186 



"Spotting" of Apples in (treat Britain 



dark brown, slightly sunken spots in Wellington resemble a scurf; in 

 Tamplin they are often round, sunken, numerous and very small. 



Minute black markings of various kinds are frequently present in 

 the brown spots which add a great variety of minute detail. The spot 

 may be almost uniformly black (September Beauty, Rev. W. Wilks, 

 Early River, Wolf River), or black dendritic markings may appear 

 (Newton Wonder). These appearances are due to the presence of fungi 

 with dusky mycelium, for example, Alternaria, Denudium pullulans, etc. 

 Again, the spot may be dotted in various patterns with the dark sclerotial 

 or other reproductive bodies of various fungi, and the pattern will vary 

 with the kind and degree of development each has attained. The fol- 

 lowing fungi have been found to produce this "dotted" effect: 



(a) (6) 



Fig. 1. Photographic reproduction showing mummification following "spotting" of apples. 



(1) Pleospora pomorum — black sterile perithecia. 



(2) Valsa sp. — necks of the perithecia. 



(3) Polyopeus purpureus — dark brown pycnidia (Early River, 



Stirling Castle). 



(4) Myxosporium mali — black sclerotial bodies. 



(5) An unidentified fungus with thick glistening walls — black 



sclerotia. 



Perithecia often escape recognition since only a portion of the peri- 

 thecium (Pleosjjora), or only the extremity of the neck (Valsa) protrudes 

 above the surface of the apple. 



It is not meant to be understood that the spots named are necessarily 

 of different origin ; a purple spot and a brown may differ in aspect merely 



