E-44

Brush Management MethodsTommy G. Welch

Mechanical Methods...............................................1Hand grubbing. ..........................................................1Power grubbing. ........................................................6Bulldozing. ................................................................7Shredding. ................................................................7Roller chopping. ........................................................8Root plowing. ............................................................8Heavy offset disk. .....................................................9Chaining. ..................................................................9Cabling. ...................................................................10Railing. ....................................................................10Raking and stacking. ...............................................10Root rake. .......................................................... .....10Brush rake. ..............................................................11Stacker. .......................................................... ........11

Chemical Methods. ............................................. ..11Broadcast application. .............................................11Individual-plant treatment. .......................................12

Prescribed Burning. ..............................................17Biological Methods. ..............................................17Summary. .............................................................17

Brush Management MethodsTommy G. Welch*

Brush plants now exist on more rangelandthan at anytime in recorded history. Althoughthe number of acres of dense brush has re-duced since the mid- 1960’s, the areas sup-porting a thin stand of brush have increased.This indicates invasion of brush into newareas and reinvasion on acres where brushwas previously controlled.

Brush has long been considered one of themajor management problems confrontingowners and managers of rangeland. A densestand of brush usually minimizes grass cover.Reduced grass cover results in loss of live-stock production, increased soil erosion andinefficient use of rainfall. Heavy brush infesta-tions may significantly reduce the amount ofwater available from rangeland watersheds.The increased soil erosion reduces waterquality and can reduce capacity of waterreservoirs through siltation.

Brush also has some desirable attributes. Itprovides food and cover for many wildlifespecies. Certain livestock enterprises such asgoats utilize brush as food. The presence ofsome brush plants also is often aestheticallypleasing. Brush plants such as mesquite maybe useful for wood furniture, firewood andcharcoal briquets.

Brush has both positive and negative charac-teristics. Thus, brush should be managed tomeet the established ranch objectives.

Brush control methods are used to managebrush, Many methods have been developed inthe past 50 years, and each method has appli-cations for which it is best adapted. Seldom isthere a best method for any ranch situation.Often more effective brush management maybe obtained by using a combination of brushcontrol methods in a sequence during aperiod of several years. An integrated manage-ment system can minimize the use of herbi-cides, while improving grass cover andmaintaining or improving surface and sub-

* Associate Department Head and Extension Program Leader forRangeland Ecology and Management, The Texas A&M Univer-sity System.

surface water quality. Therefore, before select-ing a method, evaluate feasible alternativesrelative to 1) degree of expected control, 2)characteristic weaknesses, 3) expected treat-ment life, 4) secondary effects (i.e., release ofa secondary undesirable plant), 5) applicationrequirements, 6) effect on wildlife habitat, 7)cost and benefit and 8) safety.

For most effective brush management, a planshould be developed outlining the purpose ofbrush management (what is to be accom-plished and why), what methods will be usedwhere and when and what is the appropriatefollow-up management (grazing and main-tenance brush control). The plan must beconsistent with the ranch objectives and bepart of the overall ranch plan. An effectivebrush management plan will help meet long-term objectives for the ranch, as well as forthe rangeland, livestock and wildlife re-sources.

Selection of brush management methods isimportant. Methods should be selected on thebasis of ranch objectives, resources available,expected response, economics and personalpreference. Brush management methods, in-cluding mechanical, chemical, biological andprescribed burning will be described here.

Mechanical Methods

Equipment used for mechanical brush man-agement is designed to remove either the topgrowth or the entire plant. Methods that re-move only top growth generally provide short-term woody plant control because mostspecies will resprout. Methods that effectivelyremove part of the root system with the topprovide longer term control (Table 1).

Hand grubbing

Hand grubbing may be effectively used as amaintenance practice for small brush plantswhen the number of plants per acre is small(Figure 1). This labor intensive practice maybe used to control nonsprouting species andspecies that sprout from the stem base if they

1

Table 1. Expected responses ofrangeland vegetation to brush management treatmentsand special considerations.

Expected Brush Treatment Life SpecialTreatment Responses (yr) Forage Responses Considerations

Broadcast Herbicide Application

Spike 20p Effective control of 10+ Maximum release by Use decision shouldsome species (eg. (Greatly dependent on second or third grow- be based on soil tex-oaks, white brush): abundance of tolerant ing season, highly ture and brush standlittle control of species) dependent on ratio of composition (Also seemesquite, Texas tolerant to susceptible remarks for Grazonpersimmon, prick- species ET + Grazon PC)lypear, lime prickly-ash and others

Grazon ET + Good to excellent top- 5-7 Forage release by end Alternative treatmentGrazon PC, kill season of applica- of first growing for tolerant speciesBanvel + tion; 50% or more season; maximum should be consideredGrazon PC plants may resprout production by second at outset of planning

depending on species, or third season afterseason and initial applicationeffectiveness.

