Chemicals designed to kill off plant species are developing a vital role in attempts to repair ecosystems damaged by invasive species.
In agriculture, herbicides are normally selected to preserve one valuable crop species and kill off every other species. In contrast, at a session at the American Chemical Society in Denver on Monday, researchers outlined projects using herbicides in the opposite way: to remove unwanted, invasive species while preserving and promoting the diversity of native plants.
“Herbicides are a lot more selective than we give them credit for,” George Beck, of Colorado State University, told the meeting.
One of Beck’s projects involves using an herbicide called aminocyclopyrachlor to control invasive Russian Knapweed (Acroptilon repens). At a site in Colorado his team have run tests using varying levels of the pesticide to remove this weed before reseeding with native plants. In control plots only 3 of 16 native species managed to establish a foothold. In sites treated with the herbicide, 15 of the same species were established.
Speaking about the fears some members of the public have about herbicides, Beck said, “Herbicides are not going to alter the Earth’s orbit around the Sun. They can be used to promote native plant communities.”
Kurt Getsinger, of the US Army Corps of Engineers, told the meeting how his group is using aquatic herbicides to control waterborne invasive species. Echoing Beck, Getsinger notes that in public perception “the typical focus is the risk side”.
By careful consideration of individual situations, herbicides can be used to massively decrease the amount of invasive species such as Eurasian watermilfoil (Myriophyllum spicatum) in lakes and other waterways, allowing native species to return, he said. For example, some invasive species start growing earlier than natives, so applying herbicides early in the season can knock them back and allow native species flourish when the start to appear later.