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Publication #FOR310

Herbicides for Weed Control in Eucalyptus Culture1

Anna Osiecka and Patrick Minogue2

Introduction

Eucalyptus is a diverse genus with over 700 species, most of which are native to Australia. Numerous Eucalyptus species and hybrid clones have been introduced in temperate climates throughout the world and grown as ornamental trees as well as for fuel and fiber. There is renewed interest in planting this fast-growing tree in the southeastern United States for mulch, pulpwood, and bio-energy. However, several silvicultural challenges exist, and competing vegetation control is a significant one.

Young Eucalyptus trees are very sensitive to the adverse effects of plant competition, especially in the initial months after planting. The photographs below illustrate the effect of weed competition on the growth of Eucalyptus urograndis five months after an April planting of six-week-old rooted cuttings in Quincy, Florida.

Figure 1. 

When grown without weed control, Eucalyptus urograndis is approximately two feet tall at five and a half months after planting in a study at Quincy, Florida.


Credit:

Anna Osiecka, University of Florida


[Click thumbnail to enlarge.]

Figure 2. 

In the same Quincy study, E. urograndis grown with near complete weed control is nine to ten feet tall at the same age.


Credit:

Anna Osiecka, University of Florida


[Click thumbnail to enlarge.]

Currently, directed applications of the herbicide glyphosate are widely used, but this herbicide is non-selective and requires very careful application and shielding of trees in order to avoid injuring or killing Eucalyptus plantings. Because glyphosate does not provide residual weed control, frequent repeated applications are necessary, resulting in significant costs to growers. Development of weed resistance is also an issue with repeated applications of the same herbicide.

This publication provides a list of herbicides with different active ingredients labeled for weed control in Eucalyptus plantings for various use sites (plantations, ornamentals, etc.) as described by herbicide labels (Tables 1 and 2). It gives examples of products for each active ingredient, but it is not meant to be all-inclusive. Inclusion of a product trade name in this publication does not constitute an endorsement of a product or a company because other products manufactured by different companies might be equally suited for the intended use. It must be noted, however, that two herbicides with the same active ingredient can have very different labels and use patterns. For example, Alligare SFM 75 is labeled for Eucalyptus (supplemental labeling), while DuPont Oust® XP is not, even though both contain 75% sulfometuron methyl active ingredient. It is essential that the herbicide you choose is specifically labeled for Eucalyptus culture in Florida (personal communication, Charlie Clarke, Florida Department of Pesticide Registration, November 30, 2009).

Guide Information

This publication is a general guide and is not intended to provide specific treatment recommendations. The user must always read and follow the label instructions for a specific product being used. Herbicide labels are accessible at CDMS (all accessed December 5, 2012). Failure to follow the directions for use and precautions on the labels may result in poor weed control or tree injury and may be a violation of the law. The effectiveness and safety of the use of a particular herbicide in a given situation greatly depends on many factors (Osiecka and Minogue, 2011) including the Eucalyptus species, stage of growth and weeds to be controlled. If repeated applications are needed, the maximum use rate per year and the minimum interval between applications must be observed.

Table 1. Herbicide Listing by Active Ingredient, Trade Name, and Use

Table 1 lists the active ingredients, trade names and manufacturers for various herbicides labeled for Eucalyptus culture and the ranges of labeled application rates for different uses, including site preparation prior to planting, herbaceous weed control (HWC) as a directed spray (applied directly to target weeds without contacting Eucalyptus), or HWC over-the-top (OTT) of Eucalyptus using a selective herbicide to which the species is tolerant. The appropriate herbicide application rate depends on crop-tree tolerance to the herbicide and the weed species present, their stage of growth, and density. Soil characteristics such as texture and acidity (pH) are important in determining the appropriate selective herbicide rate for those herbicides absorbed by plants from the soil (soil-active herbicides). It is always advisable to use the lowest rate that will provide an acceptable level of weed control for a specific situation.

All glyphosate products are non-selective and can be applied either for site preparation prior to planting or as a carefully directed spray to weeds after planting. Unlike other products labeled for Eucalyptus culture, glyphosate is effective in controlling established weeds, but it provides no residual control. Pre-emergent herbicides such as sulfometuron methyl may be mixed with glyphosate to provide residual weed control. However, herbicides with residual soil activity must be used according to the labeled herbicide rate and application frequency restrictions to avoid Eucalyptus injury from root uptake.

