198 DISEASES OF ECONOMIC PLANTS 



BEAN 



Pod spot, anthracnose {Colletotrichum lindemuthianum 

 (Sacc. & Magn.) B. & C.). — First described in 1878 

 in Germany, this disease is very widely known and is 

 especially destructive. It develops so rapidly that beans 

 delivered to the cars for shipment in apparently healthy 

 condition may, upon arrival at their destination, be quite 

 badly spotted. The loss is often 20 per cent, and occa- 

 sionally is reported as total. 



Upon the pods the disease appears as dark-colored spots, 

 usually sunken, varying in size from 1-10 mm., or more if sev- 

 eral spots coalesce. The border of the spot is often tinged 

 with red, the center rust colored. Old pod spots overly- 

 ing seeds within cause spots upon these seeds. The pod 

 spots are much more noticeable and unsightly upon light- 

 colored than upon green beans. 



Upon the stems and leaves similar spots are found. 

 They are especially noticeable upon young stems still 

 blanched and upon the seed leaves. On older leaves they 

 may be upon the veins, blackening and killing them and 

 bringing death to the leaf. Leaves are thus often entirely 

 cut off from the plant. 



The wax varieties are especially susceptible, while the 

 limas are quite resistant. 



The fungus is carried to fields largely by diseased seeds, 

 by beans bearing the spots above mentioned. Such seeds 

 result in infected seedlings which serve as a multiplying 

 ground for the fungus and result in its spread and general 

 attack upon the field. 



In fields where the disease is well established upon stems 

 and leaves the damage is great in loss of starch-producing 



