174 



Bulletin 395 



sclerotial and from cinnamon buff to maroon in color. On cellulose 

 agar the fungus grows very slowly, there being only a slight digestion 

 of the cellulose in the immediate proximity of the fungous mass. 



Conidia are seldom produced in culture, and some difficulty was 

 experienced in obtaining spores for use in inoculation experiments. It was 

 found that a sudden change in the humidity of the culture brought about 



a production of 

 conidia in suffi- 

 cient numbers for 

 use. It is to be 

 noted, however, 

 that the produc- 

 tion of conidia is 

 not continuous. 

 The fungus was 

 removed from a 

 dry atmosphere 

 to very moist con- 

 ditions. This sud- 

 den change caused 

 a production of 

 conidia almost 

 immediately, very 

 similar to the man- 

 ner in which they 

 are produced in 

 nature. Small 

 conidiophores 

 arise over the 



The older cells are globose and usually filled with oil globules and red fuUgOUS maSS and 

 pigment. The mycelium is from a culture on potato agar. X1132 . i-i 



bear conidia which 

 are similar to those occurring on the canes. When Plectodiscella veneta is 

 grown continuously under moist conditions, few or no spores are produced. 



Fig. 20. MYCELIUM OF PLECTODISCELLA VENETA 



INOCULATION EXPERIMENTS 



Inoculations with spores from the Gloeosporium stage 



The proof of the pathogenicity of the fungus depended on its constant 

 association with the anthracnose until 1910, when Lawrence made a few 

 inoculation experiments. He used the fruits of the blackberry, and inocu- 

 lated them with conidia from the leaves and the canes. He was unable 



284 



