STATUS OF SOME NEW HERBICIDES

U.S. Department of Agriculture

Forest Service

General Technical Report SO-21
SUMMARY

This paper reviews the past 15 years of research at Ale&ndria. Louisiana.

on 10 of the newer herbicides that are in use or show prom&e. Only formulations with relatively high activity are included.

The report is based on more than 60 studies, including soil. foliar. and injection applications. The outlook is good for effective substitutes for herbicides

now in use. and for new products that hiill control a broader array of species with

greater consistency.

I

lj herbicides are handled, applied, or disposed of improperly they may be

injurious to humans, domestic animals, desirable plants, andpollinating insects, 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.

The use of trade, firm, or corporation names in this publication is for the

information and convenience of the reader. Such use does not constitute an

oficial endorsement or approval by the U.S. Department of Agriculture of

any product or service to the exclusion of others which may be suitable.

I 1

1978
Status of Some New Herbicides

W E MANN, JR. AND M. J. HAYNES

Research to find more effective and less expensive

methods of controlling cull hardwoods has been conducted continuously over the past three decades at

Alexandria, Louisiana. Ammate in chopped cups,

2,4,5-T in frills, aerial spraying, and tree injection with

undiluted herbicides are some of the innovations originating from this work that have saved landowners millions of dollars in site preparation, release, and stand

improvement.

This paper summarizes the performance of 10 effective or promising herbicides that have been evaluated

over the past 15 years at Alexandria. The information

was obtained in about 60 studies, each of which tested

two or more formulations. In all, about 30 formulations

were evaluated, but many were ineffective or withdrawn by the manufacturer.

Only a few of the 10 herbicides are registered for

specific uses in forestry: others are registered for nonforestry purposes, and several have no registration or

only experimental registration. Data given here will aid

in improving current practices and perhaps even in obtaining registrations.

Herbicides were tested for efficacy when applied to

the foliage. to the soil, and injected into the base of

trees. Some (such as pellets) were suitable only for soil

application: most liquid formulations were tested by

tree injection and foliar spraying. Procedures that were

standard in tests are:

1. Tree injection incisions were made with a 1.75-

inch bit within 2 inches of groundline. Spacing between

incisions was measured from edge to edge.

2. Soil application co&isted of uniformly distributing

pellets, granules, or powders in a band 12 to 24 inches

wide about 12 inches from tree base.

3. Foliar sprays were appligd with backpack mist

blower or garden sprayer.

4. Topkills were estimated two growing seasons after

treatments were applied.

Herbicides are arranged alphabetically by common

or trade names. The manufacturers of herbicides mentioned in this paper are listed in Appendix A. Since

the text is restricted to highlights of the studies, detailed

results of some of the more important studies are given

in Appendix B. Publications emanating in whole or

part from these studies are listed in Appendix C.

Many trials were made with mixtures of herbicides,

of which only a few are mentioned. Also, about a

dozen studies were conducted that attempted to combine soil and foliar herbicides (usually applied about

30 days apart). None of these are reported, although

in several instances results obtained from application

of one of the herbicides applied alone as a check have

been used.

Throughout this paper the performance of herbicides is described in general terms like high or satisfactory, marginal, or unsatisfactory kills. Definitions for

these terms vary by method of application. Generally,

foliar sprays are satisfactory or effective if top defoliations are 75 percent or higher, marginal when between

60 and 74 percent, and unsatisfactory when below 60

percent. Criteria for kills with tree injection are slightly

higher.

W. F. Mann. Jr. is Chief Silviculturist and M. J. Haynes is Forestry Technician. USDA-Forest Service. Southern Forest Experiment Station.

Pineville. Louisiana.
Statistical tests were made in all comparisons, but

they are not reported. Emphasis has been placed on

overall efficacy rather than relative performance.

GLWHOSATE

Glyphosate is a new herbicide that shows considerable promise. It has been tested in two water-soluble

liquid formulations: (1) MON 2139, now registered as

Roundup, containing 3 pounds acid equivalent (ae)

per gallon with a surfactant, and (2) MON 0139 containing 4 pounds ae per gallon without the surfactant.

MON 2139 has experimental registration for foliar

spraying and tree injection of unwanted hardwoods

on forest sites.

Tree Injection

In 1973 both formulations were tested by tree injection with blackjack oak1 and sweetgum, 5 to 7 inches

d.b.h. A l-ml dose of undiluted herbicide was applied

in May in three incisions about 6 inches apart. Topkills were 97 and 100 percent for the two formulations,

an excellent result given the wide spacing of incisions.

The control, 24-D amine: gave only 80-percent control.

Glyphosate (MON 0139) was compared with Tordon 101 on blackjack oak and sweetgum. Trees were

injected with 2 ml of undiluted chemical in one and

two incisions in winter and spring. Trees were grouped

in two diameter classes-3.5 to 5.0 inches and 6.0 to

7.5 inches. Overall, glyphosate outperformed Tordon

101 and resulted in excellent kills with only four exceptions, three of which involved a single incision (Appendix B, table 1). A single injection of glyphosate was effective on all sizes of sweetgum in each season.

In another study, Glyphosate (MON 0139), Tordon

101, and Velpar were compared on sweetgum, blackjack oak, and hickory ranging from 5 to 9 inches d.b.h.

Treatments were applied in May using 1 ml per incision

with incisions spaced at 7-inch intervals. Glyphosate

gave excellent kills, except with hickory, and was better

overall than the other two herbicides (Appendix B,

table 2). A 1:l mixture of glyphosate and Tordon 101

gave higher kills than either herbicide alone, and was

fairly effective on hickory.

In another injection study (Appendix B, table 3), 2

ml of undiluted glyphosate (MON 0139) injected in

June with incisions 5 inches apart gave almost complete topkill of red and blackjack oaks. Glyphosate

‘Scientific names of species are given in Appendix D.

22.4-D is registered for control of broadleaf weeds and certain susceptible woody perennials on agricultural lands, rangelands and

pastures as well as such noncrop areas as rights-of-way. drainage

ditch banks and vacant lots.

(MON 0139) mixed with equal parts of 2.4-D amine

was superior to Tordon 101R and 2,4-D amine alone

on sweetgum (Appendix B, table 4).

Glyphosate is an excellent herbicide for injection.

More precise guidelines for use on upland species

and prescriptions for bottomland species are needed.

Mixtures of glyphosate and less costly herbicides

should also be investigated.

Foliar Spray

As a foliar spray, Glyphosate (MON 0139) was initially tested on 4-year-old sweetgum, red oak, and

green ash in a brush nursery. It was applied in May

with 3 pounds ae in 10 gallons of water per acre.

Topkills were satisfactory, except on red oak, and were

comparable to or better than results with 2 pounds of

2,4,5-F ester.

