Symptoms of anthracnose appear first as small, circular, slightly sunken lesions on the surface of ripening fruits. Several lesions may coalesce, causing extensive decay of the fruit. Eventually, secondary microorganisms invade the lesions and cause a complete rotting of the fruit. The fungus is capable of surviving in infected plant debris and in the soil. During rainy weather, spores of the fungus are splashed onto the fruit.
Most infection takes place on ripe or over-ripe fruit.
Green fruit also may be infected, although symptoms do not develop until the tomatoes begin to mature. Several cultural practices help reduce the incidence of anthracnose. Mulching around the tomato plants prevents splashing of inoculum from the soil onto the fruits. Staking tomatoes increases air movement and decreases the likelihood of favorable environmental conditions for infection. Avoid overhead watering and remove infected or rotting fruits from the plant.