Infected rachises and shoots develop black, elongated lesions which often split the green tissue. Numerous lesions give the surface a blackened, scabby appearance. Leaf lesions often are numerous with brown or black brown coloration and become covered with black, pimple-like fruiting bodies. These infections usually do not become visible until late summer. When infections on shoots are numerous, they often run together and form dark blotches that crack.
Cluster stems can blight and become brittle if infections are high.
These clusters usually break and the fruit is lost. This fungus also causes a fruit rot. Infected fruit will turn brown, shrivel and eventually drop. In winter, cane infections can be observed. The disease is caused by the fungus, Phomopsis viticola .