

Brooks : The Fruit Spot of apples 435 



* 



This constant occurrence of the same fungus in the diseased 

 tissue suggested that it might be the cause of the trouble. In 

 view of the fact that fungi had been reported as being present in 

 late stages of Fruit Spot, but had not been found to be present in 

 earlier stages and again that no fungus had been reported as a 

 factor in producing the trouble, one did not seem justified in 

 drawing any conclusions until further studies had been made. It 

 was important to determine whether the fungus is present in the 

 earliest stages of the spots and whether it can be made to produce 

 similar effects by artificial inoculation. Also, it was of interest to 

 know from what sources the fungus can be obtained. 



Sources from which the fungus has been obtained 



For an investigation of this phase of the subject some fifty 



lots of apples were tested and as many as six hundred separate 



cultures made. More than ninety per cent, of the cultures made 



rom the green spots and about seventy per cent, of those made 



rom the red spots gave a pure growth of the same fungus. More 



than fifty per cent, of the contaminations obtained from the red 



spots were due to Sphaeropsis malorum Berk. It was found that 



e fungus could be isolated from spots covered with a smooth 



and glaucous epidermis as well as from those having a lenticel in 



e center. The compound microscope revealed the fact, however, 



at the spots that seemed to be covered by an unbroken epidermis 



,n reality had a stoma at the center. 



n the summer of 1907 spots were tested for the fungus from 

 th e r CarlieSt a PP earanc e. The same fungus was obtained from 

 ^ese earliest stages as was found in the later ones. Cultures of 

 J^ungus were obtained from Talman Sweets and Gravensteins 

 in ugust 2 h and from Baldwins on August 28. In these as 

 ben u Gr Cases ^ e tissue for inoculation was removed from 



thes tHe epidermis b >" means of a sterilized knife. At this time 

 spots had little or no brown corky growth beneath them. 



annl L m . past two y ears tne fungus has been isolated from 



thei 



foil 



Michigan. Ma 



low' USeUs ' from Tor °nto and Montreal in Canada, and from the 

 v, ng points in New Hampshire : Webster, Durham, Lee, 



Wilton 



Madbury, Walpol 



