Anthracnose of Tomatoes (Black dot)

Colletotrichum coccodes

Black dot can normally be indentified by a dark brown to grey blemish on the potato’s surface. The visable black dots (black microsclerotia) often give the potatoes a ‘sooty’ looking appearance, which can develop into a silvery looking sheen during storage.

Black dot can affect all parts of the plant not just the tubers – stems, roots and stolons can also be infected  Black dot causes wilt symptoms above ground and severe rotting of roots, shoots and stolons below ground, leading to discoloured tubers, plant decline and a reduction in yield.

Anthracnose of Tomatoes. Early symptoms appear on ripe fruit as small, slightly sunken, watersoaked circular spots. The lesions increase in size, become more depressed, and the central portion darkens. The darkened area contains many small, dark, fungal structures from which masses of salmon-colored spores are released in moist weather. As the fungus spreads within the fruit, a semisoft decay occurs. Anthracnose lesions on a single fruit often merge and result in large rotted areas. In addition, secondary organisms often move into these lesions and rot the fruit completely.

The fungus can infect both green and red fruit and is able to penetrate the cuticle of uninjured fruit. When green fruit is infected, it does not show spotting until it begins to ripen. Tomato fruit become increasingly susceptible as they approach maturity. On ripe fruit, lesions become visible within 5 to 6 days after infection.