Reclaim + Effective control of 5-10 Same as for Grazon Same as for GrazonGrazon PC mesquite: Good to (Dependent on abun- ET + Grazon PC ET + Grazon PC

excellent topkill dance of tolerantseason of application: species)40% or more plantsmay resprout depend-ing on species, seasonand initial effective-ness

Grazon P+D Effective control of 2-3 Forage release by end Provides only short-Chinese tallowtree; of first growing term control of brushgenerally topkills season; maximum unless followed byMacartney rose for during year after subsequent treat-at least one growing application mentsseason; many speciesof weeds controlled;may reduce topgrowthof mesquite by >80%year of applicationwith most plantsresprouting

Banvel + Mesquite topkill good 5 Same as for Grazon Same as for GrazonGrazon ET to excellent year of ap- ET + Grazon PC ET + Grazon PC

plication; response ofother species variable

Reclaim, Effective control of 7-10 Same as for Grazon Same as for GrazonReclaim + mesquite; good to ex- ET + Grazon PC ET + Grazon PCGrazon ET cellent topkill season

of application; 40% ormore plants mayresprout dependingon initial effectiveness

2

Table 1. Continued

Treatment Expected Brush Treatment Life Forage Responses Special

Responses (yr) Considerations

2,4-D Good control of sand 2-3 Forage release by end Repeated treatment

sagebrush; may (for sand sagebrush) of first growing season required for sustained

reduce topgrowth of 1 improvement or follow

Macartney rose by (for others) with prescribed burn->80% year of applica- ing

tion; little control ofother brush species;some weeds control-led when treated atthe proper growthstage

Weedmaster Many species of 1-3 Same as 2,4-D Repeat treatment

weeds controlled; may often necessary

reduce topgrowth ofmesquite by >80%year of applicationwith most plantsresprouting

—

Grazon PC Somewhat more effec- Depends on species See Grazon ET + See Grazon ET +

tive than 2,4-D mix- Grazon PC Grazon PC

ture on Macartneyrose; effective controlof pricklypear,huisache, blackbrushacacia, twisted acaciaand other hard-to-killspecies

Individual Plant Treatments

Primarily as maintenance treatment after broadcast treatment; or for scattered stands of woody plants; forage releaseafter treatment is usually minimal

Spike 20P Complete kill depend- Depends on brush Injures grasses in Do not apply nearing on dosage and reinvasion rate local area of herbicide desirable trees such

brush species deposition as oaks

Grazon PC Controls small 5+ May temporarily in- May be especially use-

(high-volume huisache, pricklypear, jure grasses in local ful for spot treatment

foliar twisted acacia, area of herbicide following prescribed

application) Macartney rose, ashe deposition burning

juniper, easternredcedar, redberryjuniper and manyother woody plants

Grazon ET + Good to excellent top- 5+ See Grazpm PCGrazon PC, kill season of applica-Banvel + tion; 30% or moreGrazon PC plants may resprout

depending on species,season and initialeffectiveness

3

Table 1. Continued

Treatment Expected Brush Treatment Life Forage Responses SpecialResponses (yr) Considerations

Reclaim + Excellent topkill of 5-10 See Grazon PCGrazon PC mesquite season of (Dependent on species)

application; 20% ormore plants mayresprout dependingon initial effectivenessand species

Reclaim, Excellent top kill of 7+Reclaim + mesquite season ofGrazon ET application; 20% or

more plants mayresprout dependingon initial effectiveness

Banvel + Mesquite topkill good 5+Grazon ET, to excellent in seasonBanvel, of application; 50% orGrazon ET more plants may

resprout dependingon initial effectiveness

Grazon P+D Effective control of 5+ See Grazon PCChinese tallowtree,Macartney rose andhoney locust

.

Grazon PC Controls ashe juniper 5+ May temporarily in- Do not apply near(soil and eastern redcedar jure grasses in local desirable trees suchapplication) area of herbicide as oaks

deposition

Velpar L Controls acacias, Depends on brush Kills grasses in local Do not apply nearhackberries, oaks, reinvasion rate area of herbicide desirable trees suchjunipers and deposition as oaksmesquite on sand-clay loams

Grazon ET, Controls most species 5+ May temporarily in-Crossbow, except junipers and jure grasses in imme-Diesel lime pricklyash diate area of woody(basal bark plant, depending onapplication) rate and carrier

Grubbing Control non-sprouters 5+ Pits remove grass Most effective for lightand basal sprouters if cover but trap water; to moderate stands ofgrubbed to first root; hand seeding may be single-stemmed plantsless effective on root effective for grasssprouters establishment

