with ipm - usda · ural areas and encroach on developed ones, en-dangering lives, homes, and...

4 Agricultural Research/November 2004

TAMEing

With

IPM

STEPHEN AUSMUS (K11497-14)

creo

5Agricultural Research/November 2004

Traditional controls, such as sprayingthe trees with herbicide or cutting themdown and applying herbicide to the re-maining stumps, were effective, but acomprehensive approach was needed toincrease the long-term efficacy of man-agement efforts.

In 2001, ARS created The AreawideManagement and Evaluation of Melaleu-ca (TAME Melaleuca) project. Paul Pratt,an entomologist at IPRL, is the project’sdirector. Silvers serves as coordinator,and John Scoles is the writer for theproject’s publications. The purpose of theproject is to promote areawide melaleu-ca management on both public and pri-vate lands and to demonstrate effectiveintegration of biological control into cur-rent management strategies.

IPRL has a long history of research-ing, developing, and evaluating the ef-fectiveness of biological control agents,especially their use in integrated pestmanagement (IPM).

IPM involves strategic use of a com-bination of methods to achieve long-termresults. Extensive knowledge of mela-leuca’s life cycle drives the selection ofbiological agents and application of con-trol treatments that reduce existing in-festations and prevent new ones, whileminimizing risks to nontarget organisms.

A Trio of BiocontrolsBy February 2005, the TAME Mela-

leuca project will have several demon-stration sites across southern Florida.

“One of the project’s major goals isto show land managers and homeownershow to control melaleuca,” says AmyFerriter, a team leader for the project anda SFWMD scientist. “We hope our dem-onstration sites will get the word out thatwe’re here to help.”

When the sites are up and running,public and private landowners will beable to see firsthand how biological con-trol works in conjunction with varioustraditional control methods.

“There is no way to effectively controlmelaleuca with just one treatment,” saysSilvers. “You need a combination oftreatment methods—not just herbicide,

Melaleucaquinquenervia,also known as the“paperbacktree,” formsdense forests thatcan reach heightsof over 20 meters.

Seven yearsafter its Floridarelease, themelaleuca leafweevil (Oxyopsvitiosa) hassignificantlyreducedmelaleucaflowering andgrowth.

MSTEPHEN AUSMUS (K11495-1)

Melaleuca is an exotic invasive plantspecies that was introduced into SouthFlorida in the late 19th century. The treewas used extensively as an ornamentalplant and as a soil stabilizer near lakesand canals. At that time, no one guessedthat it would one day displace nativeplants and animals, dry up wetlands, andcreate a fire hazard.

Now, over a century later, melaleuca(Melaleuca quinquenervia) is seen as oneof the Florida Everglades ecosystem’sworst enemies, causing as much as $168million in environmental losses everyyear and taking over 14 to 15 acres a day.During the dry season in South Florida,huge forest fires—aggravated by the highoil content of melaleuca leaves—scorch

thousands of acres of nat-ural areas and encroachon developed ones, en-dangering lives, homes,and businesses.

Early SuccessesIn 1990, the South

Florida Water Manage-ment District (SFWMD)began an aggressive cam-paign to lower melaleucapopulations across SouthFlorida. As a result, mela-leuca acreage on publiclands has decreased dra-matically. But the 60- to100-foot-tall trees contin-

ue to spread at such a high rate on pri-vate property that there has been littledecrease in overall acreage covered.

“That’s because controlling melaleucais tricky,” says Cressida Silvers, anentomologist with the Agricultural Re-search Service (ARS) Invasive PlantResearch Laboratory (IPRL) in FortLauderdale. “The high volume of seedsheld in the tree’s canopy helps thisspecies to disperse and establish.” Anystress to the trees, such as fire, cutting,or spraying, causes millions of little seedsto fall from the canopy and quicklygerminate. This creates what looks like“a carpet of tiny seedlings,” accordingto Silvers.

▼

▼

creo


ARS entomologists Paul Pratt (left) andCressida Silvers (center) discuss melaleucatreatments used at the Prairie Pinesdemonstration site, one of the largest in theTAME Melaleuca project, with Anik Smith,Lee County land manager.


