual groundcherry is temporary.

PEANUTS

Seedbed preparation Before planting and Control of all weeds is Improper land preparation and cultivaand cultivation; after emergence. affected by seedbed tion often increase incidence of

bury litter at least preparation; cultiva- southern blight, which may drastically

3 inches deep with tion between rows reduce peanut yields and quality;

moldboard plow in controls all weeds. broken stands intensify weed probpreparing flat seed- lems; rough seedbeds complicate use

bed; shallow- of herbicides.

running, nondirting,

flat sweeps are most

satisfactory for

cultivation.

Incorporate pre- From 2 weeks to im- Most annual weeds; Incorporate vernolate about 3 inches

planting vernolate mediately before suppression of deep; usually temporary stunting and

(2.5) in soil. planting. nutsedge. leaf fusion of peanuts; do not use seed

of poor vitality.

259-763 O - 67
22 AGRICULTURE HANDBOOK 3 3'2, U.S. DEFT. OF AGRICULTURE

TABLE 3.—Weed control in field row crops—Continued

Treatment Time of application Weeds controlled Remarks

PEANUTS—continued

Sesone (3), 2,4-DEP

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

DNBP (9-12).

DNBP (6) alone or

DNBP (L5) 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).

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 l}^-2 inches in

diameter (3- to 5-leaf

stage).

Within 1 month after

peanuts first crack

soil; use 1-2 applications.

Most small-seeded

annual weeds.

_do-

_do_

.do_

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 and

wet weather.

Can be used if needed as followup

treatment after emergent mixtures;

apply when weeds first become visible; protect peanuts from spray

with shields or similar devices.

SAFFLOWER

EPTC (3-5) _.

Barban (0.38)

MPMT (0.5)-

Several weeks to immediately before

planting.

When wild oats have 1-2

true leaves (approximately 4 inches high).

If saffiower is at least 3

inches tall and weeds

are less than 2 inches

tall.

Winter annual weeds

including volunteer

cereals.

Wild oats

LambsquartersIncorporate in top inch of soil immediately after application.

Apply as broadcast spray.

Do.

SORGHUM

Cultivation. _ _ _ _ Before planting to destroy several weed

crops and after crop

emergence until layby.

After sorghum is 2

inches tall until stalk

begins to stiffen.

After planting but before crop emergence.

do

All weeds 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.

Effective only on shallow-rooted

seedling weeds.

Some injury to sorghum may occur;

plant sorghum 1 inch deep or deeper

to increase safety margin; do not

use atrazine on sorghum grown in

coarse-textured soil.

Plant sorghum 1 inch deep or deeper

to increase safety margin.

Do.

Rotary hoe in and

between rows.

Preemergence

atrazine (1-2).

Preemergence CDAA

All seedling weeds young

enough to be uprooted.

Most small-seeded

annual weeds.

do -_

(1-2).

Preemergence pro- do _ do

pazine (1-2.5).

Postemergence atrazine (2-3).

After crop emergence Most annual weeds less

than 1 inch tall.

Apply as broadcast spray in sorghum;

or if necessary to cover weeds, use

directed basal spray.
SUGGESTED GUIDE FOR WEED CONTROL 1967

TABLE 3.—Weed control infield row crops—Continued

23

Treatment Time of application Weeds controlled Remarks

SORGHUM—continued

Postemergence 2,4-D

(0.25-0.5).

FlameWhen crop is 4-12

inches tall.

After sorghum is 12

inches tall.

Most broadleaved

annual weeds.

Topkill of most small

weeds.

Apply as foliage spray to crop and

weeds while sorghum is 4r-12

inches tall; basally directed spray

in sorghum 6-12 inches 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

field 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

inches.

2-3 shallow cultivavations at depths

no greater than 2

inches.

Cultivate in.row with

rotary hoe at high

speed.

Cultivate between

rows with tools

such as sweeps.

Dalapon (3.7-7.5) ;

use 0.5-percent

surfactant in spray.

Amiben (2-3) or

linuron (1-3).

CDAA (4-5) or

trifluralin (0.5-1).

6-8 weeks before

planting.

2-4 weeks before planting.

When beans have 1-3

trifoliate leaves and

weeds in emerging

seedling stage.

As needed after emergence and until beans

become too large.

In spring when johnsongrass is approximately

1 foot high (at least

4 weeks before planting soybeans).

After planting but

before emergence.

_do_

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.

All weeds.

JohnsongrassMost small-seeded

annual grasses.

_do_

Alternating disk with field cultivator

is as effective and more economical

than using 1 implement; 2 cultivations may be applied 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 third trifoliate.

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 amiben preemergence to

control seedling johnsongrass not

affected by dalapon treatment.

Preemergence herbicides Ukely to

cause injury on very light-textured

sandy soils; soybeans may be

injured severely by linuron on soils

low in organic matter.

Preemergence herbicides likely to

cause injury on many very lighttextured sandy soils; trifluraUn is

usually incorporated in soil.
24 AGRICULTURE HAN'DBOOK 3 32, U.S. DEPT. OF AGRICULTURE

TABLE 3.—Weed control infield row crops—Continued

Treatment Time of application Weeds controlled

SOYBEANS—continued

Nonfortified naphthas

(same as for cotton)

at approximately

20 gal. per acre of

land actuallytreated.

2,4-DB (0.2)

2,4-D wax bars (6

bars for 4 rows).

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.

After most sesbania

plants have grown

above soybeans.

Most small-seeded

annual weeds in

seedHng stage; kills

tops of most small

perennial weeds.

Cocklebur

SesbaniaSUGAEBEETS

Cultivation. Postemergence (variable).

Incorporate preplanting diallate (1.5-2)

in soil.

IPC (3-5)

Pebulate (4-5) or

EPTC (2-2.5).

Incorporate preplanting pyrazon (4-4.8)

in soil.

Preemergence

endothall (5.5).

Preemergence

pyrazon (3-4).

Preemergence TCA

(5-7).

Postemergence barban

(0.62-0.75).

Postemergence

dalapon (2-3).

Immediately before

planting.

do

-__ do.

.do_

After planting but before

crop emergence.

do

_do_

When wild oats in 2-leaf

stage.

When crop has emerged

until it has 4 true

leaves and grassy

weeds are less than 3

inches tall.

Small weeds in rows;

all weeds between

rows.

Wild oatsWild oats, volunteer

cereals, some other

annual grasses.

Most annual grasses,

many annual broadleaved weeds.

Many annual broadleaved weeds.

Many annual weeds

Many annual broadleaved weeds.

Most annual grasses

except wild oats and

volunteer cereals.

Wild oats

Remarks

Apply as laterally directed spray to

10-inch band centered over row at

less than 1 inch above soil (5 gal.

per 13,068 row-feet) ; do not treat

beans more than 4 weeks old.

Apply as broadcast foHage 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.

Wax bars are suspended from boom or

rod attached to rear of tractor so

as to travel 2-3 inches 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 weedcontrol operation.

Most small grassy 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.

Apply as broadcast foliage spray.

Do.
SUGGESTED GUIDE FOR WEED CONTROL 1967,

TABLE 3.—Weed control infield row crops—Continued

25

Treatment Time of application Weeds controlled Remarks

SUGARBEETS—Continued

Postemergence endothall (0.75-1.5).

Postemergence

pyrazon (4).

When crop has emerged

until it has 6 true

leaves and weeds are

less than 23^ inches tall.

When crop has emerged

but before weeds have

more than 2 true

leaves.

Smartweed, wild buckwheat, some^ other

broadleaved weeds.

Many annual broadleaved weeds.

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 sugarbeets.

SUGAKCANE

Fallow plowing 6-8 fallow plowings Johnsongrass from seed

during spring and and rhizomes.

summer before sugarcane is replanted.

Atrazine, simazine. Immediately after plant- Most annual grasses. Apply re-treatments in directed sprays.

diuron, or monuron ing or ratooning; most many small-seeded

(2-4) ; for organic may be repeated and/ broadleaved annual

soils of Florida: or supplemented with weeds.

CDAA (8) plus other herbicides during

2,4-D (2); for

Hawaii only:

growing season.

Ametryne (4-8).

Preemergence fenac Fenac immediately after Johnsongrass from seed. Apply fenac broadcast in Florida; apply

(6-8) ; for Louisiana planting in Florida and most annual grasses. fenac and TCA-silvex on 24- to 30-

only: Repeat applications of TCA (8)

in early spring to fall- many broadleaved inch band in Louisiana (J^ of row

planted cane in Louisi- weeds. width).

plus silvex (3). ana; TCA-silvex after

planting, in early

spring, and 4-5 weeks

later.

Dal apon (2-4) alone Young succulent weeds Most annual grasses. Apply as directed spray, usually as supor combined with at any time after crop some small-seeded plement to preemergence treatment;

TCA (5-7) and emergence and before broadleaved weeds; in apply atrazine when seedling weeds

2,4-D (2) ; for cane closes in; 1-3 Hawaii many perennial are approximately 13^ inches tall;

Florida primarily : applications may be grasses and broad- dalapon or other chemicals control

Atrazine (3.2); for necessary. leaved weeds. larger weeds.

Hawaii only:

Diuron (2-3.2) plus

surfactant, PCP (5)

emulsified in naphtha, or ametryne

(2-4).

2,4-D (approximately Postemergence when 2,4-D controls chick- Apply as broadcast foliage spray.

2) ; for resistant needed to weeds grow- weed, henbit, mornweeds: 2,4,5-T or ing vigorously. ing-glory, pigweed;

silvex (approxi- other chemicals conmately 1). trol these weeds plus

dogfennel, groundcherry, koa haole

(Leucaena leucocephala), nightshade,

wild lettuce.

Mixture of TCA (8) Early spring when cane Johnsongrass from rhi- Apply as foliage spray on 24-inch band

plus dalapon (4.5) and Johnsongrass are zomes, most emerged (3^ of row width) when temperature

)lus silvex (3) ; in approximately 10 annual weeds. is above 65° F.

Louisiana, ratoqn inches tall.

crop only.
26 AGRICULTURE HANDBOOK 3 3-2, U.S. DEPT. OF AGRICULTURE

TABLE 3.—Weed control infield row crops—Continued

Treatment Time of application Weeds controlled Remarks

TOBACCO

Commercial urea, 1

lb., plus calcium

cyanamide, 0.5 lb.,

per sq. yd., or

methyl bromide, 1

lb. per 100 sq. ft.

Urea-cyanamide or cyanamide in October in

mid-Atlantic States.

All annual weeds in

plant beds.

For plant beds only; thoroughly mix

urea-cyanamide or calcium cyanamide with upper 3 inches of soil by

disking or raking; apply methyl

bromide to well-pulverized seedbed

under gasproof cover; methyl bromide is very poisonous; many users

employ specially trained personnel

to apply it.

Shallow cultivation may improve effectiveness.

Diphenamid (4) Immediately after transplanting and before

any weed emergence.

Most annual grasses,

some small-seeded

broadleaved weeds.

TABLE 4.—Weed control in close-drilled field crops

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

Treatment Time of application Weeds controlled Remarks

ESTABLISHED ALFALFA

Flaming.

Drying of soil in

irrigated areas by

increasing interval

between irrigations.

Shading by crop

Frequent, shallow

cultivation.

CIPC (6) (granular

formulation) or

DCPA (10).

Diuron (1.5-3.2) or

simazine (1).

DNBP (1.25-2.2) plus

20-50 gal. diesel or

weed oil plus 50-

100 gal, water.

Twice at 3-day interval

in stubble after

harvest.

Whenever feasible during growing and

harvesting season.

In early spring and in

stubble after harvest.

To moist soil before

dodder attaches to

host in spring.

In winter when legumes

are dormant or semidormant.

After first hay crop is

removed but before

regrowth starts.

Dodder seedlings, dodder

attached to stubble.

Dodder

_do_

Dodder seedlings _

Dodder seedlings, some

annual weeds; DCPA

provides some control

of attached dodder.

Many annual weeds

Annual broadleaved

weeds.

Spot naming can be used also for

isolated patches of dodder in seed

crop.

Alfalfa, through shading after it is 2

feet tall, provides important part of

full-season control of dodder if

dodder is controlled by other

methods while alfalfa is less than 2

feet tall.

Supplement with cultural practices

described previously to obtain full

season control; DCPA registered for

use only on seed crops.

Apply before germination of weeds or

while still seedlings; remove or burn

crop residue before treating; simazine registered only for use on seed

crops in Pacific Northwest.

