FORAGE CROPS 377 



do. After ripening of the head, the diseased parts appear 

 shrunlcen. The grain itself is hollow, shrunken, covered 

 with a thick-felted mycelium, and is incapable of germi- 

 nation. 



Only a few spikelets upon the head may be affected, these 

 occupying any position, — basal, terminal, or intermediate, 

 — or the whole head may be diseased. The loss occurs in 

 injury to the quality of the grain and diminution in quan- 

 tity. 



Selby has recently shown that seedlings in the field are 

 often killed by this disease, which is carried over in the seed. 

 In this way as high as 5.9 per cent of death in seedlings has 

 been caused, and it is doubtless chiefly in this manner that 

 the fungus is carried from crop to crop. 



FORAGE CROPS 



ALFALFA 



Leaf spot {Pseudopeziza Medicaginis (Lib.). Sacc). — 

 No other disease of alfalfa is so widely, even universally, 

 present as is this leaf spot. It constitutes the most impor- 

 tant, in most sections the only really important, disease of 

 this crop. It seems to be always, everywhere, under all 

 conditions, present to some extent, and it often becomes of 

 serious importance through the decrease in vigor which it 

 causes, and by the loss in hay brought about by the shedding 

 of the leaves. Pammel in Iowa in 1891 estimated the loss 

 in some fields at 50 per cent. It was first described in 

 Europe in 1832, and noted in the United States in 1875. 



The leaves first show small brown to black spots, irregular 

 or circular, which extend through the leaf and are thus 