In a follow-up study in the brush nursery, 3 pounds

ae of glyphosate (MQN 0139) in 20 gallons of water

killed sweetgum, re&,ioak, and green ash more effectively than tebuthiuron (2 pounds active), 2,4,5-T (2

pounds active), or picloram (1 pound active)?

In the first field study, 2 pounds active of glyphosate

(MON 0139) were compared with 2 pounds of 2,4,5-T

ester, 2.54 pounds of Tordon 101, and 2.74 pounds of

Tordon 101R in 20 gallons of water per acre. Treatments were applied in late May to mixed brush on an

upland site. Topkills ranged from 73 to 79 percent for

all formulations except Tordon lOlR, which gave 65

percent control (Appendix B, table 5).

As a foliar spray glyphosate needs much more testing, particularly at different rates of application. Tests

of this herbicide should use the MON 2139 formulation because it has an experimental registration. A defoamer is needed with glyphosate, especially when it is

applied as a foliar spray.

KRENITE

Krenite is formulated as a liquid containing 4

pounds active ingredient (ai) per gallon that can be

mixed with water. It is registered as a foliar spray for

weed and brush control on industrial sites, tank farms,

rights-of-way, and drainage ditches, and is reportedly

safe to use around ponds and water supplies. The primay use of Krenite is to inhibit bud break in the spring.

To inhibit bud break unwanted plants are drenched in

the fall, 30 to 40 days before senescence. This method

32.4.5-T is registered for control of herbaceous and woody plants in

forests. on rights-of-way. and on rangelands and pastures.

‘Picloram is the active ingredient in Tordon 101. Tordon 101R. Tordon IOK. and Tordon 22K.

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is especially good in recreational or scenic areas because aesthetically objectionable brownout of foliage is

avoided. Fall-spray tests are underway, but results are

not yet available.

One study of Krenite applied by tree injection has

been completed (Appendix B, table 3) and another is

in its second year. When 4 ml of undiluted Krenite was

injected in June and incisions spaced 5 inches apart,

high kills of red and blackjack oaks 5 to 7 inches d.b.h.

were obtained. However, Tordon 101, glyphosate

(MON 0139), Velpar, and Garlon 3A (Dow M-3724)

were equally effective at only 2 ml per incision.

In a current study, Tordon 101, glyphosate (MON

0139), Velpar, and Garlon 3A (Dow M-3724) are being

compared. Red oak, blackjack oak, sweetgum, and

hickory were injected with 1 and 2 ml of undiluted

herbicide per incision as follows: trees 3 to 5 inches

d.b.h. received one incision, trees 6 to 8 inches two

incisions, and trees 9 to 11 inches three incisions. Firstyear results (which are not always reliable) indicate

Krenite performs satisfactorily on all but hickory and it

is as effective as the other formulations in the test, but

it is slower acting than most herbicides used for tree

injection. Available information seems to show that

Krenite has more promise in southern forestry when

injected than when sprayed.

TEBUTHIURON

Tebuthiuron was formulated in a variety of ways during its development, including small pellets containing

10, 20, 30, and 40 percent active ingredient, an 80.

percent wettable powder marketed under the trade

name Spike, and large (lo-gram) pellets containing

about 10. 20, and 30 percent active ingredient. Studies

have been conducted with most of the formulations.

Currently, only the 20.percent pellets and the 80.percent wettable powder are available. The wettable powder is registered for use around industrial sites, railway

roadbeds, and tank farms. The 20-percent pellets have

a permit for experimental use in controlling brush on

range lands. Granules in l- and 5-percent formulations are also registered for some industrial uses, but

we have not tested them.

Tebuthiuron has been tested in 17 studies, starting in

1973, most often by soil application alone or in combination with foliar sprays. Several studies were conducted with the wettable powder. Because of the major

changes in available formulations, only a few of the

more important studies are summarized here.

Broadcast

Tebuthiuron showed promise from the first study in

which it was included. Ten-percent ai pellets were compared with lo-percent bromacil (Hyvar X)5 pellets in

April when broadcast at 4, 8, and 12 pounds ai per

acre. The 4-pound rate of tebuthiuron controlled a

broad array of hardwoods (including oaks) well. The

two high rates gave almost complete control. In contrast, all rates of bromacil achieved only marginal control, ranging from 63 to 81 percent, and several

prevalent species were resistant (Appendix B, table 6).

When lo-percent pellets of tebuthiuron, Tordon

lOK, and Velpar were broadcast in April, on an upland

site, at 4 pounds per acre, tebuthiuron was most effective (Appendix B, table 7). Broadcast at 8 pounds per

acre. Velpar and tebuthiuron were effective, and both

were superior to Tordon 10K.

In another study, on an upland brushy site, tebuthiuron (lo-percent pellets) and Tordon 10K were compared by broadcasting 6, 8, and 10 pounds ai per

acre in March. Contrary to early findings, the 6-pound

rate of tebuthiuron waS unsatisfactory, although the

two higher rates were e#ective. Tordon 10K was effective at all rates.

Several other studies on upland sites showed that an

8-pound-per-acre rate of tebuthiuron is required for

satisfactory control. Some variation in effectiveness

probably was caused by differences in upland soils.

Lower dosages were effective on the sandier soils and

higher rates were needed on heavier. finer-textured

soils.

A study conducted on a bottomland site that compared tebuthiuron and Tordon 10K broadcast at 4 and

8 pounds (active) per acre showed Tordon 10K was

more effective at both rates, but only the g-pound rate

was satisfactory. Since the high rate of tebuthiuron

gave only a 68.percent kill, the minimum rate on these

sites should be at least 10 pounds per acre.

Tebuthiuron is a potent soil herbicide when broadcast, equal or superior to bromacil and Tordon 10K.

But because its persistence in the soil limits its utility,

no further broadcast studies are planned.

Banding

Tebuthiuron was also evaluated as lo- and 40.percent pellets. by banding individual trees on a sandy

loam soil in May. It was compared with Tordon lOK,

Velpar, and a combination of Tordon 10K and tebuthiuron at rates of 0.5 and 1.0 gram (active) per inch of

trunk diameter (Appendix B, table 8). Concentration of

tebuthiuron pellets had no important influence on kills.

The l-gram rates gave 93 and 97 percent control of

5Hyvar X. whose active ingredient is bromacil. is registered for use on

noncropland for nonselective weed and brush control and for selective control in certain crops.

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post oak, but only 35 and 50 percent control of

hickory.

Tebuthiuron does have merit for banding individual

trees. Banding trials should be conducted at rates from

1 to 3 grams of active material per inch of diameter.

Tree Injection

Tebuthiuron was also evaluated by tree injection in

three studies, but it was inferior to Tordon in all trials.

The liquid for injection was made by adding 0.5 and

1.0 pound ai of the 80-percent wettable powder to 1

gallon of water, but since the powder does not dissolve in the carrier, its lethal action may be limited.

