Roundup herbicide is used to eradicate black locust trees, which are considered an invasive species in some states. The Plant Conservation Alliance says, "Black locust poses a serious threat to native vegetation in dry and sand prairies, oak savannas and upland forest edges, outside of its historic North American range." The use of Roundup has become controversial since a 2008 research study connected its inert ingredients to human cell distortions.
Locust trees grow 30 to 80 feet in height on an extensive fiberous root system. Young saplings have smooth green bark, older trees have shaggy bark with flat-topped ridges. Locust flowers are pea-like, fragrant and yellow or white. They bloom in May and June. Black locust trees are native to southern Appalachia and the Ozark mountains, where it is grown as a rot-resistant hardwood. Black locust has been cultivated in other areas as a source of nectar for honeybees.
Black locust tree propagation is by rhizome spread and stump suckering. Easy spread by rhizome propagation has resulted in black locust tree invasion of native species in many areas of the country. The Wisconsin Department of Natural Resources describes the problem as "dense clonal stands shade out most understory vegetation, such tree groves can be detrimental to native vegetation." The extensive network of connected roots make black locust effective for soil erosion control but difficult to limit its spread.
Black locust is classified as an invasive species in part of the United States and is therefore subject to control by municipal agencies. In New York it is crowding out the native plants, including lupine.Chemical weed control with glyphosate (Roundup) has become common where other methods of eradication have failed. Mowing and burning are effective only in reducing the tree's spread from one parent or clone.
Although the active ingredient in Roundup is identified as non-toxic to humans by the EPA, its inert ingredients have come under scientific scrutiny. A team of French researchers at the University of Caen "suspects that Roundup might cause pregnancy problems by interfering with hormone production, possibly leading to abnormal fetal development, low birth weights or miscarriages," according to a report in "Scientific American." The inert ingredients in Roundup amplify the toxic effects even at low concentrations.
A French university research team, led by molecular biologist Gilles-Eric Seralini, said, "Its results highlight the need for health agencies to reconsider the safety of Roundup." Herbicide manufacturers are not required to list inert ingredients on their products and they are not subject to EPA testing regulations. The Plant Conservation Alliance recommends planting grasses, herbs, shrubs and trees that are native to the local area rather than black locust trees.