Dicamba herbicide drift onto plants growing adjacent to farm fields causes significant delays in flowering, as well as reduced flowering of those plants and results in decreased visitation by honeybees, according to researchers at Penn State and the Pennsylvania Association for Sustainable Agriculture. “Because of the challenge of glyphosate-resistant weeds, new types of transgenic crops that are resistant to synthetic-auxin herbicides including dicamba and 2, 4-D will be widely planted in coming growing seasons, raising concerns about damage from these drift-prone herbicides,” said John Tooker, associate professor of entomology, Penn State. The team examined the crop species alfalfa (Medicago sativa), which requires insect pollination to produce seeds, and the native plant species common boneset (Eupatorium perfoliatum), which is highly attractive to a wide range of pollinator species. “We found that both plant species are susceptible to very low rates of dicamba — just 0.1 to 1 percent of the expected field application rate can negatively influence flowering,” said Tooker. “By extension, we expect that other broadleaf plant species are similarly susceptible to this sort of damage from drift-level doses.”
This article appears in the February 2016 issue of Acres U.S.A.