i6o Bulletin 395 



in which the percentage of infected blackberries at certain pickings was 

 as high as fifty. 



Even more striking is the fact that in certain localities in New York 

 State the growers have been obliged to discontinue the raising of berries. 

 They attribute the cause of the failure of the crop to the anthracnose 

 disease. In a report of a survey of small fruits in western New York, 

 Buchholz (191 1) states that by a conservative estimate seventy-five per 

 cent of the black raspberry patches were diseased with anthracnose. 

 He states also that the average yield of the raspberr>^ at one time, was 

 two thousand quarts per acre in this section, while now even in favor- 

 able years it is difficult to obtain this quantity. Furthermore a planta- 

 tion formerly yielded a crop annually for a period of from six to seven 

 seasons, while in recent years only about four crops are harvested from 

 a plantation. That a correlation exists between the general prevalence of 

 the anthracnose disease and the reduction in yield of the crop in late 

 years is evident. 



SYMPTOMS 



The anthracnose disease appears on the canes, the petioles, the pedicels, 

 and the leaves of the raspberry. Lawrence (1910) reports that in Wash- 

 ington it occurs commonly on the fruit of the blackberry and rarely on 

 the fruit of the loganberry. The writer has not observed these fruits 

 to be affected in New York State. 



ON THE CANES 



The presence of the disease is first noticed in the spring when the young 

 shoots are about six inches high. Small reddish purple spots, which are 

 slightly raised, are seen singly or in groups on the tender canes, first 

 appearing a short distance from the growing tip. The spots enlarge slowly, 

 and the centers become sunken and assume a pale buff color while the 

 advancing margin is raised and purple. A single lesion is more or less 

 oval in outline, the greater diameter lying along the shoot; but usually 

 the spots anastomose and form irregular blotches which frequently 

 encircle the cane (fig. 12, and fig. 13, a). In the center of each spot is 

 a small pustule visible to the naked eye. Later in the season, with the 

 further growth of the host, longitudinal cracks appear in the spots. During 

 the winter these enlarge so that in the spring the second year's growth 

 is often split to the pith (fig. 13, b). 



A somewhat different type of lesion has been found on the shoots of 

 the purple-cane and red varieties of the raspberry. It differs from the 

 spot described above in that a knotty growth develops, which occasionally 

 becomes twice the diameter of the normal cane. These knots arise from 

 lesions formed when the tissue is very young and tender, and in some cases 

 cause a distortion of the cane. This type of injury, which has never 



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