INSECTS AND DISEASES THAT DESTROY FORESTS 69 



For example, chestnut blight is a fungous dis- 

 ease that is killing many of our most valuable 

 chestnut trees. The fungi of this disease worm 

 their way through the holes in the bark of the 

 trees, and spread around the trunk. Diseased 

 patches or cankers form on the limbs or trunk of 

 the tree. After the canker forms on the trunk, 

 the tree soon dies. Chestnut blight has killed 

 most of the chestnut trees in New York and 

 Pennsylvania. It is now active in Virginia and 

 West Virginia and is working its way down into 

 North and South Carolina. 



Diseased trees are a menace to the forest. 

 They rob the healthy trees of space, light and 

 food. That is why it is necessary to remove them 

 as soon as they are discovered. In the smaller 

 and older forests of Europe, tree surgery and 

 doctoring are practised widely. Wounds are 

 treated and cured and the trees are pruned and 

 sprayed at regular intervals. In our extensive 

 woods such practices are too expensive. All the 

 foresters can do is to cut down the sick trees in 

 order to save the ones that are sound. 



There is a big difference between tree dam- 

 ages caused by forest insects and those caused 

 by forest fungi and mistletoe. The insects are 



