Symptoms and Signs
Powdery mildew starts as white powdery blotches on leaves, leaf stems, and fruit epicarp. Later in the season, these blotches turn brown to black and have a netted appearance. The blotches on fruit become russeted and multiple blotches cause leaves to yellow, turn brown, and die. Infected leaves and fruit may be distorted and misshapen. Similar symptoms can be found on rachises, fruit stems, petioles, underside of leaf blades, and young shoots.
Comments on the Disease
The disease commonly occurs on the Trabonella cultivar. Red Aleppo is more susceptible than the Kerman cultivar.
The occurrence of powdery mildew on pistachio trees is uncommon and sporadic. No management is recommended.