Bean Anthracnose 137 



Infection was also brought about, in an experiment, by placing recently 

 affected vines or pods on or in the soil before the bean plants appeared. 

 On August 8, 1910, vines of the current year badly affected with anthrac- 

 nose were placed in a flat and covered to the depth of an inch with soil. 

 On the surface of this soil, fifty hand-sorted Refugee Wax bean seeds 

 were planted. These were covered lightly with soil. The soil came from 

 a neighboring field that had not produced beans for years. The flat 

 was then placed outdoors and watered once with well water. All the 

 seeds produced plants, which on August 22 were not affected on any part 

 above ground. On August 29 forty-two plants had appeared, of which 

 thirty-five, or 83| per cent, showed lesions on stem, on leaves, or on 

 both. 



On August 22 one hundred clean Refugee Wax seeds were planted in 

 clean soil in a flat and covered lightly with soil. Over the surface was 

 placed a quantity of immature pods badly spotted with anthracnose and 

 producing spores. On September 6 ninety-eight plants had appeared, 

 of which ninety-four, or 95.9 per cent, were infected. 



Halsted (1896:286) has shown how beans planted in ground on which 

 diseased plants were grown the year before, gave from four to six times 

 as many spotted pods as did beans grown on new land; he found also 

 (1896:288 and 1897:330) that mulching the soil with diseased pods from 

 the preceding season caused an increase in the number of spotted pods 

 over those in soil mulched with hay. This would lead to the belief that 

 the fungus is capable of living over winter as spores in the soil or as spores 

 or mycelium in the diseased pods. I * I 



Observations were made each year from 1910 to 1914 to determine 

 whether soil which the preceding year had produced plants badly affected 

 with anthracnose could serve as a source of inoculum to seedlings. 

 Healthy seed planted in such soil gave in every instance seedlings that 

 were free from anthracnose and remained so for a considerable time 

 afterward. 



Tests were made to determine whether the fungus can live over winter 

 in old pods and vines. Badly spotted pods stored in paper sacks in an 

 attic were found during the late winter and early spring to possess a thin 

 black mycelial growth over their surface outside of the old lesions, and 

 scattered thickly in places on this growth were small black bodies 



