Environmental influence on symptom expression in Verticillium wilt of chrysanthemum

Symptom expression in Verticillium wilt of chrysanthemums was found to be correlated with flowering. Regardless of the time of inoculation, symptoms did not appear until buds were apparent on the plants. The number of propagules recovered from these plants increased rapidly as they approached full bloom. The lack of symptoms in vegetative plants was not due to sparsity of either mycelial colonization of the xylem vessels or fungal propagules, but to some other factor.