Bui. 712, U. S. Dept. of Agriculture. 



Plate I. 





Apple Powdery Mildew— I. 



Fig. 1. — A late stage of foliage infection on Pry or Red watersprouts. Note that many of the 

 leaves have been shed and that those remaining are covered with conidia and are somewhat 

 folded longitudinally. The twigs are covered with mycelium, embedded in which may be 

 seen the dark patches of perithecia, usually located at the base of a leaf and extending up on 

 the petiole. Fig. 2. — Mildew russeting of a Black Ben Davis apple, August, 1916. Fig. 3. — 

 Mildewed blossom cluster from a Pryor Red tree. Note the abundance of conidia over 

 leaves and blossoms and the deformity of the blossoms. 





