When BASF asked Midwest farmers in 2010 about weeds that most concerned them, the majority called out common lambsquarters as their main worry. Marestail was second. Ragweed species came in third, and common waterhemp was fourth.
In the latest 2012 survey, one in five growers listed waterhemp as the top glyphosate-resistant weed they expect to show up on their farms during the 2012 season, with marestail and lambsquarters listed as the No. 2 and 3 weeds to watch, respectively.
The dramatic shift was no surprise to Dan Westberg, Ph.D., Technical Market Manager, at BASF. "In 2011, we saw glyphosate-resistant waterhemp explode across the Midwest," said Westberg. "It was a tipping point for farmers and another sign that we have to think beyond glyphosate alone for weed control."
Spreads like wildfire
â€¨â€¨Waterhemp, by its very biology, has the ability to cause major problems if left uncontrolled.
"Waterhemp is a prolific seed producer that can create detrimental seed banks farmers must deal with for years," said Westberg. "Waterhemp also emerges throughout the season, so it's a weed that is poised to spread like wildfire - which makes the resistant populations especially dangerous."
Even more troubling, waterhemp populations with resistance to multiple herbicide sites of action are also rapidly expanding. Of the 10 states that have now confirmed glyphosate-resistant waterhemp, three have waterhemp populations with resistance to multiple sites of action.1
Corn and soybean waterhemp solutions
For growers looking to control waterhemp in their crops, it is essential to update weed control programs with new strategies, such as using multiple herbicide sites of action and utilizing effective preemergence herbicides.
"With waterhemp, starting clean with a good residual herbicide that offers an additional site of action is key to staying clean all season long," said Westberg. "Early season weed control helps reduce the seed bank and minimizes weed pressure for better in-season control with post-emerge herbicides."