TORDON 101

Tordon 101 is registered for application by injection

and when mixed with 2,4,5-T for foliar spraying. It has

been on the market for about 10 years. It is a liquid

containing 2 pounds ae of 2,4-D amine and 0.54

pound ae of picloram per gallon.

Tree Injection

Over the past 15 years, Tordon 101 has been included in 18 individual injection studies. Initially, it was

compared with 2,4-D amine, the standard chemical

used for tree injection when testing began. Several

comparisons of Tordon 101 and 2,4-D amine have

been made (Appendix B, tables 9 and 10). Later Tordon 101 was used as a standard for evaluating other

herbicides.

Tordon 101 has killed as much or more unwanted

vegetation as 2,4-D amine in all comparisons, regardless of season, species, or site. It is effective on species

that are difficult to kill with 2,4-D amine, including

sweetgum, hickory, swamp privet, ironwood, pecan,

and red maple. Tordon 101 is most effective when

applied in late summer and winter, unlike 2,4-D which

is most effective in spring and early summer.

Soon after Tordon 101’s effectiveness was demonstrated, tests were conducted to determine if oneincision doses of 4 to 5 ml would kill several prevalent oak species, 2 to 8 inches d.b.h. Single incisions

were not consistently satisfactory, although Tordon 101

again outperformed 2,4-D. Two incisions of 5 ml each

gave acceptable kills of oaks up to 7 inches d.b.h.

When comparing Tordon 101 and 2,4-D amine it

should be recognized that the acid equivalents are not

the same. Tordon 101 contains 2.54 pounds ae per

gallon, while 2,4-D has 4.0 pounds. However, Tordon

101 is about three times more costly than 2,4-D.

Since Tordon 101 is more viscous than many other

herbicides, the liquid flows slowly from the injector.

This may be a problem, especially in winter but it can

be circumvented by mixing the herbicide with equal

parts of water and increasing the dosage proportionately.

On upland sites, a l-ml dose of undiluted Tordon

101 in incisions spaced 5 inches apart is recommended in all seasons for trees 5 inches d.b.h. and

larger. For smaller trees, a l-ml dose in two incisions

is adequate. Local tests should be conducted to see if

a wider spacing of incisions can be used in the dormant season. On bottomland sites, 1 ml in incisions 3

inches apart is recommended.

Foliar Spray

We have not adequately tested Tordon 101 as a

foliar spray. In studies conducted in the brush nursery

with high-volume applications, it showed no superiority

over 2,4,5-T ester. In a field test with mixed species of

brush, it gave marginal kills comparable to those

achieved with 2,4,5-T Little emphasis was placed on

foliar-spray studies ‘$f Tordon 101 because early test

results showed it hadyno superiority over 2,4,5-T alone

and priority was giv& ,to a mixture of picloram and

2,4,5-T Newer, more promising foliar sprays that have

been tested in the last few years have shown this to be

a valid decision. .

TORDON 1OlR

Tordon lOlR, also a liquid, has about one-half the

concentration of each active ingredient as Tordon 101,

a total of 1.37 pounds ae per gallon. It is registered

for application by tree injection and frilling, but not as

a foliar spray. The manufacturer states it is ready to use

and gives no instructions for dilution. It is comparable

to Tordon 101 mixed 1:l with water, because it is less

viscous, and flows quickly from an injector.

Tree Injection

In the first test of this formulation, May injection of

1 ml of undiluted chemical with incisions 5 inches

apart resulted in 92 percent kill of red oaks 4 to 12

inches d.b.h. The same treatment with undiluted 2,4-D

amine gave 99 percent kill. Defoliation of sweetgum

with a l-ml dose in incisions at 3-inch intervals averaged 51 percent for Tordon 101R and 67 percent for

2,4-D amine. Apparently, the concentration of this material is too low for l-ml doses at wide spacing to be

effective.

Until additional information is available from several

studies that are underway, it seems advisable to rely on

experience with Tordon 101 and use a 2-ml dose at

5-inch intervals.

Foliar Spray

Only one foliar spray study of Tordon 1OlR has

been conducted. It compared 2.74 pounds ae or 2 gallons of Tordon 1OlR to 2 pounds ae of 2,4,5-T ester

per acre. Both herbicides were mixed with water and

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I

applied in May at a rate of 20 gallons per acre. Topkill

averaged 76 percent for 2,4,5-T and 65 percent for

Tordon 101R. In the same study, Tordon 101 applied

at 2.54 pounds per acre effected 75 percent topkill. It

appears that both Tordon formulations are about as

effective as the standard spray treatment with 2,4,5-T

ester, and they may be adequate substitutes for

2,4,5-T But they should not be used for pine release

because conifers are highly sensitive to picloram.

TORDON 155

This is a liquid, oil-soluble formulation containing

4.0 pounds ae of 2,4,5-T ester and 1.0 pound ae of

picloram per gallon. It is registered as a basal-bark and

dormant-season top spray. It has, however, been evaluated by tree injection and as a spring-applied foliar

spray.

Foliar Spray

The first foliar-spray test was started in 1964. A

locally mixed formulation of Tordon 155 was applied

in May at 2.5 pounds (0.5 gallon) per acre in a drench

spray to a stand of dense brush. A 2.0.pound-per-acre

spray of 2.4.5-T ester was used for comparison. Both

formulations used oil as the carrier and both were

about equally effective, killing over 85 percent of the

hardwoods.

In 1971; the manufacturer furnished several combinations of herbicides for test. A formulation equivalent

to Tordon 155 was sprayed on small, mixed brush at

2.5 pounds per acre in 10 gallons of oil and compared

to 4.0 pounds per acre of 2,4,5-T ester. Topkills averaged 74 and 72 percent, respectively. Tordon 155 excelled on red maple. 2.4.5-T was most effective on

dogwood. and they were equally effective on the other

species.

Included in the same trial was a mixture of 2,4.5-T

and picloram that was similar to Tordon 155. It had

4.0 pounds of 2.4.5-T ester and 0.75 pound of picloram per gallon. not quite as much picloram as a gallon

of Tordon 155. It was applied like the other formulations at a rate of 4.75 pounds per acre. Overall. topkills

from this formulation were slightly higher than from

4.0 pounds of 2.4.5-T ester alone (Appendix B. table

11).

Another study compared Tordon 155 and 2.4.5-T

ester as top sprays in January or foliar sprays in June

at rates of 3.0 and 6.0 pounds in 30 gallons of diesel

oil per acre. All treatments resulted in satisfactory topkills, ranging from 79 to 91 percent in winter and 87 to

94 percent in summer. Differences between the two

herbicides were small and unimportant in both seasons. The high rate of 2.4.5-T was no more effective

than the low one: doubling the rate of Tordon 155 increased topkills about 12 percentage points, which

hardly justifies the added cost (Appendix B. table 12).

Studies conducted so far indicate that as a foliar

spray, Tordon 155 may be slightly more effective than

2,4,5-T when total pounds of active ingredient are the

same, but the higher cost (about doubleI of Tordon..

