152 Keport of the Department of Botany. 



this is about the time the first berries are setting. The exact date 

 will vary in different localities and in different seasons. If the 

 first pruning is delayed until the new shoots have become several 

 inches long it is inevitable that some of the diseased canes will 

 be overlooked. This difficulty was encountered in the experi- 

 ment. Besides, some late infections of the previous season are 

 hard to detect under the most favorable conditions. 



Perhaps a third factor in the failure of the treatment was 

 the close proximity of the treated plats to untreated plats 

 in which the disease was prevalent. Our present knowledge 

 of the mode of dissemination of the fungus is so imperfect that 

 we are unable to accurately estimate the importance of this factor. 



The results of the experiment being as they are, we can no 

 longer recommend summer pruning for the control of necrosis. 

 It should be said, however, that it will probably assist greatly in 

 keeping cane-borers under control and will improve the appear- 

 ance of the plantation. The expense of four treatments will vary 

 from $2 to $4 per acre according to the age of the plants and the 

 virulence of the disease. With the rows six feet apart the affected 

 canes may be removed at any time without material injury to 

 either fruit or foliage. It is understood, of course, that most of 

 the dead wood should be removed during the winter when other 

 work is least pressing. 



It is regrettable that summer pruning has proven a failure, 

 because, at present, no other line of treatment can be confidently 

 recommended. The planting of vigorous-growing varieties such 

 as Wilder may give some relief. An experiment on the control of 

 necrosis by spraying is in progress. 



