412 



MANUAL OF FRUIT DISEASES 



lesions are found most commonly on the canes (Fig. 120), 

 although the berries may be directly affected. All or only a 

 portion of a cane is involved, in which case the foliage suddenly 

 wilts and becomes dry. Often only a single branch wilts; 

 the remainder of the plant then continues normal activities 

 and appearances (Fig. 120). Frequently only a portion of a 

 cane is blighted, such symptoms becoming evident as soon as 



the leaves unfold 

 in the spring. 

 Lesions commonly 

 center about a 

 wound left in prun- 

 ing, from which 

 point they extend 

 downward. There 

 is a tendency on 

 black varieties for 

 the disease to affect 

 only one side of a 

 cane. The dis- 

 eased area is brown 

 and the cane be- 

 comes very brittle 

 at such points. 

 Very early in the 

 blighting of a cane, black fruit-pustules of the pathogene 

 appear on the lesions (Fig. 121) ; from these pustules 

 masses of reproductive bodies ooze out on the bark, giving the 

 affected portion a brownish smoke-colored appearance. The 

 spots are not always limited in extent; in some cases they 

 are generalized, the wood cracks, and the bark peels off at the 

 lower portion of the affected cane. 



The cane-blight disease may be confused with the work of 

 the raspberry-cane borer (Oberea bimaculata). But in cane- 



FIG. 120. Raspberry cane-blight ; healthy plants 

 on right, blighted canes on left. 



