548 



Minnesota Plant Diseases. 



The fungus passes the winter in this diseased portion of the 

 cedar and in the following year the winter spores are produced 

 in early spring. They are formed in a large number of cone- 

 shaped groups arising from little saucer-like depressions, scat- 

 tered all over the surface of the cedar apple. Each spore is 

 provided with a long stalk which swells up in rainy weather. 

 Since the winter spores are produced in large numbers there 

 are formed long (G. macropus) or short (G. globosum) beak- 

 like, gelatinous masses with a bright, orange-brown coating of 



Fig. 181.— Cedar apples of red cedar. 1. Showing the swollen branches of the cedar with 

 the winter spore gelatine masses removed (Gymnosporangium globosum). 2. Cedar 

 apple of the same fungus with the gelatinous masses of winter spores. 3. Cedar apples 

 caused by another rust fungus (Gymnosporangium macropus), showing masses of winter 

 spores. 4. Same as 3, but larger specimen. Original. 



spores. The cedar apples are therefore very conspicuous in 

 wet weather. Some cedar apples (G. globosum) produce win- 

 ter spores for several seasons in succession while the others 

 (G. macropus) produce spores only one season and then die. 

 The winter spores grow out immediately, while still in the 

 gelatinous mass, and produce a number of tiny spores (spo- 



