Forest Health Technology Enterprise Team http://www.fs.fed.us/foresthealth/technology PROVIDING TECHNOLOGY FOR FOREST HEALTH PROTECTION Tree of Heaven Biological Control

Tree of heaven, (Ailanthus altissima) (Mill.) Swingle is a member of the Simaroubaceae family, and native to central China. It was first introduced to the United States in 1784 in Philadelphia, PA. It was later introduced to gold-mining areas of California in the mid-1800s. Tree of heaven occurs across the U.S. and is reported to be invasive in natural areas in at least 30 states.

Nature of Ecological Damage Tree of heaven is a fast-growing deciduous tree with an extensive root system and prolific seed production, making it a serious invasive pest plant of disturbed urban sites. In rural areas tree of heaven Biology and Traditional Control easily invades cropland, fencerows, forest edges and Tree of heaven may be confused with several sumac forest openings, as well as untillable, rocky areas species (Rhus spp.) as well as butternut and black where it can form dense thickets crowding out native walnut (Juglans spp.). The sumacs have red upright seed vegetation. Moreover, tree of heaven produces clusters as opposed to the samaras of tree of heaven. alleopathic chemicals in its root system that prevent Walnut and butternut produce hard-shelled nuts. other plants from becoming established near it. Tree of heaven has a thin pale gray bark. It has two types of branches; sterile long shoots may be up to 18 feet in length, while short shoots that produce flowers are only 18 inches in length. The malodorous, pinnately compound leaves, may be up to 3 feet long. Fruits are one-seeded, dry schizocarps similar to maple (Acer spp.) fruits that are easily wind-dispersed. The shallow, wide-spread roots produce root shoots that become dense thickets of trees. The root shoots may appear up to 90 feet from the parent. Tree of heaven also sprouts from stumps, root crown and the bole.

Biological Control In 2004, surveys for natural enemies of tree of heaven were initiated in China. Following preliminary host range testing of several potential agents a host-specific weevil herbivore, Eucryptorrhyncus brandti was identified as the most promising natural enemy. Clockwise L to R: Leaves and flowers; colorful, one-seeded shizocarps In 2006, a colony of the weevil was established and biological control agent, a weevil, Eucryptorrhychus brandti. Forest Health Technology Enterprise Team http://www.fs.fed.us/foresthealth/technology PROVIDING TECHNOLOGY FOR FOREST HEALTH PROTECTION at the quarantine facility of Virginia Polytechnic also been recovered on tree of heaven in VA and OH. Institute and State University in Blacksburg, VA. The The weevil E. brandti has been shown to procedures for rearing the weevil and additional host successfully carry and transmit V. nonalfalfae to tree of range testing was completed. A petition for its release heaven. Also a large percentage of surviving weevils in the U.S. was submitted to the Technical Advisory Group overwintering in the soil were able to carry viable V. (TAG) for Biological Control of Weeds in 2011 and their nonalfalfae propagules externally. recommendation was to conduct additional host range Following extensive host range testing, the testing which is in progress. fungus is being distributed at various test sites within the In 2002, a native vascular wilt fungus, Verticillium state of Pennsylvania for establishment and developing nonalfalfae, was observed in Pennsylvania causing infestation. A revised petition has been submitted to the significant mortality to tree of heaven. This fungus has TAG for release of the weevil.

FOR MORE INFORMATION CONTACT:

Richard Reardon, Program Manager Biological Control & Biopesticides USDA Forest Service 180 Canfield Street Morgantown, WV 26505 Phone: 304-285-1566 Fax: 304-285-1564 E-mail: [email protected]