340 



Kansas State Board of Agriculture. 



The rust of alfalfa attacks the leaves, occurring on the under side. It 

 is different in appearance from the ordinary leaf spots, in that the epi- 

 dermis (outer layer) of the leaflets is ruptured, exposing a mass of 

 reddish-brown spores or reproductive bodies of the fungus. (See Fig. 

 282.) This spore mass when viewed under the magnifying lens appears 

 to rest in a rupture in the leaf blade. (See Fig. 283.) These ruptures 

 or pustules are only about one thirty-second of an inch in diameter, and 

 they may occur numerously or sparingly on the leaves. (See Fig. 282.) 



FIG. 282. Alfalfa leaf (under side), showing rust postules (enlarged). 



283. A rust postule on an alfalfa leaf, greatly enlarged. 



