New York Agricultural Experiment Station. 17') 



Even where the Maci'ophoma spore masses were not outwardly 

 conspicuous it was often found that just beneath the loose outer 

 bark, which peels off readily, there was an abundance of white 

 spores and mycelium. 



The Macrophoma was found associated with all stages of the 

 <^anker (but not constantly), even with the very beginning of the 

 canker where it was often the only fungus to be found. Small, 

 dead, sharply delimited areas of bark one inch in diameter fre- 

 quently showed multitudes of the exuded spore masses and noth- 

 ing else. 



Since the spores of Macrophoma malorum are about the size 

 and shape of the spores of Sphwropsis malorum Pk. and differ 

 from them only in being uncolored, the opinion has been ad- 

 vanced that the former is only an immature stage of the latter; 

 but we believe that the two forms are distinct species. It is 

 true that immature SpJicBropsis spores are uncolored, but the 

 colorless stage is quickly passed and when full grown they are 

 generally colored; whereas the Macrophoma spores remain un- 

 colored indefinitely after attaining full size. The fact of their 

 expulsion in May is evidence of their maturity at that time, but 

 they show no color. Moreover, Paddock ^^ j^^s seen the hyaline 

 spores germinate so there can no longer be any doubt that the 

 MacroplwmAi is distinct from Sphwropsis mAilorum. 



It appears to us that Macrophoma malorum is parasitic upon 

 apple bark, but Paddock's^^ inoculations gave only negative re- 

 sults. If it is a parasite the lesions formed by it are very similar 

 to those of Sphceropsis. 



Cytospora Canker. — About the middle of May Mr. Paddock 

 called our attention to dead patches of bark on several apple 

 trees in the Station orchard and pointed out the fact that while 

 the dead areas resembled those produced in the early stage of 

 Sphwropsis canker, they were, nevertheless, slightly different 

 and were inhabited by a different fungus which proved to be a 

 species of Cytospora. The affected patches were discolored, 



"Paddock, W. Bui. 1S5 of this Station, p. 212. 

 "L. c. 



