FORAGE CROPS 



This group of crops, of high aggregate value and agricul- 

 tural necessity, does not possess an acreage value which 

 warrants such expensive modes of treatment as spraying. 

 Protection against disease here must, in general, consist in 

 modifications of agronomic methods tending to produce 

 thriftier, more resistant plants, crop rotation to diminish the 

 parasites, variation of time of sowing or harvesting to evade 

 disease. Forage diseases are especially troublesome since 

 they frequently prohibit planting of certain leguminous crops 

 much desired in the rotation. 



Legumes 

 ALFALFA 



Leaf-spot ^^^' '*^^ (Pseudopeziza medicaginis (Lib.) Sacc.) — 

 No other disease of alfalfa is so universally prevalent. It 

 constitutes the most important, in most sections the only 

 really important, disease of this crop. Loss in vigor of the 

 plants and loss in hay, by shedding of the leaves, result. 

 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 

 visible from both sides. They are about 1-2 mm. in di- 

 ameter, and are not sharply bordered, but shade off grad- 

 ually into the surrounding tissue. With a hand lens very 

 small, spore-bearing organs may be seen in the centers of 

 the older spots, first as shiny amber-colored elevations. 

 These elevations soon crack open and expose very small, 

 cup-shaped sporiferous bodies, which remain surrounded by 

 portions of the ruptured epidermis. Badly diseased leaves 

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