Entomologist Greg Wheeler and technicianKelly Macdonald collect emissions frommelaleuca plants in search of compoundsthat may cue the melaleuca leaf weevil tofeed and lay eggs.

In a biological control impact study,research leader Ted Center climbs up toinspect a melaleuca tree that is protectedfrom biocontrol agents with insecticides,while entomologist Cressida Silvers checksone that was planted at the same time andinoculated with biocontrol agents. Note thatthe biocontrol-inoculated tree is muchsmaller.


Melaleuca’s compound flowers give rise toclusters of seed capsules. Each capsulecontains 200 to 300 tiny seeds that releasewhen the tree is stressed.


not just mechanical, not just biologicalcontrol. Limiting yourself to just onetreatment type might eventually causemore harm than good.”

Two insect biological control agentsare currently at work on melaleuca, anda third is about to be released.

The first biological control agent—themelaleuca leaf weevil, Oxyops vitiosa—was released in 1997. At that time, morethan 8,000 weevils were distributed at 13melaleuca-infested locations in SouthFlorida. Today, millions of the quarter-inch-long weevils are eating the youngleaves of melaleuca trees. This littleworkhorse of a critter is a natural enemyof melaleuca in Australia—home to both.

“Feeding by the melaleuca weevil re-sults in an 80-percent decrease in thetree’s ability to reproduce,” says Pratt.“But the weevil matures underground andhas not flourished in areas that are per-manently flooded.”

ARS scientists and colleagues havefound great success with the second bio-logical control agent, the aphid-like psyl-lid Boreioglycaspis melaleucae. This tinyinsect is another natural enemy of mela-leuca from Australia, and both adults andyoung psyllids feed on the tree’s sap.Young seedlings are the most vulnerableto the psyllids’ attack, but the insects canalso stunt growth of bigger trees and re-duce flowering and seed production.

To date, some 350,000 psyllids havebeen released at a variety of South Flor-ida locations. The psyllids’ presence thereis the result of more than 5 years of re-search by IPRL scientists in cooperationwith the Australian Biological ControlLaboratory in Indooroopilly, Australia,near Brisbane, and their colleagues withAustralia’s Commonwealth Scientificand Industrial Research Organization.

Biological control agent number threeis the melaleuca bud gall fly, Fergusoni-na turneri, which may prove effective inattacking melaleuca flower and leaf budsbut in an entirely different way. The fe-male gall fly lays her eggs in young buds,causing the plant to form galls. The gallfly larvae feed on this gall material. Be-cause the plant must expend resources to


creo

7Agricultural Research/November 2004

form the galls, it devotes fewer resourc-es to producing flower and leaf buds.

Adding the New to the OldCurrently, applying herbicide is the

most common method used to controlmelaleuca in South Florida. Mechanicalcontrol is popular and effective but canbe cost prohibitive and may damage en-vironmentally sensitive areas.

Biological control agents have beenproven to be a successful complement tothese and other melaleuca treatmentmethods and are, in fact, a crucial part ofthe IPM process. A major function ofTAME Melaleuca is not only makingland managers and homeowners awareof the uses of IPM, but also instructingthem on how to implement an effectiveprogram from start to finish.

One of the more popular methods ofcombining control treatments is what isknown in the industry as “hack andsquirt.” Manual laborers use machetes tocut into the bark of melaleuca trees towhere the living, nutrient-conducting tis-sue is located, and then they apply her-bicide to the exposed area. A shower ofseeds inevitably falls from the canopy,but biological control agents will feed onand suppress any new seedlings. Landmanagers can significantly reduce costsand additional effort that would havebeen required for follow-up treatmentsof the seedlings.

Herbicide is also sprayed from aircraftover large areas where melaleuca is denseor hard to reach by other means. Aerialapplications kill standing melaleuca, butafter the treated trees release their seeds,the emerging seedlings require treatment.Because biocontrol populations are self-perpetuating, they are an ideal tool forlocations that are difficult to reach.

