Typically, there are two generations of European corn borers in Iowa. The first flight of moths start to lay eggs in mid- to late June while the second flight begins in late July or early August. The reason is that the earliest corn often is planted on the best ground, it grows faster, it should be taller, and therefore is more likely to attract the largest number of first-flight moths when they are laying eggs. Planting a majority of the Bt corn first follows the same reasoning of the first recommendation. By spreading out Bt corn plantings on large acreages, the earliest and latest plantings are protected where most of the yield loss is expected to occur.
Bt corn is a novel tool for managing a serious insect pest of corn.
Because of its rapid development and entry into the market, we are evaluating these planting strategies, plus a spectrum of other research topics. We will keep you informed as we learn more about the management of the European corn borer with Bt corn. Bt corn first. Plant regular hybrids second. Bt corn last.