Soft, sunken spots
Sunken, dark spots can be caused by more than a dozen species of Colletotrichum, the fungal disease known as anthracnose. Affected crops include pepper, bean, tomato, eggplant, cucumber, muskmelon, watermelon, pumpkin, spinach, and pea. Sunken black lesions develop that may be covered with salmon-colored spores under wet, humid conditions. On tomatoes, the soft sunken lesions develop dark centers. The fungus overwinters in seeds, soil, and plant residue.
Lay a mulch of shredded leaves, dried grass clippings, or newspaper covered with straw under plants. Pick fruits regularly and quickly remove infected fruits. Avoid contact between soil and fruit. Avoid overhead watering during humid, cloudy weather. Remove all plant residue at the end of the growing season. Infected plant residues can be composted at sustained high temperatures- greater than 120° F. Otherwise, residues should be bagged up and discarded as garbage.