ESTABLISHED GRASSES

Plant in rows and cultivate between rows.

Dicamba or prometryne (2-3.2) in

eastern Oregon;

IPC (4) in eastern

Washington.

Soon after first postharvest irrigation.

Summer annuals.

Downy brome_

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.
SUGGESTED GUIDE FOR WEED CONTROL 1967

TABLE 4.—Weed control in close-drilled field crops—Continued

27

Treatment Time of application Weeds controlled Remarks

ESTABLISHED GRASSES—Continued

2,4-D, 2,4,5-T, After seedling crop Most broadleaved weeds. _ Easier to control small, actively growMCPA, or silvex grasses have 3-5 ing, young weeds than large, slowly

(0.5-0.75) or di- leaves; established growing, old weeds; use higher rates

camba (0.25-0.5). crop grasses not treated after boot stage

but can be re-treated

after harvest.

only on well-estabhshed stands.

ESTABLISHED LEGUMES ^

Mechanical tillage When weeds are seed- Many annual weeds Species present will determine when

(shallow) or flaming lings before seeding crop, tillage can be practiced.

fields with field between hay and seed

weed burners. crops, and in dormant

stages.

2,4-DB (0.5-2) Any time during growing Many annual and pe- Treat weeds when less than 3 inches

season before legumes rennial broadleaved tall, or preferably when less than

bud. weeds that are not 1 inch tall, and growing actively ;

legumes and that are use higher rates only for established

not resistant to 2,4-D. legumes; not registered for use on

lespedeza.

DNBP (1.9-2.5) or Preharvest Desiccation of all weeds Treatment before legume seeds are

PCP (4-6) in 5-10 before harvest. mature may reduce their yield and

gal. diesel oil, or quality ; legumes as well as weeds

endothall (0.52- are desiccated by treatment; DNBP

0.65) in 5-10 gal. not registered for use on lespedeza ;

water, or diquat diquat not registered for use on

(0.5-0.75) in 20-40 lespedeza or birdsfoot trefoil.

gal. water.

ESTABLISHED LEGUMES ^

IPC (3-4). In winter when legumes

are dormant or semidormant.

Winter annual grasses,

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.

ESTABLISHED GRASSES ^

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 broadleaved winter annuals.

Treatments listed may be unsatisfactory in area other than Washington or

Oregon; remove or burn all crop

residue before treating; IPC or CIPC

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

Diuron (1.6)_ In winter when trefoil

is dormant or semidormant.

Apply before germination of weeds or

while seedlings; burn or remove crop

residue before treating.

See footnotes at end of table.
28

Treatment

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

TABLE 4.—Weed control in close-drilled field crops—Continued

Time of application Weeds controlled Remarks

Select fields relatively

free of weeds; tillage

of land in late summer and early fall is

helpful.

Spring tillage

Diallate (1.5-2)

Barban (0.31-0.37)._

MCPA (amine or sodium salts) (0.12-

0.60) or 2,4-D

(amine salt) (0.12-

0.25).

TCA (5), dalapon

(0.75), or mixtures

of these two with

MCPA (0.25).

Late summer, early falL

Before planting.

In spring before sowing..

When wild oats are in 2-

leaf stage.

When flax is 2-6 inches

tall and weeds are

small.

-do.

Use of weed-free crop

seed.

Rotate with row crops

such as soybeans,

cotton, grain sorghums, safflower.

Rotate with pasture. __

Phosphate fertihzation

of other crops preceding rice or of rice

just before it is

flooded for first

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.

At planting. _.

In previous seeding or

just before first

flooding. *

Late summer, fall, and

early spring before

planting.

Perennials, annuals.

Wild oatsdo.

do.

Many broadleaved weeds.

Most annual grasses.

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.

Apply in top spray.

Apply in top spray; higher rates than

those hsted 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 in top spray; mixture controls

both grasses and broadleaved weeds.

EICE

Barnyardgrass, beakrush,

curly indigo, Mexican

weed, red rice,

sesbania.

Many grasses, broadleaved weeds, sedges,

aquatic weeds.

Reduces infestations of

aquatic weeds, broadleaved 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.

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 waterseeded rice without stimulating barnyardgrass but may increase problems

with aquatic weeds.

Reduces infestations of Hsted weeds; in

some cases can help eradicate some

weeds.

Reduces infestations but does not

eradicate listed weeds.
SUGGESTED GUIDE FOR WEED COKTROL 19 67

TABLE 4.—Weed control in close-drilled field crops—Continued

29

Treatment Time of application Weeds controlled Remarks

BICE—continued

Water

management at

seeding.

Flood rice to depth of

4-8 inches just after

rice and grassy

weeds emerge.

Timing of nitrogen

application to rice.

Molinate (3).

MC PA, silvex, 2,4-D,

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

amine salt or lowvolatile ester formulations.

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.

After rice is well tillered

but before jointing.

Barnyardgrass, brachiaria, curly indigo,

sesbania, sprangletop.

Barnyardgrass, most

annual grasses.

Barnyardgrass, other

annual grasses,

aquatic weeds.

Barnyardgrass, sprangletop, annual umbrellasedge in water-seeded

rice.

Arrowhead, burhead,

curly indigo, ducksalad, fimbristylis,

gooseweed, Mexican

weed, redstem, sesbania

(coffeebean), smartweed, spikerush,

umbrella-sedge, waterhyacinth, waterhyssop,

waterplantain, waterprimrose.

White barnyardgrass not controlled

unless water is held 6-8 inches

deep for 3-4 weeks; water seeding

encourages some aquatic weeds

such as algae, ducksalad, annual

spikerush, annual umbrella-sedge ;

therefore, dry seeding rice by

drilUng 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 inches deep immediately after application; crossdisking or cross-harrowing with

implements going 4-6 inches deep

has been satisfactory; safe only on

water-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 curly indigo are

present; treat only when temperature

is 70°-95° 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; rain 1-6 hours after spraying

may reduce effectiveness.

259-763 O - 67
30 AGRICULTURE HANDBOOK 3 32, U.S. DEFT. OF AGRICULTURE

TABLE 4.—Weed control in close-drilledßeld crops—Continued

Treatment Time of application Weeds controlled Remarks

RICE—continued

Propanil (4.5-6).

Propanil (4-4.5).

Propanil (3-5) in

10-15 gal. water for

aerial spraying or in

15-25 gal. water for

ground spraying.

When grassy weeds are

through water and

oldest grass is 6-8

inches above water

(42-50 days after

seeding).

Usually 35-45 days after

seeding when oldest

grass is 5-6 inches

above water and

broadleaved weeds and

sedges are just above

water.

Soon after crop and

weed emergence when

grassy weeds have 1-3

leaves and broadleaved weeds or sedges

are 1-5 inches tall.

Barnyardgrass, other

annual grasses,

broadleaved weeds,

Barnyardgrass, other

annual grasses,

broadleaved weeds.

Barnyardgrass, brachiaria, curly indigo,

fimbristylis, gooseweed, sesbania (coffeebean), annual spiderrush, annual

umbrella-sedge, many

other annual weeds.

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 inches) ; treat when grass has

resumed rapid growth and is 5-6

inches tall (similar to shallow-water

culture) ; spray droplets of 200-400

micron diameter are preferable to

coarser or ñner sprays; do not mix

propanil with other pesticides or

additives; insecticides such as

carbaryl, parathion, and methyl

parathion may cause injurious interactions if used within 15 days before

or after propanil application.

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 or

additives; 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 or additives; insecticides

such as carbaryl, parathion, and

methyl parathion applied 15 days

before or after propanil have severely injured rice.

WHEAT

Diuron (1). After planting but before emergence.Most small-seeded

annual weeds.

Follow recommendations of State

agricultural experiment station or

extension service weed specialists;

suggested only for winter wheat in

Northwestern United States.

BARLEY

Diallate (1-1.25)_ Preemergence before

crop sprouts are >^

inch long.

Incorporate in soil.
SUGGESTED GUIDE FOR WEED CONTROL 1967

TABLE 4.—Weed control in close-drilled ßeld crops—Continued

31

Treatment Time of application Weeds controlled Remarks

BARLEY, OATS, AND WHEAT

2,4-D or MCPA After cereals are well Cocklebur, dock, field Wheat is most tolerant of these to

(0.25-1). tillered (usually 4-8 bindweed, lambs- 2,4-D; oats is least tolerant but

inches tall) but be- quarters, mustard, more tolerant to MCPA; in Northfore boot stage. pigweed, plantain. eastern, North Central, and Midprickly lettuce, rag- western United States 0.5 pound per

weed, shepherds-purse. acre or less is recommended.

smartweed, sunflower,

wild radish, wild

vetch, yellow-rocket.

BARLEY AND WHEAT UNDERSOWN WITH LEGUMES

Postemergence 2,4-D

or MCPA (0.12-

0.25).

After cereals are well

tillered (usually 4-8

inches tall) but before

boot stage.

Mustard, yellow-rocket,

other broadleaved

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.

DURUM WHEAT AND HARD RED SPRING WHEAT

Triallate (1)

Barban (0.25-0.37)

In fall before spring

planting.

When wild oats are in 2-

leaf stage but not after

crop reaches 4-leaf

stage.

Incorporate in soil.

FALL-SEEDED BARLEY, OATS, AND WHEAT

Dicamba (0.25) _ Postemergence in spring

before joint stage.

Wild buckwheat, corncockle, cowcockle, dogfennel, most weeds

susceptible to 2,4-D.

Mixtures of 0.12 lb. of dicamba and 0.12

lb. of 2,4-D per acre will control

mustards better than dicamba alone.

SPRING-SEEDED OATS AND WHEAT

Dicamba (0.12) for

oats and (0.12-0.25)

for wheat.

Postemergence during 2-

to 5-leaf stage of crop.

Wild buckwheat, corncockle, cowcockle, dogfennel, most weeds

susceptible to 2,4-D.

Mixtures of 0.12 lb. of dicamba and 0.12

lb. of 2,4-D per acre will control

mustards better than dicamba alone.

^ 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

orchardgrass, perennial ryegrass, and tall fescue.

fescue,
32 AGRICULTURE HANDBOOK 332, U.S. DEPT. OF AGRICULTURE»

TABLE 5.—Control of perennial weeds in cropland

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

Treatment Time of application Weeds controlled Remarks

ALL KINDS

Methyl bromide Any time during spring, All weeds, weed seed. Apply under gasproof cover after

fumigation, 1 lb. summer, or fall. rootstocks. thorough tillage of soil; methyl

per 100 sq. ft. bromide is very dangerous to man and

warmblooded animals; most users

employ personnel specially trained in

its use; for control in small, specialized areas.

Intensive cultivation. _ Frequency depends on Most perennial weeds More than one season required to control

species and climatic some species; system may be comconditions. bined with competitive crops and

chemicals; follow local recommendations.

BROADLEAVED WEEDS

Amitrole (4) After harvest of crop, Canada thistle, hoary- Re-treat as necessary; frequently used

but before Oct. 1. cress, leafy spurge. as spot treatment; mixture of amipoison-ivy. trole and ammonium thiocyanate

is also effective.

Picloram (1-2.5) Foliage during growing Many perennial broad- Not registered for use on cropland except

season or in late fall leaved weeds except as spot treatment; in which case crops

as soil treatment. hoarycress. in treated areas must not be used for

food, feed, or grazing for at least 2

Silvex (3) Late fall or early spring- _ Smooth bedstraw _ _ Usually re-treatment will be necessary;

observe treated areas and re-treat as

required.

Sodium chlorate (640- During growing season. _ . Most perennial broad- Soil sterilants; primarily used to treat

960) (or sodium leaved weeds. small patches; treatments will sterchlorate-fire ilize soil from 1 to several years;

retardant mixture). spring or fall preferred to summer^

treatments in some areas; sodium

chlorate without fire retardant creates

severe fire hazard when in contact

with combustible materials such as

clothing and wooden floors.

2,3,6-TBA (15-20) or do Field bindweed, most Treatment may prevent crop producPBA (35-40). other broadleaved tion for 1-3 years; not registered

perennial weeds. for use on cropland except as spot

treatment.

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

usually bud stage.

Canada thistle, field

bindweed, hoarycress.

Usually re-treatment will be necessary;

observe treated areas and re-treat

sowthistle. as required; check labels for restrictions as to crop species and other

precautions.

2.4-D (1-4) do Bur-ragweed, dogbane. Do.

leafy spurge, Russian

knapweed.

GRASSES

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.

Fall or spring before

planting corn.

In spring when quackgrass is 4-10 inches

tall.

