Bean Anthracnose 195 



beans with these as a basis for hybridization is being made, the resistance 

 being readily tested by artificial inoculation in the field, the cold frame, 

 or the green-house. Selections can be made of large numbers of indi- 

 viduals by artificially inoculating them while in the seedling stage. Any 

 showing marked resistance can be allowed to mature seed, and further 

 tests can be made with them. Investigators are beginning to realize that 

 the selection of plants resistant to disease is a most practical and satis- 

 factory method of disease control, and even now work of this kind is 

 engaging the attention of phytopathologists to a very marked degree. 



As already stated (page 149), there are many varieties of beans which, 

 while susceptible to one strain of the pathogene, are resistant to the 

 other. It has been observed that often only one variety of beans is grown 

 in a given locality; for example, Shepard (1919) reports that in 1918 pea 

 beans constituted 76 per cent of all beans grown in Orleans County and 

 77 per cent of all grown in Monroe County, while in Yates County only 

 6 per cent of all beans are pea beans while 30 per cent are White Marrow, 

 29 per cent are Yellow Eye, and 15 per cent are Red Kidney. It happens 

 that the pea bean referred to is susceptible to strain alpha of the pathogene 

 but resistant to strain beta, while the other varieties mentioned are 

 susceptible to strain beta but resistant to strain alpha. It is very likely 

 that in regions where the pea bean is grown, strain beta does not exist 

 to any great extent, and the introduction of clean seed of varieties resistant 

 to this strain, even if susceptible to the other, would give crops of these 

 varieties free from anthracnose for a few years. "Eventually the beta 

 strain would appear, and, its host being prevalent, would develop 

 abundantly in years favorable for it. Similar results could be expected 

 from the introduction of the pea bean, or any other variety resistant 

 to the beta strain, into localities where this strain is the only one prevalent. 

 There are other factors, to be sure, which tend to discourage a change 

 in varieties in a given locality, and these have largely operated to prevent 

 such changes. 



Consideration of prophylactic measures 



Bean anthracnose occurs to a serious extent in New York only during 

 two or more wet seasons in succession, and the losses occasioned at such 

 times are often forgotten by the grower in the dry seasons that intervene. 

 It is a question with him then whether the time and the money needed for 



