Northeastern IPM Center
Cornell researchers: no magic in a bottle for tough perennial weeds

Gardeners who want to avoid conventional herbicides have traditionally had two options for weed control: hand weeding and mulching. Until recently, no least-toxic herbicides have been available that meet their needs.

But new alternative products, some used by organic growers, are increasingly available. Yet few independent evaluations have assessed how well they work. And studies to date show that while these herbicides work well on annual weeds, they don't offer one-shot control of established perennials, which bounce back quickly from energy stored in their roots.

Now researchers with Cornell University's New York State Integrated Pest Management (NYS IPM) Program have taken a different tack.

"We're comparing two alternative herbicides to hand weeding in an established garden," says Betsy Lamb, ornamentals team leader with the NYS IPM Program. "We're asking if alternative herbicides help save time. And which method is most effective?"

Their trials in Geneva and Rochester, New York, compare AllDown, a citric acid and garlic formulation, and BurnOut II, made with clove oil and soap. Each week, researchers apply AllDown or BurnOut II as needed on some sections of each garden while carefully hand weeding replicate sections, being sure to remove roots.

Though the season isn't over and they haven't crunched the numbers, Lamb's IPM team sees a pattern emerging. Both the hand weeded plots and BurnOut II plots look equally as good--or bad, for gardeners who prefer not see any weeds at all. And Lamb guesses they won't see much difference in how long it takes for gardeners to achieve the same level of control.

Until recently, control in the AllDown plots hasn't been adequate. The IPM team thinks that maybe the clove oil in BurnOut II, combined with an ingredient commonly found in shampoo, helps it stick to the leaves better, giving BurnOut II more time to work.

The take-home lesson? "There's no magic in a bottle for gardeners who need alternatives that work on perennial weeds--and would rather not weed by hand," Lamb says. "But that can be true of any product."

IPM seeks least-toxic solutions to pest problems. Find out more about the NYS IPM Program at www.nysipm.cornell.edu.



For more information contact Betsy Lamb
Email: EML38@cornell.edu
Phone: 607 254 8800,

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