138 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



[Vol. 10 



A reisolation of strain 7 was used as a source of inoculum. By July 

 7, pycnidia were numerous on stem, petioles, and 2 pods of the 

 older plant of Pot 31, while the younger plant showed no infection 

 of any part. The bell jar was removed from this pot at this 

 date. In Pot 27, the oldest pod bore pycnidia and infection was 

 evident on 2 other pods, while no infection was manifest on the 

 younger plant. By July 13, 8 pods of the older plant in Pot 31 

 bore pycnidia. No pycnidia were present on pods of the younger 

 plant, but numerous small browned spots, points of infection, 

 were visible. In Pot 27, the older plant had shed all its leaves 

 and pycnidia were present on the stem, petioles, and all the pods. 

 The younger plant maintained the green color of its leaves and 

 infection was apparent on 3 pods but no pycnidia had yet de- 

 veloped. 



On September 22, 2 plants bearing 7 pods each were inoculated 

 by inserting pycnidial material of strain 7 into the pod walls. 

 The plants were then covered with bell jars for 2 days. By the 

 end of the seventh day, 8 of these pods gave visible evidence 

 of infection. The plants were destroyed by rats before further 

 observations could be made. 



Inoculations have been made at various times by placing pods 

 ranging from very young to full-grown and mature in moist 

 chambers and spraying them with suspensions of spores. Under 

 these conditions pycnidia develop on all pods regardless of 

 stage of maturity in from 9 to 12 days. 



In order to test the pathogenicity of the ascospore-producing 

 strain, it was necessary to use cultures arising directly from 

 ascospores. By following the usual procedure, cultures of strain 

 17 were obtained which are known to have arisen from a single 

 ascus. On March 11, 1923, inoculations were made on the pods 

 of plants growing in the greenhouse at the Missouri Botanical 

 Garden. These pods varied in the state of maturity from those 

 in which the ovules had not begun to swell to those which were 

 fully half mature and 1}4 inches long. Inoculations were made 

 by inserting crushed perithecia into the tissues of the pod wall, 

 using due precaution not to puncture through into the cavity. 

 The plants were covered with newspaper for 48 hours to prevent 

 the wounds from drying before the fungus could start growth. 



