Apple Powdery Mildew
Apple Powdery Mildew (Podosphaera leucotricha). This fungal disease occurs where ever apples are grown and is particularly severe where climatic conditions favour its life cycle. Severity of the disease depends upon present and past weather conditions, cultivars and control procedures. The disease does not kill trees as such, but losses occur from fruit russetting and general debility of the trees, affecting yield.
Varieties vary in their susceptibility to powdery mildew Cox's Orange Pippin is susceptible whilst Bramley Seedling is less so. Some of the newer apple varieties are extremely susceptible. Pears can be affected by this fungus which has spread from apple orchards nearby.