In a recent study in Science of the Total Environment, researchers found that the use of the weed killer Roundup had the opposite effect in plants. Instead of killing them it contributed to their growth when applied at much lower concentrations not tested before.
The study, which will be published in print in the December issue of the journal, shows that even at low levels in soil, Roundup is responsible for hormesis – a phenomenon where plants actually benefit from lethal or toxic substances.
The authors – Dr. Lok R. Pokhrel, assistant professor of environmental health in Temple University’s College of Public Health, and Dr. Istvan Karsai, from East Tennessee University, cite the common practice of using Roundup in aerial sprays to cover larger pieces of ground. In doing so, the herbicide can “drift” into soil outside of where it was meant to be sprayed.
“Ever increasing pesticide use is counterproductive as the ‘drifted’ herbicides may promote weed growth; and weeds compete with food crops making this a threat to our growing demand for food worldwide,” said Dr. Pokhrel.
“Our original goal in this study was to see the effects of herbicide on developmental stability. Instead of distorted sickly looking plants that were expected, we rather observed increased growth and vitality at low dose exposure in weeds.”
The authors cite the double roles Roundup can play in the environment: “… increased weed populations can lead to severe agro-economic impacts as weeds intensely compete for limited resources with food crops, thereby affecting crop yields. On the other hand …drifted low levels of herbicide in soils can promote plant biomass and reproduction comparable to that can be achieved applying chemical fertilizer…”
The seven month-long study tested Roundup on Bryophyllum pinnatum, an invasive succulent commonly referred to as a miracle plant by the USDA.