Only herbicides with physiological selectivity can be applied over-the-top of Eucalyptus trees, and their application must be carefully calibrated to ensure that the precise amount of active ingredient per acre is applied. Healthy trees, free of stress from transplanting or drought are most tolerant to over-the-top herbicides. Generally, it is advisable to wait two weeks after planting seedlings or rooted cuttings so that trees recover from the stress of transplanting before applying herbicides over-the-top. Selectivity is enhanced if the amount of spray contacting the tree foliage is minimized by using drop nozzles or off-center nozzle systems. While label directions for some herbicides, such as oxyfluorfen, state that this herbicide can be applied only to dormant trees, many labels state that applications should not be made over-the-top of Eucalyptus during the flush of new growth. Herbicide injury is more detrimental to Eucalyptus grown for ornamental purposes than to Eucalyptus grown for fiber.

Pre-emergent herbicides are soil-active, and many of these herbicides must be applied before weed emergence because they kill only germinating weeds (e.g., pendimethalin). Other pre-emergent herbicides also provide control when applied post-emergence of weeds (sulfometuron methyl), but generally the best results are obtained when weeds are small. Since soil-active herbicides are absorbed by plant roots, they should not be applied after Eucalyptus transplanting until soil is firmly settled around the roots. Rainfall or hand watering after transplanting will help to settle the soil. In addition, soil-active, pre-emergent herbicides must be made available in the soil solution to “activate” them after application, usually by rain or irrigation. For optimum weed control, some require quick activation (e.g., Snapshot 2.5 TG within 3 days), while others are less sensitive to degradation on the soil surface and allow for a larger window (e.g., 3–4 weeks for GoalTender®). Shallow cultivation (mixing herbicide into the upper 1–2 inches of soil) can also activate some herbicides (e.g., Snapshot® 2.5 TG), while deeper cultivation after application usually reduces effectiveness because the herbicide concentration is reduced.

Post-emergent herbicides may be absorbed by the roots and foliage (e.g., sulfometuron methyl), or only by the foliage (e.g., glyphosate). Complete and uniform spray coverage on weed foliage and the addition of a surfactant may improve absorption and the performance of foliar-active herbicides. Several important selective herbicides used for weed control in Eucalyptus (sulfometuron methyl, oxyfluorfen, flumioxazin) have both soil and foliar activity and can be used either pre- or post-emergence, but applications of these herbicides are most effective when made to weeds at a seedling stage and their effectiveness diminishes as the weeds mature.

Weed composition is the first factor to consider when choosing a herbicide. Non-selective herbicides can kill a broad spectrum of weed species when used at an appropriate rate. Some selective herbicides (e.g., oxyfluorfen and sulfometuron methyl) control both grasses and broadleaf weeds at rates tolerated by Eucalyptus, while others are effective only against grasses (e.g., fluazifop-P-butyl and sethoxydim) or broadleaves (e.g., clopyralid). The effectiveness of some herbicides is limited to annual weeds, which as a rule are easier to control then the perennials. Perennial vines and woody plants are most difficult to control, and few selective herbicide options are available for Eucalyptus culture. These plants should be controlled prior to planting.

Table 2. Herbicide Listing by Labeled Eucalyptus Taxa and Sites

Table 2 provides Eucalyptus taxa for which the listed herbicides have been labeled. Some labels mention only the genus Eucalyptus, while others specify species or even cultivars. It is possible that some herbicides could be applied to other Eucalyptus species in addition to the ones listed in Table 2. However, we have observed that different Eucalyptus taxa may exhibit different tolerance to herbicides labeled generally for Eucalyptus. It is advisable to first test the herbicide on a small number of plants at a specific site and stage of growth to determine selective herbicide rates for a particular Eucalyptus variety.

Since different taxa within the genus Eucalyptus can be used for forestry or ornamental objectives, both forestry and horticultural herbicides have been included in this publication. A herbicide cannot be legally used on a site for which it is not labeled. Moreover, it cannot be used in a state for which it has not been registered. While most herbicides are registered country-wide, some have state-wide exclusions (e.g., SFM 75), and others are registered in a specific state (e.g., Assure® II) or even specific counties (e.g., Clopyralid 3). Therefore, it is imperative to carefully read labels before deciding on a herbicide for a specific purpose.

