Why Haven't The Ears On My Corn Developed Well?

Do the ears have tunnels and chewed kernels?

Can you spot any light yellow, green, pink or brown caterpillars up to 2 inches long, with lengthwise stripes?

Can you spot any beige, brown-spotted, up to 1 inch long caterpillars with brown heads?

Have the kernels at the ear tips or upper half been hollowed out?

Are the ears misshapen or with areas of underdeveloped kernels?

Have the leaves been mottled yellow and green?

Is your corn planted in a long row or was there no wind during the pollinating season?

Do the ears or tassels have enlarged galls on them?

Those caterpillars are Corn earworms larvae. Adults are tan moths. Cover plants with row cover until tassels emerge to exclude the first generation of pests, especially if you have had problems in previous years. Spray BTK as soon as any feeding holes are found. Make sure to spray the undersides of leaves and insides of unfolding leaves where pests feed.

European corn borer larvae fit that description. Adults are pale yellow to tan moths with wavy lines on their wings. Cover plants with row cover until tassels emerge to exclude the first generation of pests, especially if you have had problems in previous years. Spray BTK as soon as any feeding holes are found. Make sure to spray the undersides of leaves and insides of unfolding leaves where pests feed.

Armyworm larvae are greenish-brown caterpillars up to one and a half inches long, with a characteristic inverted Y on the head. Adults are pale gray moths and have a 1 and a half inch wingspan. Cover plants with row cover until tassels emerge to exclude the first generation of pests, especially if you have had problems in previous years. Spray BTK as soon as any feeding holes are found. Make sure to spray the undersides of leaves and insides of unfolding leaves where pests feed.

Sap beetles are small, black beetles with yellow spots that invade ears after the silks turn brown. Handpick beetles or spray ear tips with a commercial pyrethrin solution for severe infestations. Sap beetles can be trapped in containers baited with fermenting fruit.

Maize dwarf mosaic virus causes these symptoms. There is no cure. Destroy infected plants. Prevent problems by controlling aphids, which spread the virus as they feed and perennial weeds such as Johnsongrass that can harbor the disease. Tolerant cultivars are 'Bell-ringer', ‘Bi-guard', 'Bunker Hill', 'Earlibelle’, ‘Enforcer', 'Merit' and 'Silverette'.

Insufficient or ineffective pollination can cause undeveloped bare tips, scattered kernels or entirely bare cobs. Plant corn in a block, rather than a long row to ensure effective wind pollination. Insects feeding on silks before pollination occurs can prevent pollination, as can very dry conditions. Control insects that feed on silk and keep the soil moist, but not wet, to ensure even pollination.

Nutrient deficiencies can cause misshapen or underdeveloped kernels. Ears with bare, undeveloped tips can be caused by potassium deficiency. Phosphorus deficiency causes small, irregular ears. If ears are misshapen and kernels have corky, brown bands at their bases, suspect boron deficiency. Spray young plants with seaweed extract or compost tea to help prevent deficiencies.

Corn smut is a disease that causes these symptoms. Young galls are firm and whitish, older ones are spongy and filled with black powder. Remove galls before they split open and destroy infected plants. Do not compost them. Prevent problems by planting resistant cultivars such as 'Bellringer', 'Gold Cup', 'Merit', 'Sweet Sue' and 'Viking'.

If the ears have tips exposed or if they are stripped and missing, suspect animal pests - birds or raccoons. Birds peck at tips of ears, exposed tips turn dry and greenish-brown. Raccoons harvest ripe, juicy corn. Repel birds with loud noises or visual scare devices. Frustrate raccoons by surrounding your com with a 3-strand electric fence with wires 3"-4" apart and off the ground.