155 and the need for oil in the mixture may easily

offset the small advantage Tordon 155 may have.

Tree Injection

Tordon 155 has been evaluated by tree injection in

three studies. In the first. the Tordon formulation was

mixed 1:l with oil and injected in red maple and sweetbay with 1 and 2 ml in incisions at l-, 3-, and 5-inch

intervals. (Mixing with oil in this ratio reduced the acid

equivalent from 5.0 to 2.5 pounds per gallon.) The

control, 2,4-D amine, was injected undiluted. Treatments were applied irrApril to trees 4 to 8 inches d.b.h.

Both herbicides gave &elIent kills of sweetbay, even

at the widest spacing ofihcisions. 2,4-D failed badly on

red maple, but Tordon 155 gave an 89.percent kill

even at the widest intervals. Adding a small amount of

picloram to 2,4,5-T (as well asto 2,4-D) seems to increase its activity on hard-to-kill species,

The next study compared Tordon 155 mixed 1:l

with oil to Tordon 101 and oil-soluble 2,4-D amine

(3 pounds se/gallon), on 4- to 8-inch blackjack oak,

post oak, and hickory. One-ml doses were applied in

one and two incisions per tree in May and December.

None of the May treatments were fully satisfactory.

Tordon 101 and Tordon 155 gave comparable kills

and both were better than 2.4-D. Winter applications

of both Tordon 155 and 2,4-D were far inferior to Tordon 101. which effected satisfactory topkills with two

incisions (Appendix B, table 10).

Finally, Tordon 155 and undiluted 2.4-D amine were

compared on blackjack and red oaks ranging from 5 to

7 inches d.b.h. Treatments were applied in May with

one incision per tree and dosages of 2, 3, and 5 ml.

No treatment gave satisfactory topkills (41 to 72 percent) and differences between herbicides were small.

When injected, Tordon 155 seems less effective than

Tordon 101. but slightly superior to 2.4-D amine.

TORDON 10K

Tordon 10K is a pelleted herbicide containing 11.6

percent picloram (or 10.0 percent ae) as the active ingredient. It is registered for use in forestry by banding

individual trees and broadcasting.

OCosts vary by manufacturer and quantities purchased. making come

parisons difficult.

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Banding

Tests of Tordon 10K as a soil herbicide were started

in 1962 by banding individual trees.,The control was

Hyvar X (as a wettable powder containing 80 percent

ai), the most effective soil herbicide at that time. Test

species were red and blackjack oaks on a sandy loam

soil, and sweetgum and ironwood on a silt loam soil.

4 to 9 inches d.b.h. Both herbicides were applied in

April at 0.25, 0.5, and 1 gram (active) per inch of

trunk diameter. Tordon was satisfactory on ironwood at

the two high rates and on sweetgum at all rates. Both

oaks were resistant to Tordon 10K. Hyvar X was effective on blackjack oak and sweetgum at the lowest rate,

but was unsatisfactory on the other two species at the

highest rate. Overall. both herbicides were about

equally effective.

Red oak, sweetgum, and ironwood from 4 to 12

inches d.b.h. were banded in March with the same two

herbicides at 1.0, 1.5, and 2.0 grams per inch of diameter. The site was a low terrace with a silty clay soil.

Kills, even at the 2-gram rate of Tordon. were very low

on all species. In contrast, Hyvar X gave satisfactory

kills of sweetgum and red oak at the 1.5.gram rate,

but was ineffective with ironwood at all rates.

A study installed in May (ordinarily too late for maximum effectiveness) compared Tordon 10K. tebuthiuron pellets. and Velpar 90 percent water-soluble powder at 05 and l-gram rates for each inch of trunk

diameter. Test species were post oak and hickory 4 to

10 inches d.b.h. Tordon 10K was unsatisfactory on

post oak and gave satisfactory kills of hickory only at

the l-gram rate. The other two herbicides were fully

effective on post oak at the high rate. This study suggested Tordon may be a good candidate to mix with

the other herbicides where hard-to-kill species like

hickory are prevalent. Late application may have been

a major factor in reducing Tordon’s control of oak.

In a final banding study, Tordon 10K and lo-percent

bromaci17 pellets were compared on post and blackjack

oaks 4 to 10 inches d.b.h. at 1 and 2 grams ai per inch

of trunk diameter. Treatments were applied in March,

April. May, and June. Tordon was unsatisfactory in all

months at both rates, but bromacil was acceptable except at the l-gram rate in June. The high resistance of

oaks to Tordon 10K was clearly demonstrated in this

study.

Banding is ideally suited for small tracts where hardwoods are 4 inches d.b.h. or larger, especially when the

landowner doesn’t want to inject trees. In such cases,

Tordon 10K is useful, especially on sandier soils. It

should be applied at a minimum of 1.5 grams per inch

7 Bromacil IS no longer avadable in pellet form

of trunk diameter: more for oaks or when treating

finer-textured soils. As with all soil herbicides, applications should be made in March or April when rainfall

is high. Hyvar X is an excellent soil herbicide, but powder is difficult to apply.

Broadcasting .

Tordon 10K was also tested for broadcasting, again

using 10 percent bromacil pellets for comparison. Both

herbicides were broadcast in March at rates of 2.5,5.0.

and 7.5 pounds per acre. Plots, located on a poorly

drained upland site, had dense stands of small brush.

Kills were marginal at the high rate, averaging 73 percent for Tordon 10K and 66 percent for bromacil.

In a study designed to determine effects of litter on

herbicide effectiveness, 2,4, and 10 pounds of Tordon

10K were broadcast in March on plots with mixed

brush 2 to 12 feet tall. The lo-pound rate gave 93

percent kill, corn&red to 73 and 56 percent for the

two lower rates, No &her herbicide was tested. Removal of litter did not im&ove defoliation at any rate.

Tordon 10K and 10 percent tebuthiuron pellets

were compared by broadcasting in March on a sandy

loam soil at 2, 4, and 6 pounds per acre. At the 4-

pound rate, Tordon 10K was satisfactory and more

effective than tebuthiuron. At the high rates, both herbicides were comparable. Unlike tebuthiuron, Tordon

gave marginal kills of resistant oak.

Tordon 10K and lo-percent tebuthiuron pellets

were also evaluated at 4- and 8-pound rates on a

creek-bottom site with small brush. Pellets were broadcast in May to avoid flooding. Kills averaged 89 percent for Tordon and 68 percent for tebuthiuron. Tordon was relatively ineffective on oaks, but was superior

on most other species. the best performance of Tordon

10K to that time.

In a comparison of Tordon 10K and tebuthiuron

pellets on an upland soil, pellets were broadcast in

March at 6. 8. and 10 pounds (active) per acre. Tordon

was satisfactory at all rates, as was tebuthiuron at the

two higher rates (Appendix B. table 13). A 1:l mix of

the two herbicides was as effective as Tordon alone.

