DISEASES OF ALFALFA AND CLOVER 



Charles Gregory, Ithaca, N. Y, 



Assistant Professor of Plant Pathology, Cornell University. 



LEAF SPOT 



(See introductory paragraph under diseases of timothy, page 



2757.) 



Leaf spot, Pseudopeziza medicaginis (Lib.) Sacc, is always 



found on alfalfa and clover leaves, and sometimes on the stem. It 



is particularly severe during rather dry seasons. 



On alfalfa there are pro- 

 duced small yellow spots, 

 which, if abundant, will 

 cause dropping of the 

 leaves. The new leaves 

 may become infected as 

 they develop and each new 

 period of infection results 

 in new spots on all leaves. 

 Hence the older, lower 

 leaves are most severely 

 diseased and are first to 

 drop. The abundant up- 

 per foliage will mask the 

 diseased condition of the 

 lower leaves unless the 

 trouble is particularly 

 severe. 

 On clover, the spots are large and brown. It may cause drying 



and withering of the leaves and petioles, but the leaves do not fall 



from the plant as in alfalfa. The disease is not so serious on 



olover. 



There is no practicable control method. The only thing to be 



done is to cut the crop before the disease becomes too severe and 



thus save as many of the leaves as possible. 



[718] 





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Fig. 670.- 



The Leaf 



FALFA. 



Spot on Al- 



