Start Clean, Stay Clean Planting into a weed-free field, applying residual herbicides and knocking back that first weed flush reduces competition and yield loss. By Amanda Huber Reduce Weed Competition: • Plant into a clean field and use preemergence herbicides quickly. • Preemergence herbicides work on germinating weed seed, not growing plants. • Be proactive with the use of residual herbicides. • Weeds must be actively growing to absorb postemergence herbicides. • Herbicide efficacy is reduced when applied to weeds under stress, such as drought. • Use enough spray volume to achieve good coverage. • Do not delay herbicide application to wait for more weeds to emerge. • Scout frequently, and read pesticide labels.
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big part of getting the crop off to a good start is managing weeds. The key is planting into a clean field and then applying preemergence herbicides as quickly as possible behind the planter. Timely irrigation and/ or rain will be needed to activate the herbicide and prevent weeds from emerging. As with most farming activities, this is easier said than done, especially where Palmer amaranth is concerned. University of Georgia Extension Weed Specialist Eric Prostko says, “You can’t plant into a field where pigweed is already up. You need herbicides or tillage or both.” Still Learning About Pigweed Learning to manage Palmer amaranth has taken years for any grower who has encountered it. Even now, lessons are still being learned, sometimes painfully. “I had a call from a grower who let pigweed get 4 to 5 feet tall in a field,” Prostko says. “Before planting, he mowed the whole field and then rototilled it twice. All the weeds were pretty well chopped up, and he thought he had done a good job. He planted and put out a preemergence herbicide. “A week later he called to say the preemergence herbicide didn’t work. In the field, the chopped-up plants had rooted back and were growing again. “Preemergence herbicides do not work on growing plant material. Preemergence herbicides work on seeds that are germinating,” he says. “What the grower spent going through the 100-acre field, rototilling twice, herbicide, all that was money lost. The pigweed was not controlled, and now it was growing in the field and interfering with the growth of his peanut crop.”
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THE PEANUT GROWER • APRIL 2020
PEANUTGROWER.COM