Bulldozing Effectively controls 2-3 Dozer blade may Soil disturbance willmost plants that are remove grass; seeding be greater than foruprooted, but many of grasses may be grubbing; bestplants may be left effective adapted for light torooted; rooted plants moderate stands ofthat are sprouters will single-stemmed non-regrow rapidly; sprouting plantsgrowth form changedfrom single- to multi-stemmed form

4

Table 1. Continued

Treatment Expected Brush Treatment Life Forage Responses SpecialResponses (yr) Considerations

Broadcast Mechanical Methods

Chaining Effectively controls 2-3 Forage released year Soil water must beOne-way most plants that are of treatment, declines adequate to allow

uprooted, but many as brush regrows uprooting of plants;plants may be left chain may ride over orrooted; rooted plants break off tops of smallwill regrow rapidly; plants; pricklypeargrowth form changed may be increasedfrom single- to multi-stemmed form

Chaining Generally uproots 4-5 See above See abovetwo-ways more plants than one-

way chaining

Raking + Generally a follow-up 1-2 See above Effectively removesstacking to other treatments; and consolidates

some uprooting and debris resulting fromremoval of small previous treatment;brush and prick- localizes pricklypearlypear; sometimes padsused for top removalof Macartney rose

Stacking Effective for removal >5 Released year of treat- May be used to thinof pricklypear Depending on rein- ment heavy stands of prick-

vasion rate lypear; also removessmall- to medium-sized woody plants

Roller Most plants regrow 2-3 See above Can use on largerChopping rapidly; growth form brush than with most

changed from single- shredders; mayto multi-stemmed prepare adequateform; pricklypear seedbed for seedingcover increased grasses

Shredding See above See above See above Generally cannot beapplied when mostplants basal diameter>4 inches

Rootplowing Highly effective in kill- 10-20 Most existing forage Should be followed bying most species if plants destroyed. seedingdone properly. Not ef- Most forage produc-fective on some plants tion year of treatmentthat can root from is from annualssevered or brokenplant parts such aspricklypear

Offset disk Effective on smaller, 10 See above See aboveshallow-rooted brushspecies such as white-brush

5

Table 1. Continued

Treatment Expected Brush Treatment Life Forage Responses SpecialResponses (years) Considerations

Biological

Goating

Prescribedburn

Effective in combina-tion with prescribedburning, rollerchopping, shreddingand other mechanicalmethods that stimu-late basal and/or rootsprouting on shin-oaks and other mixedbrush

IControls non-sprout-ers such as ashejuniper, easternredcedar and prick-lypear; sproutersregrow rapidly

>5Depending on contin-ued use of goats

Prescribed Burning

Goats will utilize largeamounts of shinoak ifstock density is highenough and goats areremoved when brushis defoliated andreturned when newleaves develop

2-5

Figure 1, Hand grubbing for complete removal of smallplants,

are uprooted below the lowermost bud. Handgrubbing is best accomplished when the soilis moist.

Forage released year Effectiveness dependsof treatment, declines on intensity of fire.as brush regrows Quantity, continuity

and distribution offine fuel (grass) aswell as weather areimportant factorsthat determine fireintensity

Power grubbing

Power grubbing is effective on nonsproutingspecies and species that sprout from the stembase, provided they are uprooted below thelowermost bud (Figure 2). Power grubbing ismost useful with scattered plants that arelarge, enough (at least 3 feet tall) to be seeneasily by the equipment operator. The size ofplant that can be effectively grubbed dependson the size of tractor and grubber used.

Soil texture and water content affect grubbingefficiency. The efficiency of power grubbingdecreases as soil clay content increases andwater content decreases. On dry clay soils,many plants may be cut off near the groundlevel by the grubber blade, leaving part of thebud zone in the soil. Likewise, grubbing ondeep sands may not be successful becauseaccumulation of soil around plant bases in-creases the depth requirement for effectivegrubbing. Grubbing in shallow, rocky soils isusually hard on equipment, less effective andmay leave the soil surface extremely rough.

6

Bulldozing

Figure 2. Power grubber for cutting roots 4 to 14 inchesbeneath the soil surface.

Various types of low-energy power grubbershave been developed. These grubbers areused on small crawler and rubber-tired trac-tors (Figure 3). Low-energy grubbers may beused to control thin stands of small brushplants. These grubbers are not recommendedfor plants with root diameters greater than 4inches,

Pits are left in the soil surface where brushplants are removed. Runoff water will accumu-late in these pits increasing the water infiltra-tion. However, the soil surface may becomeextremely rough if high densities of brush aregrubbed. The pits allow a good chance forestablishing desirable grasses if seeds arescattered in the pits in early spring.

Figure 3. Low-energy power grubber for use on row croptractors.

The bulldozer (a crawler tractor equipped witha heavy-duty pusher blade) is used to severwoody stems at or below the soil surface(Figure 4). Since few plants are uprooted bybulldozing, it is best adapted for use on largenon-sprouting species in scattered stands. Ifsprouting species are bulldozed, expect plantsto resprout unless the bud zone is removed.Bulldozing may cause considerable soildisturbance.