More recently, Tordon 10K. tebuthiuron. and Velpar

pellets, all with 10 percent active material, were compared by broadcasting in April at 4 and 8 pounds per

acre. The site had a sandy loam soil and dense hardwoods. Tordon ranked third in effectiveness at both

rates: tebuthiuron gave the highest kills (Appendix B,

table 7).

Tordon 10K is an effective soil herbicide when

broadcast at 10 pounds (active) per acre. Like other

soil herbicides. it should be applied in late winter or

early spring when rains occur regularly. Why Tordon

outperformed tebuthiuron in some studies and not in

6
others is unclear; it may have been due partly to the

prevalence of oaks. which are resistant to Tordon. Resistance of oaks is a major disadvantage of this herbi

tide. Its greatest value may be in mixing with other

herbicides that are lethal to oaks.

TORDON 5K

This is a new. pelleted formulation that has about

half as much picloram (the active ingredient) as Tar

don 10K. The added weight is a decided drawback

when broadcasting. If 10 pounds ai per acre is to be

broadcast, 200 pounds of material must be distributed.

But one potential advantage is rapid infiltration into

the soil.

Tordon 5K and 10K have been compared in only

one study. They were broadcast in May on an upland

soil at a 6-pound rate. Topkills were 55 and 75 percent

for the 5K and 10K formulations.

Additional studies are planned with Tordon 5K. but

primarily as a banding treatment where weight is less

critical than with broadcasting.

TRICLOPYR

Triclopyr. a relatively new herbicide, was initially

made available for preliminary research in two formu

lations; M-3724. a water-soluble amine containing 3

pounds ae_ per gallon, and M-4021. an oil-soluble.

water-emulsifiable ester containing 4 pounds ae per

gallon, The amine formulation is now registered for

foliar spraying and carries the trademark Garlon 3A

Herbicide.

In our studies, the amine formulation has been used

for tree injection and the ester formulation for foliar

spraying, the same pattern that was followed with the

phenoxy herbicides (2.4-D amine and 2.4.5-T ester).

Foliar Spray

Garlon 3A Herbicide was initially evaluated as a foliar spray in the hardwood brush nursery at 2 pounds

ae in 20 gallons of water per acre. Trees were sprayed

in May, Topkills of red oak were unacceptable and

were marginal for sycamore and green ash. They were.

however. comparable to those from 2 pounds per acre

of 2,4,5-T ester.

As part of an evaluation of combined soil and foliar

applications, Garlon 3A was sprayed on mixed brush in

June at 1.5 pounds in 10 gallons of water per acre.

Defoliation with Garlon 3A alone averaged 60 percent.

which was promising, given the low concentration of

the spray.

Triclopyr in its ester formulation (containing 4

pounds ae per gallon) was also appraised as a foliar

spray on mixed brush. A rate of 2 pounds in 20 gallons of water per acre applied in May gave 79 percent

topkill, comparable to that from 2 pounds of 2,4,5-T

ester used as a check. When triclopyr (M-4021) was

mixed 1:l with 2,4,5-T ester (total 2 pounds active) or

Tordon 101 (total 2.27 pounds active), defoliations

were as high as with triclopyr alone (Appendix B, table

8).

Triclopyr (M-4021) was compared with 2,4,5-T estef

as a foliar spray in January and June at 3 and 6

pounds in 30 gallons of oil per acre. Topkills from

winter applications were excellent at both rates, and exceeded 2,4,5-T by 8 to 11 percentage points. Results

from summer treatment were similar for both herbicides at the 3-pound rate. but triclopyr was more effective at the high rate (Appendix B, table 12).

Tree Injection

Triclopy-r has not only shown promise as a foliar

spray. but has given high kills when injected. A 2-ml

dose of undiluted Garl& 3A (M-3724) applied in June

with incisions 5 inches &art gave complete topkills of

red and blackjack oaks. IJndiluted Tordon 101, glyphosate. and Velpar at the same dosage were also

highly effective (Appendix B, table 3).

In a follow-up study, a l-ml dose of a 1:l mixture of

undiluted Garlon 3A and 2,4-D amine (total 3.5 pounds

active) injected in May gave perfect kills of red oak with

incisions 5 inches apart and 95 percent kill of sweetgum with incisions 3 inches apart. Tordon 1OlR and

2,4-D amine were about equally effective in l-ml doses

on red oak, and less effective on sweetgum, a species

resistant to tree injection (Appendix B. table 4). Garlon

3A shows exceptional promise for application by tree

injection.

Undiluted Garlon 3A is included in a comprehensive

injection study still underway with red oak, blackjack

oak. sweetgum, and hickory. Doses were. applied in

July at 1 and 2 ml of undiluted material per incision.

Number of incisions varied with tree size: hardwoods

3 to 5 inches d.b.h. have one incision, trees 6 to 8

inches have two incisions, and trees 9 to 11 inches

have three incisions. At the end of the first growing

season, Garlon 3A and Tordon 101 both gave high

kills of all species. Both triclophyr formulations show

enough promise to merit additional research by tree

injection and foliar spraying.

VELPAR

Tests have been conducted with hexazinone (the

trade name of which is Velpar) formulated as a 90.

percent ai water-soluble powder. 10 and 15 percent ai

pellets, and a liquid containing 2 pounds ai per gallon.

Only the powder is registered. and it is limited to spraying around industrial sites, rights-of-way, tank farms

7
and for weeding in Christmas tree and established

conifer plantations.

Banding

In its initial evaluation, the 90.percent, water-soluble

powder was compared to Tordon lOK, tebuthiuron,

and a 1:l mixture of Tordon 10K and tebuthiuron. In

May, 4- to lo-inch d.b.h. post oak and hickory trees on

a sandy loam soil were banded at rates of 0.5 and 1.0

gram ai per inch of tree diameter. Both rates of Velpar

were effective on post oak, but gave low kills of hickory

(Appendix B, table 8). No formulation was as effective

as Velpar on post oak only the high rate of Tordon 10K

alone or the Tordon-tebuthiuron mixture controlled

hickory satisfactorily.

In a banding study on a sandy loam soil, Velpar applied in May at 1 gram active per inch of trunk diameter gave excellent results with blackjack oak but

marginal results with red oak. Tebuthiuron and bromacil in the same study were as effective as Velpar on

blackjack oak but unsatisfactory on red oak. Low kills

overall were attributed to late applications.

Velpar appears to be an excellent herbicide for banding hardwoods. Ten-percent pellets are available for

trials, and studies should be conducted using rates

higher than 1 gram per inch of diameter.

Broadcasting

Broadcasting Velpar pellets has also given encouraging results. In a comparison of 10 percent pellets of

Velpar, tebuthiuron, and Tordon 10K applied in April

on an upland site at 4 and 8 pounds ai per acre,

tebuthiuron was most effective at both rates and Velpar

ranked second (Appendix B, table 7). Both herbicides

controlled hardwoods satisfactorily, while Tordon 10K

gave marginal kills.