Additional Resources

The following Additional Resources (all accessed December 4, 2012) can be helpful in developing herbicide prescriptions for vegetation management in Eucalyptus:

Reference

Osiecka, A. and P. J. Minogue. 2011. Considerations for developing effective herbicide prescriptions for forest vegetation management. University of Florida Cooperative Extension Service Circular FOR 273. 8 p. http://edis.ifas.ufl.edu/fr335

Tables

Table 1. 

Herbicides labeled for weed control in Eucalyptus culture (products in bold are labeled for Eucalyptus plantations)

Active

Trade name

Manufacturer1

ai

Registered Uses

Activity

Target weeds

Ingredient (ai)

   

concetration

Site

HWC2

HWC

             

(Common name)

   

in product

Prep

Directed3

OTT4

 

PRE-

POST-

Grass

Broadleaf

Vine

Woody

       

Product application rate/Acre

Unit

emergent

       

clopyralid

CleanSlate®5

Nufarm

3 lb/gal ae9

 

1/3-2/3*

1/3-2/3*

pint

no

yes

no

yes

yes

yes

clopyralid

Clopyralid 36

Alligare

3 lb/gal ae

 

1/3-2/3*

1/3-2/3*

pint

no

yes

no

yes

yes

yes

clopyralid

Stinger®7

Dow

3 lb/gal ae

 

1/3-2/3*

1/3-2/3*

pint

no

yes

no

yes

yes

yes

clopyralid

Transline®8

Dow

3 lb/gal ae

 

1/3-2/3*

1/3-2/3*

pint

no

yes

no

yes

yes

yes

                           

dithiopyr

Dimension® 2EW

Dow

2 lb/gal

 

1.4-2*

no10

pint

yes

no

yes***

yes***

no

no

                           

flumioxazin

SureGuard®

Valent

51%

8-12

8-12*

no

oz

yes

early

yes

yes

yes

no

                           

fluazifop-P-butyl

Fusilade® II

Syngenta

2 lb/gal

no

1-1.5

1-1.5

pint

no

yes

yes

no

no

no

                           

glyphosate

Accord® XRT

Dow

5.4 lb/gal

1.5-8

no

no

qt

no

yes

yes

yes

yes

yes

glyphosate

Accord® XRT II

Dow

5.4 lb/gal

1.5-8

no

no

qt

no

yes

yes

yes

yes

yes

glyphosate

Buccaneer®

Tenkoz

4 lb/gal

0.5-5

0.5-5*

no

qt

no

yes

yes

yes

yes

yes

glyphosate

Buccaneer Plus®

Tenkoz

4 lb/gal

0.5-5

0.5-5*

no

qt

no

yes

yes

yes

yes

yes

glyphosate

Honcho®Plus

Monsanto

4 lb/gal

0.5-5

0.5-5*

no

qt

no

yes

yes

yes

yes

yes

glyphosate

Roundup PowerMax®

Monsanto

5.5 lb/gal

0.3-3.3

0.3-3.3*

no

qt

no

yes

yes

yes

yes

yes

glyphosate

Roundup WeatherMax®

Monsanto

5.5 lb/gal

0.3-3.3

0.3-3.3*

no

qt

no

yes

yes

yes

yes

yes

             

qt

           

isoxaben

Gallery® 75 Dry Flowable

Dow

75%

no

0.66-1.33*

0.66-1.33*

lb

yes

no

no

yes

some

no

isoxaben +

Snapshot® 2.5 TG

Dow

0.5%

no

100-200*

100-200*

lb

yes

no

yes***

yes

some

no

trifluralin

2%

                           

oryzalin

Oryzalin 4 PRO

Alligare

4 lb/gal

 

2-4*

2-4*

qt

yes

no

yes***

yes***

partly

no

oryzalin +

XL 2G

Helena

1%

no

200-300*

200-300*

lb

yes

no

yes***

yes

partly

no

benefin

1%

                           

