There are several reasons for ears falling off of corn plants. Ear droppage may be caused by both genetic and environmental factors. Corn breeders try to discard the experimental hybrids with a tendency to drop ears and select hybrids with good ear retention.
• I had observed a lot of European corn borer damage in conventional corn fields this year in July. Larvae of second brood of borer can tunnel into the shank and weaken the attachment of ears to the shank.
• During crop scouting recently, I noticed several dropped ears in a corn field. Investigation revealed that corn borers were one of the causes of ear droppage in conventional hybrids.
• Check the shank attachment of each hybrid. Select those with strong attachment with good ear retention characteristics.
• Select hybrids with tolerance to Diplodia ear rot, the whitish fungus that usually starts at the base of ears, causes ear rot and can result in ear droppage as well. This disease can also causes stalk rot.
• If you are going to use conventional hybrids for premium or other reasons, make sure to use appropriate insecticides to control corn borers during the appearance of the first brood. Otherwise, my advice is to use corn borer resistant Bt hybrids. The Bt trait really works great and protects plants throughout the life of the corn plant.
• Now is a good time to walk your corn fields and notice if one hybrid is better than the others in this regard. Check with your seed rep for hybrids with good ear retention and tolerance to Diplodia ear and stalk rot.