Additional studies of soil-applied Velpar are needed

on upland and bottomland sites to determine optimum

rates and the minimum interval that must elapse between application and planting. Currently available

data indicate Velpar does not persist in the soil long

enough to affect planting survival when used for site

preparation. Moreover, it controls herbaceous vegetation as well as woody plants.

Tree Injection

Velpar was evaluated for tree injection as the 90.

percent powder before the liquid formulation became

available. Four pounds (active) per gallon were mixed

in water and injected in May at 1 ml in incisions 7

inches apart. Study trees were sweetgum, blackjack

oak, and hickoy, 5 to 9 inches d.b.h. Topkills were

excellent with oak, intermediate with sweetgum, and

very low with hickory. Undiluted Tordon 101 and glyphosate (MON 0139) were more effective than Velpar,

especially on hickory (Appendix B, table 2). Spacing of

incisions was wide, however, a severe test that probably

contributed to the relatively low kills from all herbicides.

When the liquid formulation of Velpar (DPX-3674-L)

became available it was compared with five other herbicides applied in June on red and blackjack oaks, 5 to

7 inches d.b.h. (Appendix B, table 3). All formulations

effected high kills, except tebuthiuron. which was in

wettable powder form.

A 1:l mixture of Velpar and 2,4-D amine outperformed 2,4-D alone and Tordon 1OlR on sweetgum

and did as well on red oak (Appendix B, table 4).

Several other herbicide mixtures in the study gave

kills of red oak in excess of 90 percent. On sweetgum,

a resistant species, glyphosate (MON 0139), Velpar,

tebuthiuron, and triclopyr (Garlon 3A) each mixed 1:l

by volume with 2,4-D amine gave satisfactory kills.

Liquid Velpar is an excellent candidate for tree injection. Its major drawback is ineffectiveness on hickory. Studies are uQderway to determine optimum

dosages and incisioitt.spacing for upland and bottomland species.

Evaluations of Velpar for foliar spraying are not completed because the liquid fo_rmulation for such studies

only became available during the last year. However,

we intend to give high priority to foliar-spray studies.

DISCUSSION

Herbicides play a key role in managing pines and

hardwoods in the South. As mechanical site preparation declines and more owners of small tracts intensify

management practices, herbicides will probably grow in

importance. The time is critical. Herbicides and other

pesticides are under careful scrutiny for their impact

on the environment and all of its living organisms.

The cost of developing, testing, and registering a

new herbicide cannot be justified by forestry use alone.

Ordinarily, most new formulations tested in our research have large anticipated or actual agricultural or

other nonforesty uses. This means the basic toxological evaluations are completed, so registration for forestry is relatively easy after data on efficacy are

obtained, provided there are no unique environmental

problems and the manufacturer judges forestry use

will be profitable.

Forest managers are now in a fairly good position

regarding tree injection and site preparation. Substitute

herbicides are available in the event one is withdrawn

from the market. A substitute for 2,4,5-T or Silvex for

pine release is needed, but there are new herbicides

being tested that seem likely to be adequate.

Certainly new herbicides will be more costly than

the phenoxy compounds in wide use today. This

should not be an obstacle to conducting research. We

8
can often expect greater efficiency for the higher price,

and nonchemical alternatives to phenoxy herbicides

are also very expensive.

2,4.5-T and Silvex! both primarily used as foliar

sprays, are being examined by environmental officials.

If they are banned, Tordon 101 may be used for site

preparation: it is too toxic to pines for release application. Garlon 3A, triclopyr (M-4021), glyphosate, and

possibly Velpar will be suitable for foliar spray once

they are registered. Tests of these herbicides should

be intensified to support any applications the manufacturers may submit.

2.4-D. like 2.4,5-T and Silvex, is a phenoxy herbicide,

but it has not been suspected of containing a dangerous contaminant. A few years ago. it was the primary

herbicide for tree injection. Recently, however, many

landowners switched to Tordon 101 and Tordon lOlR,

both highly effective on a broad array of species. including those resistant to 2,4-D. Krenite. Velpar, glyphosate. and Garlon 3A also seem to be good candidates for tree injection. and will be given priority in

future studies.

“Silvex IS currently registered for use in forests for control of woody.

herbaceous and aquatic plants. It is also registered for use on industrial sites. rights-of-way. in ponds. farmyards. pastures. rangeland.

and in rice and sugar cane.

Soil herbicides are not used extensively in southern

forestry because most products are expensive and their

effectiveness is closely related to soil properties. Moreover, they must be applied in early spring when rainfall is high and trees are growing actively. Tordon 10K

is effective on many hardwood species (excluding

oaks) and dissipates fast enough for use in site preearation. Many of the other soil herbicides tested have

persistence problems. Velpar is an exception: preliminary data indicate pines can be planted in the first

winter after its application. It has an added advantage

in that it kills many herbaceous plants that compete

with pines in the first few years.

Applying soil herbicides in bands around individual

trees shows promise, theoretically. Our tests have probably been too conservative: higher rates of application

are needed for greater consistency.

Mixtures of herbicides to control a broader array of

unwanted trees is an @portant approach to the hardwood problem that car&ot be overlooked. Testing mixtures must be given high’priority, even though it greatly

expands the research workload, because early results

have shown great potential benefits.

The prospect for more effective herbicides is good.

Development of new formulations should be accelerated and registration should be coordinated more

closely among manufacturers, researchers, and users.
APPENDIX A

Manufacturers Furnishing Mentioned Herbicides

Glyphosate

Hyvar X (Bromacil)

Krenite

Tebuthiuron

Tordon 101

Tordon 1OlR

Tordon 10K

Tordon 5K

Tordon 155

Triclopyr or Garlon 3A Herbicide

2,4-D and 2,4,5-T

Monsanto Company

E. I. DuPont DeNemours & Co.

E. I. DuPont DeNemours & Co.

Elanco Products Company

Dow Chemical Company

Dow Chemical Company

Dow Chemical Company

Dow Chemical Company

Dow Chemical Company

Dow Chemical Company

Experimental samples obtained

from a number of companies

Velpar E. I. DuPont DeNemours & Co.

