DECATUR, Ill. (DTN) -- Two recent farmer polls point to the fact that weeds are becoming increasingly resistant to herbicides or at the very least, more difficult to control.
In October 2013, 42% of DTN subscribers responding to an online poll said weeds on their farms had been confirmed as resistant to one or more herbicides. Only 27% of the farmers said they had confirmed resistant weed problems when asked the very same question in a 2012 DTN poll that involved 487 people.
Another 32% of the 390 farmers responding in 2013 say they've noticed increased weed pressure, but don't have confirmed resistance. That compares to 29% suspecting they had problems in 2012.
A comprehensive weed-resistance survey of more than 200 growers conducted in September 2013 by BASF, a major chemical and seed trait company, found three out of every four growers surveyed suspect glyphosate resistance as a cause of tough-to-control weeds.
Those suspicions have already caused 77% of the growers polled by BASF to either change or plan to change their weed management program to address glyphosate resistance. Of those growers questioned, 88% said they now use multiple or overlapping sites of action in their weed control programs.
The BASF growers ranked waterhemp as their toughest-to-control weed -- indicating a strong Midwest response since it is not a problem in southern states. Ragweed (common and giant), lambsquarters, marestail, morningglory and Palmer amaranth followed as the most problematic weeds mentioned.
Palmer amaranth has been the weed to worry about in southern states. The aggressive weed has begun to gain ground in Midwestern states. Iowa became the latest state to confirm the pigweed species has taken root. Weed scientists in Michigan, Indiana and Illinois have reported the weed is spreading.
Pamela Smith can be reached at email@example.com
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