How to Best Control Black Swallowwort

Black swallowwort is a difficult to control invasive vine that thrives in natural areas and perennial cropping systems in northeastern North America. To date, though, little is known about how the weed responds to mowing or to various herbicidal controls.

To begin to fill the research gap, a team from the USDA’s Agricultural Research Service and Cornell University conducted a three-year field study – now featured in the journal Invasive Plant Science and Management.

Researchers explored how black swallowwort responded to glyphosate and to triclopyr – each applied as a two percent solution, with and without mowing. They found that glyphosate formulations were effective in reducing aboveground black swallowwort biomass, but they were less effective in reducing cover and stem densities. Mowing failed to enhance the efficacy of the glyphosate applications on a consistent basis.

By comparison, the team found that triclopyr was generally ineffective in controlling black swallowwort, even when combined with mowing.  The only significant effect of the herbicide was to increase grass cover.

The takeaways: Annual applications of glyphosate can be useful in managing black swallowwort infestations. The jury is out, though, on triclopyr. Higher rates and more frequent applications need to be investigated to determine its potential usefulness.

Want to learn more? Read the open access email in Invasive Plant Sciences and Management here: “Response of Vincetoxicum nigrum (Black Swallowwort) to Herbicides plus mowing

Image: Black swallow-wort, like many invasive species, is difficult to manage, so various tools like herbicides need to be assessed to provide land managers effective options for their particular situation.

Photo credit: Jeromy Biazzo

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