Chemical residues in soil may injure

crops other than corn year after

treatment.

Re-treatments may be necessary.
SUGGESTED GUIDE FOR WEED CONTROL 1967

TABLE 5.—Control of perennial weeds in cropland—Continued

33

Treatment Time of application Weeds controlled

GRASSES—continued

Spot spraying with

dalapon at 1 lb. or

TCA at 2 lb. per 5

gal. water; or aromatic oils.

Dalapon (5-20) followed by disking

after 2 weeks.

EPTC (3-6).

MH (4) followed by

plowing in 4-8

days.

TCA (25-50) or dalapon (5-20).

During growing season

from hand applicators

while weeds are less

than 15 inches tall;

to foliage or stems of

weeds.

In spring when grass is

15 inches tall or after

clipping any time

when grass is this

height.

To freshly tilled soil in

early spring.

To foliage in early

spring.

To foliage and soil surface 1 week before

plowing in late fall or

early spring.

Most glasses; oils will

also kill tops of broadleaved weeds; will

control but not eradicate perennial grasses.

JohnsongrassQuackgrass

do.

Remarks

Add }i pt. surfactant to each 5 gal.

spray mixture for herbicides mixed

in water; spraying lower 6 inches of

weeds is usually adequate; keep

contact with crop plants to minimum as these treatments will kill

or injure most crops; usually not

practical when weeds to be sprayed

exceed 1 plant per 20 feet of row.

Use foUowup program for seedling

control.

Thoroughly work soil before and after

application.

Corn or sugarbeets may be planted

as soon as soil preparation is completed; not registered for use on

other agronomic crops.

Plant to clean-tilled crops in following year; use preemergence herbicides to control seedlings; spot treat

all survivors.

Amitrole (4). When weeds are 12-18

inches tall.

SEDGES

Amitrole (4) followed

by disking after 2

weeks.

Incorporate EPTC

or vernolate (3) in

soil.

2,4-D (1-2)

In spring; repeat as

needed for 2-3 years.

In spring

4-5 applications during

growing season for

2 years.

Purple nutsedge

Yellow and purple nutsedge.

Purple nutsedge

Spray foliage.

Follow label instructions and restrictions.

Herbicide labels specify crops that can

be planted after each treatment.

More effective where heavily fertilized

crops or grasses can be grown in

conjunction with herbicide treatment.

WEED CONTROL IN HORTICULTURAL CROPS

Weed control in horticultural crops is a highly

complex problem because of the large number of

diflFerent 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 controUing 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.
34 AGRICULTURE HANDBOOK 332, U.S. DEPT. OF AGRICULTURE

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 hmitations 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 6-11.

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 locahty 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 broadleaved weeds. Conversely, otners may be effective on only broadleaved 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 spray or

granules, 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

crop. Granules may also be used as preplanting

and preemergence treatments as a matter of

convenience.

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 6.

TABLE 6.—Weed control in vegetables

Crop and herbicide

Asparagus:

Amiben

Dalapon

Monuron

Sesone

Simazine

Beans, lima:

Amiben

CDAA

CDEC

CIPC

DNBP (alkanolamine

salt).

Trifluralin

Beans, pole:

CIPC

EPTC

Beans, snap:

CDAA

CDEC

CIPC

DCPA

DNBP (alkanolamine salt)

EPTC

Trifluralin

Beets:

CDEC

Endothall

Pyrazon

Sodium chloride.

TCA (sodium

salt).

Broccoli:

CDEC

DCPA

Trifluralin.

Brussels sprouts:

CDEC

DCPA....

Trifluralin.

Pounds of

active

ingredient

per acre

3

7-14.

1-1.5

2-4..

2-4..

2

4

6

^4..

3-9..

0.75

2-4.

3___

4

6

2-4..

6-12.

3-9..

0.75.

2r-á.

6.5.

4...

200-300.

6-9

2-4.

10.5.

2-6-

10.5.

1

Time of application

Preemergence.

Preharvest, postharvest.

Do.

Do.

Do.

Preemergence.

Do.

Do.

Do.

Do.

Preplant, soil

incorporated.

Preemergence.

Preplant, preemergence, postemergence, soil

incorporated.

Preemergence.

Do.

Do.

Do.

Do.

Preplant, preemergence, postemergence, soil

incorporated.

Preplant, soil

incorporated.

Preemergence.

Do.

Preemergence, postemergence; see

area restrictions

on label.

Postemergence.

Preemergence.

Preplant, pretransplant, posttransplant.

Preemergence, posttransplant.

Preplant, posttransplant, soil incorporated.

Preemergence, postemergence, pretransplant, posttransplant.

Preemergence, posttransplant.

Preplant, posttransplant, soil incorporated.
SUGGESTED GUIDE FOR WEED COJSTROL 1967 35

TABLE 6.—Weed control in vegetables—Continued TABLE 6.—Weed control in vegetables—Continued

Crop and herbicide

Cabbage:

CDAA_

CDEC_

DCPA

Trifliiralin _

Cantiiloup :

CDEC

DCPA

NPA (sodiumsalt).

Caraway, Stoddard

solvent.

Carrots:

CIPC

DCPA

Linuron.

Stoddard solvent.

Cauliflower:

CDEC

DCPA

Trifluralin _

Celery:

CDAA_

CDEC_

Stoddard solvent .

Chicory, CDEC___-.

Collards:

CDEC

CIPC

DCPA

Corn, sweet:

CDAA

CD AA plus

TCBC.

CDEC

DNBP (alkanolamine salt).

Linuron

Simazine

2,4-D.__.

2,4-DEP .

Cucumbers:

CDEC 2-4_

NPA (sodium 2-6-

salt).

See footnotes at end of table.

Pounds of

active

ingredient

per acre

4-6_

2-6_

10.5-

1

2-4--

10. 5_

2-6_-

«-

2-6--

10.5-

1-2-

(0-

2-6-

6-10-

1

4__-

2-4-

(0-

2-4.

2-4_.

1-2-.

10.5-

4

1.25 plus

2.5.

6

7.5-9

1---

2-4.

0.25-0.5-

6

Time of application

Preemergence, posttransplant.

Preplant, preemergence, pretransplant, posttransplant.

Preemergence,

posttransplant.

Preplant, soil incorporated for transplants.

Preemergence.

Do.

Preemergence, posttransplant, lay-by.

Preemergence,

postemergence.

Do.

Seed crop only at

planting or transplanting.

Preemergence,

postemergence.

Do.

Preplant, preemergence, pretransplant, posttransplant.

Preemergence,

posttransplant.

Preplant, soil incorporated for

transplants.

Posttransplant.

Preemergence,

posttransplant.

Preemergence,

postemergence.

Do.

Do.

Do.

Do.

Preemergence.

Do.

Do.

Do.

Do.

Preplant, preemergence, soil incorporated.

Preemergence, postemergence.

Immediately after

planting.

Preemergence.

Preemergence, posttransplant.

Crop and herbicide

Dill, Stoddard

solvent.

Eggplant, DCPAEndive, CDEC___

Escarole, CDEC__

Garlic:

CIPC

DCPA.

Hanover salad:

CDEC

CIPC

Kale:

CDEC

CIPC

DCPA

Lentils:

Diallate

IPCLettuce:

CDEC

IPC

Mint:

CIPC --

Diuron

DNBP (alkanolamine salt).

Mustard greens:

CDEC

DCPA

Okra:

CDEC

Trifluralin

Onions:

CDAA

CIPC

DCPA

KOCN

Monuron

Sulfuric acid

Parsley, Stoddard

solvent.

Parsnips:

Linuron

Stoddard solvent

Peas:

CDAA

CIPC

Diallate

DNBP (alkanolamine salt).

IPC

Pounds of

active

ingredient

per acre

(0-

10.5-

2-4-.

2-4-.

2-4-_

6-10.

2-4-

1-2-

2-4..

1-2..

10.5-

1.5-.

4---.

2-4---.

3-4.5-.

2-4.__.

l-2__-.

3-4.5..

2-4---.

10.5--.

2-4---.

1

6

4^8---.

10.5...

16-20.

1.6

O—-

(^)-—.

1.5

(0--.

4

4-6---

1.4-1.5

/6-9-..

11.5-2..

4-8....

Time of application

Preemergence, postemergence.

Transplant, lay-by.

Preemergence.

Do.

Preemergence, postemergence.

Preemergence,

transplant.

Preemergence.

Do.

Do.

Do.

Do.

Preplant, preemergence, soil incorporated.

Preplant, preemergence, postemergence, soil incorporated.

Preemergence, pretransplant.

Preemergence.

Do.

Do.

Do.

Do.

Do.

Do.

Preplant, soil

incorporated.

Preemergence,

postemergence.

Do.

Preemergence,

posttransplant.

Preemergence,

postemergence.

Do.

Postemergence.

Preemergence.

Postemergence.

Preemergence,

postemergence.

Preemergence.

Preplant, preemergence, soil

incorporated.

Do.

Preemergence.

Postemergence.

Preplant, postemergence.
36 AGRICULTURE HANDBOOK 3 32, U.S. DEPT. OF AGRICULTURE

TABLE 6.—Weed control in vegetables—Continued TABLE 6.—Weed control in vegetables—Continued

Crop and herbicide

Peas—Con.

MCPA (amine

or sodium

salt).

MCPB

Peas, southern:

DCPA

Trifluralin

Peppermint:

Diuron

Monuron

Peppers:

Amiben

DCPA

Diphenamid- _

Trifluralin

Potatoes:

CDAA.

Dalapon_

DCPA__

Diallate.

Diphenamid_

DNBP (alkanolamine salt).

EPTC

Linuron _

Sesone _ _

2,4-DEP_

Pumpkins, NPA

(sodium salt).

Radish, CIPC__>

Spinach:

CDEC

CIPC_

IPC._

Squash, amiben _

Sweetpotatoes:

Amiben

CDAA

DCPA

Diphenamid _ _

EPTC

Pounds of

active

ingredient

per acre

0.75.

0.25-0.75_

6-10

0.25-1. __

2.4

2.4

3-4

6-10

5

3-4.

3__.

6-10.

1.5..

4-6.

3-6_

3-6.

1...

3.6.

2-4.

l-2_

3-6.

3-4.

3

4

6-10.

4-6. .

7.5..

Time of application

Postemergence as

prebloom.

Early postemergence.

Preemergence.

Preplant, soil incorporated.

Last cultivation

before emergence.

Do.

At transplanting or

lay-by.

Posttransplant.

Immediately after

seeding or within

1 month after

transplanting.

Preplant, soil incorporated postemergence on

direct seeding,

posttransplant.

Preemergence, layby.

Preplant, preemergence, lay-by.

At planting.

Preplant, soil incorporated.

Immediately after

planting.

Preemergence.

Preplant, soil incorporated, drag-off,

lay-by incorporated.

Preemergence.

Preemergence, postemergence, lay-by.

After clean cultivation at lay-by.

Preemergence.

Do.

Preemergence, postemergence.

Preemergence.

Preemergence, postemergence.

Do.

At transplanting.

Posttransplant.

Do.

At transplanting.

Do.

Pounds of

Crop and herbicide active

ingredient

per acre

Time of application

Tomatoes:

Amiben 3 Posttransplant.

CDEC 2-4 Preemergence, posttransplant.

DCPA 10.5 Lay-by.

Diphenamid 4^6 Immediately after

seeding or within

1 month after

transplanting.

Pebulate 4 Preplant, postemergence, soil

incorporated.

Trifluralin 1 Preplant, soil incorporated for

transplants or

postemergence on

direct seeding.

Turnip greens:

CDEC 2-4 Preemergence.

CIPC 1-2 Do.

DCPA 10.5 Do.

Turnips, CDEC 2-4 Do.

Upland cress, CIPC. 2 _ Do.

Watermelons, NPA 2-6 Preemergence,

(sodium salt). posttransplant.

* 50-100 gal. per acre.

2 114 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 herbicidal 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 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 7. 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.
SUGGESTED GUIDE FOR WEED CONTROL 1967 37

TABLE 7.—Weed control in deciduous tree fruits and TABLE 7.—Weed control in deciduous tree fruits and

nuts nuts—Continned

Crop and herbicide

Apples:

AMS_

CIPC___

Dalapon>

Dichlobenil _.

DiphenamidDiuron

DNBP (butylphenol) .

Simazine

Apricots:

Aromatic oil

emulsion.

Dalapon

Cherries:

Dichlobenil _

Simazine

Olives:

Aromatic oil

emulsion.

