H. WORMALD 197 



Aug. 21 by placing mycelium from an agar plate culture in wounds on 

 opposite sides using the canker Monilia on one side and M. fruciiifena 

 on the other. The result was the same for all four; that half of the 

 apple infected with M. frucfigena produced numerous large yellow 

 pustules and remained brown, while the side infected with the canker 

 form became quite black in from three to four weeks and developed no 

 pustules at all or from one to three minute barren tufts of hyphae. 

 The side inoculated with M. fructigena became shrunken at a much 

 more rapid rate than the other. 



Similar experiments were performed about the same time using the 

 canker-producing Monilia and the hyaline M. cinerea strain. Again 

 that side of the apple infected with the former soon became black and 

 bore few or no pustules, while the opposite side produced, as a rule, 

 numerous greyish pustules and remained brown for some weeks, becoming 

 however gradually darker until it was almost black ; as before the 

 shrinking of the skin was most pronounced on the pustular side. 



Later other apples of the same variety were inoculated using the 

 same three strains of Monilia but infecting each apple with but one of 

 the three. The results conformed with those obtained previously ; 

 those apples infected with M. fructigena became almost covered with 

 large yellow pustules often becoming confluent, those with the hyaline 

 strain of M. cinerea produced smaller greyish pustules, while those with 

 the canker form remained sterile or produced a few scattered tufts of 

 aerial mycelium usually sterile. 



The apples used in these experiments were such as show ed no apparent 

 injury before inoculation; they were obtained from trees growing in the 

 College plantation and taken immediately to the laboratory and inocu- 

 lated. As the crop was picked during the first week of October sub- 

 sequent inoculations were made on apples (of the same variety) from 

 the fruit- storage shed. On such fruit the results were practically as 

 before except that the barren liyphal tufts produced by the canker- 

 strain were rather more numerous than in previous experiments. This 

 was probably due to small abrasions caused during the operations of 

 picking and storing or to minute cracks produced in the skin on drying, 

 thus allowing hyphae to grow out into the air. But even then the 

 difEerence between these results and those obtained with the other two 

 forms of Monilia was still conspicuous. 



Whether similar results are to be obtained with other varieties of 

 apples has not yet been determined but it appears evident that the 

 Monilia causing the blossom wilt and canker of apple trees produces 



