1923] 



LEHMAN — POD AND STEM BLIGHT OF SOYBEAN 139 



Seven days after the time of inoculation, 6 of 11 pods inoculated 

 showed definite infection, the fungus having grown through the 

 pod and killed the tissues opposite the point of inoculation. By 

 the end of 14 days from the time of inoculation, 9 pods showed 

 infection and one had formed pycnidia on the diseased area. 

 The fungus was reisolated from these diseased pods and behaved 

 in every way like parallel cultures started from the tube cultures 

 used as the source of inoculum. Inoculations made on the same 

 date as those mentioned above, but with the imperfect strain 

 No. 14, yielded at the end of 14 days 9 infected pods out of 9 

 inoculated. No difference was apparent in the appearance of 

 diseased pods and the course of the disease resulting from inocu- 

 lation with the two strains. 



In a second test, 24 pods were inoculated with the ascospore 

 strain, No. 17, and 17 pods with the imperfect strain, No. 14. 

 By the end of 8 days, 10 of the former and 11 of the latter showed 

 definite signs of infection. At the end of 15 days, 19 of the former 

 and 16 of the latter were diseased. 



By way of summary of the foregoing record of inoculations, 

 it may be said that infection can be accomplished even under 

 adverse conditions of temperature and moisture by inserting 

 the inoculum into the wall of the pod. This method is almost 

 invariably successful where average atmospheric humidity 

 obtains in conjunction with average summer temperatures. 

 Atomizing with spore suspensions does not result in uniformly 

 successful infections except when, by natural or artificial means, 

 a relatively high atmospheric humidity is maintained for several 



days. Such conditions obtain during our usual summer rainy 

 season and may be approximated, although unsatisfactorily so 

 from the standpoint of host reaction, by the use of bell jars in 

 the greenhouse. The results of these inoculations, considered 

 in conjunction with the isolations detailed above, furnish con- 

 clusive evidence that the organism herein described and named 

 Diaporthe Sojae is the cause of soybean pod blight. 



Manner op Infection 



The exact manner by which hyphae of the fungus causing pod 

 and stem blight of soybean enter the plant has not been fully 



