POWDERY MILDEW OF CHERRY 



99 



cultivated and wild plants belonging to Rosaceae ; it also 

 occurs on species of Vaccinium and Diospyros. 



It appears on young leaves and tender shoots as small 



Fig. i6. — Phyllactinia suffulta. ±, hazel leaf with 

 fungus ; 2, perithecia, a ; appendages, b; mycelium, c; 

 ascus escaping from a perithecium, ^, X75; 3, asci con- 

 taining spores, X300. 



white patches, which soon spread and run into each other, 

 forming a thin white felt ; both surfaces of the leaf are 

 attacked. Chains of conidia are first formed, and later in 



