- Blossom-end rot can be a serious problem of peppers. It first appears as a small, water-soaked lesion at the fruit's bloom end or along its sides. The lesion enlarges and becomes tan -- it can eventually cover much of the fruit and can be invaded by a secondary pathogen that may turn it darker. This disorder is caused by a lack of calcium, or a demand that the growing fruit has for calcium that exceeds its uptake. To manage for this disorder, maintain a soil pH around 6.5, use nitrate nitrogen for fertilizer and avoid over-fertilization, and prevent drought stress.
- Bacterial soft rot, caused by Erwinia carotovora, first appears on leaves, which develop dark veins but light tissue before progressing to cause dark, dry stem cankers and eventually affects fruit. Fruit lesions initially appear as light or dark-colored, somewhat sunken and water-soaked. Lesions expand quickly and may eventually ooze and be infected by a secondary pathogen. The bacteria responsible for stem rot can be present on seed or transmitted by water or corn borers and infection is most prevalent where there is warm, moist weather and a high fertilization rate. Use proper sanitary practices after handling infected plants, and observe a suitable crop rotation schedule.
- Anthracnose, or ripe rot, is caused by an infection of fungi of the genus Colletotrichum. This pathogen causes the development of circular or angular lesions on fruit; leaves and stems can also host lesions. Pink or orange spores may form in rings on the lesions. The fungus can survive on infected plant debris or seed and is spread during warm, wet weather by splashing water. To avoid anthracnose use treated or disease-free seeds and transplants, rotate crops, avoid overhead watering and, if necessary, apply protective fungicides.
- Peppers infected by Phytophthora capsici can show symptoms on any plant part. If the plant is mature when infected, fruit will be affected from the stem end first. Fruit tissue appears water-soaked, fruit will shrivel and, during wet conditions, white fungal growth may appear. To avoid Phytophthora, do not plant peppers in low, wet fields and practice crop rotation.