Last August, Bruce Potter, plant pathologist at the Southwest Research and Outreach Center office in Lamberton, Minn. said, “So far it’s been a slow year for aphids.” This year, Potter is saying much the same (and plant pathologists don’t like to prognosticate).
Potter’s July 16 newsletter read: “Soil moisture is only one of the factors that can influence early season soybean aphid populations. Areas with early-planted soybeans, soils testing lower in potassium and nearby buckthorn often see aphids first. Fields with hail damage or drown-outs may see aphid populations late in the season if soybean maturity is delayed or soybeans planted late.”
Potter adds, “I start paying attention once I find more than 50 percent of the plants infested with at least one aphid. It’s not yet threshold, but aphids per plant can increase rapidly once most plants have been colonized. Cooler weather this late June/early July may have temporarily stalled some aphid populations. But late July heat and moisture has certainly triggered lots more activity. So my advice to growers … be out there and doing your counts.”
Rich Sigurdson, Olivia, Minn. aerial applicator, had in past seasons employed up to five Piper [SIC] Air Tractors waging war on aphids. And this season, the battle against circospira leaf blight on area sugar beets has been intensive. “Yes, for a few days we had four planes spraying,” Sigurdson said. “During the warm, humid conditions of late June/early July we were respraying some fields every four to five days. The blight was exploding very rapidly.”
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