202 MANUAL OF TREE DISEASES 



In the same region as above, the Rocky Mountain juniper is 

 attacked by Gymnosporangium Betheli Kern. Irregular gall- 

 like knots are produced which are two or three times the 

 diameter of the normal branch. Several knots breaking out ad- 

 jacent to each other form galls similar to the black knots com- 

 mon on plum and cherry. Short wedge-shaped spore-horns 

 about an eighth of an inch long are pushed out from the bark of 

 the galls. Several species of haw are known to be the alternate 

 hosts for this rust. 



In northwestern and southwestern United States, the Rocky 

 Mountain, Utah and one-seed junipers are attacked by Gym- 

 nosporangium Nelsoni Arthur. Hard woody globose galls as 

 large as two and one-half inches are formed. The spore-masses 

 are flattened and about an eighth of an inch high. The alter- 

 nate hosts of this species are the quince, pear and species of 

 service-berry. 



The red juniper in northeastern and north central United 

 States is attacked by Gymnosporangium comiculans Kern. 

 Irregularly lobed excrescences as large as an inch in diameter 

 are produced. The spore-horns are conical and about one- 

 eighth of an inch high. The alternate hosts are species of serv- 

 ice-berry. 



Fusiform Branch-Swellings 

 Caused by species of Gymnosporangium 



In addition to cedar-apples and galls or knots, several species 

 of the rust-fungi cause long spindle-shaped swellings of the 

 branches of species of juniper. The life history of these fungi 

 is discussed on page 192 and only the hosts and outstanding 

 characteristics of the diseases are given below. 



In eastern, southeastern and central United States, the red 

 and dwarf juniper and J. sibirica are commonly affected by 

 Gymnosporangium germinale (Schw.) Kern. The branches are 

 slightly enlarged, often for several inches in length. The spore- 