Diuron

Simazine

Pounds of

active ingredient per acre

Time of application

TREE FRUITS

54 in 100

gal.

water.

8

11

Peaches:

Aromatic oil

emulsion.

Dalapon

DichlobenilDiphenamid

3. 2_

L9-

2-4.

11_.

2-4_

0).

L6

2-4

0)

11

6.

6_

In wetting spray to

poison-ivy in full

leaf.

During dormancy.

As spot spray around

base of trees over

4 years old to control grass.

Early spring or after

clean cultivation.

After clean cultivation but not within 90 days of

harvest.

Winter or spring.

Coarse spray to

ground cover when

weeds are small.

In spring before

weeds emerge.

Directed spray on

young growing

weeds.

As spot spray

around base of

trees to control

grass when weeds

are small.

Granules preemergence to weeds.

Soil treatment in late

' fall or early spring

on dormant crop

more than 1 year

old.

Directed spray on

young growing

weeds.

Split application fall

and spring.

Broadcast single

directed application to soil before

weeds emerge; apply in late fall or

midwinter.

Directed spray on

young growing

weeds.

Spot spray on growing grass when

weeds are small.

Granules in early

spring.

After clean cultivation, not within 90

days of harvest.

Crop and herbicide

Pounds of

active ingredient per acre

Time of application

TREE FRUITS—Continued

Peaches—Con.

DNBP (butylphenol) .

1.9 Directed coarse spray

to ground cover

when weeds are

small.

Simazine. 4 As soil application

around established

trees before weeds

emerge; after harvest to early spring.

Pears:

AMS _ 54 in 100 In wetting spray to

gal. poison-ivy in full

water. leaf.

Aromatic oil (1) Directed spray on

emulsion. young growing

weeds.

Dalapon 11__ Spot spray on growing grass when

weeds are small.

Dichlobenil 6 Granules in early

spring.

Diuron. _ _ 1.6 Directed spray during dormancy,

winter and spring.

DNBP 1.9 Directed coarse spray

on ground cover.

Simazine 4 Directed spray during dormancy on

well-established

trees.

Plums:

Aromatic oil (0 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

cover when weeds

are small.

Simazine 4 Directed soil treatment on wellestablished plantings when weeds

are small.

TREE NUTS

Almonds, aromatic (1) Directed spray on

oil emulsion.

Walnuts, aromatic (1)

young growing

weeds.

Do.

oil emulsion.

1 40-100 gal. per acre.

See footnote at end of table.
38 AGRICULTURE HANDBOOK 3 32, U.S. DEFT. 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 8. 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 8.—Weed control in citrus and subtropical

fruits and nuts

TABLE 8.—Weed control in citrus and subtropical

fruits and nuts—Continued

Pounds of

Crop and herbicide active

ingredient

per acre

Time of application

Avocados:

Aromatic oil 0) Directed spray on

emulsion. young growmg

weeds.

Monuron L6 Soil treatment in

spring and fall

under well-established trees in

California (selected areas only).

Simazine 2-4 Apply to orchard

floor before weeds

emerge, following

final preparation

of grove.

Pounds of

Crop and herbicide active

ingredient

per acre

Time of application

Citrus (grapefruit,

lemons, oranges) :

Aromatic oil (0 Directed spray on

emulsion. young growing

weeds.

Diuron 1.6 Soil treatment in

fall and spring in

groves established

1 year or more in

Arizona and California (selected

areas only).

'2 During rainy season

on established

plantings of

Simazine '

lemons in Arizona and California.

9.6 Oranges in Texas ^ and Florida.

Dates, aromatic (0 Directed spray on

oil emulsion. young growing

weeds.

Limes, aromatic oil (}) Do.

emulsion.

Macadamia nuts:

Dalapon 9 On established grass

before crop

harvest and after

gleaning nuts.

Diuron 2-4 Soil treatment;

directed spray

immediately

after harvest.

Simazine or 2-4 Soil treatment beatrazine. fore harvest and

after gleaning

nuts.

Pineapples:

Diuron 1.6-3.2 Soil treatment immediately after

planting or after

harvest.

Monuron 1.6-3.2 Do.

Simazine 3.2-4 Do.

See footnote at end of table.

1 40-100 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
SUGGESTED GUIDE FOR "WEED CONTROL 1967 39

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 9. 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.

TABLE 9.—1Veed control in small fruits

Crop and herbicide

Pounds of

active ingredient per acreTime of application

Blackberries:

CIPC 2-6

1-2

2-4

6-12

1-2

2-4

0.25-0.5

8.8

1-4

800

2-4

0.25-0.5

1-2

Soil treatment in

Diuron

dormant crop.

Soil treatment in

Simazine

Blueberries:

CIPC

dormant crop 1

year old or more.

During dormancy of

crop.

Do.

Diuron Soil treatment in

Simazine _

2,4-D

dormant crop 1

year old or more.

During dormancy of

crop.

Before burn during

dormancy.

Postharvest as

Cranberries:

Dalapon

Dichlobenil

Ferrous sulfate. _ _

Simazine

2,4-D

directed spot spray

on growing grasses.

Granules, prebloom

or postharvest.

Spring to midsummer.

Soil treatment in

dormant crop in

Massachusetts

only.

On growing weeds

during dormancy

of crop.

Soil treatment in

dormant crop 1

year old or more

in early winter.

Gooseberries,

diuron.

Grapes:

CIPC 10-14

15

Directed spray in

early spring on

dormant crop.

Directed spot spray

on growing grass

during vegetative

growth of crop.

Dalapon

TABLE 9.—Weed control in small fruits—Con.

Pounds of

Crop and herbicide active

ingredient

per acre

Time of application

Grapes—Con.

Diuron 1-2 Soil treatment in

dormant crop

established at

least 3 years.

DNBP (alkano- 1.25 Dormant application

lamine salt). to ground under

trellis.

Simazine 2-4 Soil treatment from

late fall to early

spring on crop

established at

least 3 years.

Raspberries:

CIPC 2-6 During dormancy of

crop or at time of

planting.

Diuron 1-2 Soil treatment in

early winter on

dormant crop

established at

least 1 year.

Sesone 2-4 Directed soil treatment in dormant

or vegetative crop.

Simazine 2-4 During dormancy of

crop.

Strawberries:

CIPC 1-2 During dormancy to

control established

and germinating

chickweed.

DCPA 9 Soil treatment after

transplanting or

lay-by cultivation.

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 0.25-0.5 Spray young growing > weeds after

harvest.

2,4-DEP 4 Preplant or posttransplant in

nonharvest year;

postharvest in

production fields.
40 AGRICULTURE HANDBOOK 3 32, U.S. DEFT. OF AGRICULTURE

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 individual 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 famiUes, 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 lowcost 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 10. 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 10.—Weed control in ornamental plants

TABLE 10.—Weed control in ornamental

plants—Continued

Herbicide

Pounds

of active

ingredient

per acre

Tolerant plants

CDEC

CIPC

4r-6

6-10

Use directed spray or granules on soil in established

ornamental plantings:

Azalea, euonymus, gladiolus, iris, juniper,

Potentilla, privet, spirea,

yew.

Use directed spray or granules

on soil in established

plantings: Arborvitae, aster,

Astilhe, azalea, balsam,

barberry, birch, bluebell,

boxwood, camellia, carnation, cedar, chrysanthemum,

columbine, coralbell, creeping juniper, dahlia, delphinHerbicide

Pounds

of active

ingredient

per acre

CIPCDCPA_

DichlobeniL-^_ _

Diphenamid_

DNBP (alkanolamine

salt).

Neburon_

NPA (sodium

salt).

6-10

10-15

4-6

4-6

10.5

4-6

Tolerant plants

ium, 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,

moutóng bride, mourning

pinks, petunia, pokerplant,

purple coneflower, rose,

salvia, scarlet sage, snapdragon, variegated privet,

verbena, yew, zinnia.

Use directed spray or granules

on soil in established ornamental plantings: American

elm, barberry, boxelder,

boxwood, Chinese elm,

cottonwood, eastern redcedar, euonymus, fir, forsythia, green ash, hackberry, holly, honeylocust,

juniper, pine, privet, pyracantha, rose, Russian-olive,

spruce, yew.

Use directed spray or granules

on soil in established ornamental plantings: Evergreen, deciduous trees.

Use directed spray or granules

on soil in established ornamental plantings: Dahlia,

Dutch iris, gladiolus, lilac,

lily, narcissus, privet, spirea,

tulip, yew.

Use directed spray or granules

on soil in established plantings: Arborvitae,

Chamaecyparis, euonymus,

firethorn, forsythia, honeysuckle, juniper, pine, privet,

yew.

Use directed spray or granules

on soil in established ornamental plantings: Azalea,

cottonwood, holly, maple,

plum, rhododendron.
SUGGESTED GUIDE FOR WEED CONTROL 1967 41

TABLE 10.—Weed control in ornamental

plants—Continued

Herbicide

Sesone.

Pounds

of active

ingredient

per acre

3-4

Tolerant plants

Simazine_

Stoddard

solvent.

Trifluralin.

2-3

(0

0.5-1

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, multiflora rose, Norway spruce, redcedar, red

oak, red pine, red spruce,

rose, Russian-olive, Scotch

pine, Siberian elm, whitecedar, 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.

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 difficult and time consuming.

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 ilex.

Weed seed and the underground parts of

perennial weeds in coldframes, hotframes, and

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.

Soil fumigant herbicides and their use are described briefly in table 11. Specific details for

effective use of fumigants under local conditions

are available from weed research specialists in

State agricultural experiment stations.

TABLE 11.—Weed control with soilfumigant herbicides in horticultural plant beds and nurseries

Herbicide

DMTT.._

Methyl

bromide.

SMDC

Pounds of

active ingredient per 100

sq. ft.

0.67

1-2

0. 67-1

Method of application after

preparation of soil for planting

Apply wettable powder suspended in water in sprinkling can or sprayer or mix

powder with sand and

spread in lawn spreader;

mix herbicide to depth of

5-6 inches; sprinkle-irrigate

with 1-2 inches of water;

wait 3 weeks or longer

before planting.

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 herbicide with sprinkling can or hose proportioner; mix herbicide to

depth of 5-6 inches;

sprinkle-irrigate immediately

to desired depth of control;

plant 1-^30 days after

treatment depending on

soil composition and moisture content.

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, DMTT, 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,
42 AGRICULTURE HANDBOOK 3 32, U.S. DEPT. OF AGRICULTURE

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

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 broadleaved 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, 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 problems and in some

cases will reduce weed populations. Th's 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 fertihty in humid

regions. Also, where woody plants tend to dominate the vegetation, they must be removed to

achieve efficient production of forage because

most 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. Fortunately

selective herbicides are now available that will

aid in dealing with many of these problems.

Selective herbicides, by killing unwanted species,

may hasten the succession to more desirable plants.

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.

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.

The herbicides 2,4-D, 2,4,5-T, süvex, and MCPA

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 2,4-D,

2,4,5-T, and MCPA, are known to produce marked

changes in the chemical composition of treated

plants. Some herbicides affect the palatabiUty

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 12). 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

often desirable to defer the grazing during the

growing season for 1 or 2 years.
SUGGESTED GUIDE FOR WEED CONTROL 1967 43

TABLE 12.—Weed control in forage crops, pastures, and rangelands

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

Crop and treatment Time of application Weeds controlled Remarks

FORAGE CROPS

Alfalfa and birdsfoot trefoil :

New seedings:

CIPC (2) Postemergence, late fall

or early winter.

Chickweed Do not use if grass is planted with

legume.

Dalapon (2) 4 weeks after seeding or Crabgrass, foxtail Stunts alfalfa temporarily ; repeat

when grasses are less treatments later in summer; no

than 3 inches tall. injury to trefoil; do not feed

first year's growth to dairy

cows or animals being finished

for slaughter.

Dalapon (2-4) plus When weeds are 2-3 Weed grasses, broad- Repeat dalapon treatment for

2,4-DB (1.5). inches tall. leaved weeds. grasses that germinate in summer; do not feed first year's

growth to dairy cows or animals

being finished for slaughter.

DNBP (0.75-1.5) When weeds are small Chickweed, henbit. Often injures birdsfoot trefoil;

and seedlings have 2 or Depperweed, weed use in alfalfa or alfalfa-grass

more true leaves. bromegrass. mixtures only.

DNBP amine salts After emergence of Bitterweed, lambs- Injures trefoil.

