The alfalfa weevil are active in Wisconsin and could be detrimental to your second cutting. Managing agronomist Steve Hoffman with In Depth Agronomy in east central Wisconsin says this drought isn’t helping. He recommends you sweep your fields and apply insecticide if you find larvae.
“Here in Eastern Wisconsin, we are seeing pretty high levels of alfalfa weevil larvae in the second crop regrowth,” Hoffman says. “These weevil larvae look like small caterpillars, and they can eat the growing crown bud as fast as it grows. Especially in these drought conditions that we have, they can eat at the rate that that alfalfa would want to grow.”
Hoffman says to scout your second crop with a sweep net. The official threshold for alfalfa weevil larvae in second crop is two larvae per sweep. But he recommends when it’s this dry, to lower your threshold to one larvae per sweep. If your field meets that threshold, Hoffman says to apply an insecticide.
“The drought slows the growth rate of alfalfa, so alfalfa would have a hard time outgrowing the damage that these weevil larvae are going to do,” he says.
He says the weevil enjoy dry weather, and with the high heat over the past week, the beetles came out of the woods to lay their eggs. He notes that if the alfalfa weevil larvae are not controlled, they will be a detriment to your alfalfa yield for this second cutting.
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