10
APPENDIX B

Tables

Table l.- Topkill of blackjack oak and sweetgum lvhen injected with 2 ml of undiluted Tordon 101 and

glyphosate in two seasons

Herbicide Active material

per gallon

Pounds

Incisions

per tree

Number

Tordon 101

Glyphosate

(MON 01.19)

1

7

2.54 1

2

1

2

4.0 1

2

Tree

size

D.b.h.

x.5-5.0

355.0

6.0-7.5

6.0-7.5

41 40 87 35

64 x5 9% 90

12 34 47 25

31 57 73 42

55 92 100 100

89 99 100 100

45 61 94 98

6.0-7.5 69 94 97 100

x.5-5.0

3.5-5.0

6.0-7.5

Table 2.-Topkill of three common hardwoods when injected in

May with 1 ml of undiluted herbicide in incisions 7 inches

llpllti

Active Species

Herbicide material Blackjack

per gallon Sweetgum oak Hickory

Tordon 101 2.54 79 97 76

Glyphosate

(MON 0139) 4.0 100 99 63

Velpar 4.0 73 97 6

1:l mix of

Tordon 101

and

glyphosate 1.27+2.0 100 98 82

11
Table 3. - Topkill of two oak species 5 to 7 inches d.b.h. injected undiluted at 5.inch intervals in June

Herbicide Active material Dose per

per qallon incision

Topkill

Red oak Blackiack oak

Pounds MI . . . . . . percent.

Tordon 101 2.54 2 100 98

Glyphosate (MON 0139) 4.0 2 100 98

Krenite 4.0 4 89 99

Velpar (DPX-3674-L) 2.0 2 100 99

Triclopyr (Garlon 3A) 3.0 2 99 100

Tebuthiuron (80% WP) 3.0 4 86 90

Table 4. - Topkill of red oak and sweetgum 4 to 12 inches d.b.h. injected with 1 ml per incision in May with

several herbicides and mixtures

Species and

herbicide

Active material

per gallon

Pounds

Spacing of

--’ incisions

._, Inches

Topkill

Percent

Red oak

2,4-D amine

Tordon 1OlR

1:l mix of triclopyr (Garlon 3A) and 2,4-D amine

1:l mix of Velpar DPX-3674-L and 2,4-D amine

1:l mix of tebuthiuron and 2,4-D amine

1:l mix of glyphosate (M-0139) and 2,4-D amine

-4

4.0 5 99

1.37 5 92

1.5+2.0 5 - 100

1.0+2.0 5 100

1.5+2.0 5 97

2.0+2.0 5 100

Sweetgum

2,4-D amine

Tordon 1OlR

1:l mix of triclopyr (Garlon 3A) and 2,4-D amine

1:l mix of Velpar DPX-3674-L and and 2,4-D amine

1:i mix of tebuthiuron and 2,4-D amine

1:l mix of glyphosate (M-0139) and 2,4-D amine

4.0 3 67

1.37 3 51

1.5+2.0 3 95

1.0+2.0 3 89

1.5+2.0 3 94

2.0+2.0 3 91

Table 5. - Topkill of small hardwoods by foliar spraying nine herbicides and mtiures applied in water at ZOgallons per acre

in May

Herbicide

Active material

per acre

Pounds

Average

topkill

Percent

2,4,5-T ester

Triclopyr M-4021

Tordon 101

Tordon 1OlR

Glyphosate (0139)

1:l mix of 2,4,5-T ester +

triclopyr (M-4021 1

1:l mix of 2,4,5.T ester +

Tordon 1OlR

1:l mix of 2,4,5-T ester +

glyphosate (0139)

1:l mix of triclopyr (M-4021) +

Tordon 101

2.0 76

2.0 79

2.54 75

2.74 65

2.0 73

1.0+1.0

1.0+1.37

1.0+1.0 62

l.O+ 1.27

75

78

78

12
Table 6 .-Comparison of pelleted tebuthiuron and bromacil when broadcast in April at three rates on an

upland site

Herbicide and rates’ Post Blackjack

oak oak

Topkill

Sumac Tree Dogwood All

sparklebery species

Tebuthiuron

4 pounds

8 pounds

12 pounds

..~~ . . . ~.~ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . percent . . . . . . . . . . . . . . . . .

99 Xl 98 _ 100 91

_ 98 100 100 100 98

100 100 100 - 100 99

Bromacil

4 pounds

8 pounds

12 nounds

99 76 36 10 100 81

96 7.5 50 6 100 63

100 100 43 9 100 77

‘Pellets contained 10 percent active material: rates based on active material per acre

Table 7.- Topkill of mtxed hardwoods by broadcasting firdon IOK,

tebuthiuron. and Velpar pellets’ on an upland soil a&two

rates in April L’

Herbicide

Tookill ‘.‘,

4 pounds 8 pounds

Tebuthiuron

Tordon 10K

Velnar

. . . percent

91 96

70 78

83 92

‘All pellets contained 10 percent active material: rates are active

material per acre.

Table 8.- Topkill of post oak and hickory when four soil herbicides

were applied in bands in May

Herbicide

Active Rate per

material inch

per pound of d.b.h.’

Topkill

Post oak Hickorv

Tordon lOK10% pellets

Tebuthiuron -

10% pellets

Tebuthiuron -

40% pellets

Velpar -

90% powder

Percent Grams percent .._...

10 0.5 27

1.0 30

10 0.5 45

1.0 97

79

90

15

35

40 0.5 66

1.0 93

90

30

50

0.5

1.0

91

100

12

42

1: 1 mix of Tordon

10K and 10%

tebuthiuron

pellets 10 0.5 11 33

1.0 11 87

‘Active material

13
Table 9. -Selected comparisons of undiluted 2.4-D amine and Tordon 101 for controlling hardwoods 5 to 9

inches d.b.h. by tree injectron

Herbicide

2.4-D amine

Tordon 101 2.54

2.4-D amine 4 0

Tordon 101 2.54

2.4~D amine 4.0

Tordon 101 2.54

2,4-D amine 4.0

Tordon 101 2.54

2.4-D amine

Tordon 101

Concen~

tration

(a.e.!‘gal.)

Lb.

4.0

4.0

2.54

Dosage/

incisron

Spacing

of

incisions

Season

applied

Inches

7

7

9

7

7

Two

incisions

One

incision

Two

incisions

One

Incision

Two

incisions

Two

incisions

MI.

1

2

1

2

1

2

1

2

1

1

1

0.5

0.5

2

4

2

4

1

1

Winter

Winter

Winter

Winter

Winter

Winter

Winter

Winter

Winter

Winter

Winter

Spring

Spring

x? _

90

66

X8

.

42

33

18

51

100 92

98 _ 100

99 _ 100

100 _ 96

54 46 0

97 100

95 --’ 90

94

97

74 :i, 38

92 Xl

Summer

Summer

99 Y _

74

Summer

Summer

100

88

Summer 70 11 42

Summer 100 74 54

Topkill

Oak Sweetaum

Percent----

Hickow

14
Table 10. - Topkill of three common upland hardwoods injected with 1 ml of undiluted 2,4-D amine, Tordon 101, and diluted Tordon 155 in May and December

Season and

herbicide

May injection

2.4-D amine’

Tordon 101 2.54

Tordon 1552 2.5

December injection

2.4-D amine’

Tordon 101 2.54

Tordon 1552 2.5

Active material

per gallon

Lb.

3.0

3.0

Incisions Post oak Blackjack

oak Hicko y

Number . . . . . . percent.

