Bean Anthracnose. 295 



taken on the point of a pin and placed in a drop of water. Only one 

 of these tiny spores is necessary to start a spot. Under favorable 

 conditions these spores spread from pod to pod until practically every 

 bean in a large field may be affected." 



CONTROL OF THE DISEASE. 



In considering the methods of combatting this disease three or four 

 possible means are presented. First, seed treatment; Second, spraying; 

 Third, the planting of clean seed; Fourth, selection and breeding of 

 resistant or immune varieties. 



Seed treatment. — As pointed out above this is of doubtful value, 

 and cannot be recommended, at least not from investigations yet made. 

 If some method of eradicating the disease by treating the seed could 

 be worked out, it would certainly be the most acceptable means of 

 getting rid of so troublesome a fungus. At present, however, the grower 

 cannot afford to spend time and money along this line. It is a problem 

 for the experimentor alone. 



Spraying. — This also has been quite fully discussed in the criticism 

 on bulletin 239, and need receive no further consideration here. 



Clean seed. Clean seed will grow clean beans. — It is on this proposi- 

 tion that most of the work of our future investigations on this disease will 

 be based. When the writer found that neither the sorting of the seed, 

 nor the spraying of the fields proved effective in practice, he turned 

 his attention to the matter of clean seed. From a very careful study 

 of the fungus that caused the disease, and from observations which he 

 had made in the field, it seemed pretty conclusive that the fungus 

 is carried over from one season to the next, largely, if not entirely in 

 the seed. If then, some method can be found by which perfectly clean 

 seed can be obtained, the problem will be solved. Several experiences 

 have pointed to the conclusion that this would work out in practice. 

 A variety of Black V/ax beans were brought by the writer from Indiana 

 in the spring of 1904, and planted in a garden where no beans had been 

 grown, at least for many years. These beans gave a crop perfectly 

 free from the anthracnose and this was more remarkable, since prac- 

 tically all of the beans whether of this or other varieties, grown in neigh- 

 boring gardens were badly spotted that season. Seed saved from this 

 crop was planted the following season, 1905, in a garden where, the pre- 

 vious season, beans had been badly affected with the pod spot. More 

 than that, they were planted in almost the identical place where the 

 diseased beans had been grown in 1904. Again, they gave a crop 

 perfectly free from the anthracnose, while as before the same variety 