Figure 4. Bulldozer for severing woody stems at orbelow the soil surface,

Shredding

Shredding uniformly removes brush topgrowth but rarely kills woody plants,especially those capable of sprouting fromroots or stem bases, Drag-type shredders(Figure 5) are most efficient on plants withstem basal diameters of less than 2 1/2inches, although heavy-duty, hydraulicallyoperated shredders may remove woody plantswith trunk diameters of 4 inches or more.

Woody plants may regrow rapidly followingshredding. For example, honey mesquite,lotebush, twisted acacia and whitebrushreplace 50 percent of their original heightsduring the first growing season after shred-ding. Several other woody species replace 50percent of their height during the secondgrowing season. Repeated shredding generallycauses the number of stems and size of thebud zone (basal stems) to increase. Plantsthat have been shredded repeatedly are moredifficult to control with herbicides and mayrequire more energy to remove by grubbing

7

Figure 5. Drag-type shredder for removing top growth ofbrush plants with stems less than 2½ inches in diameter.

than plants that have not been shredded.Shredding can increase the plant densities ofMacartney rose and pricklypear because frag-ments of rose canes or pricklypear pads scat-tered over the soil surface may take root.Spreading of such species is minimized byshredding during hot, dry periods.

Although shredding provides only short-termcontrol of most undesirable plants, sufficienttime may be allowed for grass to grow andprovide fine fuel for prescribed burning.Shredding may increase browse availabilityand quality by increasing the number ofyoung, succulent sprouts. Shredding mayalso improve livestock handling efficiency byincreasing accessibility and visibility for themanager.

Roller chopping

Roller choppers are drums with severalblades running parallel to the axis of theroller (Figure 6), The drums vary in size; sometypes are filled with water to increase theirweight, Roller choppers are more durablethan shredders and can be used on largerbrush and rougher topography.

Roller chopping, like shredding, kills fewplants. Forage response and treatment lifeare similar to those described for shredding,Likewise, roller chopping Macartney rose andpricklypear may result in a significant in-crease in plant density as cane and pad frag-ments take root.

Chopper blades may penetrate the soil sur-face from 6 to 10 inches deep. Thus, soil dis-turbance may be sufficient to improve waterinfiltration. Seeded grass stands have beenestablished on seedbeds prepared by offset,tandem roller choppers. Prescribed burningmay be used to suppress brush regrowth insuch stands. Roller chopping may also beused as a low-cost seedbed preparation follow-ing rootplowing.

Figure 6, Roller chopper for removing top growth ofbrush plants.

Rootplowing

Rootplowing is a nonselective treatment usedto sever woody plants in moderate to densestands of brush. A rootplow is a V-shapedblade, 10 to 16 feet long with several shortfins attached perpendicular to the blade

(Figure 7). It is mounted on and pulledbehind a crawler tractor with the blade 8 to15 inches below the soil surface.

Rootplowing will control most brush species,It is least effective on shallow-rooted speciessuch as whitebrush and cacti. However,ground cover of pricklypear and tasajillo mayincrease dramatically following rootplowing.By disturbing the soil surface and underlyingimpermeable zones, rootplowing also in-creases the water infiltration rate into somesoils.

Although rootplowing is a highly effectivebrush control method, it causes considerablesoil disturbance and destroys most perennialgrasses and forbs. Thus, seeding is oftennecessary as a follow-up treatment. This is aserious limitation when used on arid range-land in far West Texas. If a rootplowed areais not seeded, most forage production for thefirst several years will be from annual andother plants low on the successional scale.

8

Heavy offset disk

Figure 7. Rootplow for cutting roots 8 to 15 inchesbeneath the soil surface.

The carrying capacity for cattle is reduceduntil higher successional grasses becomeestablished. The flush of annual forbs on root-plowed areas may drastically improve wildlifeforage supply until perennial grasses becomedominant. The soil disturbance and destruc-tion of vegetative cover on rootplowed areasmay stimulate the germination of some brushspecies such as huisache.

Rootplowing is costly, but the benefits of thepractice may exceed 20 years. Rootplowing isbest suited for deep friable, fertile soils whererevegetation is feasible. The effectiveness isgenerally reduced on shallow rocky soils anddeep clay soils.

Heavy offset disks may effectively controlsmall, shallow-rooted brush species such aswhitebrush (Figure 8). Because of the limitedsoil depth (6 to 8 inches) reached by the offsetdisk, it is generally ineffective on plants withdeep bud tissues such as mesquite. Diskingdoes not work well on rocky soils either. Disk-ing is less effective just before or immediatelyafter rain because many plowed plantsreestablish root systems. The extreme soildisturbance and possible damage to existingperennial vegetation caused by disking makethe method most applicable to deep soils thatcan be seeded.

