By now you have heard the story: there are two economic thresholds suggested for managing soybean aphids--10 or 250 aphids per plant. The difference is remarkable for anyone who has scouted for soybean aphids in Iowa. At 10 aphids per plant, it's hard to imagine a year when we would not treat possibly millions of acres of soybeans in Iowa. Although 10 aphids per plant can reproduce into hundreds if not thousands per plant, this type of dramatic outbreak has not occurred consistently in Iowa. During the 2004 growing season, it was uncommon for fields in Iowa to reach even 100 aphids per plant.
Iowa State University
O'Neal, Matthew E., "Different thresholds, different states: Why?" (2006). Integrated Crop Management News. 1181.
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