Ears with tunnels and chewed kernels.
Causes: Corn earworms; European corn borers; fall armyworms. Leaves and silk may be chewed. Stalks and tassels may be tunneled and may snap off. Corn earworm larvae are light yellow, green, pink, or brown caterpillars up to 2" long, with lengthwise stripes. Adults are tan moths. See page 77 for an illustration of this pest.
European corn borer larvae are beige, brown-spotted caterpillars up to 1" long, with brown heads. Adults are pale yellow to tan moths with wavy lines on their wings. See page 77 for an illustration of this pest.
Armyworm larvae are greenish brown caterpillars up to I'/j" long, with a characteristic inverted Y on the head. Adults are pale gray moths and have a 1 Wi" 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.
Use insect-specific pheromone traps to catch male moths of various pest species, or ask your local extension agent when moths appear in your area. If you are growing large quantities of corn, you may want to try using a blacklight trap to catch all types of moths; be aware that many kinds of beneficial insects are also attracted to and killed by these traps. When moths are present, spray plants with pyrethrin in the evening to prevent pests from laying eggs.
Even before the tassels emerge, check the upright, topmost leaves of your plants every 2-3 days for signs of caterpillar feeding. 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.
Once silks appear, spray them with BTK or sprinkle a few grains of granular BTK directly on each silk. Apply a few drops of mineral oil to each silk 4-5 days after they wilt to discourage any resident pests, or inject a few drops of parasitic nematode suspension around the tip of the ear to kill larvae.
Kernels at tips or upper half of ears hollowed out. Cause: Sap beetles. These small black beetles with yellow spots 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.
Ears with dried tips exposed; ears stripped or missing. Causes: Birds; raccoons. Birds peck at tips of ears, exposed tips turn dry and greenish brown. Raccoons harvest ripe, juicy corn, usually the night before you would pick it yourself. Repel birds with loud noises or visual scare devices. Frustrate raccoons by surrounding your corn with a 3-strand electric fence with wires 3"-4" apart and off the ground. See "Stopping Animal Pests" on page 408 for further information.
Ears misshapen or with areas of undeveloped kernels. Causes: Poor pollination; nutrient deficiency; viral diseases. 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 soil moist, but not wet, to ensure even pollination.
Ears with bare, undeveloped tips can also be caused by potassium deficiency. Phosphorus deficiency also causes small, irregular ears. See page 77 for an illustration of this condition. 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. Confirm deficiencies with a soil test and amend soil as needed.
Viral diseases such as maize dwarf mosaic can cause poor kernel formation at base of ears or bare ears. See "Leaves mottled yellow and green" on page 78 for more symptoms.
Ears or tassels with enlarged galls. Cause: Corn smut. 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'.
Dogwoods are deciduous trees or shrubs, usually with opposite leaves. These plants provide year-round landscape interest with their showy flowers, attractive fruit, striking fall color, and interesting bark. Use dogwoods as specimen plants, in woodland plantings, or as informal barriers.
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