oxyfluorfen

Galigan® 2E

MANA

2 lb/gal

4-6

4-6

4-6**

pint

yes

yes

yes

yes

no

no

oxyfluorfen

Galigan® H20

MANA

4 lb/gal

2-3

2-3

2-3**

pint

yes

yes

yes

yes

no

no

oxyfluorfen

Goal®2XL

Dow

2 lb/gal

4-6

4-6

4-6**

pint

yes

yes

yes

yes

no

no

oxyfluorfen

GoalTender®

Dow

4 lb/gal

2-3

2-3

2-3**

pint

yes

yes

yes

yes

no

no

oxyfluorfen

Oxyflo 2EC

Willwood

2 lb/gal

4-6

4-6

4-6**

pint

yes

yes

yes

yes

no

no

oxyfluorfen

OxyStar™ 2E

Albaugh

2 lb/gal

4-6

4-6**

4-6**

pint

yes

yes

yes

yes

no

no

                           

pendimethalin

Pendulum® 2G

BASF

2%

100-200

100-200*

100-200*

lb

yes

no

yes***

yes

no

no

pendimethalin

Pendulum® 3.3 EC

BASF

3.3 lb/gal

2.4-4.8

2.4-4.8*

2.4-4.8*

qt

yes

no

yes***

yes

no

no

pendimethalin

Pendulum® AquaCapTM

BASF

3.8 lb/gal

2.1-4.2

2.1-4.2*

2.1-4.2*

qt

yes

no

yes***

yes

no

no

                           

quizalofop P-ethyl

Assure® II11

DuPont

0.88 lb/gal

 

15-30

15-30

fl oz

no

yes

yes

no

no

no

                           

sethoxydim

Sethoxydim SPC

Nufarm

1 lb/gal

no

up to 3.75

up to 3.75

pint

no

yes

yes

no

no

no

                           

simazine

Princep® Liquid

Syngenta

4 lb/gal

no

2-4

2-4

qt

yes

no

yes***

yes***

yes***

no

simazine

Simazine 4L

Winfield

4 lb/gal

no

2-4

2-4

qt

yes

no

yes***

yes***

yes***

no

                           

sulfometuron

SFM 7512

Alligare

75%

3-5

1-4

1-4**

oz

yes

yes

yes

yes

yes

no

*Established trees; **Dormant trees; ***Annual

1 Manufacturers' names are abbreviated. For the full name click on the link.

2 HWC = Herbaceous weed control

3 Directed = Application directed at the target species, without contacting the crop species (directed spray, spot treatment, wiper application)

4 OTT = Over-the-top of crop species (do not apply during bud swell, bud break, or at time of the flush of new growth)

5 Not registered for Eucalyptus tree plantations in Florida; not registered in some counties in New York state

6 Restrictions in some states; in Florida can be used only in Bay, Bradford, Calhoun, Escambia, Franklin, Gadsden, Gulf, Hamilton, Jackson, Jefferson, Lafayette, Leon, Liberty, Madison, Okaloosa, Santa Rosa, Suwannee, Taylor, Wakulla, Walton, and Washington Counties.

7 Not registered for Eucalyptus tree plantations in Florida

8 Registered for Eucalyptus tree plantations in all states except Florida

9 ae = Acid equivalent

10 no = Not labeled for this use

11 Registered for Eucalyptus pantations in Hawaii only

12 Supplemental labeling; not registered for Eucalyptus plantings in California

Table 2. 

Herbicides labeled for the culture of various Eucalyptus species at different registered use sites (products in bold are labeled for Eucalyptus plantations)

Common name

Trade name

Labeled species

Labeled use sites

clopyralid

CleanSlate®1

Eucalyptus spp.

Eucalyptus tree plantations1

clopyralid

Clopyralid 32

Eucalyptus spp.

Eucalyptus tree plantations

clopyralid

Stinger®3

Eucalyptus spp.

Eucalyptus tree plantations3

clopyralid

Transline®4

Eucalyptus spp.

Eucalyptus tree plantations4

       

dithiopyr

Dimension® 2EW

E.citriodora

Field-grown ornamentals

       

flumioxazin

SureGuard®

Eucalyptus spp.

Field-grown deciduous tree species

       

fluazifop-P-butyl

Fusilade® II

E.microtheca, E.polyanthemos, E.rostrata5, E.rudis, E.spathulata; directed spray: E.citriodora, E.nicholii

Field-grown ornamentals

       

glyphosate

Accord® XRT

Eucalyptus spp.

Forestry site preparation

glyphosate

Accord® XRT II

Eucalyptus spp.

Forestry site preparation

glyphosate

Buccaneer®

Eucalyptus spp.

Non-food tree crops; ornamentals; forestry site prep

glyphosate

Buccaneer Plus®

Eucalyptus spp.

