Good Fruit Grower

May 1

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Organic & Sustainable Ag PHOTO by ricHard leHnerT Heavenly HOST A study suggests that the tree of heaven could serve as a trap tree for brown marmorated stinkbug. [PHOTO by jOHn delanO, HammOnd, indiana Tree of heaven is an invasive species that outcompetes other plants by using allelopathic chemicals. [PHOTO by luis Fernandez Garcia Peter Jentsch is studying how to use tree of heaven as a trap tree to keep brown marmorated stinkbugs out of orchards. by Richard Lehnert Seed pods on the tree of heaven are fed on heavily by brown marmorated stinkbug. When that food source runs low, the bugs head for fruit orchards. F or brown marmorated stinkbugs, the tree of Tree of heaven can grow as large sets seed prolifically and is aggressively at 80 feet tall. heaven appears to be just that—a heavenly place invasive, spreading quickly to disturbed to live. areas and suppressing competition by "They can live there and rear their young there—they have producing allelopathic chemicals. It regrows quickly from sprouts and is absolutely no incentive to go anywhere else," says Tim hard to eradicate. It is considered a noxious weed in many areas. Lampasona, a research assistant at Cornell University's Hudson Valley When Oregon State University entomologist Dr. Peter Shearer first saw Laboratory in Highland, New York. Lampasona works in the entomology the brown marmorated stinkbug in Hood River, Oregon, it was in tree of lab of Peter Jentsch, and he recently spoke heaven. to members of the International Fruit Tree That was true in the Hudson Valley as well. The tree was found to harAssociation during a visit to the lab. bor high populations of brown marmorated stinkbug throughout the Researchers at the lab now think that growing season and to complete two full generations there, Jentsch wrote tree of heaven may be a much-preferred in a progress report on his work with the stinkbug. Highest numbers were host of brown marmorated stinkbug. found feeding and developing on the female A. altissima fruiting clusSo, why do the stinkbugs leave the tree ters. In one of three monitored orchards where the stinkbug was found to and go elsewhere? Population pressure, live on A. altissima, it did not migrate to feed on tree fruit; it stayed on the mostly, Lampasona said. Their populatree of heaven. tions build up, and pretty soon they need "On farms where A. altissima was absent from deciduous woodlands to look for food elsewhere—and that's or hedgerows bordering tree fruit, adult stinkbugs emerged from the what brings them into fruit growers' arboreal habitat late in the growing season to move into and feed intenorchards, where they are highly unwelsively on apple," Jentsch said. "These late-season populations caused —Tim Lampasona come. Feeding on developing seedpods in severe economic injury on three farms in Ulster and Orange counties." the tree of heaven earlier in the season decreases food quality, which may Last year, the Jentsch lab conducted a trap tree study. Using commeralso prompt insects to move to other food resources, Jentsch said. cially available insecticide injection and implant products, commonly He thinks the stinkbug's strong preference for tree of heaven creates used in ornamental insect pest management, the insecticide Acephate the potential for it to be used as a trap tree and thus a management tool. was introduced shortly after fruit set. A second application was made at If the trees were treated periodically using systemic injections to kill the the onset of the second generation. bugs, populations would not reach levels at which the stinkbugs left to A substantial number of stinkbugs were killed in the treated trees. find food elsewhere. Jentsch said using insecticide injections to reduce the numbers of Tree of heaven can reach 80 feet tall. It has sumac-like leaves and flowstinkbugs on trees of heaven might result in lower populations and beters, although the flower bunches are less compact than sumac. Like the ter tree health, and make the tree more attractive to the stinkbugs so brown marmorated stinkbug, tree of heaven hails from China and Souththey don't migrate to orchards. east Asia. It was brought to the United States in 1784, 40 years after its Jentsch chose tree injection instead of spraying because it would be introduction in Europe. In China it is called chouchun (literally meaning very difficult to manage these wild trees, which may not be on property foul-smelling tree) and is used in many traditional Chinese medicines. usually managed for agriculture. The tree, Ailanthus altissima, was originally planted as an ornamental He will continue his tests this year to study the importance of this for its colorful fall seed cluster, but the male tree smells foul, and the tree tree as a primary host of the brown marmorated stinkbug. "They can live there and rear their young there—they have absolutely no incentive to go anywhere else." • 30 May 1, 2013 GOOD FRUIT GROWER

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