S7nall Fruits 



107 



brittle. This cane-blight is often erroneously attributed to a 

 borer or to drought, or winter injury. 



The damage is often as high as 25 

 or 50 per cent of the crop, and the dis- 

 ease is said to be present to some extent 

 in nearly all of the raspberry planta- 

 tions in New York. Cuthbert, Marl- 

 boro, Ohio, Gregg, Kansas, and the 

 wild red raspberry are susceptible. The 

 Columbian is more resistant. 



The disease is disseminated largely 

 by infected nursery stock or even by 

 the soil adhering to the roots of diseased 

 plants, and is conveyed from plant to 

 plant by wind or rain, by pickers, or 

 by workmen while pruning and layer- 

 ing, also by tools used in cultivation. 

 See soil diseases, p. 26. Since the fun- 

 gus can live on dead fragments of canes, 

 etc., upon the ground, these prove 

 fruitful means of propagating the pest. 



To prevent the disease, care in the 

 selection of healthy plants is necessary. 

 Plants should not be set where the 

 disease has prevailed in previous years. 

 When the fungus has gained access to 

 a plantation, all dead canes should im- 

 mediately be cut out and burned and 

 all fragments scrupulously removed 

 from the ground. Spraying is of doubt- 

 ful value. 



Spur-blight ^^^' ^^^ {Mycosphcerella 

 rubina (Pk.) Jacz.). — On black and 

 red raspberry canes in autumn, sharply defined, brown or 

 bluish black areas from 2-10 cm. long occur on the bark, 

 never on the wood. In the spring these spots bear numer- 

 ous small pycnidia. 



Fig. 53. — Raspberry 

 discolored by spur- 

 blight. After Stew- 

 art and Eustace. 



