LEGUMES FOR SEED 



227 



pounds of copper sulphate, 4 pounds of stone lime to 50 gallons of water. 1 

 Too strong a solution may injure the plant. The first application should be 

 made when the first pair of true leaves begins to unfold, about two weeks 

 later, and again when pods are forming. Lands for beans should not receive 

 manure made by feeding bean straw, especially if the straw is diseased. 



Bean blight is a bacterial disease, producing on the leaves and pods large 

 watery patches. On the leaves the spots become dry and brittle, and on the 

 pods soft and rotten, but not shrunken and black, as in anthracnose. The 

 pods are not destroyed unless attacked when they are young, but the bacteria 

 may gain entrance to healthy appearing seeds, and thus 

 propagate the disease when these seeds are planted. It is 

 much less common and destructive than anthracnose. There 

 is no demonstrated method of combating the disease. Seeds 

 which have come from affected fields should not be planted, 

 and the tops from such fields should be destroyed by fire, 

 and the fields so affected should not be used for beans for 

 some years, although the length of time a field may remain 

 infested is not known. Spraying as for anthracnose, but 

 oftener, is, however, recommended. 



Bean rust is a fungous disease occurring principally on 

 the under side of the leaves, and rarely upon the stems or 

 the pods, producing small rusty-brown or black spots. It is 

 rarely destructive. As the disease winters in the old leaves, 

 burning the tops is recommended. It is said to be combated 

 by spraying as for anthracnose. This disease also occurs on 

 the cowpea. 2 The downy mildew (Phytophthora phaseoli 

 Thax.), occurring on lima beans, has not been reported on 

 field beans. 



Sean seedling 

 showing the 

 anthracnose 

 spots on stem 

 and seed 

 leaves. 



(After Halsted) 



271. INSECTS. While there are a number of insects, 

 which may damage field beans, such as bean leafbeetle, bean 

 ladybird, blister beetles, cutworms and other caterpillars, 

 plant-bugs, leaf-hoppers and plant lice, the special and most 

 destructive enemy of the bean is the common *bean weevil 

 (Brnchus obtectus Say). 8 This insect and the fungus, an- 

 thracnose, are the two great obstructions to the culture of beans. It is impos- 

 sible to raise field beans extensively south of the forty-first parallel on account 

 of the attacks of this insect, even were the climate suitable. It indeed may be a 

 question whether it is the climate or this insect which restricts its culture. The 

 bean weevil is a brownish beetle about one-eighth inch in length. The eggs are 

 laid in the green pods in the fields. The larvae find their way into the maturing 

 beans and continue to breed in the stored seed. A large number may develop in 

 a seed. They are thus capable of exhausting fhe bean and ruining it for any 



*New York Cornell Sta. Bui. No. 239 (1906), p. 207. 

 2 Iowa Sta. Bui. No. 61 (1902), p. 139. 



8 "Insects injurious to beans and peas"; in U. S. Dept. Agr. Yearbook 

 1898, p. 233. 



