SMALL FBUITS 145 



become coated with a reddish dust, shaken from the dis- 

 eased leaves. This rust was observed as early as 1817, 

 in Kamchatka, and is very widely distributed in the United 

 States, Europe, and Asia, upon some nine species of Rubus, 

 both cultivated and wild. It is known from Maine to 

 Minnesota and Florida to California, and is in some cases 

 very destructive. 



Examination of a diseased plant shows that its growth 

 has been much retarded by the fungus ; the leaves are 

 curled, distorted, unusually small, and lacking in green 

 color. Plants so affected never recover, and are useless. 

 Preceding by some two or three weeks the conspicuous red 

 rust above referred to occurs another stage of the disease 

 that is often overlooked. This consists of a thick growth of 

 small columnar, glandlike structures, chiefly upon the 

 upper side of the leaf, and present even before the leaves un- 

 fold. These structures (spermagonia) become more distinct 

 as the leaves enlarge. 



The mycelium of the causal fungus when once established 

 in the cane lives in it from year to year, spreading through- 

 out the plant. Spraying is therefore useless. In fact the 

 onlj' successful way of combating this disease is to remove 

 and burn all affected plants. Diseased plants are valueless 

 and are a menace to the healthy plants. 



Late rust (Kuehneola albida (Kuhn.) Magn.). — As 

 the name implies, this rust usually appears late in the 

 season, this distinguishing it from the red rust, which is 

 most abundant in the spring. The spores are not so abun- 

 dant as those of the red rust, but occur in small, pale yellow 

 or whitish spots scattered on the underside of the leaf. 

 This disease has not as yet been sufficiently prevalent to 



