372 



Journal of Agricultural Research 



Vol. V, No. 9 



Table II. — Spore and ascus measurements of the brown-rot fungus as given by various 

 investigators — Continued 



FROM AMERICAN SOURCES 



Fungus and investigator. 



Chlamydosporea. 



Sclerotinia friictigena: 

 Norton (1902). . . 



Aderhold and Ruhl- 

 and (1905) 



Reade (1908). . 

 Pollock (1909). 



Matheny (19 13). 



[7 by 



Plum .... 

 In culture 



Peach . 

 Plum. 



14.4 to 24 by 9.6 to 



14.4 



9.6 to 14.4 by 7.2 to 



10.8 

 14.7 by 9-9 



45 to 60 by 



3 to 4 

 89.3 to 



107.6 by 



5.9 to 6.8 

 125 to 215 



by 7 to 10 

 130 to 179 



by 9.2 to 



6.2 to 9.3 by 

 3.1 to 4.6 



10 to 15 by 



5 to 8 

 11.4 to 14.4 



by 5 to 7 



13s to 190 

 by 6.9 to 

 10.5 



13s to 173 

 by 6.8 to 



10.5 to 14.5 

 by 5.2 to 



7-5 

 9.3 to 14.2 

 by 5 to 7.4 



SCLEROTINIA STAGE 



The apothecial stage of the local brown-rot fungus has been found in 

 abundance in the University of Minnesota Experiment Station orchard 

 during the last few springs. It appears during the blooming period of the 

 plums. The ascospores showed the characteristic refractive globules 

 which Aderhold and Ruhland (1905) pointed out as being one of the char- 

 acters which make it possible to distinguish between 5. cinerea and S. 

 fructigena, the latter species containing none. 



Some doubt has existed in regard to the exact time required for the 

 production of the perfect stage after the formation of the sclerotium or 

 mummy. The field observations of Norton (1902) and others seem to 

 indicate that the apothecia are formed the second spring after the rotting 

 of the fruit — i. e., in approximately 18 months. Other investigators 

 (Dandeno, 1908) have thought that they may be produced the spring 

 following the rotting of the fruit. No experimental evidence has come 

 to the notice of the writer which shows definitely the period required for 

 the production of apothecia; therefore, the following experiment was 

 performed. 



During the fall of 191 3 two lots of mummied plums and one of apples 

 were buried. Lot i consisted of i plum each of 16 varieties which had 

 been rotted in the laboratory. These were buried on October 8, 1913, 

 about K to I inch deep in a shallow box, which was then placed level with 

 the ground on a shaded hillside. Lot 2 consisted of (A) 106 fruits from 

 8 varieties of plums which had rotted in the field under field conditions 

 during the fall of 191 3, and (B) 30 mummies of 3 other varieties which 



