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Soybean aphids popping up
Is it going to be a big year for soybean aphids?
The bugs are out there, Corn Belt crop experts say. But, thus far, numbers are far from economic thresholds, leading many to suggest a wait-and-see attitude when it comes to taking on the pest as August -- the most critical month for soybean development -- begins.
"Reports from northern and central Indiana counties, including our scouting efforts at the Diagnostic Training Center, reveal that soybean aphids are present, but in very low numbers," says Purdue University entomologist Christian Krupke. "We are finding infestations of just one to five aphids on a plant (and most plants have no aphids), usually a female surrounded by offspring."
Adds Ohio State University Extension entomologist Ron Hammond: "Surveying fields in areas of northern Ohio suggests that the soybean aphid continues to build up in numbers and in fields infested . . . these newer finds showed very low aphid numbers, with only a small portion of the fields infested at the current time. Most aphids are being found in the new growth at the top of the plant."
So, aphids are out there, but in numbers certainly far below those that warrant treatment right now. But will that threshold be reached? Right now, Krupke says weather conditions are in the bug's favor.
"It has been several years since Indiana producers have had to manage this pest, but this may be a year when we break the trend in some fields," he says. "The dry and cooler temperatures we are experiencing presently favor soybean aphid reproduction, so soybean fields should be scouted very soon."
There's more to it than just weather, adds Hammond. Depending on your location, migrations of larger aphid populations could put your fields at greater risk, making scouting a high priority moving into August.
"A close watch should be kept on fields in the northern third of Ohio to prevent aphid populations from reaching economic levels. Whether future buildups come from aphids currently in the field or from migrations from states (especially Michigan) and provinces (especially Ontario) to our north where economic populations are already occurring remains to be seen," he says. "But there is no doubt that we will have fields in Ohio that reach economic levels in August. Remember that the threshold for treatment is 250 aphids per plant."