Proceedings, 1915. 21 



Okanagan the part played by bees in distributing the disease has so seized upon 

 the minds of the growers that any person setting up an apiary is regarded with 

 considerable disfavour by the rest of the community. Now, I do not know that 

 any one has ever noticed a correlation between the number of bees kept and the 

 prevalence of blight. From what has been previously said, it will also be seen that 

 a very few bees may be as effective in spreading the disease as a large number. 

 However, if many bees are kept and there is a scarcity of flowers in early spring, 

 it is possible they might be more attracted to running cankers and thus produce 

 more primary blossom-infection. On the other hand, proper setting of the fruit is 

 largely dependent on bees, and in the districts mentioned there are some indications 

 of defective pollination. On the whole, it would be much better policy to make 

 every possible effort to clean out hold-over cankers rather than place bee-keeping 

 under a ban, as in any case it will not be possible to control or exterminate wild bees. 



In the spread of the disease later in the season several insects are implicated, 

 the tarnished plant-bug, aphides, and leaf-hoppers being probably the worst offenders 

 in this part of the country. In Ontario the bark beetle (Scnli/tus rufluIosuR) has 

 been shown to be a. very potent agent in disseminating firenblight in the pear. If a 

 pear-tree is suffering from attacks of both blight and bark-beetles, there is great 

 danger of the beetles leaving sucli a tree and boring into healthy adjacent trees, 

 and thus communicating Ijlight, which is often " body -blight " and rapidly fatal to 

 the tree. 



D. H. Jones records a case where a pear-tree infected with body-blight was cut 

 down but not removed. The beetles migrated from this tree into two rows of young 

 pear-trees adjoining, with the result that CO jjer cent, of these became attacked, a 

 beetle being found in every blight area. This beetle has not, I believe, been yet 

 discovered in British Columbia, but beetles of similar habits occur and such infec- 

 tions may be considered possible. 



The extent of the danger resulting from leaving the blight-cuttings under the 

 tree instead of at once removing and burning them is a matter of practical impor- 

 tance. While the danger may not usually be great, it may become considerable under 

 certain conditions. I have seen fresh cuttings of blight-infected twigs lying on the 

 ground and swarms of ants running over and amongst them and then up the trees. 

 Aphides were present on the twigs of the trees, and ants are very prone to mingle 

 with aphides on account of the honey-dew they excrete. If fresh exudate had been 

 present on the blight-cutting, we should have had all conditions present for reinfec- 

 tion of the trees. At the time the weather was hot and dry and moist exudate was 

 not observed, thus reducing the chances of infection under the circumstances to a 

 minimum. 