Chaining

Chaining is used to knock down and thinmoderate to thick stands of brush (Figure 9).Chaining alone gives only temporary control.It is most effective on trees 4 to 18 inches indiameter in a density of no more than 400plants per acre. Small, “switchy” brush willbend under the chain or break off above thesoil surface. To obtain maximum control, thesoil-water content must be sufficient for plantcrowns and (or) lateral roots to be pulled com-pletely out of the soil. Chaining under theseconditions, however, may increase the coverof pricklypear. Two-way chaining, coveringthe area twice in opposite directions, usuallygives better control than one-way chaining.Chaining can be used on rough, rocky terrainwith only moderate soil disturbance.

Figure 8. Heavy offset disk for control of shallow-rooted brush species.

9

Railing

Figure 9. Heavy anchor chain pulled between twocrawler tractors for knocking down trees 4 to 18 inchesin diameter.

The percentage of brush plants actually killedby chaining is often low, and regrowth mayberapid. However, herbaceous production mayincrease the year of treatment, given averageor greater rainfall. This may provide adequatefine fuel for prescribed burning to removedebris and suppress brush growth. Rakingand stacking may be necessary to removewoody debris after chaining areas of heavybrush cover. Less debris allows maximumdevelopment and utilization of range foragesand minimizes livestock-handling problems.

Chaining has been used successfully in com-bination with aerial application of herbicides.Chaining two or three years after aerial spray-ing reduces time required to chain and alsoimproves brush kill by uprooting partly deadlarge plants.

Cabling

Cabling is similar to chaining but, because oftheir lighter weight (usually 2.5 to 3 inches indiameter), cables tend to ride over the tops ofsmall brush and woody debris, leaving manyplants intact. Cabling is most effective onupright, nonsprouting species of moderatesize, such as ashe juniper, and when the soilmoisture content is conducive to uprootingthe plants.

Soil disturbance is slight. Cabling will spreadpricklypear when conducted under conditionsoptimum for woody plant removal. However,cabling during dry periods has been used tocontrol cholla.

Two or more railroad irons dragged in tandemmay be used for control of pricklypear, othercacti and small nonsprouting woody plants.Maximum cactus control is obtained by rail-ing when the soil surface is extremely dry, thetemperature is hot and dry weather followsthe treatment and desiccates the pads. Soildisturbance is minimal, so herbaceousresponse depends on soil moisture conditionsfollowing treatment.

Raking and stacking

Raking and stacking are used to collect andpile debris left from other mechanical treat-ments, such as rootplowing. Occasionallystacking is used as an initial treatment tocontrol pricklypear and to remove the topgrowth of mature, dense Macartney rose.

Brush rakes used to collect and pile debrisleft from other mechanical treatments causeminimal soil disturbance. Stacker rakes usedto remove and stack pricklypear and matureMacartney rose will disturb the soil morethan a brush rake. These rakes penetrate thesoil 6 to 10 inches deep and are used to con-trol whitebrush and to prepare a clean, firmseedbed after rootplowing. The following im-plements are used in raking and/or stackingoperation:

Root rake - a drag-type rake (Figure 10)pulled behind a crawler tractor to removedebris on and beneath the soil surface follow-ing rootplowing. The primary purpose of thisimplement is to clean and smooth the landsurface for seedbed preparation. By removingwoody plant crowns and root tissues from thesoil, root raking reduces the probability ofresprouting.

Figure 10, Root rake for removing debris on andbeneath the soil surface.

10

Brush rake - a front-end rake (Figure 11)pushed by a crawler tractor to pile debris leftby a previous practice. Brush rakes haveopen tines that gather debris without majoraccumulations of soil. They may be used oneither disturbed or firm soil surfaces.

Figure 11, Brush rake for piling debris left by aprevious practice.

Stacker - a special front-end rake (Figure 12)modified with closed tines near the soil sur-face. It uproots or shears off woody plants atground level and gathers them with lessdebris loss than the brush rake. Modifica-tions include turned-in ends (V-shaped) and asteel plate across the tines near the soil sur-face. Additional pads may be added to thebottom tines to support the stacker’s weightand hold it in the correct position for the soilsurface. The implement works on a firm soilsurface and is especially effective for removalof pricklypear.

Figure 12. Stacker for uprooting or shearing offwoody plants at ground line and gathering debriswith minimum loss.

