242 MAINE AGRICULTURAI, EXPERIMENT STATION. I913. 



decay of apple fruit but that strains of one species are more 

 actively parasitic than the others. 



Inoculations oe Pears. 



Three pears were inoculated September 16, 1909, with mate- 

 rial of F II from apple. The fungus spread rather rapidly 

 through the tissues and caused the complete decay of the pears. 

 The mycelium of the fungus grew out over the surface forming 

 little tufts. 



August 16, 1910, 3 green pears in each case were inoculated 

 with F I, II and III from apple and with F XII, the organism 

 carried as F. putrefaciens. Eight days later each of the pears 

 showed a decayed area about one cm. in diameter. F XII and 

 F I grew out around the points of inoculation producing myce- 

 lium of a dull red color. F II and III showed white aerial 

 mycelium at the points of inoculation and Fusarium II was pro- 

 ducing large numbers of spores, most of which were of the 

 obovate type although some septate spores were observed. One 

 month after the time of inoculation the entire surface of each 

 pear inoculated with F XII or with F I was covered by myce- 

 lium which showed red, yellow and white colors. These two 

 fungi gave a very similar appearance on the decaying pears. 

 Fig. 112 to 114 are illustrations showing the extent of the decay 

 17 days after the time of inoculation. 



Potato Inoculations. 



Potato tubers have been inoculated a number of times with 

 each of the Fusarium forms isolated from apples as well as 

 with forms from other sources. The potatoes were inoculated 

 by making a small injury with a sterilized needle or scalpel and 

 placing in this a small amount of fungus material from a pure 

 culture. The inoculated tubers were kept in closed glass jars 

 at the temperature of the laboratory. Nearly all of the fungi 

 made some growth at the points of inoculation but this did not 

 spread into the uninjured tissues to cause decay. Surface 

 injuries to the potato tuber soon become dried out and covered 

 by a corky layer which prevents the entrance of the mycelium 

 unless the tubers are kept under conditions of considerable 

 moisture. 



