ANNUAL MEETING AT LEXINGTON. 



295 



We will now brietly describe several of the parasitic fungi which 

 attack the apple, and the first species is known to botanists as 



ROESTELIA PENICILLATA. 



This fungus belonge to the order Uredinefe, and its life history is 

 both interesting and peculiar. This fungus is very common in most of 

 the eastern States, but it rarely attacks cultivated apple trees in this 

 section of the country. The fungus occurs very abundantly, however, 

 on the leaves of the wild crab apple, and occasionally attacks the culti- 

 vated apple. This species attacks the apple leaf, producing circular 

 spots in the leaf. The spots are usuallj^ one-fourth of an inch in diam- 

 eter, but they vary exceedingly in size and shape. Frequently the 

 spots are so numerous that the entire leaf is twisted and distorted by 

 the growth of the fungus. The color of the spot is reddish yellow, and 

 the outer edge is usually colored dark brown. Occasionally the spots 

 are sterile ; which means that nothing is visible but the colored spot 

 described above. 



Frequently, however, we find the epidermis on the underside of the 

 leaf ruptured, and a cup shaped body protruding therefrom. (A. Figure 

 I.) The margin of the cups ultimately become deeply split and fringed, 



I / 



o»'C';^ 



m 



T"'^ 



•m -^^^ 



2 2 



A. Roestalia, section through leaf of Hawthorn, showing cups 1, 1, 1. 



B. Fusicladium dendriticuni. 1, 1, 1, spores of fungus. 2, 2, spores germinat- 

 ing, o, 3, part of apple showing spots natural size. 1, ], 1, 2, 2, highly magnifled. 



C. Podosphce a tridactyla. 1, Ripe perithecium. 2, ascus containing spores. 

 3, tuft of conidia spores. 4, conidium germinating. 1, 2, 3, highly magnitied. 



