Above ground symptoms of rot on peppers or eggplants include rapid wilting and death of affected plants. Tap roots and smaller lateral roots show water-soaked, very dark brown discoloration of cortical and xylem tissue. Very few lateral roots remain on diseased plants and the tap roots may also be shorter compared with those of healthy plants. Stems are usually infected at the soil line and may girdle. Stem lesions are first dark green and water soaked, then later dry and turn brown.
Life cycle
The fungus that causes Phytophthora root and crown rot survives in soil as spores (oospores) for several years. Water, temperature, and soil texture are the major factors affecting the development of root and crown rot. The presence of water is mandatory; soil saturation for as little as 5 to 6 hours can result in infection. Optimum temperature for plant infection is 75 to 92°F. Contaminated seed and transplants or soilborne inoculum are sources of primary infections. Irrigation water often disseminates fungal propagules from infested areas to other parts of the garden. Increased frequency and duration of irrigation favor disease development. Symptoms usually appear following a warm, wet period. The disease is severe in fine-textured soils that drain slowly and in highly compacted soils. The Phytophthora species that attacks peppers and eggplants also affects tomatoes.
Solutions
Plant on raised beds with well-drained soil. In heavy soils that are poorly drained, root and crown rot may be reduced by carefully managed drip irrigation. The disease can be effectively prevented by a program integrating crop rotations of 2 years that excludes susceptible plants (corn, beans, or strawberries would be good rotation choices), with irrigation management, clean seed, and transplants. Some resistant cultivars may be available.
For more information, see the Phytophthora Root and Crown Rot Pest Note.
