JUNIPER DISEASES 201 



and a few produce spore-cushions on the normal green twigs and 

 scale-like leaves. The life history of these fungi is described on 

 page 192. The main characteristics of the forms causing abrupt 

 swellings are given below. 



The red juniper is affected in southeastern and south central 

 United States by Gyvmosporangium trachysorum Kern. Small 

 knots or galls as large as an inch in diameter and an inch and a 

 half long are formed on the small branches. The spore-horns are 

 pushed out from these galls and are wedge-shaped and less than 

 a half inch long. The alternate stage occurs on species of haw. 



In the same region the red juniper is attacked by Gymnospo- 

 rangium floriforme Thaxter. Small gall-like excrescences as 

 large as one-half inch across and occasionally globose swellings 

 an inch in diameter are formed on the branches. The horns of 

 spores are cylindrical and pointed and vary from an eighth to 

 one-half inch in length. One species of haw (Cratcsgus spathu- 

 lata) is known to be the alternate host for this rust. 



Along the coast of the Gulf of Mexico from Mississippi to 

 Florida, several species of juniper often show reddish brown 

 globose galls, a quarter to one-half inch in diameter. The fungus 

 causing this gall is Gymnosporangium bermudianum (Farlow) 

 Earle. This species is peculiar and is different from all others 

 of this group in that no alternate host is required for its develop- 

 ment. Both the teliospores and seciospores are formed on the 

 same galls on the juniper. The cluster-cup stage is followed 

 by teliospore masses smaller than a pin-bead. 



In northwestern United States and adjacent Canada, the 

 dwarf juniper and Juniperus sibirica are attacked by Gymnospo- 

 rangium juniperinum (L.) Mart. Hemispherical swellings half 

 an inch to two inches long are formed on the larger branches 

 and more or less globose galls an inch in diameter appear on 

 the smaller branches. The spore-masses are flat and cover large 

 areas of the galls. The alternate hosts are species of mountain 

 ash. 



