178 Bulletin 395 



Canes that are affected with anthracnose are, as a rule, more susceptible 

 to winter injury than are unaffected canes. In a field in which the disease 

 is present, the canes that are found to have been killed during the winter 

 are the ones that were severely affected by anthracnose and other diseases. 



CONTROL 



CULTURAL METHODS 



It has been observed by the writer that cultural methods greatly favor 

 the distribution of the pathogene to the new raspberry plantings. The 

 method of propagation of the blackcap and the purple-cane raspberry 

 is no doubt accountable for this. These varieties are propagated by means 

 of tip layers, which many growers do not remove in the spring until the 

 young shoots have reached a height of a foot or more. By this practice 

 it is maintained that the young plants are afforded a better chance of 

 development. However, during this period the old diseased canes act 

 as a source of inoculum to the new shoots, which become infected and thus 

 the disease is carried to the new plantation. On the other hand, if care 

 is taken to dig the roots before they sprout or before the fungus on the old 

 canes sporulates, which in New York State is sometime near the middle 

 of May, a healthy setting can be obtained. In the case of the red varieties, 

 which it is necessary to propagate by means of suckers, the young plants 

 should be procured from fields where it is known that anthracnose does 

 not exist, or the canes should be carefully examined for lesions of the 

 disease. The red varieties of the raspberry are very resistant, and there- 

 fore it is not uncommon to find a field free from the disease, from which 

 young suckers may be selected. As a raspberry plantation is com- 

 paratively short-lived, the selection of healthy plants at the beginning 

 is a long step in the control of the disease. Moreover, observations 

 indicate that the pathogene does not spread rapidly from one field to 

 another. The character of the fungus would further substantiate this 

 view, as the sticky walls of the conidia render them not readily adapted 

 to dissemination by the wind. 



The eradication of anthracnose after it has once become established 

 in a field is a difficult process. Pruning out the diseased canes has been 

 recommended, but this is not desirable in the majority of cases since 

 usually the disease has become widely spread before it is noticed and 

 without the entire eradication of the sources of inoculiim but little good 

 can be accomplished. Sturgis (1900) cites an instance in which the 

 majority of infected canes were removed and the disease was checked. 

 The season was dry, however, and this probably accounts for the re- 

 duction in infection. No doubt the removal of od canes immediately 



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