(0.75-1.5) in 20-40 alfalfa seedlings when quarters, mustard,

gal. water. weeds are small. pigweed, ragweed,

sneezeweed, tarweed.

EPTC (2-4) Immediately before Weed grasses, some Mix with soil by disking or

planting alfalfa or broadleaved weeds. vigorous harrowing; herbicide

birdsfoot trefoil. volatile, lost if applied on wet

soil or allowed to remain on

surface for short time.

2,4-DB amine salts or Postemergence when Broadleaved weeds Can be applied at later stage of

esters (1-1.5) in 5-20 weeds are less than 3 growth than DNBP; do not

gal. water. inches tall. ^raze or feed treated plants to

ivestock within 30 days after

application.

Established stands:

CIPC (2) In fall when legumes are

dormant and weeds

Chickweed

small.

Diuron (2) In fall after crop is dormant or early spring.

Annual weeds in Northwestern States.

Stands must be at least 1 year old.

Diuron (3) do Downy bromegrass Do.

DNBP amine salts (2) In fall when legumes are Chickweed, henbit, yel- Re-treatment in late winter or

in 20-40 gal. water. dormant and weeds low-rocket seedlings. early spring necessary for heavy

small. infestations.

2,4-D or MCPA Early dormant stage of Sensitive broadleaved Use only as emergency measure if

(0.12-0.25).

Alfalfa:

CIPC granular (6)

legume. weeds. weed infestation threatens crop.

Before or during dodder

emergence and/or after

Dodder Timing critical.^

first cutting.

Weed burner Stubble following first do Kill top growth with light flame;

cutting. burn patches clean when vegetation has dried.

Clovers—alsike, crimson,

ladino, red, and

white—new seedings:

CIPC (2) Late fall or early winter. _ Chickweed Do not use if grass is mixed with

CIPC, EPTC, or IPC Immediately before Weed grasses, some

clover.

Disk into soil before weed ger-

(4). planting clover. broadleaved weeds. mination.

IPC (4) Postemergence when do Do not use if grass is mixed with

clover has at least 3 clover.

true leaves.

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

TABLE 12.—Weed control in forage crops, pastures, and rangelands—Continued

Crop and treatment Time of application Weeds controlled Remarks

FORAGE CROPS—Continued

Clovers—ladino, red, and

sweet :

New seedings:

DNBP (0.75-1.5) in When weeds are small Chickweed, henbit, Do not graze treated areas or feed

20-40 gal. water. and clovers have 2 or pepperweed, weed treated forage to livestock bemore true leaves. bromegrass. fore first cutting.

DNBP amine salts After emergence of Bitterweed, lambs- Do.

(0.75-1.5) in 20-40 clover seedlings when quarters, mustard, piggal. water. weeds are small. weed, ragweed, sneezeweed, tarweed.

2,4-DB (1-1.5) in Postemergence when Broadleaved weeds Can apply at later stage of legume

20-40 gal. water. weeds are less than

3 inches tall.

growth than DNBP.

Established stands:

CIPC (2) In fall when clovers are

dormant and weeds

Chickweed _ _ __

small.

DNBP amine salts (2) do Chickweed, henbit, Re-treatment in late winter or

in 20-40 gal. water. yellow-rocket seedlings. early spring necessary for

heavy infestations.

2,4-D or MCPA Early dormant stage of Sensitive broadleaved Use only as emergency measure if

(0.12-0.25). clover. weeds. weed infestation threatens

seed crop.

PASTURES AND GRASS-SEED FIELDS

Grasses:

New seedings:

Summer fallow 1 year before planting Perennial weeds includ- Reduce or eradicate these species

grass. ing bermudagrass,

Canada thistle,

johnsongrass, quackbefore planting grasses.

Thorough tillage in 1-2 years preceding

grass.

Annual broadleaved Where winter annual grasses are

intertilled crops. planting grass. weeds, annual grasses. 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.

Silvex (0.5-0.75) After grass seedlings Chickweed, henbit. Do not exceed 0.5 lb. of silvex per

have reached 2-4 leaf knotweed. acre until grasses become well

stage. established.

2,4-D amine salts or do__» Broadleaved weeds If land is heavily infested with

esters (0.75). seeds of annual grasses, delay

application until broadleaved

weeds are 12-15 inches tall to aid

in preventing germination of

weedy grasses.

Sprigged stands of Just before or just after Annual broadleaved and Use 1.5 lb. of herbicide per acre on

bermudagrass, sima- sprigging before weeds weed grasses. sandy soil; delay grazing or hay

zine, or diuron (3.2). emerge. harvest at least 5 months after

treatment.

Seed fields:

CIPC or IPC (2-3)____ Late fall-- Winter annual weeds in Especially effective on annual

Northwestern States. grasses.

Diuron (2-3) Late fall, established Winter annual weeds in- Do not use on light sandy soils.

fields. cluding bromegrass.
TABLE 12.

SUGGESTED GUIDE FOR WEED CON^TROL 1967

'Weed control in forage crops, pastures, and rangelands—Continued

45

Crop and treatment Time of application Weeds controlled Remarks

PASTURES AND GRASS-SEED FIELDS —Continued

Pastures:

Renovation on soils

too hilly or stony to

be plowed, dalapon

(7.4).

In humid areas, amitrole

(1) plus dalapon (4).

Late summer

Late summer

Sod, weed grasses.

Broadleaved weeds,

weed grasses.

PERMANENT PASTURES AND RANGELANDS

Pastures:

Fertilize adequately,

mow when grass becomes coarse, graze

area intensively.

2,4-D amine salts or

esters (0.5-1).

2,4-D esters (l-2)_

Broomsedge_

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

or silvex (1-2).

2,4,5-T amine salts or

silvex (1-2).

Rangelands:

Silvex low-volatile esters

(0.67).

Silvex or 2,4,5-T lowvolatile esters (0.5-1).

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.

Usually late spring

Between February and

May.

When weeds are most

susceptible.

Fall, winter, or spring

May 15-June 30_

Full leaf stage and growing actively.

After spring growth and

before soil moisture is

depleted in upper 8-10

inches.

New twig growth 3

inches or longer and

before soil moisture is

depleted in upper 8-10

inches.

Bitterweed, boneset,

burdock, Canada

thistle, chicory,

dandelion, ironweed,

pigweed, ragweed,

sneezeweed, tarweed.

Curly dock, wild garlic,

wild onion.

Broadleaved weeds.

Bedstraw, chickweed,

henbit, knawel.

Yucca

Shinnery oak_

Big sagebrushRabbitbrush.

Graze turf heavily during summer,

then kill undesirable grasses;

disk dead sod 3-5 weeks after

treatment and seed; control

broadleaved weeds by selective

herbicides in new seeding with

2,4-D or 2,4,5-T.

Combination gives excellent control of sod and some broadleaved

weeds; disk dead sod 3-5 weeks

after treatment and reseed; do

not graze for 8 months after

treatment.

Consult local authorities for

recommended rates and times of

fertilizer application.

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.

May injure legumes, then seriousness of weed infestation will

determine use of herbicide;

remove milk cows from pastures

for 7 days after spraying; if

poisonous weeds or woody plants

are in area, remove livestock

for 3 weeks after treatment.

These herbicides kill lespedeza and

seriously injure true clovers;

remove milk cows from pasture

7 days after spraying.

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.

Properly timed mowing also controls sagebrush; can be done

where terrain is not too rough.

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

moisture is critically low.
46 AGRICULTURE HANDBOOK 332, U.S. DEPT. OF AGRICULTURE

TABLE 12.—Weed control in forage crops, pastures, and rangelands—Continued

Crop and treatment Time of application Weeds controlled Remarks

PERMANENT PASTURES AND RANGELANDS continued

Rangelands—Con.

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

gal. water, diesel oil,

or oil-water emulsion.

2,4-D esters (1-2) in 3-4

gal. water, diesel oil,

or oil-water emulsion.

2,4-D esters (1.5-3)

2,4-D esters (2)_

2,4-D esters (3-5)

2,4-D low-volatile esters

(2).

2,4,5-T esters (1) plus

2,4-D (2).

2,4,5-T esters or silvex

(2).

2,4,5-T esters or silvex

(2-4).

2,4,5-T low-volatile

esters (0.33).

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 or silvex lowvolatile esters (8) in

100 gal. diesel oil.

2,4,5-T low volatile

esters (32) in 100 gal.

diesel oil or undiluted.

In May or early June

with 6-8 inches of new

growth.

After full foliage (usually last part of May).

(Early spring, 3- to 5-leaf

stage.

Fully emerged but bebefore flower stems

appear.

Bud to early bloom stage.

lEarly bolting stage. _

Prebloom stage

Early branching, prebloom stage.

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 buds form.

Foliage in spring when

soil moisture is adequate for growth.

50-90 days after first

leaves appear in spring.

When soil is dry

Basal spray summer or

winter.

Summer or winter.

When plants are growing

rapidly.

Any time

Sand sagebrush

Buckbrush

Deathcamas

Low larkspur. .

Locoweed, princesplume,

silvery lupine, twogrooved milkvetch,

waterhemlock, woody

aster.

Tansy-ragwort

Orange sneezeweed

Halogeton

Post oak

Timberline milkvetch.

Blackjack oak, post oak..

Tall larkspur

Velvet mesquite

Honey mesquite

Agarita, catclaw, elbowbush, huisache, mesquite.

Baccharis, bayberry,

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, tree

of heaven, walnut,

wild chinaberry, willow.

Ash, black gum, blackjack oak, bur oak, elm,

hickory, pin oak, post

oak, red maple, red

oak, sweetgum, sycamore, water oak, white

oak, willow oak.

Chalk cactus, pricklypear, tasajillo.

Hardwood species more

than 1 inch in diameter.

Diesel oil preferred for lowest

gallonage.

Repeated annual sprayings may

be necessary; correct timing

important.

Spraying ineffective if treatment

is delayed.

Do not graze sprayed areas for at

least 3 weeks after treatment.

Repeated annual applications may

be necessary; do not graze

sprayed areas for at least 3

weeks after treatment.

Near trails and bed grounds.

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 2-3 consecutive years.

Do not graze sprayed areas for at

least 3 weeks after treatment.

In arid Southwest re-treat within 2

years.

Tops killed; re-treatment necessary

in 5-7 years.

Apply to frills, stumps, or basal

trunks.

Do.

Do.

Wetting spray.

Tree injector or other injecting

equipment; apply in cuts 2

inches apart at base of tree.

1 See U.S. Department of Agriculture Farmers' Bui. 2211, Controlling Dodder in Alfalfa.
SUGGESTED GUIDE FOR WEED CONTROL 1967 47

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.

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 13 contains information about herbicides

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 lawn 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 71), Controlling

Lawn Weeds With Herbicides, and Farmers'

Bulletin 2183, Using Phenoxy Herbicides Effectively.

TABLE 13.—Weed control in lawns and other turf areas

[Numbers in parentheses=pounds of active Ingredient]

Treatment Time of application Weeds controlled Remarks

NEW SEEDINGS

Methyl bromide (1) When soil temperature Weed grasses and broad- Well-prepared, moist seedbed; apply

per 100 sq. ft. is above 65° F. leaved weeds—all under gastight cover; follow manuplant parts including facturer's instructions; seed lawn

seeds and seedling 2-3 days after application; this soil

parts; also disease fumigant is deadly poison.

organisms, nematodes,

insects.

Siduron (0.25) per Before weed-grass germi- Crabgrass, other annual Treat before, during, or after seeding;

1,000 sq. ft. nation. grasses. water within 3 days if no rain; use

only on bluegrass and fescue lawns.

ESTABLISHED LAWNS (wiTH WEED GRASSEs)

Benefin, 1.5 oz. per

1,000 sq. ft.

Bensulide, 4r-5 oz. per

1,000 sq. ft.

Before weed emergence.

do

Do not overseed within 3 months after

treatment.

Do not overseed within 6 months after

treatment.
48 AGRICULTURE HANDBOOK 3 32, U.S. DEPT. OF AGRICULTURE

TABLE 13.—Weed control in lawns and other turf areas—Continued

Treatment Time of application Weeds controlled Remarks

ESTABLISHED LAWNS (wiTH WEED GRASSES)—Continued

Calcium arsenate Late March or early Crabgrass Poisonous chemical; keep children and

(10-16) per 1,000 April, before weed animals off sprayed areas until after

sq. ft. emergence. first rain.

DCPA (0.25) per do do

1,000 sq. ft.

