A fine, grayish to violet fungal growth can be seen on the underside of affected leaflets. Downy mildew is most likely to be a problem in the spring. Varieties with resistance to downy mildew are available. Contact your district agriculturist for information on resistant varieties. If mildew is severe in the spring, do not delay the first cut.
Harvesting removes most of the infected tissue and reduces the humidity in the crop canopy.
Warmer summer temperatures will reduce the chance of mildew damage to the regrowth. Rotate with non-legume crops. Phytophthora Root Rot Phytophthora root rot. Phytophthora root rot is only severe in wet or poorly drained soil. Low soil temperatures and high clay content also increase the risk.