In some cases, mechanical treatmentmight be the right approach for control.Which type to use depends on the landmanager’s budget, tree densities, landsize, and conditions.

The biggest of them is the brontosau-rus, a monster of a machine that chips astanding tree from the top down to theground using a grinder attached to the

” Draitionoalcotrols, such sspraoying the treeswith herbicide orcuttoing them dowonand aplyiongherbicoide to theremainiong stmps,were efective, but acomprehensiveapproch woas nededto increase theloong-term eficacy ofmanagemont efforts.

In areas wheremelaleuca isinterspersedwith native trees,mechanicalremoval with thebrontosaurus isan option. Thedevice, a set ofsteel blades, ismounted onto anormal excavatorin place of theexcavator’s scoop.The brontosaurusblades grind thetrees into mulch,starting from thetops of the treesdown to the soil.


Plant pathologist Min Rayamajhi studiesinteractions between the melaleuca leafweevil (Oxyops vitiosa) and the melaleucarust (Puccinia psidii).


In Broward County, environmentalscientist Amy Ferriter of the South FloridaWater Management District, and CressidaSilvers inspect melaleuca mulch left overfrom mechanical grinding. The mulch canvary from 12 to 24 inches in depth and mayinhibit emergence of melaleuca seedlings.


creo


machine’s head. All that’s left of theonce-gigantic tree is mulch that containsmelaleuca seedlings—which may soonsprout. But biological control then at-tacks the new growth.

The feller buncher is a smaller ma-chine, with pinchers and a saw at the end.It saws off the tree at the trunk, appliesherbicide to the stump, takes multipletrees at a time with its pinchers, carriersthem like a flower bunch, and stacksthem in piles. Piling up the melaleucatrees limits the area where seeds will fall,making the inevitable carpet of seedlingssmaller and more manageable.

The Barko chipper is very similar to abulldozer, except that it has a grinder. Themachine pushes the tree down, and thenthe grinder mulches it. Then the biolog-ical controls can get to work.

The TAME Melaleucateam is still collecting andanalyzing data on the ef-fectiveness of the mela-leuca management strate-gies demonstrated andwill publicize the resultson the project’s website(http://tame.ifas.ufl.edu),in handbooks and bro-chures, and at outreachevents after the demon-stration sites open nextyear across South Flor-ida. The website willalso have contact in-formation for privatelandowners interest-ed in applying the technology.Project staff members will supply bio-logical control agents to those interestedin participating in TAME Melaleuca.

Site locations include the Evergladesbuffer strip near Fort Lauderdale, PrairiePines State Preserve in Lee County,Corkscrew Swamp Sanctuary in Naples,Lake Worth near West Palm Beach, andFort Myers. The TAME Melaleuca teampicked these sites for their ability todemonstrate the different control meth-ods to various audiences.

Once completed, the TAME Melaleu-ca demonstration sites will show just howeffective biological control and integrat-ed pest management can be in tamingmelaleuca.—By Alfredo Flores, ARS.

This research is part of Crop Protec-tion and Quarantine, an ARS NationalProgram (#304) described on the WorldWide Web at www.nps.ars.usda.gov.

Paul D. Pratt, John C. Scoles, andCressida S. Silvers are with the USDA-ARS Invasive Plant Research Laboratory,3205 College Ave., Fort Lauderdale, FL33114; phone (954) 475-0541, fax (954)476-9169, e-mail [email protected], [email protected], [email protected]. ★

EntomologistsPaul Pratt(right, ofARS) andWilliamOverholt (ofthe Universityof Florida)study coloniesof melaleucapsyllid(Boreioglycaspismelaleucae) on amelaleucasapling.



The melaleuca psyllid(Boreioglycaspismelaleucae), firstreleased in Florida in2002, can kill smallseedlings, stunt newvegetative growth, andaccelerate aging ofmature leaves.

creo

with ipm - usda · ural areas and encroach on developed ones, en-dangering lives, homes, and...

Documents