DSMA and similar After weed-grass emer- Crabgrass, dallisgrass. Follow instructions on label; may

arsonates (1.5-2.5) gence; re-treat at 7- goosegrass, sandbur. slightly discolor turf.

per acre. to 10-day intervals

until control is obtained.

Siduron (0.25-0.5) per Before weed-grass Crabgrass, other annual

1,000 sq. ft. germination. grasses.

Spot treatment when Clumps of nimblewill, Will injure all grasses in treated spot;

grasses actively grow- orchardgrass, quack- carefully treat weeds; if applied in

ing. grass, timothy. warm moist soil, possible to reDalapon (0.25) in 1 sçed in 3-6 weeks.

gal. water per 1,000 July; repeat 3-4 weeks Bermudagrass Lawn grasses also killed by treatsq. ft. later; water between ment; reseed 3 weeks after second

applications. application if temperatures are

high, 6 weeks if temperatures are

low; if soil is dry, water thoroughly

before seeding.

DMTT plus SMDC Early August; repeat 4-6 do Follow manufacturer's directions; re-

(0.5-1) per 100 sq.

ft.

Petroleum naphtha, 1

weeks later. seed 3-4 weeks after second application.

Spot treatment when Clumps of nimblewill. Carefully treat weeds; also will kill

gal. per 1,000 sq. ft. grasses actively grow- orchardgrass, quack- lawn grasses.

(use full-strength ing. grass, timothy.

coarse spray).

ESTABLISHED LAWNS (WITH BROADLEAVED 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.

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.

2,4-D (1) plus

dicamba (0.25)

amine salts per acre.

2,4-D (0.5) plus

silvex (0.5) lowvolatile esters per

acre.

When weeds are actively

growing.

When plants are small

Actively growing weeds. _.

do

Late fall; repeat in late

winter or early spring

each year.

When weeds are smalL__

When weeds are small

in cool weather of

early spring.

Chickweed, clover, henbit, knotweed, purslane, red sorrel.

Burclover, henbit, knotweed, pennywort.

Burclover, chickweed,

ground-ivy, henbit,

knotweed, pennywort,

violet, white clover,

woodsorrel.

Buckhorn plantain,

curly dock, dandelion.

Knotweed, wild garlic,

wild onion.

Chickweed, clover,

henbit, knotweed,

red sorrel.

do

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.

Fasten piece of kitchen sponge to end

of stick or broom handle, dip sponge

into solution, and spot treat broadleaved weeds by pressing moist

sponge against crown of each plant;

delay mowing 24-48 hours.

Fasten piece of kitchen sponge to end

of stick or broom handle, dip sponge

into solution, and spot treat broadleaved 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.

Do not exceed recommended rate

and avoid flowers and shrubs;

esters and amines not compatible.

Do not allow spray to drift onto

trees and shrubs.
SUGGESTED GUIDE FOR WEED CONTROL 1967

WEED CONTROL IN NONCROPLAND

49

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 heu of gates greatly facihtate

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

utiUty line poles in concrete to ehminate 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,

Hquid 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.

CONTROL WITH HERBICIDES

Choice of Herbicides and Rates

In choosing an herbicide or a mixture of herbicides

and the rate of application 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, broadleaved weeds, mixed vegetation, or

woody plants; (2) the objective—total vegetation

control (soil sterilization—bare soil), selective

control of broadleaved 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 broadleaved 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 appHed 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 hght 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 will 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 finding wide use 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
50 AGRICULTURE HANDBOOK 3 32, U.S. DEPT. OF AGRICULTURE

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,

utihty poles, and buildings, under guardrails and

transformer cages, along pipeUnes, 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 ñood 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 fohage 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 in

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

fohage sprays, aerial spraying with a hehcopter,

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

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 14. 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.
SUGGESTED GUIDE FOR WEED CONTROL 1967 51

TABLE U.—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

BROADLEAVED HERBACEOUS WEEDS (SELECTIVE CONTROL IN DESIRABLE GRASSES)

Annuals, shallow-rooted perennials, and

seedling perennials:

Dicamba (0.5-1)

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

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

Deep-rooted and other hard-to-kill

perennials:

PBA (20-60)

Picloram (2-3) _

Picloram plus 2,4-D mixture (follow

instructions on label).

TCBP (8-16)

2,3,6-TBA (10-30)

2,4-D (2-4) __

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

Early weed growth in spring_

Early growth to first bloom__

do

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.

Rapid vegetative growth to early

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

During early growth or in fall when

ground is not frozen.

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.

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 difficult to control with

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

WEEDY GRASSES WHERE CONTROL OF BROADLEAVED WEEDS NOT NECESSARY

An nuals and seedling perennials:

Aromatic oil, 40-80 gal. per acre

Dalapon (5-10)

DNBP or PCP fortified fuel oil",

40-80 gal. per acre.

Established perennials (bermudagrass,

Johnsongrass, paragrass, quackgrass, reed canarygrass) :

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

Dalapon 2 (10-15) _

Dalapon 2 (20-30).

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)

Spray young growth

Spray young growth 4-8 inches tall.

Spray young growth

-do

Spray young growth 6-18 inches

tall.

Early growth to early heading

Spray young growth

When weeds are actively growing.

On aftermath growth in fall or as

soil treatment.

See footnotes at end of table.

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

TABLE U.—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 BROADLEAVED WEEDS NOT NECESSARY Continued

Established perennials (Phragmites,

reed canarygrass) :

Amitrole (8-12)

Amitrole-T (4-6)

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)

Amitrole or amitrole-T (10-20)

Dalapon2 (15-30)

DNBP fortified fuel oil, 120-160

gal. per acre.

2,4-D (60-80).

On young growth 10-15 inches talL

On young growth before heading—

On young growth 10-15 inches talL

do

do

Repeat 2-3 times each growing season

to suppress growth; use only in

drainage ditches and marshes.

Repeat every 6-8 weeks as necessary

to eliminate stand; use only in

drainage ditches and marshes.

Repeat as necessary to suppress growth

to desired extent; use only in drainage ditches and marshes.

Repeat every 4-6 weeks as necessary

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 BROADLEAVED AND GRASS WEEDS

Annuals, biennials, shallow-rooted

perennials, and seedling perennials

{lower rates) ; established deeprooted and other hard-to-kill

perennials {higher rates) :

Amitrole or amitrole-T (3-5; 6-12)___

Amitrole plus simazine mixture

(follow instructions on label).

AMS (50-100; 400-1,000).

Aromatic oil, 40-80 and 120-160

gal. per acre.

See footnotes at end of table.

Repeat as necessary to maintain control or to eliminate or reduce stand;

do not use along irrigation canals,

reservoirs, lakes, ponds.

Gives longer lasting control than

amitrole alone; do not use along

irrigation canals, reservoirs, lakes,

ponds.

Mix ^2-2 lb. per gal. water and spray

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

lakes, ponds, canals, and strearas

including domestic water supplies

at rates up to 200 lb. per acre.

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

or reduce stand.
SUGGESTED GUIDE FOR WEED CONTROL 1967 53

TABLE U.—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

MIXED HERBACEOUS BROADLEAVED AND GRASS WEEDS Continued

Annuals, biennials, shallow-rotted perennials, and seedling perennials

(lower rates) ; established deeprooted and other hard-to-kill perennials (higher rates)—Con.

Borate (sodium), 30-120 lb. per

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

Borate mixtures with sodium

chlorate and/or other chemicals

(follow instructions on label).

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)

Before period of adequate precipitation.

Soil applications before period of

adequate precipitation; spray applications on early growth to

first bloom.

Early growth to first bloom or before period of adequate precipitation.

Spray foliage and make soil applications before period of adequate

precipitation.

do

Diuron or monuron (5-20; 20-80)___ Before period of adequate precipitation.

DNBP or PCP fortified fuel oil,

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

Erbon (120-160).

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)

Prometone (10-15; 20-60)

Simazine or atrazine (5-20; 20-40) __

Young growth to first heading.

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

Spray when weeds are about 12

inches tall.

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

Young growth to first heading, _

Spray young growth.

Spray early growth to first heading..

Spray early growth to first heading;

soil applications before period of

ample precipitation.

Early growth to early bloom or

heading.

When weeds in active growth stage. _

Apply broadcast as soil treatment.

Use where soil sterilization (bare soil)

desired.

Apply 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 broadleaved 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.

Simazine requires more precipitation

for effective root kill; remains

effective in soil longer.

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

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

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

Weed and treatment Time of application

UNDESIRABLE WOODY PLANTS

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

and other species susceptible to

2,4-D, 2,4-D (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

AMS (60) in 100 gal. water.

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

FenuronTCA (12-25)-

Picloram (6-8.5).

At full leaf in spring or early

summer.

_do_

Spray over freshly cut stump or in

frills or notches cut around base

of tree.

At full leaf in spring or summer

Picloram plus 2,4-D mixture (follow

instructions on label).

Silvex (2-4)

2,3,6-TBA (10-20)

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

Just before or during period of

adequate precipitation.

Spray at full leaf stage or broadcast before or during period of

adequate precipitation.

Broadcast granules just before or

during period of adequate

precipitation.

Spray at full leaf during vigorous

growth.

Spray at full leaf during active

growth; spring treatments best

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

Spray foliage and soil when conditions suitable for active growth.

Spray at full leaf during active

growth; spring treatments best

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

Remarks

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 inches around

circumference of tree ; crystals may

be sprinkled liberally over cut stumps

or in frills or notches.

Spray to thoroughly wet foliage; 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,

Osage-orange, persimmon, sassafras.

Available in liquid, granular, and

pelleted formulations for spray or

broadcast applications.

Highest rate is necessary for ash,

black gum, 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, Osage-orange.

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 broadleaved

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

formulation of 2,4-D at 1 to 2 lb. per acre.
SUGGESTED GUIDE FOR WEED CONTROL 1967

CONTROL OF AQUATIC WEEDS

55

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 eflScient 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

beconiing 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 cattaüs 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, wiUow, and certain other emersed or marsh

species can be eUminated 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 Moving.—Self-propelled and boatmounted mowers that cut off submersed or

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 kiUing small patches of waterHlies and

watershield, cut leaves off below the water surface
56 AGRICULTURE HANDBOOK 332, U.S. DEPT. OF AGRICULTURE

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., Israeh 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 water-hyacinth;

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

water-hyacinth in 1902 and submersed weeds in

1927. However, most of the 19 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 Precautionsin Use ofAquatic Herbicides

A few aquatic herbicides, such as sodium

arsenite, 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

aU general precautions for the safe use of herbicides

described on page 3 and the special precautions in table 15, 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 15. 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 appUcation are given m 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 froni

aquatic weed specialists of State and Federal

agencies famiUar with the particular local

situation.
SUGGESTED GUIDE FOR WEED CONTROL 1967

TABLE 15.—Control of aquatic weeds (irrigation canals, drainage ditches, streams, lakes, ponds,

reservoirs, marshes)

57

Type and kind of aquatic

weed or aquatic site

Herbicide ^ Rate or

concentration ^

Remarks

FLOATING WEEDS (UNATTACHED, TOPS ABOVE WATER)

Alligatorweed (floating

mats), duckweed,

waterfern (Salvinia),

waterlettuce :

General control (all

weeds).

Near crops sensitive to

2,4-D:

Duckweed (nonflowing water).

Water-hyacinth

Water-hyacinth and

waterlettuce.

More positive eradication—alligatorweed

floating mats.

2,4-D amine salts or

low-volatile esters.

Diquat (cation).

Amitrole-T

Diquat (cation).

Ester of silvex __

2-4 lb. per 100 gal.

diluent.

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 0.12 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 first bloom; re-treat when regrowth 2-4

inches above water; 2-4 applications required for control; use for irrigation or

domestic purposes.

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

Broadleaved species:

General control

Arrowhead, lotus,

pickerelweed, smartweed, spatterdock,

spikerush, waterprimrose, white

waterlily, other plants

with waxy leaves.

Rooted, emersed alligatorweed.

Grass and grasslike species:

Perennial grasses and

sedges, e.g., cutgrass,

Johnsongrass, knotgrass, paragrass,

quackgrass, common

reed (Phragmites),

ripgut sedge.

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

silvex.

2,4-D (low-volatile

ester).

Ester of silvex

(spray).

Amitrole or

amitrole-T.

2-4 lb. per acre.

1-4 lb. per acre.

8 lb. per acre.

,Dalapon_

8-16 lb. per acre_

20-30 lb. per acre___

See footnotes at end of table.

