176 



Bulletin 395 



masses were then transferred to sterilized bean pods in tubes containing 

 several centimeters of water. The bean pods served primarily as supports 

 on which the fungus could be placed above the water. The cultures were 

 then placed in an incubator at a temperature of 24° C, and by the end 

 of three days a sufficient number of conidia were produced. By dropping 

 the fungous mass into a small quantity of water the spores readily fell 

 off and could be sprayed on the infection court. The germination of these 

 conidia was fairly rapid, a germ tube being developed in about five hours; 



but the proportion of germination 

 was low, in most cases between 

 five and ten per cent. 



Early in the winter of 1 914-15 

 a number of roots of the Colum- 

 bian variety of raspberry were 

 planted in the greenhouse. Owing 

 to the earliness of the dormant 

 period and to the unfavorable 

 conditions within the greenhouse, 

 the plants grew slowly and gave 

 a very stunted growth. All in- 

 oculation experiments with these 

 plants gave negative results. As 

 already stated, the anthracnose 

 lesions appear only on tender 

 succulent canes, and apparently 

 the canes which had developed 

 slowly on the green-house plants 

 were too hard and woody for the 

 fungus to infect. 



Later, about the first of March, 

 191 5, a few raspberry plants of 

 a red variety, which were tender 

 and growing rapidly, were pro- 

 cured. On March 4 two canes were sprayed with a suspension of conidia 

 from a culture of the fungus developed from a single ascospore, and the canes 

 were covered with bell glasses lined with moist filter paper. These glasses 

 were plugged at the top with cotton and allowed to remain over the canes 

 for two days before removing. Two other canes in the same bed remained 

 untreated. On March 20, small purple spots had appeared on one of 

 the canes. These infections grew slowly, much more slowly than an 

 anthracnose lesion developing in the field, but spots typical of those caused 

 by Gloeosporium venetum were produced. Microscopical examination of 

 the spots showed conidia of Gloeosporium venetum. 



286 



Fig. 21. ANTHRACNOSE LESIONS OX CANES OF 

 BLACK RASPBERRY PRODUCED BY AJiTIFICIAL 

 INOCULATION 



The canes were inoculated on April is, 1915, with 

 spores from a culture of Pleclodiscella venela which had 

 developed from a single ascospore 



