Three out of four U.S. growers suspect that glyphosate resistance is a cause of their hard-to-control weeds, according to a new survey by BASF. As a result, 76% of these growers have already changed their weed management program to address resistance.

Many growers have experienced lower yields, which they attribute to resistant weeds, BASF said, and they have also spent more time and invested more money in their crops due to resistant weeds.

In the survey, growers identified how they plan to change their programs in 2014:

• More than two-thirds of growers indicated that they would be applying a preemergence herbicide this season, and more than half are planning to add an additional herbicide to their existing program.
• Half of growers surveyed plan to use more than one site of action.
• 47% of growers said they plan on using overlapping residual herbicides to control resistant weeds.

“These results show that growers are beginning to understand the need for a comprehensive weed management approach,” said Greg Armel, Ph.D., technical market manager, BASF. “Growers are realizing the importance of using residual herbicides and multiple, overlapping herbicide sites of action.”

Nearly two-thirds of respondents said waterhemp was the most difficult to control, while 54% said that ragweed species were the toughest to control. Lambsquater