Photographer: Charles T. Bryson, USDA ARS Source: Bugwood.org Copyright: CC BY 3.0 US
Vernicia fordii is a deciduous tree that can grow over 60 feet tall. The bark is smooth, thin, and exudes white sap when cut. The leaves are simple, heart-shaped or with three lobes, and 6-10 inches long. The white flowers have 5 petals with red veins, and they bloom before the leaves emerge. The toxic fruits can grow up to 3 inches in diameter and are reddish green when fully developed.
The seeds are rich in unsaturated oils that have been used as the foundation of many textiles and products including, lacquers, varnishes, paints, linoleum, oilcloth, resins and artificial leather. The oil’s various applications has made it especially valuable, therefore human interaction has allowed this plant to spread outside of its native range. Unfortunately, this plant can have a very dangerous ecological impact. ALL PARTS OF THE TREE ARE POISONOUS TO HUMANS. The leaves create a skin rash much like poison-ivy and one seed can be fatal if to humans if consumed!
Flowers bloom before leaves emerge on the tree, and require pollinators to be fertilized. Following fertilization the flowers will turn into fruits that contain 3-4 seeds within. Trees are able to reproduce by seeds within the fruits, and through vegetative reproduction from underground stems. It survives best in temperate to tropical habitats, with full sun exposure and mildly acidic soils.
In the early 1900s the United States was importing millions of gallons of tungoil with demand steadily increasing. The Gulf Coast farmers were looking for a suitable cash crop to plant were thousands of acres had been cleared. By 1927 there were some 400 growers with over 10,000 acres of tungoil trees. Its production declined by the 1940s, leaving many of the trees to establish themselves in disturbed habitats. In 1905, the tree was successfully introduced from Florida to Texas. In Florida it is considered an invasive and noxious weed but has yet to make the Noxious Weed List. It is well established in Georgia, Alabama, Mississippi and Louisiana. In Texas it has been reported from 3 counties: Montgomery, Walker and Hardin, as early as 2010.
China and Vietnam
U.S. Habitat: Forest edges, right of ways and urban green spaces.
U.S. Present: AL, CA, FL, GA, LA, MS, PR, and TX
The first step in management is prevention and education/ If possible, mechanical removal of the trees should happen before seed production. However, since they can reproduce vegetatively through suckers, if the tree is not fully removed it could spread and create new saplings. These trees respond well to triclopyr herbicides if they’re directly applied to the stump quickly after cutting. For basal bark treatments a 25% triclopyr solution with diesel fuel also works well. Researchers are looking into the biological control benefits of the flea beetle Aphthona nigriscutis.
Brown, K.; Keeler, W. 2005. "The History of Tung Oil" (PDF). Wildland Weeds 9 (1): 4–6.
Council, G. E. P. P. 2006. List of non-native invasive plants in Georgia. Center for Invasive Species and Ecosystem Health, Warnell School of Forestry and Natural Resources, University of Georgia, Athens, Georgia.
Miller, J. H., Chambliss, E. B., & Loewenstein, N. J. 2010. Field Guide for the Identification of Invasive Plants in Southern Forests. DIANE Publishing.