Some diseases affecting green pepper plants can easily be confused with other types of problems. Early detection and treatment of common plant diseases could save this year's crop. Understanding more serious issues helps gardeners avoid problems next season. Avoid many diseases by using good planting techniques and choosing disease resistant varieties.
Root diseases often begin because of tight soil structure--heavy clay or soil low in organic material--and poor drainage. Grow seedling pepper plants in good potting soil to avoid damping off illness that quickly kills new plants. Don't overwater. Older plants may suffer from root rot due to over watering. Leaves of affected plants wilt and roots turn brown and soft. Avoid illnesses due to soil fungi by planting in raised beds and well drained areas.
Crown Rot first affects the stem of the pepper plant just above the soil. Infected soil overwinters the disease and the infection is more common in wet areas. Black lesions girdle the stem, sometimes hidden beneath a layer of green tissue. The spatter of heavy rain spreads disease spores to other plants. Infective droplets spawn black lesions on branches of mature plants, killing the affected part. Planting on raised beds or mounds helps drain water away from plant stems and prevents the disease from taking hold. Destroy infected plants--don't throw them on the compost heap.
White mold spores survive in soil for years after the first occurrence of the disease. During extended periods of wet weather patches of cottony white mold appears on the stems and branches of pepper plants and other common garden vegetables. Space plants wide enough to allow good ventilation. The extra sunlight and air movement controls moisture levels and prevents serious damage. Crowded plantings provide perfect conditions for mold growth.
Anthracnose fungus attacks both leaves and fruit, causing black lesions that soon develop a pus-like central mass of spores. Remove and destroy affected fruits. Fungicides control the spread of the illness. Maneb and Cabrio are both effective treatments. Anthracnose and other fungal diseases persist in soil. Rotate crops even in small gardens. Work plenty of organic matter into the soil each year but don't plow infected plants under. Spots on immature peppers don't always mean disease. Direct sunlight can sunburn the new fruits and cause small brown patches. Sunburn damage does not turn black.
Many common weeds harbor the cucumber mosaic virus. Aphids moving from plant to plant spread the disease to garden vegetables including peppers. Interplanting peppers between rows of corn gives some protection, as does controlling weeds in and near the garden. Thrips, a common garden insect, transmit another problem--the tomato spotted wilt virus. Smoking tobacco may spread the tobacco mosaic virus to garden plants. Viral infections cause stunting of plants and curled and spotted leaves. Buying certified disease free seed each year ensures a clean start.