Oak Mildew

[sean]

Came across this fine example in a verge yesterday.

 

Powdery mildew of oak is caused by the fungus Erysiphe alphitoides (also known as Microsphaera alphitoides) and it is a common foliar pathogen of oak throughout Europe. First found in England in 1908, it was considered a contributory factor in the oak dieback episode the 1920s.

 

Erysiphe attacks young leaves and soft shoots, covering them with a felty-white mycelium, causing them to shrivel and blacken. Mild overcast conditions are optimal for development of the disease, which usually appears in summer when warmer conditions prevail. (Forestry Commission)

[woodyguy]

Commonly and unfairly known as American oak mildew but comes from Mangos in the far east I seem to remember.