1 28 37 21

2 49 44 45

1 28 45 35

2 76 82 70

1 23 16 71

2 75 57 76

1 11 31 18

2 45 49 34

1 78 --’ 64 66

2 87 ri 93 97

3.

1 10 ‘24 61

2 26 66 90

‘Oil~soluble formulation that has been as effective as water-soluble 2,4-D amine with 4 pouvds (ae) per

gallon.

Gordon 155 diluted 1:l with oil to reduce active ingredient per gallon.

Table 11. - Topkill of six preualent brush specres when sprayed in May with 2,4,STester, Tordon 15.5, and CI

mixture similar to Tordon 155 wrth 10 gallons of oil per acre

Herbicide Rate per

acre (ae)

Pounds

Blackjack Sweet- Black- Huckle- Dog Red

oak gum gum berry wood maple Avg.

. .._....... ~.~ . . ~~~~ percent ~.~~ ~.~ . ~~~.~ ~.

2,4.5-T ester

Tordon 155

Formulation

similar to

Tordon 155

4.0 50 97 93 55 91 60 74

2.5 48 99 93 45 67 78 72

4.75 76 100 99 74 90 76 86

15
Table 12. - Topkill of mixed hardwood brush with three herbicides

applied at hue rates in winter and summer using 30 gallons of oil per acre

Season and herbicide Active material

ner acre

Topkill

Pounds Percent

January

2,4,5-T ester 3.0 a4

6.0 85

Triclopyr (M-4021 ) 3.0 92

6.0 96

Tordon 155 3.0 79

6.0 91

2,4,5-T ester 3.0 87

6.0 37

Triclopyr (M-4021) 3.0 89:

6.0 98”

Tordon 155 3.0 83

6.0 94

.

Table 13. - Topkill of mixed, small hardwoods by broadcasting pellets of Tot-don IOK, tebuthiuron, and an equal mkture of

the two at three rates on an upland soil

Herbicides Active Pounds (ai) per acre

ingredient 6 8 10

_._._..__..__._._....... percent .__.__.___...__.........

Tordon 10K 10 86 95 92

Tebuthiuron

1:l mix of Tordon 10K

and tebuthiuron

10 66 91 89

10 83 94 94

16
APPENDIX C

Publications Emanating from Herbicide Studies

in Alexandria, Louisiana

Brady. Homer A.

1969. Herbicide mixtures promising for hardwood control by foliar

spraying. Proc. South. Weed Sci. Sot. 22: 245-250.

1971. Initial defoliation as predictor of topkill in brush-control

spraying. Proc. South. Weed Sci. Sot. 24:246-250.

- -

1971. Other brush-control sprays compared to 2.4.5.Tester. Proc.

South. Weed Sci. Sot. 24: 251-254.

-. Fred A. Peecy. and Paul Y Burns.

1969. Erratic results from aerial spraying of midsouth hardwoods.

J. For. 67: 393-396.

Fitzgerald. Charles H.. Fred A. Peecy. and Datin E. Fender.

1973 The Southern Region. J. For. 71: 148-153.

McLemore. B. F.

1977. Control of hardwoods with chemicals In Proc. Site Prep.

Workshop (West). Alexandria. La.. April 27. 28. 1977. p. 11-15.

1977. Controlling hardwood brush with soil-applied herbicides.

Proc. South. Weed Sci. Sot. 30: 256-259.

Peevy. Fred A.

1969. Control of woody plants erratic with soil herbicides. Proc.

South. Weed Sci. Sot. 22: 257-259.

1969. Several herbicides and mixtures show promise for injection

of cull hardwoods. Proc. South. Weed Sci. Sot. 22: 251-256.

-.

1970. Banding soil herbicides not promising for hardwood con

trol. Proc. South. Weed Sci. Sot. 23: 225-229.

-.

1970. Site effect on herbicidal efficiency. Proc. South. Weed Sci. Sot.

23: 237-240.

1971. Application date and dosage influence kill of hardwoods by

soil application of bromacil. fenuron. and picloram. Proc. South.

Weed Sci. Sot. 24: 271-273.

-. ._

1971. Wide-spaced inject+ of herbicidal mixtures for controlling

weed trees. Proc. South.@zed Sci. Sot. 24: 263-267.

-.

1972. How to kill hardwoods by injection. Weeds Today. 8-9. 17.

Winter.

.

-.

1972. injection treatments for controlling resistant hardwood species. Proc. South. Weed Sci. Sot. 25.252-256.

1972. Injection treatments for killing bottomland hardwoods.

Weed Sci. 20: 566-568.

-.

1973. Bromacil and picloram under southern upland hardwoods.

Weed Sci. 21: 54-56.

1975. Soil-applied herbicides for upland hardwoods. Proc. South.

Weed Sci. Sot. 28: 223-225.

-.

1975. Timber stand improvement-tree injection and pellets. In

Herbicides in Forestry. p. 85~92. Proc. John S. Wright For. Conf..

Purdue Univ.

-.

1976. Additives to herbicides failed to improve crown kill of injected hardwoods. Proc. South. Weed Sci. Sot. 29: 295-298.

1976. Injected oil- and water-soluble herbicides give similar kills.

Proc. South. Weed Sci. Sot. 29: 291-294.

~. and H. A. Brady.

1972. Role of herbicides in southern forestry. Proc. 1972 Nat.

Conv.. Sot. Am. For.. p. 102-107.

17
APPENDIX D

Common and Scientific Names of Listed Species

Common name

Blackgum

Blackjack oak

Dogwood

Green ash

Hickory

Huckleberry

Ironwood

Pecan

Post oak

Red maple

Red oak

Sumac

Swamp privet

Sweetbay

Sweetgum

Sycamore

Tree sparkleberry

Scientific name

Nyssa sylvatica Marsh. _ i,

Quercus marilandica Muen&%..

Cornus florida L.

Fraxinus pennsylvanica Marsh. ..

Carya sp.

Vaccinium sp.

Osty virginiana (Mill.) K. Koch

Caya illinoensis (Wangenh.) K. Koch

Quet-cus stellata Wangenh.

Acer rubrum L.

Quercus falcata

Rhus sp.

Ligustrum sp.

Magnolia virginiana L.

Liquidambar styraciflua L.

Platanus occiden talis L.

Vaccinium arboreum Marsh.

18
Mann, W. F., Jr. and M. J. Haynes.

1978. Status of some new herbicides. U.S. Dep. Agric. For. Serv.

Gen. Tech. Rep. SO-21, 18 p. South. For. Exp. Stn., New Orleans, La.

Summarizes 15 years of research on 10 herbicides that are now in

use or show promise. The report is based on more than 60 studies,

including soil, foliar, and injection applications.

Additional keywords: Hardwood control, tree injection, foliar spraying, soil application, banding herbicides, site preparation, release,

weeding, stand improvement.

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402

Stock No. 001-001-00448-1

* - U. S. Government Printing Office: 1979-m-672-223