Root and
Crown Rot Complex (fungi and bacteria - Fusarium spp. Verticellium
spp., Phytophthora spp., and others): This complex is one of our most troublesome
alfalfa and clover problems. Stand decline is the most noticeable symptom (Note
Illustration). Decline usually begins during the second year after planting and
gradually becomes more severe. Early symptoms include yellowing and wilting of
stem tips (photo 3) or entire shoots (photo
4) which eventually die. Plants are normally stunted and have an increased
number of small, shortened stems and small leaves. Roots may be rotten or simply
have a few discolored lesions (photo 5). Reddish-brown
streaks are usually evident when the outer bark is removed. Rotting may occur
only at the crown area of the plant (photo 6).
Control is difficult. Use of tolerant alfalfa varieties is often the best method
of control. Do not allow water to stand in a field for extended periods.