Non-food tree crops; ornamentals

glyphosate

Honcho®Plus

Eucalyptus spp.

Non-food tree crops

glyphosate

Roundup PowerMax®

Eucalyptus spp.

Non-food tree crops

glyphosate

Roundup WeatherMax®

Eucalyptus spp.

Non-food tree crops

       

isoxaben

Gallery® 75 Dry Flowable

E.camaldulensis, E.cinerea, E.microtheca, E.sideroxylon

Field-grown ornamentals

isoxaben+trifluralin

Snapshot® 2.5 TG

E.camaldulensis, E.cinerea, E.microtheca, E.sideroxylon

Field-grown ornamentals

       

oryzalin

Oryzalin 4 PRO

E.camaldulensis, E.cinerea, E.nicholii, E.sideroxylon

Field grown ornamentals

oryzalin+benefin

XL 2G

E.camaldulensis, E.cinerea, E.nicholii, E.sideroxylon

Field-grown ornamentals

       

oxyfluorfen

Galigan® 2E

E.camaldulensis, E.pulverulenta, E.viminalis,

Eucalyptus plantings

oxyfluorfen

Galigan® H20

E.camaldulensis, E.pulverulenta, E.viminalis,

Eucalyptus plantings

oxyfluorfen

Goal®2XL

Eucalyptus spp.

Eucalyptus plantings

oxyfluorfen

GoalTender®

Eucalyptus spp.

Eucalyptus plantings

oxyfluorfen

Oxyflo 2EC

Eucalyptus spp.

Eucalyptus plantings

oxyfluorfen

OxyStar™ 2E

Eucalyptus spp.

Eucalyptus plantings

       

pendimethalin

Pendulum® 2G

E.sideroxylon 'Rosea'

Ornamentals; tree plantations site prep and maintenance

pendimethalin

Pendulum® 3.3 EC

E.sideroxylon 'Rosea'

Ornamentals; tree plantations site prep and maintenance

pendimethalin

Pendulum® AquaCapTM

E.cinerea, E.sideroxylon 'Rosea'

Ornamentals; tree plantations; pulpwood and fiber farms

       

quizalofop P-ethyl

Assure® II6

Eucalyptus spp.

Eucalyptus plantations (Hawaii)6

       

sethoxydim

Sethoxydim SPC

E.citriodora, E.globulus, E.lehmannii, E.polyanthemos, E.robusta, E.sideroxylon

Trees; deciduous tree farms

       

simazine

Princep® Liquid

Eucalyptus spp.

Shelterbelts

simazine

Simazine 4L

Eucalyptus spp.

Shelterbelts

       

sulfometuron

SFM 757

Eucalyptus spp.

Eucalyptus site preparation and release7

1 Not registered for Eucalyptus tree plantations in Florida; not registered in some counties in New York state

2 Restrictions in some states; in Florida can be used only in Bay, Bradford, Calhoun, Escambia, Franklin, Gadsden, Gulf, Hamilton, Jackson, Jefferson, Lafayette, Leon, Liberty, Madison, Okaloosa, Santa Rosa, Suwannee, Taylor, Wakulla, Walton, and Washington Counties.

3 Not registered for Eucalyptus tree plantations in Florida

4 Registered for Eucalyptus tree plantations in all states except Florida

5 E. rostrata is a synonym for E. amaldulensis.

6 Registered for Eucalyptus plantations in Hawaii only

7 Supplemental labeling; not registered for Eucalyptus plantings in California

Footnotes

1.

This document is FOR310, one of a series of the School of Forest Resources and Conservation Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date February 2013. Visit the EDIS website at http://edis.ifas.ufl.edu.

2.

Anna Osiecka, senior biological scientist, School of Forest Resources and Conservation Department, University of Florida, IFAS, North Florida Research and Education Center, Quincy, Florida 32351; and Patrick J. Minogue, assistant professor of silviculture, School of Forest Resources and Conservation Department, University of Florida, IFAS, North Florida Research and Education Center, Quincy, Florida 32351.

The use of trade names in this publication is solely for the purpose of providing specific information. UF/IFAS does not guarantee or warranty the products named, and references to them in this publication do not signify our approval to the exclusion of other products of suitable composition. All chemicals should be used in accordance with directions on the manufacturer's label.


The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county's UF/IFAS Extension office.

U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.