This plant disease is caused by a fungus (Colletotrichum piperatum) that is a common rot of peppers. Both green and ripe fruit are attacked and become worthless. Occasionally spots may occur on leaves and stems. The fungus is most active in warm (70° to 80°F), wet weather. When it is severe, many fruits become infected in a short period. Heavy dew, overhead watering, fog, and drizzling rain provide the water necessary for infection. The fungal spores are carried on and in seed. Young plants can become infected through the diseased seed, although the disease is not evident until the fruit forms. Spores are spread to healthy plants by splashing water, people, and tools.

This plant disease is caused by a bacterium (Xanthomonas vesicatoria) that also attacks tomatoes. It affects leaves and fruit at any stage of growth. The bacteria are most prevalent after heavy rains and in very warm weather (75° to 85°F). In damp weather, with frequent splashing rains, they spread very rapidly, often resulting in complete leaf drop. Fruit is unsightly but edible if the blemishes are removed. Molds and decay organisms may enter the fruit through the corky spots and rot the fruit. The bacteria are carried on seed and persist from one crop to the next in the soil and on diseased plant parts left in the garden.

A lack of calcium in the developing fruit causes blossom-end rot on peppers, tomatoes, squash, and watermelons. This lack results from slowed growth and damaged roots caused by the following factors. 1. Extreme fluctuations in soil moisture, either very wet or very dry. 2. Rapid plant growth early in the season, followed by extended dry periods. 3. Excessive rains that smother root hairs. 4. Excess soil salts. 5. Cultivation too close to the plant. Damage is most severe on the first fruits. It starts at the blossom end (farthest from the stem), enlarging to affect up to half of the fruit. Moldy growths are from fungi or bacteria that may invade the damaged tissue. Other than the rotted area, the fruit is edible.

Several species of cutworms attack plants in the vegetable garden. The most likely pests of young pepper plants are surface-feeding cutworms. A single surface-feeding cutworm can sever the stems of many young plants in 1 night. Cutworms hide in the soil during the day and feed only at night. The adult cutworms are dark, night-flying moths with bands or stripes on their forewings.

Ostrinia nubilalis This moth larva is a destructive pest of peppers, corn, tomatoes, beans, and eggplant. The worms feed and promote decay inside the fruit. The borers spend the winter in plant debris, pupate in the spring, and emerge as adults in early summer. The adults are tan moths with dark wavy lines on their wings. The moths lay clusters of 15 to 30 white eggs on the undersides of leaves. Overlapped eggs resemble fish scales. In midsummer, the eggs hatch, and young borers enter the fruit at the cap. After feeding for 1 month inside the fruit, they pupate; later they emerge as adults to repeat the cycle. Two to three generations occur per year. Cool, rainy weather in early summer inhibits egg laying and washes the hatching larvae from the plants, reducing borer populations. Very dry summers and cold winters also reduce borer populations. Peppers are edible if the damaged part is cut away.

Manduca quinquemaculata or M. sexta Hornworms feed on the fruit and foliage of peppers, eggplant, and tomatoes. Although only a few worms may be present, each worm consumes large quantities of foliage and causes extensive damage. The large gray or brown adult moth with yellow-and-white markings emerges from hibernation in late spring and drinks nectar from petunias and other garden flowers. The worms hatch from eggs laid on the undersides of leaves and feed for 3 to 4 weeks. Then they crawl into the soil and pupate; later they emerge as adults to repeat the cycle. One generation occurs per year in northern parts of the United States, two to four in southern areas.