Chemical Methods

Herbicides used on rangeland may be formu-lated as liquids or pellets and applied bybroadcasting or to individual plants. Theseherbicides include Grazon ET (triclopyr),Banvel (dicamba), Grazon PC (picloram),Reclaim (clopyralid), Crossbow ( 1:2 mixture oftriclopyr and 2,4-D low volatile ester), GrazonP+D ( 1:4 mixture of picloram and 2,4-Damine), Weedmaster ( 1:3 mixture of dicambaand 2,4 -D amine), Velpar L (hexazinone) andSpike 20P (tebuthiuron), Degree of brushcontrol with herbicides depends largely onspecies susceptibility, rate of application andmethod of treatment (Table 1). Consult Chemic-al Weed and Brush Control Suggestions forRange/and (B- 1466) by the Texas AgriculturalExtension Service for specific recommenda-tions on each problem situation. The follow-ing descriptions are intended as generalinformation only.

Broadcast application

Liquid herbicides are usually applied aeriallyin 2 to 5 gallons per acre of an oil:watercarrier (Figure 13). When applied with groundequipment (cluster nozzle or boomsprayer),the herbicide-carrier volume is 10 to 30

Figure 13, Aerial herbicide application for brush control,

gallons per acre (Figure 14), Pelleted herbi-cides may be applied aerially with specialapplicators. They may also be broadcast byground equipment, such as backpack-airblastapplicators and whirlwind-type spreaders.

For best results, liquid herbicides must beapplied when growing conditions optimize her-bicide absorption by the plant. For example,foliar-applied herbicides usually should be

11

I

●

Figure 14. Cluster nozzle used for ground broadcast application of herbicides.

applied to mesquite after the leaves havematured in the spring and the soil tempera-ture at 12 inches of depth is 75°F or more.Macartney rose, blackbrush acacia andhuisache maybe sprayed during spring orfall. Generally, best results are obtained whengrowth conditions allow development of fullfoliage and the plants are not water stressedor damaged by insects, leaf diseases, hail orfrost. Climate and growth conditions oftenlimit the use and effectiveness of liquidherbicides.

Conditions for application of the pelleted her-bicide are less restrictive than for liquid herbi-cides. The best time for application is beforeperiods of expected rainfall and plant growth.Movement of herbicide into the soil by rainfallfollowed by a period of active plant growthallows maximum uptake and translocation ofthe herbicide by the plants. Thus, applica-tions in fall or late winter/early spring aremost common. Low drift potential and thelengthy time for application are major advan-tages of the pelleted herbicide. Effectivenessof Spike 20P is affected by clay and organicmatter content of the soil. To achieve a givenlevel of brush control, the herbicide rate mustbe increased as clay and (or) organic mattercontent increases.

Forage production may increase significantlyduring the first growing season after a liquidherbicide is applied. When Spike 20P is used,the greatest increase generally occurs two ormore growing seasons following application.Abundance and diversity of herbaceousplants may be reduced by some herbicides.The degree of forage response is influenced by

species, quantity and vigor of herbaceousplants present at the time of application, aswell as by rainfall and management followingtreatment. In time, grass production generallydeclines as woody plants reestablish andcanopies are replaced. The length of timebefore grass production returns to pretreat-ment levels varies considerably depending onthe herbicide and brush species treated(Table 1). Some foliar-applied herbicide treat-ments may regress to pretreatment forageproduction within three to five years. How-ever, some soil-applied herbicide treatmentshave a projected treatment life of over 20years.

Individual-plant treatment

Herbicides used for broadcast applicationmay also be used for treatment of individualplants. In addition, some herbicides arelabeled for individual-plant treatment only.Individual-plant treatments are usually moreeffective than broadcast treatments with thesame herbicide when plant kill is the evalu-ation criterion.

Individual-plant treatment is best suited forcontrol of thin stands of brush. Thus, it isideally used as a maintenance treatmentfollowing broadcast treatment to extend treat-ment life. Individual-plant treatment may alsobe used to selectively thin a brush stand andto control brush in selected areas while leav-ing brush in other areas. It may also be effec-tively used for control of brush along fence-lines, around watering areas and aroundcorrals.

12

Individual-plant treatment methods includecut-stump, basal bark, soil, high-volumefoliar and carpeted roller applications. Cut-stump treatment uses diesel fuel oil, keroseneor a herbicide applied to the surface of afreshly cut stump and the basal plant partsbelow the cut. Application is continued untilrunoff occurs and the liquid begins to puddleat the soil surface (Figure 15).

Three types of basal bark methods are avail-able. Conventional basal treatment is theapplication of diesel fuel oil, kerosene or aherbicide/diesel fuel oil mixture (2 to 4 per-cent herbicide) to the lower 12 to 18 inches ofthe trunk of a brush plant (Figure 16). Thesolution is applied completely around thetrunk with sufficient volume to allow runoffand puddling at the soil surface near theplant base.

Figure 15. Cut-stump herbicide application formaintenance control.

Low volume basal treatment uses a mixturecontaining 25 percent herbicide and 75 per-cent diesel fuel oil. The mixture is applied tothe lower 12 to 18 inches of the trunk to wetthe trunk but not to the point of runoff (Fig-ure 17). The higher herbicide concentrationallows for more penetration of herbicidethrough the bark of the plant.

