BULLETIN 534, U. S. DEPARTMENT OF AGRICULTURE. 



are concerned, while many are still produced from the diseased 

 fruits. 



It is a rather curious thing that leaf infections are comparatively- 

 rare in Arkansas, "whereas in Kansas they are rather abundant. This 

 may be partly, though not wholly, accounted for by the more 

 numerous cankers and consequent heavier infection in Kansas 

 orchards. 



Fig. 1. 



-Section through a pycnidium of Phyllosticta solitaria produced in 1914 

 on a blotched spot of a young Ben Davis apple.. 



The fruiting bodies (pycnidia) are found on the newer parts of the 

 twig cankers until the cankers are about 4 years old. They are most 

 plentiful on young cankers which had begun their development dur- 

 ing the previous season. They occur on the leaves also, particularly 



in the lesions on the midrib and 

 petiole, and in the blotches on the 

 fruits. The pycnidia (fig. 1) are 

 rather small, black, glistening, sub- 

 globose or somewhat depressed, 

 varying from 75 to 250 jx in diam- 

 eter. When mature they are filled 

 with spores, but those formed late 

 in the season usually fail to ma- 

 ture. The period of maximum 

 pycnidium production is in May 

 on the twigs and in late June and early July on the fruit and leaves. 

 Those on the leaves rarely produce spores. 



The spores (fig. 2) are hyaline, one celled, and when mature are 

 filled with rather large, uniform-sized, often closely compacted 

 granules. They are oval to subglobose and measure 8 to 10 by 5.5 to 



Fig. 2. — Spores of Phyllosticta solitaria 

 from twig cankers of the Ben Davis 

 apple. Bentonville, Ark., May 25, 

 1914. 



