Do aphid infestations differ among planting dates?
Initial colonization reflects proximity to buckthorn and planting date. Populations build up more rapidly in earlier planted fields. As the summer progresses, aphids re-distribute locally and preferences shift toward younger, relatively uninfested fields. Then as long-distance dispersal becomes more prevalent and soybean canopies close, soybean aphids become more equal-opportunity colonizers. Regrowth after hail damage provides an abundance of succulent, young foliage thats extremely attractive to aphids. Should thresholds be adjusted for drought conditions? The current economic threshold (250 aphids/plant average on 80% or more of the plants economic threshold (ET) and economic injury level (EIL) of 4000 cumulative aphid-days were developed from data gathered under drought conditions. Aphids aggravate drought stress on soybean so theres less room for error. Monitor soybeans closely and treat as soon as possible after populations exceed threshold. Removing the damaging aphid population