Streamline basal treatment is the applicationof a mixture of 25 percent herbicide and 75percent diesel fuel oil or 10 percent penetrantand 65 percent diesel fuel oil. The mixture issprayed in a band (3 to 4 inches wide) com-

Figure 16. Conventional basal bark application ofherbicide for maintenance control.

Figure 17. Low-volume basal bark herbicide applicationfor maintenance control.

pletely around the trunk near ground levelor at the line dividing young (smooth) andmature (corky or rough) bark (Figure 18). Astraight stream nozzle gives the band widthrequired. Addition of a penetrant improvesease of coverage around the trunk and mayincrease penetration of the herbicide throughthe bark.

Figure 18. Streamline basal bark herbicide applicationfor maintenance control.

Best results with low-volume basal andstreamline basal applications have beenobtained on plants with trunks less than 4inches in diameter and with smooth bark.Conventional basal treatment works well onsingle-stemmed plants or plants with fewtrunks. If the trunk diameter is greater than5 inches, it should be frilled (axe cutsthrough the bark spaced no more than 4inches apart around the mainstem) and theherbicide mixture applied to the frilled area.

Best results are obtained with conventionalbasal treatments of Grazon ET in diesel fueloil or kerosene, diesel fuel oil alone or kero-sene alone when the soil is dry. Low-volumeand streamline basal applications may bemade almost anytime; the optimum time ofapplication is during the growing seasonwhen the plants have mature leaves.

Backpack sprayers and small “pump-up”(compressed air) sprayers work well for thebasal bark treatment techniques. The conven-tional basal treatment may be accomplishedby pouring from a can with a long spout(Figure 19).

Liquid herbicides used for broadcast applica-tion may also be applied to individual plantsin a high-volume foliar application. The herbi-cides are usually mixed with water as thecarrier. The mixture is sprayed to thoroughlywet the foliage (until the mixture begins to

Figure 19. Basal bark pour application for maintenancecontrol

drip from the leaves of the treated plant). Apower sprayer, backpack sprayer or a “pump-up” sprayer may be used (Figure 20).

Figure 20. Handgun on a power sprayer used for high-volume foliar application of herbicides.

14

A mechanical device for use on rubber-tiredfarm tractors applies herbicide to individualplants in a high-volume foliar application(Figure 2 1). The equipment, available underthe tradename Brush Robot TM,sprays onlywhen the unit is in contact with a brushplant. Thus, an area with a thin stand ofbrush may be treated with the speed of abroadcast treatment but without broadcast-ing herbicide over the entire area. Thisusually results in less herbicide used peracre. The treated plants receive a volumesimilar to that from a power-handgunsprayer, which results in a higher degree ofbrush control than broadcast treatment. TheBrush RobotTM uses the same herbicide mix-tures used for high-volume foliar application.It is best suited for thin stands of brushhaving a stem height (usually 1½ to 6 feettall) and flexibility that effectively triggers thespray nozzles and also allows the tractor topass over without breaking the plant’smainstem.

Figure 21. Brush RobotTM for mechanically applyingherbicides to individual plants.

Liquid herbicides may be wiped onto brushplant leaves with the carpeted brush roller(Figure 22). It utilizes a 10-inch-diameterrotating cylinder covered with carpet that iskept wet with a herbicide mixture, The rolleris mounted on the front of a farm tractor. Theherbicide solution is wiped onto leaves and

Figure 22. Carpeted brush roller used to wipe herbicidesonto brush plants.

twigs as the rotating cylinder passes over theplant, usually at 1 to 2 feet of height (dependson height of brush plant). The roller appliesherbicide to individual plants; thus, it is effec-tive for maintenance control and for treat-ment of selected brush plants. Herbicides aremixed with water at ratios of 1:7 to 1:8. Indi-vidually treated plants usually receive ahigher concentration of herbicide than from abroadcast treatment, so the degree of kill isgreater. The carpeted brush roller is mosteffectively used on thin stands of brush withflexible stems that are 1 1/2 to 6 feet tall. Thecarpeted brush roller must be custom-made.Plans for the roller are available from thecounty Extension office or from the ExtensionRange Office, Department of Rangeland Ecol-ogy and Management, Room 225 Animal In-dustries Building, Texas A&M University,College Station, Texas 77843-2126.

Environmental and plant conditions for foliarapplications to individual plants are similar tothose for broadcast application. However, theeffective spray period may last longer into thegrowing season than for broadcast applica-tion.

Soil-applied herbicides are available in liquidand pelleted formulations, Apply measured

15

quantity of pelleted herbicide, determined byplant size, species and soil type on theground under the plant canopy (Figure 23) ofindividual brush plants. No special equip-ment is generally required for individual plantapplications. Rainfall is necessary for dissolv-ing the pellets and moving the herbicide intothe soil.

