By Dave Nanda, Ph.D., Director of Genetics and Technology for Seed Consultants, Inc.
One of my customers producing non-GMO corn for premium recently expressed some concerns that later planted corn will get more corn borers. Should he switch to a Bt hybrid?
It is known that late plantings of corn are more subject to corn borer infestation than earlier plantings. However, those fields are more vulnerable when everything else around them is planted earlier. Then the moths are attracted to the later-planted fields because they prefer that stage for laying eggs.
One should also consider how often the corn borer is an economic factor. While it’s a factor almost every year in Iowa and the western Corn Belt, it’s a major factor only two to three years out of 15 in Indiana and Ohio. The risk of corn borer pressure would be higher this year due to later planting of all corn, but risk is relative and difficult to quantify. If the farmer has a non-GMO contract for a premium, and these non-GMO hybrids typically yield as well as GMO hybrids, then he may choose to stick with the non-GMO hybrids.
However, be prepared for more stalk rot and ear droppage if severe corn borer infestation occurs. In my tests with isogenic hybrids comparing Bt vs. Non-Bt hybrids, the Bt hybrids would add 1% to 2 % grain moisture to the Bt counterpart, perhaps because of better plant health in the presence of the corn borer.
For someone without a non-GMO contract, considering switching to a BT hybrid, if available, and if you can find one at the same yield level that fits your climate and soils, it might be worthwhile insurance. Factors to consider might be losing the premium, paying extra for the price of the seed and delay in maturity.