Preventive treatments are recommended in nurseries having a history of serious Cylindrocladium leaf spot and wilt problems. Web Blight Web blight is a leaf and stem blight of Kurume and Satsuki hybrid azaleas caused by the soil fungus Rhizoctonia solani . The disease is a problem primarily in nurseries on container-grown azaleas. Warm, humid conditions are needed for disease development. Web blight may also appear on plants in winter storage under plastic.
Damage is heaviest on closely packed containers or liners irrigated with overhead sprinklers.
Irregular brown spots appear along the leaf margin, rapidly enlarge into irregular brown to black blotches, and advance toward the mid-vein until the leaf dies. Blighted leaves usually cling to diseased shoots. Blighting of the foliage usually starts on leaves closest to the soil like and spreads towards the shoot tips. Irrigate azalea container stock and liners at mid-day to reduce the time the foliage remains wet. Spacing out container stock to improve air circulation can reduce the spread of this disease.