Environmental stress can cause a white core in tomatoes
Chilling injury will cause internal fruit parts to darken. Very hot, dry weather conditions combined with low potassium levels in the soil can cause tomato fruits to develop white, pithy tissue next to the outer fruit wall or near the core. This problem varies depending on the variety grown. Keep plants well-watered during dry periods and avoid tomato cultivars that consistently have this problem.
Gray wall is another fruit disorder of tomato that causes internal fruit wall tissues to turn brown to black and die. The result is that the outer fruit skin breaks down, becomes wrinkled and soft, and develops a gray color. Cool-weather, low light, compacted soil, and excessive soil moisture are all associated with the incidence of gray wall.
Diseases and disorders that cause potatoes and other root crops to rot inside
Various diseases and disorders that cause potatoes and other root crops to rot
A large number of diseases, nutritional and physiological disorders may cause the internal tissues of fruits to become discolored and rot. This is more likely to occur in crops that are harvested and stored - potato, sweet potato, onion, carrot, and other root crops. Only store roots and tubers that are solid and free of insect or disease injury. Handle crops gently and store at the recommended temperature and humidity level. Ensure that air can move freely around stored crops and check them periodically for signs of rotting.