POWDERY MILDEW OF CHERRY 



99 



cultivated and wild plants belonging to Rosaceae ; it also 

 occurs on species of Vacdnium and Diospyros. 



It appears on young leaves and tender shoots as small 



Fig. 16. Phyllactinia suffulta. i, hazel leaf with 

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

 ascus escaping from a perithecium, e ) X7$; 3, asci con- 

 taining spores, x 300. 



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 