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 first 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

inches 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

inches 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.
58 AGRICULTURE, HANDBOOK 332, U.S. DEPT. OF AGRICULTURE

TABLE 15.^—Control of aquatic weeds {irrigation canals^ drainage ditches^ streams^ lakesj pondsj

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

Grass and grasslike speciesContinued.

Bulrushes and cattails

'2,4-D (low-volatile

esters).

Amitrole

Palapon.

4-6 lb. per acre_

6-12 lb. per acre.

15-30 lb. per acreApply 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.

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.

of wetting agent or 5-10 gal. diesel oil

plus 1 pt. emulsifier per 100 gal. spray.

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

Ponds, lakes, and reservoirs:

Algae, blue-green_

Algae, filamentous.

Rooted or anchored

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

pondweeds, waterchestnut, water crowfoot, watermilfoil,

water pennywort,

waterprimrose, waterstargrass, wildcelery.

Same weeds except alga

and chara.

See footnotes at end of table.

^Copper sulfate

(pentahydrate,

dark blue).

Dichlone_

Copper sulfate

(pentahydrate,

dark blue).

Endothall (dimethylamine salts).

Sodium arsenite

(arsenic trioxide

equivalent).

Endothall (disodium

salt).

Endothall (dimethylamine salts).

Fenac

DichlobeniL

0.1-0.5 p.p.m.w

0.02-0.05 p.p.m.w_

rO.5-1 p.p.m.w

11-2 p.p.m.w

0.05-0.2 p.p.m.w__

2-10 p.p.m.w

1-4 p.p.m.w

0.5-2.5 p.p.m.w

15-20 lb. per acre

17-10 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 dispersions; 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.

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.

Same as for sodium arsenite; increase concentration to 5 p.p.m.w. for spot treatments; follow label directions on use of

treated water.

Use only for spot treatments or where some

fish kill is not objectionable.

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.
SUGGESTED GUIDE FOR WEED COIsTTROL 1967

TABLE 15—Control ojaquatic weeds (irrigation canals, drainage ditches, streams, lakes, ponds,

reservoirs, marshes)—Continued

59

Type and kind of aquatic

weed or aquatic site

Herbicide Rate or

concentration ^

Remarks

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

Ponds, lakes, and reservoirs—Continued

Same weeds except

Elodea and wildcelery.

Same weeds except

curlyleaf pondweed,

some other pondweeds, Elodea, wildcelery.

Irrigation and drainage

canals with flowing

water—most submersed

species except waterplantain.

Drainage and irrigation

canals with flow stopped

or greatly reduced.

Reservoirs and large canals

carrying flowing water

for potable use :

Continuous feed method.

Repeated "slug" treatments.

Diquat (cation),.

Ester of 2,4-D

(granule or pellet

form).

Potassium salt of

silvex (granule or

liquid form).

Aromatic solvents

(xylene).

Acrolein

Diquat (cation)

Acrolein. _

Endothall (dimethylamine

salt).

Copper sulfate

(pentahydrate).

-do_

i'0.5-1.5 p.p.m.w

0.25-0.5 p.p.m.w..

20-40 lb. per acre.

1.5-2 p.p.m.w. or 5

lb. per acre-ft.

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).

1-2.5 gal. per c.f.s.

0.1-0.6 p.p.m.v.

0.25-1 p.p.m.w..

4-7 p.p.m.v

1.5-4 p.p.m.w

0.6-1 p.p.m.w

0.33-2 lb. per c.f.f

Apply over surface or inject below water

surface; double rates for spot treatments;

follow label directions on use of treated

water.

Low concentrations sufficient for some weeds

e.g., naiad in small ponds.

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 over surface of water or

inject liquid below surface at early stage

of weed growth; not effective in spot

treatments.

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.

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.

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

hours' exposure of weeds to treated water.

Apply below water surface continuously

along canal with especially adapted

equipment; toxic to fish.

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.
CROP, SITE, AND TOPIC INDEX

Specific crops, sites, or areas for which weedcontrol suggestions are given and special control

topics are listed alphabetically under the headings

Crops:

Alfalfa : Page

Forage crops 26, 27, 43

Seed crops 26, 27, 43

Almonds 37

Apples 37

Apricots 37

Asparagus 34

Avocados 38

Barley 30, 31

Beans:

Lima 34

Pole 34

Snap 34

Beets 34

Bentgrass 27

Bermudagrass 44

Blackberries 39

Blueberries 39

Bluegrass 27

Broccoli 34

Brussels sprouts 34

Cabbage 35

Cantaloup 35

Caraway 35

Carrots 35

Cauliflower 35

Celery 35

Cherries 37

Chicory 35

Clover:

Alsike 27, 43

Crimson 27, 43

Forage crops 27, 43

Ladino 27, 43, 44

Red 27,43,44

Seed crops 27, 43

Subterranean 27

Sweet 44

White 27, 43

Collards 35

Corn 18

Corn, sweet 35

Cotton 20

Cranberries 39

Cress, upland 36

Cucumbers 35

Dates 38

Dill 35

Eggplant 35

Endive 35

Escarole 35

Fescue, creeping red 31

Fescue, tall 27

Flax 28

Garlic 35

Gooseberries 39

Grapefruit 38

Grapes 39

sses:

Forage crops 26. 27, 32, 44

Seed crops 26, 27, 32, 44

60

crops, grazing lands and turf, noncropland, and

aquatic weeds.

Crops—Continued Page

Hanover salad 35

Kale 35

Legumes 27, 31

Lemons 38

Lentils 35

Lespedeza 27

Lettuce 35

Limes 38

Macadamia nuts 38

Mint 35

Mustard greens 35

Oats 31

Okra 35

Olives 37

Onions 35

Oranges 38

Orchardgrass 27

Parsley 35

Parsnips 35

Peaches 37

Peanuts 21

Pears 37

Peas 35

Peas, southern , 36

Peppermint 36

Peppers 36

Pineapples ^^

Plums 37

Potatoes 36

Pumpkins 36

Radish 36

Raspberries 39

Rice. 28

Ryegrass 27

Safflower 22

Sorghum 22

Soybeans 23

Spinach 36

Squash 36

Strawberries 39

Sugarbeets 24

Sugarcane 25

Sweetpotatoes 36

Tobacco 26

Tomatoes 36

Trefoil 27

Trefoil, birdsfoot 27, 43

Turnip greens 36

Turnips 36

Walnuts 37

Watermelons 36

Wheat 30, 31

Wheat, durum 31

Wheat, hard red spring 31

Grazing lands and turf:

Lawns ^^

Other turf 47

Pastures "^3

Rangelands 43
SUGGESTED GUIDE FOR WEED CONTROL 1967 61

Noncropland: Page

Choice of herbicides and rates 49

Construction aids '__ 49

Control with herbicides 49

Cultural, biological, and mechanical control 49

Special precautions in use of herbicides in non- 50

cropland

Suggested uses of herbicides in noncropland. __ 50

Use of herbicides for woody plants in noncropland 50

Aquatic weeds:

Biological control 56

Chemical control 56

Aquatic w^eeds—Continued Tage

Construction aids 55

Drainage and irrigation canals with flow

stopped or greatly reduced 59

Hand and mechanical control 55

Irrigation and drainage canals with flowing

water 59

Ponds, lakes, and reservoirs 58

Reservoirs and large canals carrying flowing

water for potable use 59

Special precautions in use of aquatic herbicides. 56

Suggested uses of herbicides for control of

aquatic weeds 56
WEED INDEX BY CROPS OR SITES

Specific weeds discussed in this handbook are

listed alphabetically by the common names approved by the Weed Society of America followed

Page

Agarita {Mahonia trifoliolata (Moric.) Fedde) 46

Alder {Alnus spp.) 54

Algae:

Blue-green (many genera) 58

Filamentous green (many genera) 58

Pithophora spp 56

Alligatorweed {Alternanthera philoxeroides (Mart.)

Griseb.) 57

Arrowhead {Sagittaria spp.) :

Emersed weeds 57

In rice 29

Ash (Fraxinus spp.) 46, 54

Ash, white {Fraxinus americana L.) 5

Aster, woody (Aster parryi A. Gray) 46

Baccharis (Baccharis spp.) 46, 54

Barley, wild (Hordeum leporinum Link) 1

Barnyardgrass (Echinochloa crusgalli (L.) Beauv.) _ 28, 30

Bayberry ( Myrica pensylvanica Loisel.) 46

Beakrush ( Rhynchospora spp.) 28

Bedstraw (Galium spp.) 32

Bedstraw, smooth (Galium mollugo L.) 45

Beech (Fagus grandifolia Ehrh.) 46

Bermudagrass (Cynodon dactylon (L.) Pers.) :

In field crops 44

In lawns and turf 48

On noncropland 51

Bindweed (Convolvulus spp.) _ 8, 12

Bindweed, field (Convolvulus arvensis L.) 31, 32

Birch (Betula spp.) 46

Bitterweed (Helenium amarum (Raf.) Rock) :

In field crops 43, 45

In pastures 58

Bladderwort ( Utricularia spp.) 6, 27

Bluegrass (Poa spp.) 10,52

Bluegrass, Kentucky (Poa pratensis L.)

Boneset (Eupatorium perfoliatum L.) 45

Boxelder (Acer negundo L.) 54

Brachiaria (Brachiaria spp.) :

In corn 19

In rice 29,30

Brackenfern (Pteridium spp.) 7

Bramble (Ruhus sp.) 8

Bromegrass (Bromus spp.) 43, 44

Bromegrass, downy (bromus tectorum L.) :

In field crops 26

In forage crops -__ 43

Broomsedge (Andropogon virginicus L.) 45

Buckbrush (Symphoricarpos spp.) 46

Buckwheat, wild (Polygonum convolvulus L.) :

In sugarbeets 25

In wheat 31

Bulrush (Scirpus spp.) :

Emersed and marginal weeds 58

In rice - 28

Burclover (Medicago polymorpha var. vulgaris

(Benth.) Shinners) 48

Burdock (Arctium spp.) 1, 45

62

by the scientific names. Names of some families

and types of weeds are also included.

Page

Burhead (Echinodorus cordifolius (L.) Griseb.) 29

Bur-ragweed (Franseria discolor Nutt.) 32

Buttonbush (Cephalanthus occidentalis L.) 55

Cabomba (Cabomba caroliniana Gray) 58

Cactus (Cactaceae) |6

Canarygrass, reed (Phalaris arundinacea L.) 51, 52, 57

Carpetweed (Mollugo verticillata L.) 7

Carrot, wild (Daucus carota L.) 1

Catclaw (Schrankia nuttallii (DC.) Standl.) 4b

Cattail (Typha spp.):

Emersed and marginal weeds ^ö

In rice ^^

Ceanothus (Ceanothus spp.) 4^

Chara (Chara spp.) ^^

Cheat (Bromus secalinus L.) 1

Cherry (Prunus spp.) 54

Chestnut (Castanea spp.) ^"

Chickweed (Stellaria media (L.) Cyrillo) :

In field crops ^5, z7

In forage crops Is

In lawns and turf ^

Chicory (Cichorium intybus L.) 45

Chinaberry, wild (Melia azedarach L.) 4b

Chinkapin (Castanea spp.) j^

Clover (Trifolium spp.) J^

Clover, white (Trifolium repens L.) 4»

Cocklebur (Xan¿/imm spp.) :

In cotton j^

In small grains ^J

In soybeans ^^

Coffeebean. (See Sesbania.)

Coontail (Ceratophyllum spp.) ^

Corncockle (A grostemma githago L.) ^^

Cottonwood (Populus spp.) ^^'^^

Cowcockle (Saponaria vaccaria L.) ^^

CrsibgrsiSQ (Digitaria spp.):

In forage crops ^7

In lawns and turf ^*

Crabgrass, hairy (Digitaria villosa (Walt.) Pers.) - 10

Crabgrass, smooth (Digitaria ischaemum (Schreb.)

Muhl.) l^

Crowfoot, water (Ranunculus spp.) '^

Cutgrass (Leersia spp.) 57

Daisy (Chrysanthemum spp.) ^

Dallisgrass' (Paspalum dilatatum Poir.) 9, 4»

Dandelion (Taraxacum officinale Weber):

In lawns and turf ^

In pastures ^^

Deathcamas (Zigadenus spp.) ^^

Dock (sorrel) (Rumex spp.) ^^

Dock, curly (Rumex crispus L.):

In lawns and turf ^^

In pastures ^

In small grains ^^

Dodder (Cuscuta spp.) 26, 43

Dogbane (Apocynum spp.) ^^
SUGGESTED GUIDE FOR WEED CONTROL 1967 63

Page

Dogfennel (Eupatorium capillifolium (Lam.) Small) :

In sugarcane 25

In wheat ]__ 31

Dogwood {Cornus spp.) 54

Downy brome (Bromus tectorum L.) 10, 26

Ducksalad {Heteranthera limosa (Sw.) Willd.) ' 29

Duckweed (Lemna spp.) 57

Elbowbush (Forestiera pubescens Nutt.) 46

Elderberry (Sambucus spp.) 54.

