This disease is caused by the fungus Mycosphaerella ligulicola . Early infection may cause blasting of the buds. This disease is caused by the fungi Stemphylium and Alternaria . These fungi cause brown or white necrotic specks surrounded by colored halos on the fully expanded ray florets when humidity and temperatures are high. This disease is caused by the fungus Botrytis cinerea .
Leaves show brown water-soaked spots.
Infected parts become covered with a grayish-brown, powdery mass of spores. This disease may be confused with Ray Blight disease. This disease is caused by Erwinia chrysanthemi . The most pronounced symptom is a rot of the upper part of the stem, resulting in wilt and collapse of the distal portion. Infected cuttings may show a brown to black decay at their bases.