RASPBERRY DISEASES 419 



normal. The lesions become whitish at the center in Sep- 

 tember and October. Later small black pustules develop. 



Cause. 



The fungus Mycosphcerella Rubina causes spur-blight. Its 

 mycelium invades the cortex, wood and pith. Within two weeks 

 after the fungus falls on the spur a typical lesion is produced. 

 The fungus apparently hibernates as immature perithecia in 

 the canes. In the spring these bodies mature their ascospores. 

 This occurs about the first of May. These spores are liberated 

 and are carried by the wind to young canes which are at this 

 time but a few inches high. 



Control. 



It has been demonstrated in Colorado that spraying will 

 prevent spur-blight. The time of inoculation necessitates that 

 spraying be done early in the spring. Bordeaux mixture 3-2-50, 

 with the addition of resin-fish-oil-soap at the rate of two pounds 

 to fifty gallons of bordeaux as a sticker, is advised. Apply to 

 the young canes only, and care should be taken to coat the por- 

 tion nearer the ground. Four applications are advised ; three 

 before picking at intervals of two weeks and one immediately 

 after picking. The first application should be made when the 

 plants are only a few (eight to twelve) inches high. This is the 

 last of May in Colorado. The second spraying follows two 

 weeks later. The third two weeks after the second. Old 

 fruiting canes should be removed and burned immediately 

 after harvest to prevent infection of new canes. 



REFERENCES 



Sackett, W. G. Spur blight of the red raspberry caused by Sphserella 

 rubina. Colorado Agr. Exp. Sta. Bui. 206 : 3-26. 1915. 



Robbins, W. W., and Reinking, O. A. Fungous diseases of Colorado 

 crop plants. Raspberry. Spur blight. Colorado Agr. Exp. 

 Sta. Bui. 212 : 45. 1915. 



Stewart, F. C., and Eustace, H. J. Raspberry cane blight and rasp- 

 berry yellows. Relation of cane blight to the discolored areas 

 on red raspberry canes. New York (Geneva) Agr. Exp. Sta. Bui. 

 226 : 354-358. 1902. 



