WEST VIRGINIA GEOLOGICAL SURVEY. 



73 



large trees in the rich soils of valleys and coves and in the deep 

 humus-filled soils of north hillsides. The fertility of the soil it- 

 self can easily be judged by the kinds and sizes of the trees which 

 it produces. Trees growing in poor soil are apt to have a starved 

 and sickly appearance, and their weakened condition induces 

 many kinds of disease. 



Relation of Excessive Cold to Tree Diseases. 



Severe winter freezing often kills the roots, twigs, and even 

 the trunks of smaller trees, thereby producing a diseased condi- 

 tion. Cracks in the bark and wood caused in this way not only 

 weaken the tree and injure the quality of the wood but permit, 

 also, the entrance of insects and fungi. Late spring frosts may 

 kill the leaves or injure them to such an extent that they are un- 

 able to perform their important work. 



Diseases Induced by Storms. , 



Storms occuring during the summer months may injure 

 trees by lightning, by wind and by hail. Injuries from the first 

 cause are comparatively slight. It is not uncommon, however, 

 for a dozen or more trees to be struck during one season in a for- 

 est of a few hundred acres, some of which will be only slightly 

 damaged and others killed outright or almost completely de- 

 molished. High winds are always disastrous to forests. Scores 

 of the finest trees are upturned by wind each year in every wood- 

 ed locality, and many limbs are broken from the standing trees. 

 Hail storms are less violent in this part of the country than in 

 the West and Northwest. The tender spring foliage, however, is 

 occasionally riddled by hail-stones in narrow belts of timberland. 

 Winds in winter, when the trees have dropped their foliage, 

 sweep harmlessly through the forests of hardwood ; but tbe coni- 

 fers are sometimes overthrown by winter as well as by summer 

 winds. The principal losses in winter result from hanging snows 

 and sleets that break the limbs and bear down and distort the 

 trunks of the younger growth. Almost every limb was obs:^rved 

 to be broken from thousands of trees growing on North Fork 

 mountain in Pendleton county after the heavy sleet which fell 



