Bui. 957, U. S. Dept. of Agriculture. 



Plate IV. 



Leaves of Ribes Infected With Cronartium ribicola. Showing Different 



Types of Attack. 



Fig. 1. — Lower surface of a leaf of Ribes aureum infected by Cronartium ribicola. Note the charac- 

 teristic isolated infected areas, with the abundant uredinia closely crowded together. Fig. 2. — A 

 Ribes bud with a single leaf which Ijears normal uredinia. This leaf is relatively old, being 

 stunted in growth by adverse conditions which have held it stationary for several weeks. Fig. 3— 

 Lower surface of an infected leaf of Ribes vulgare, horticultural variety White Transparent. Note 

 the large infected areas merging into a single one. The uredinia are not so closely crowded 

 together as in figure 1. Fig. 4. — Lower surface of an infected leaf of Ribes nigrum. ' Note the 

 general distribution of the telia, their grouping closely together, and their vigor of growth. 



