Bean Anthracnose 



131 



pinkish, pasty masses. As already mentioned, if the acervulus remains 

 dry these spores harden down to little gray or brown granulations, and the 

 spores are seldom set free under such circumstances. Ordinarily the 

 lesion becomes wet with soil moisture or later with rain or clew, and then 

 the spores separate from one another and become suspended in the water. 

 Sometimes the entire seed becomes enveloped by a moldy growth of the 

 fungus and fails to germinate; but when a diseased seed is viable and soil 

 conditions are favorable, spores may be produced in the diseased parts 

 of the cotyledons by the time they have appeared above ground. If the 

 soil is sufficiently moist as the seed is emerging from the ground, spores 

 are set free and these are able to infect the young and tender stems. 



Infection of the seedling from affected seed 



The plumule, consisting of the young leaves, is during germination 

 and for a short time thereafter in intimate contact with the cotyledons 

 (fig. 13). The water containing the suspended spores, by capillarity and 



FlG. 13. SEEDLINGS PHOTOGRAPHED TO ILLUSTRATE MANNER OF INOCULATION OF JUVENILE 

 LEAVES FROM SPORES PRODUCED ON COTYLEDON 



Seven-eighths natural size 