Figure 23. Hand application of pelleted herbicide formaintenance control.

Liquid herbicides for soil application areapplied undiluted, in measured quantities, tothe soil under the target plant. Some type ofmetering device (exact-delivery spotgun) isrequired to dispense the herbicide (Figure 24),Since these herbicides are liquid, they moveinto the soil immediately. However, rainfall isnecessary to move the herbicide into theplant’s root zone.

When using soil-applied herbicides, apply theherbicide to the soil inside the dripline (Fig-ure 25) of the plant at the rate specified onthe label. The dripline is at the edge of theplant canopy. After the herbicide moves into aplant’s root zone, it is taken up by the rootswith soil water. Death (or killing of the targetspecies) occurs slowly over one to three years.The treated plant may defoliate and releafseveral times before it is killed. Grass may diefor one to several years in a small circle undereach treated plant. The best time to applythese herbicides is before periods of expectedrainfall and plant growth, This allows move-ment of herbicide into the soil followed by a

Figure 24. Soil application with an exact delivery spotgunfor maintenance control.

Canopy width

Plantcanopy.

Dripline-

Drip-line

Figure 25. Dripline of a brush plant.

period of active root uptake as the plantsgrow,

Care must be taken when applying soil-activeherbicides near desirable trees and shrubs.To prevent injury to desirable plants, theseherbicides should be applied no closer thanthree times the canopy diameter of thedesirable plant and never uphill where watermay carry lethal amounts to the vicinity ofdesirable plants.

16

Prescribed Burning

The primary goal of prescribed burning is tosuppress brush. Fire usually does not killmany woody species because most woodyplants are capable of resprouting. Most Texasbrush species resprout from buds on thestem base and below the soil surface on rootsor on rhizomes. Thus, the effect of fire onthese plants is similar to that of any methodof top removal, such as mowing or shredding.

Prescribed burning has the following advan-tages over other brush managementtechniques:

1.

2.

3.

4.

5.

6.

7.

8.

Increased palatability, utilization andavailability of forages

Improved distribution of grazing animals

Satisfactory results on soils and terrainwhere other methods may not succeed

Minimal soil disturbance

Absence or reduced amount of herbicide

Compatibility with wildlife habitat require-ments of many game species

Suppressed parasite populations

Lower costs (compared with other methods)

A major constraint to effective prescribedburning is the amount and distribution offine fuel required to carry the fire. Generally,from 2,500 to 3,000 pounds per acre of evenlydistributed grass, dead leaves andlitter are needed.

Grazing deferment during the growing seasonbefore burning is normally required to achievean adequate fine fuel load. In many situ-ations, the degree of brush infestationlimits the area’s capability to support a fire.Some brush control treatment before burn-ing may be required to produce adequateamounts and distribution of fine fuel. There-fore, prescribed burning often is used incombination with other brush managementpractices and as a maintenance measure.Pricklypear control is accomplished with areduced rate of Grazon PC when used follow-ing a prescribed burn.

Biological Methods

Biological brush control is appealing, butbecause natural enemies (such as insects ordiseases) must attack only the target plantspecies and are difficult to control, few suc-cessful methods have been used in Texas.The most successful has been the use ofgoats. Because they are browsers, goats cancontrol plants such as oaks, greenbriar,sumac, hackberries and several of the SouthTexas mixed brush species. When browseavailability is limited, however, goats will con-sume significant quantities of forbs andgrasses. Thus, careful grazing management isnecessary to provide brush control and pre-vent damage to desired forbs and grasses.Using goats after mechanical treatments orburning may greatly extend the life of thetreatment even to the point of completely re-moving some species such as shinoak.Although goats have been used extensively inTexas to control brush, problems with preda-tors have restricted their use in many parts ofthe state.

Summary

Brush may be efficiently managed by utilizingthese methods in a planned approach. Aneffective brush management plan may bedeveloped by following these steps:

1.

2.

3.

4.

5.

6.

7.

Establish objectives for the ranch thatinclude rangeland, livestock and wildliferesources.

Conduct inventory of resources (determinebrush problem and potential response tobrush management).

Identify feasible brush control alternatives.

Estimate treatment costs and responses.

Conduct economic analyses.

Select brush control alternative.

Implement plan and monitor results(replan and revise plan as needed).

17

Acknowledgment

This bulletin was developed from Chapter 3- Brush Management Technologiesin Integrated Brush Management Systems for South Texas: Development andImplementation, B-1493, Texas Agricultural Experiment Station, 71 p., authoredby T. G. Welch, R.P. Smith and G.A. Rasmussen. Assistance with the originalchapter by R.P. Smith, G.A. Rasmussen, W.T. Hamilton and C.J. Scifres isgratefully acknowledged.