[Watertown Daily Times – April 19, 2012]
Experts want farmers across New York state to be vigilant about how they use Roundup — a commonly used herbicide also known as glyphosate — as an increasing number of farms in neighboring states are having problems with resistant weeds.
Since 2000, farms in 20 states, including Ohio, Pennsylvania and New Jersey, have developed Roundup-resistant horseweed, said Russell R. Hahn, weed scientist at Cornell University, Ithaca. Because Roundup isn’t working on the horseweed, farmers in those states have had to spend up to $100 more an acre on more costly herbicides.
There have been no documented cases of Roundup-resistant horseweed in New York state, Mr. Hahn said, but there’s a high likelihood that the weed could surface here. Because horseweed seeds are carried on the wind, they can easily spread to neighboring states.
Horseweed resistant to Roundup was first found in Delaware in 2000, and it spread to Ohio in 2002 and to Pennsylvania in 2003.
“It could potentially blow this way because it’s an airborne seed,” Mr. Hahn said. “If we had a significant storm on the East Coast, the seed could be airborne in layers of the atmosphere for hundreds of miles.”
Roundup, which also is a commonly used household product, has resulted in resistant weeds partly because of its popularity, Mr. Hahn said. The majority of farmers across the country use the product because of its relatively low cost and its effectiveness.
“Before (Roundup), you didn’t have a herbicide that could be used across so many crops,” Mr. Hahn said. “By using it so much, we may be intensifying the number of weeds that are resistant to the herbicide.”
By implementing management strategies, farmers in New York state so far have been able to ward off the problem, said Michael E. Hunter, field crops educator for Cornell Cooperative Extension of Jefferson County. Preventive measures include mixing different herbicides with Roundup to kill plants that resist it, as well as regularly rotating crops so they are consistently treated with the herbicide.
“We recommend that farmers mix other herbicide products in their spray tanks for crop rotation so that it doesn’t allow for the selection of resistant weeds,” Mr. Hunter said. “If you had five resistant horseweed plants in a field that resist it after you spray, next year you could have 100 and then 500.”
He said another distinct advantage farmers here have is a more diverse crop rotation than on farms in states such as Ohio and Indiana that almost exclusively grow corn and soybeans. That means the same fields are sprayed with Roundup year after year, while farmers in New York can take a break from spreading Roundup when they grow crops such as alfalfa and grass.
“One of the reasons we don’t have resistant populations of weeds is because our cycle isn’t the same year after year,” Mr. Hunter said. “Some fields will go years before they’re sprayed when other crops are grown, which prevents the problem.”
Among the roughly 325 farms in Jefferson County, about 75 percent of farmers who grow corn and 99 percent of those who grow soybeans use Roundup, Cooperative Extension experts said.
For more information about herbicide-resistant weeds, visit www.weedscience.org
