CARTER: ILLINOIS TREES: THEIR DISEASES 



when they are used improperly. Injury can be avoided by proper 

 care in the application of such materials. Occasionally tree in- 

 jury in caused by illuminating gas and by sulfur dioxide. 



X 





%*■■ '., 'Bt.-^' 





Fig. 11. — Trees, such as Siberian elm, with soft, brittle wood may be 

 seriously damaged by coatings of ice. 



Fig. 12. — The force of wind in tornadoes uproots many trees each year 

 and causes inestimable damage to wooded areas. The wooded area shown 

 above contained mostly oaks. 