Elm ( Ulmus spp.) 46

Elodea (Elodea spp.) ~" 58^ 59

Fescue, red (Festuca rubra L.) 'lO

Fescue, tall ~ 27

1^mxbiist>lis {Fimbristylis spp.) 29, 30

Foxisiil (Setaria spp.):

In forage crops 43

In sugarbeets 24

Garlic, wild (Allium vineale L.):

In lawns and turf 48

In pastures 45

Goldenrod (Solidago spp.) ]_"__ 6

Goosegrass (Eleusine indica (L.) Gaertn.) 48

Gooseweed (Sphenoclea zeylanica Gaertn.) 29, 30

Gorse ( Ulex europaeus L.) , 49

Groundcherry (Physalis spp.) ' 21, 25

Ground-ivy (Glechoma hederacea L.) '48

Gum, black (Nyssa sylvatica Marsh.) :

On noncropland 54

On rangeland 46

Hackberry (Celtis spp.) ] 46

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

Mey.) 46

Haw, red (Crataegus spp.) 46

Henbit (Lamium amplexicaule L. ) :

In forage crops 43^ 44

In lawns and turf ~_1 '48

In pastures ] 44, 45

In sugarcane '25

Hickory (Carya spp.) ~ 46

Hoarycress (Cardaria draba (L.) Desv.) '_ 5, 32

Honeylocust (Gleditsia triacanthos L.) '46

Horsenettle (Solanum carolinense) L 51

Horsetail rush (Equisetum spp.) 33

Huisache (Acacia farnesiana (L.) Willd.) II 46

Hydrangea (Hydrangea spp.) 46

Indigo, curly (Aeschynomenevirginica (L.) BSP.) .28, 29, 30

Ironweed (Vernonia spp.) 45

Johnsongrass (Sorghum halepense (L.) Pers.) : ~ 57

Emersed and marginal

In cotton 20 21

In grass seed fields 33] 44

In soy beans '23

In sugarcane ~_~_ 25

On noncropland I__ 51

Knapweed, Russian (Centaurea repéns L.) 32

Knawel (Scleranthus annuus L.) 45

Knotgrass (Paspalum distichum L.) :

Emersed and marginal weeds 57

In rice 28

Knotweed (Polygonum spp.) :

In grass seed fields 44

In lawns and turf 48

Koa haole (Leucaena leucocephala (Lam.) de Wit.) _ 25

Lambsquarters (Chenopodium spp.) :

In forage crops 43, 44

In safflower ' 22

In small grains 31

Larkspur, low (Delphinium nelsonii Greene) 46

Larkspur, tall (Delphinium barbeyi Huth) 46

Lettuce, prickly (Lactuca serriola L.) 31

Lettuce, wild (Lactuca spp.) 25

Locoweed (Astragalus spp.) 46

Lotus, American (Nelumbo lutea (Willd.) Pe"rs.)'I_I 57

Lupine, silvery (Lupinus argenteus Pursh) 46

Page

Madrone (Arbutus menziesii Pursh) 46

Manzanita (Arct staphylos spp.) 45

Maple (Acer spp.) I 54

Maple, red (Acer rubrum L.) "I"I 46

Maple, silver (Acer saccharinum L.) "" 46

Mescalbean (Sophora secundiflora (Ort.) Lag.)_ ' 46

Mesquite (Prosopis spp.) 46 54

Mesquite, honey (Prosopis glandulosa var. glandulosa (Torr.) Cockerell) -_____._ 46

Mesquite, velvet (Prosopis velutina (Woot.)) III 46

Mexican weed (Caperonia castaneaefolia (~L.) St.

Hil.) 28 29

Milkvetch, timberline (Astragalus sp.)___IIIIIIIII ' 46

Milkvetch, two-grooved (Astragalus bisulcatus

(Hook.) Gray) 46

Morning-glory (Ipomoea spp.) 25

Mulberry (Morus spp.) 46,54

Mullein (Verbascum spp.) ' 1

Mustard (Brassica spp.) :

In forage crops 43 44

In small grains '31

Naiad (Najas spp.) II_I 58

Nightshade (Solanum spp.) :

In sugarcane 25

On noncropland HH 51

Nimblewill (Muhlenbergia schreberi J. F. GmeL)... 48

Nutsedge (Cyperus spp.) 20, 21, 23

Nutsedge, purple (Cyperus rotundus L.) ' '33

Nutsedge, yellow (Cyperus esculentus L.) 33

Oak (Quercus spp.) :

On noncropland 54

On rangeland 45, 46

Oak, blackjack (Quercus marilandica Muenchh.) ' 46

Oak, bur (Quercus macrocarpa Michx.) 46

Oak, pin (Quercus palustris Muenchh.) 46

Oak, post (Quercus stellata Wangenb.) 46

Oak, red (Quercus rubra L.) 46

Oak, shinnery (Quercus havardii Rydb.) 45

Oak, water (Quercus nigra L.) 46

Oak, white (Quercus alba L.) 46

Oak, willow (Quercus phellos L.) 46

Oats, wild (Avena fatua L.) :

In barley 30

In flax 28

In sugarbeets 24

In wheat 31

Onion, wild (Allium canadense L.) :

In lawns and turf_, 48

In pastures 45

Orchardgrass (Dactylis glomerata L.) 48

Osage-orange (Madura pomifera (Raf.) Schneid.):

On noncropland 54

On rangeland 46

Palmetto (Serenoa repens (Bartr.) Small) 54

Paragrass (Panicum purpurascens Raddi) :

Emersed and marginal weeds 57

On noncropland 51

Pecan (Carya spp.) 46

Pennycress (Thlaspi spp.) 1

Pennywort (Hydrocotyle spp.) 48

Pennywort, water (Hydrocotyle umbellata L.) 58

Pepperweed (Lepidium spp.) 43, 44

Persimnion (Diospyros spp.) 54

Phragmites (Phragmites communis Trin.) :

Emersed and marginal weeds 57

On noncropland 52

Pickerelweed (Pontederia cordata L.) 57

Pigweed (Amaranthus spp.) :

In cotton 20

In forage crops 43, 44

In pastures 45

In small grains 31

In sugarcane 25
64 AGRICULTURE HANDBOOK 332, U.S. DEPT. OF AGRICULTURE

Page

Plantain (Plantago spp.) :

In lawns and turf 48

In small grains 31

Plantain, buckhorn {Plantago lanceolata L.) 48

Poison-ivy {Rhus radicans L.) 32, 37

Poison-oak (Rhus toxicodendron L.) 5

Pondweed (Potamogetón spp.) 58

Pondweed, curlyleaf (Potamogetón crispus L.) 59

Poplar (Populus spp.) 54

Prickly-ash (Zanthoxylum americanum Mill.) 46

Pricklypear (Opuntia spp.) 46

Princesplume (Polygonum orientale L.) 46

Puncturevine (Trihulus terrestris L.) 8

Purslane (Portulaca olerácea L.) 20, 48

Quackgrass (Agropyron repens (L.) Beauv.):

Emersed and marginal 57

In corn 18

In grass crops 32, 33, 44

In lawns and turf 48

In soybeans 23

On noncropland 51

Rabbitbrush (Chrysothamnus spp.) 45

Radish, wild (Raphanus raphanistrum L.) 31

Ragweed (Ambrosia spip.) ______ 31

Ragweed, common (Ambrosia artemisiifolia L.) :

In forage crops 43

In pastures 45

In small grains 31

Redbud (Cercis spp.) 54

Redstem (Anmania auriculata Wild.) 29

Reed, common (Phragmites communis Trin.) 57

Reeds (Phragmites spp,) 55

Retama (Parkinsonia aculeata L.) 46

Rice, red (Oryza sativa L.) 28

Rush (Juncus spp.) 33

Russian-thistle (Salsola kali (L.)) 8

Sagebrush, big (A rtemisia tridentata Nutt.) 45

Sagebrush, sand (Artemisia filifolia Torr.) 46

Sagittaria, dwarf (Sagittaria sublata (L.) Buchenau) 56

Saltcedar (Tamarix pentandra Pall.) 54

Salvinia (Salvinia rotundifolia Willd.) 57

Sandbur (Cenchrus spp.) 48

Sassafras (Sassafras spp.) 46, 54

Scotch-broom (Cytisus scoparius (L.) Link) 49

Sedge (Carex spp.) 28,33,52

Sedge, Nebraska (Carex nebraskensis Dewey) 52

Sedge, ripgut (Carex lacustris Willd.) 30, 57

Sesbania (Sesbania exáltala (Raf.) Cory):

In rice 28, 29

In soybeans 24

Shepherds-purse (Capsella bursa-pastoris (L.)

Medic.) 1,31

Smartweed (Polygonum spp.) :

Emersed and marginal weeds 57

In rice 29

In small grains 31

In sugarbeets 25

Sneezeweed (Helenium spp.) :

In forage crops 43, 44

In pastures 45

Sneezeweed, orange (western) (Helenium hoopesii

Gray) 46

Sorrel, red (Rumex acetosella L.) >. 48

Sowthistle (Sonchus spp.) 32

Spatterdock (Nuphar advena (Ait.) Ait. f.) 57

Page

Speedwell (Veronica spp.) 7

Spicebush (Lindera benzoin (L.) Blume) 46

Spikerush (Eleocharis spp.)

Emersed and marginal weeds 57

In rice 28, 29

Spirea, narrowleaf (Spiraea alba DuRoi) 46

Sprangletop (Leptochloa spp.) 29

Spurge, leafy (Euphorbia esula L.) 32

St. Johnswort (Hypericum perforatum L.) 49

Strawberry, wild (Fragaria spp.) _ 7

Sumac (Rhus spp.) 46

Sunflower (Helianthus spp.) 31

Sweetgum (Liquidambar styraciflua L.) 46

Sycamore (Platanus spp.) 46

Tansy-ragwort (Senecio jacobaea L.) 46

Tarweed (Madia spp.) :

In forage crops 44

In pastures 45

Tasajillo (Opuntia leptocaulis DC.) 46

Thistle, Canada (Cirsium arvense (L.) Scop.) :

Broadleaved perennials 32

In grass seed ñelds 44

In pastures 44, 45

Timothy (Phleum pratense L.) 48

Tree of heaven (Ailanthus altissima (Mill.) Swingle)- 46

Trumpetvine ( Campsis radicans (L.) Seem.) 54

Tules (Scirpus spp.). (See Bulrush.)

Umbrella-sedge (Cyperus difformis L.)___ 29, 30

Vetch, wild (Vicia spp.) 31

Violet (Viola spp.) 48

Walnut (Juglans spp.) 46

Waterchestnut (Trapa natans L.) 58

Watercress (Nasturtium officinale R. Br.) 55

Waterfern (Salvinia sp.) 57

Waterhemlock (Cicuta spp.) 46

Water-hyacinth (Eichhornia crassipes (Mart.)

Solnas.) :

Floating weeds 57

In rice 29

Waterhyssop (Bacopa caroliniana (Walt.) Robins.)-^ 29

Waterlettuce (Pistia stratiotes L.) 57

Waterlily (Nymphaea spp.) 55

Waterlily, white (Nymphaea tuberosa Paine) 57

Watermilfoil (Myriophyllum spp.; 58

Waterplantain (Alisma spp.):

In rice 29

Submersed weeds 59

Waterprimrose (Jussiaea spp.) :

Emersed and marginal weeds 57

In rice 29

Submersed weeds 58

Watershield (Brasenia schreberi Gmel.). 57

Water-stargrass (Heteranthera dubia (Jacq.)

MacM.) 58

Wildcelery (Vallisneria americana Michx.) 58, 59

Wildrye (Elymus spp.) 5

Willow (Salix spp.) :

Emersed and marginal weeds 55

On noncropland 54

On rangeland 46

Woodsorrel (Oxalis spp.) 48

Yellow-rocket (Barbarea vulgaris R. Br.) :

In clovers 44

In small grains 31

Yucca (Yucca spp.) 45

U.S. GOVERNMENT PRINTING OFFICE : 1967—0-25^763

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