DISEASES OF ALFALFA - VERTICILLIUM WILT

Verticillium wilt is arguably the most important disease of alfalfa in Wisconsin at this time. This disease is caused by the soil-borne fungus Verticillium albo-atrum, which infects and colonizes the plant’s water conducting (i.e., vascular) tissue. Symptoms of the disease are often most easily detected prior to the first harvest during the third year of production. This is because: a) older stands tend to be the ones that have been infected for the longest period of time and thus are most likely to show symptoms, and b) the longer period of time allowed for plant growth prior to the first harvest allows a longer period of time for symptom expression.

From a distance, alfalfa fields affected by Verticillium wilt may have a blotchy mixture of green, yellow and tan foliage. Late in the season these symptoms may resemble damage from feeding by potato leafhoppers.