VEGETABLE AND FIELD CROPS 205 



as the most serious disease of the lima bean. It was first 

 observed by Thaxter in 1889.' 



Upon the pods the disease appears as dense, woolly-white 

 growths in irregular patches. These consist of myriads of 

 the spore-bearing hyphae of the causal fungus, laden with 

 their spores. 



The mildew also attacks young shoots, petioles, flower 

 clusters and leaves, causing them to develop in dwarfed, 

 imperfect fashion and destroying their value. 



The spores are largely carried by nectar-seeking insects, 

 as is shown by the abundance of flower infection. Spores 

 are also carried by wind. Even in a season favorable to 

 the development of the disease tliorough use of Bordeaux 

 mixture, three sprayings, M'ill insure the crop. The de- 

 struction of infected trash is advisable. 



Southern blight (Sclerotium Rolfsii, Sacc. in litt.). — 

 The symptoms are wilting of the leaves, temporary re- 

 covery, yellowing, djdng, and eventually dropping. The 

 fungus usually attacks the plant just below the surface of 

 the ground, invades the cambium, and destroys it." For 

 further details see pepper. 



Leaf blotch, cercosporose {Cercospora cruenta Sacc). — 

 This occurs only upon the foliage as brownish patches, 

 causing the leaves to fall away. The spots are large, 

 angular, and limited by the vines. 



Leaf spot, isariopsose {Isariopsis griseola Sacc). — 

 This disease is chiefly limited to the foliage, producing 

 small, angular spots, over the undersurface of which the 

 fungus forms a gray, moldy covering. 



Pod blight (Phoma subcircinata Ell. & Ev.). — Phomose 



> Thaxter, R., Bot. Gaz. 14, 273, November, 1889. 



