Pioneer Agronomist On Maximizing Preemergent Herbicide Applications


Controlling weeds early is key to protecting a crop’s yield potential. Weed control programs that start with effective preplant/preemergence applications help to maximize net returns for the grower.

Weeds that germinate, emerge and grow with the crop cause the most yield loss, so getting ahead of them is essential. Preplant and preemergent herbicides can provide critical early season weed control when crops are most vulnerable to competition and weeds are easiest to treat. Preemergence herbicides can be especially effective on glyphosate-resistant weeds, such as waterhemp, Palmer amaranth and ragweed.

“Timing is important,” said Brad Mason, Pioneer Field Agronomist. “It may seem tempting to delay herbicide treatment in hopes of catching more weeds as they emerge, but it’s not advised.”

Instead, it is recommended for growers to mix up their herbicide applications and modes of treatment to help make sure they are burning down existing weeds and getting some residual protection, he said.

“Do not overuse modes of action,” Mason advised. “For an optimized herbicide program, mix it up every time you’re in that crop,” which provides better control and slows development of potentially resistant weeds.