GOOSEBERRY DISEASES 223 



The disease is far more serious in Europe than in America. 

 It is a well-recognized fact that when a fungus is introduced 

 into a new and favorable climate and among new varieties of 

 hosts, it is liable to become more destructive. In this respect 

 the gooseberry-mildew pathogene is no exception. It is now 

 established in the Old World and has become a permanent 

 factor in gooseberry culture. While the fungus is less virulent 

 in America, yet it is one of the most serious enemies of this 

 fruit. The berries are usually rendered unsalable, and some- 

 times are even destroyed. The vitality of affected bushes is 

 reduced, and they are more susceptible to winter-injury than 

 those which remain free from mildew. 



Symptoms. 



The lower parts are first affected. The disease appears in 

 May or June. In severe cases not a single berry remains free 

 from the attacks of the pathogene. The leaves and young 

 canes are also affected. At first there is a superficial whitish 

 growth having a moldy, powdery appearance. Several spots 

 may coalesce to form large patches. The leaves and tips of the 

 stems may become distorted in serious cases. Affected berries 

 are sometimes dwarfed. Finally the fruit may crack and decay. 

 In later stages the mildew patches become buff or rusty-brown 

 in color. Scattered through the felty growth, small black 

 specks may be observed. 



Cause. ' 



The American gooseberry-mildew fungus is known as 

 Spharotheca mors-uvce. The small specks mentioned above 

 are perithecia of the parasite. Within each of these bodies is 

 found a single ascus containing eight ascospores. These 

 spores remain in the perithecium during the winter, either on 

 the fallen leaves or on the canes of the past season's growth. 

 Sometimes, when the leaves disintegrate, the perithecia hiber- 

 nate in or on the soil. In the spring when the leaves are half 

 grown, or later, the ascospores are forcibly ejected from the 



