Melaleuca2 2/6/04 3:44 PM Page 1

The Green Menace from Down Under First brought to Florida from Australia around 1900, melaleuca (MEL-ah-LUKE-ah) found widespread use as an ornamental tree and as a soil stabilizer on levees and spoil islands. It was even used in early attempts to dry up the Everglades. However, as is often the case when species are introduced beyond their natural range without the associated enemies (e.g. insects, viruses) that control their population, the plant soon became a nuisance. It faced little opposition and quickly spread beyond the areas where it was intentionally planted. Melaleuca was first reported in Everglades National Park in 1967, and by 1993 was estimated to cover 488,000 acres in South Florida. Eventually, melaleuca colonized up to 20 percent of all natural land south of Lake Okeechobee. Melaleuca is now listed by federal and state agencies as a noxious weed, making it illegal to possess, sell, cultivate, or transport melaleuca in Florida.

A Century of Melaleuca Invasion in South Florida

For more information on melaleuca and its management, visit the TAME Melaleuca Web site http://tame.ifas.ufl.edu

Project Coordinator: Cressida Silvers USDA-ARS Invasive Plant Research Laboratory Ft. Lauderdale, FL (954) 475-0541

USDA-ARS is an equal opportunity employer. February 2004 http://tame.ifas.ufl.edu Melaleuca2 2/6/04 3:44 PM Page 2

Melaleuca trees are relatively fragile and shallow- Identification of Melaleuca rooted, and thus are potential hazards during Melaleuca Mulch Getting Rid of Melaleuca Scientific name: Melaleuca quinquenervia windstorms. However, the greatest threat to peo- Commercial melaleuca mulch, which has been Seeds produced by melaleuca trees are retained The most distinguishing characteristic of melaleuca ple living near melaleuca stands is fire. Due to the composted for 90 days before bagging in order to in capsules, and any environmental stress (such is its pale, papery bark that peels easily – hence its high levels of essential oils in its leaves, melaleuca kill the seeds, is some of the most environmen- as herbiciding, cutting, or burning) causes the cap- common name in Australia, paperbark tree. This trees burn extremely hot and are difficult to extin- tally-friendly and termite-resistant mulch on the sules to open and release their seeds. Attempts medium-sized tree averages 50 to 70 feet in height guish. Allowing melaleuca trees to grow near market. But producers are having a difficult time meant to control melaleuca must take into account and retains its leaves houses may increase the threat of fire to homes convincing consumers to buy it because it is not the staggering numbers of seedlings that will year-round. It flowers during dry years. Melaleuca trees are fire-adapted: the mulch that they have become accustomed to. appear within several times per year not only does fire often not kill them, but fire also The majority of mulch comes from cypress; unfor- months, as a with white, bottlebrush- promotes their spread by inducing the release of tunately, thousands of cypress trees are cut annu- single mature type flowers. Seeds are seeds and cre- ally solely for landscape mulch. A market for tree can hold up contained within woody ating ideal soil melaleuca products would provide another incen- to 100 million capsules that cluster on conditions for tive for melaleuca removal from natural lands. seeds. stems. In wetland areas, seedling As is the case such as the Everglades, establishment. We Have Paid the Price with any inva- melaleuca forms dense To date, agencies in Florida have spent $35 million sive species, stands of thin trees. One Melaleuca to control this noxious weed. The Florida successful acre can contain as grows in Department of Environmental Protection has deter- control of many as 132,000 upland habitats as well as it mined that its uncontrolled spread would signifi- melaleuca melaleuca saplings and A day after this melaleuca branch was The distinctive bark of cantly restrict the use of parks and recreation requires using trees. does in wet- cut and brought into the lab, the seed melaleuca trees. lands, and areas. It has been estimated that reduced eco- several tactics capsules began opening and releasing because noth- tourism alone could result in an estimated loss of in an integrated their contents. The Pest That Infests $168.6 million per year to Florida’s economy. approach. One ing grazes its The oil in M. quinquenervia leaves Melaleuca invades treeless sawgrass marshes and leaves, it can of these tactics is the deliberate introduction of promotes hot catastrophic wildfires. The good news is other plant communities, outcompeting native veg- become quite biological controls – natural enemies from the that something etation. No native animals are known to feed on it, a weed in pests’ home range. Already, two such insects, the can be and has and it gradually forms an ecological wasteland pastures. South Florida ranchers must keep their melaleuca weevil and the melaleuca psyllid, have been done. where little exists but melaleuca trees. The habitat pastures mowed to suppress melaleuca seedlings. cleared rigorous screening trials and have been During the 1990s, degradation resulting from invading melaleuca released across southern Florida. As of early land manage- affects wildlife across Florida south of Orlando, spring 2004, the insects have established them- Harboring Another Invasive Pest ment agencies including endangered species such as the Cape selves across South Florida, and the results have Another reason to remove melaleuca from your reduced Sable seaside sparrow, wood stork, red-cockaded been impressive. Property owners wishing to pro- property is that the tree harbors lobate lac scale. melaleuca cover- woodpecker, and Florida panther. Furthermore, tect Florida’s natural areas from this threat should This tiny insect, first found in Florida in 1999 and age on South South Florida is important to millions of birds every Melaleuca trees are closely related to remove their melaleuca trees. The first step native to India, attacks over 200 species of trees Florida public spring and fall as they migrate to and from the bottlebrush trees, and have similar involves becoming more educated about this weed and shrubs in this state. The effects of this insect flowers. They flower up to five times a lands by approxi- Caribbean and Central America to breed in North and other invasive pests. The second step is are potentially devastating to many ornamental year. mately 35 per- America. Natural vegetation is crucial to them, as it deciding how to manage existing stands and trees. and fruit-producing trees and to natural communi- cent. The South Florida Water Management provides the fruits, seeds, and insects needed to Dispose of any debris in such a way that ties. Melaleuca trees can act as a reservoir for this District estimates that the melaleuca problem fuel their journey. Melaleuca forests may look com- melaleuca seeds will not be introduced to new insect, allowing the scale to infest surrounding could be contained within the Everglades Water pletely natural, but their quality as habitat may not areas. When a melaleuca tree is cut down, the trees. Conservation areas and marshes of Lake be much better than that of a parking lot. And in remaining stump must be treated with an appropri- Okeechobee by 2009. However, the tree continues the development-driven South Florida environment, ate herbicide to prevent regrowth. Remember, it is to spread on private lands. it is imperative to keep natural areas as pristine as illegal to possess melaleuca, and any existing tree possible if we want to maintain wildlife for future can be a source of millions of seeds. generations.