48 PROTECTION OF PLANTS, 1918-19 



treated in the same way. It is of the utmost importance to get rid of the slash 

 and dying trees, that great breeding ground for boring insects and parasitic fungi. 

 In small operations, carried out on farm woodlands, slash burning is entirely 

 feasible and can be completed with very little expense. 



It is perhaps more important to give this careful attention especially to the 

 softwood trees, balsam, spruce and pine, but all our hardwoods, as well, are 

 attacked by boring insects, some of which are particularly injurious, and they are 

 very commonly injured by destructive fungi. 



The condition of the white and yellow birch in parts of Quebec Province is 

 worth noting in this connection. It was found last summer that on at least one 

 watershed in Quebec the white and yellow birches were dying in large numbers 

 from attack by the well known enemy of birch shade trees, the Bronze Birch 

 Borer. It was unusual to find an outbreak of such proportions in the forest, 

 although this insect is particularly destructive to cultivated birches. The affected 

 trees die gradually from the top downwards. Dying tops on birches may indicate 

 the disease; it is definitely identified by the numerous winding tunnels in the 

 inner bark of the afifecfed portion of the trunk. By the time the top of the tree is 

 dead the grubs are cutting their tunnels far below in the apparently healthy bark, 

 and cutting out the tree top rarely does more than check the disease temporarily, 

 and then only if the top is cut out well below the dying part. 



In woodlots, all birches with dying tops should be marked in the fall before 

 the leaves are gone and these trees cut and utilized during winter. Destruction 

 of the infested trees before June will check the spread of the beetles. 



Woodlots have almost invariably to struggle against abnormal conditions, 

 and it is only possible to preserve the health of the trees if the injurious factors 

 are removed to the greatest possible degree. It is useless to expect healthy con- 

 ditions in isolated sections of woodland if considerable quantities of dying trees, 

 bark and wood are left each season to breed great numbers of boring insects and 

 destructive fungi. All slash and dying wood should be utilized to the greatest 

 advantage and the rest burned. Dying trees and those badly injured by insects 

 and fungi should be utilized without delay. If the injurious insects and fungi 

 were kept under control for several seasons the waste from dying trees and 

 branches would be greatly reduced. 



