Gradual decline in rate of re-growth after cutting.
Affected plants have as little as a third the normal regrowth after cutting as healthy plants.
If the taproot of chronically infected plants is cut diagonally, the wood of chronically infected plants is slightly yellow with streaks or flecks of dark brown, dead wood instead of the normal white color without dark streaks. This makes diagnosis by symptoms alone difficult and unreliable. As a result, many cases of AD may not be recognized. The chief effect of AD is that a high incidence of the disease may shorten the life span of a typical alfalfa hay field. The slow re-growth of plants with AD may make hay production unprofitable.