52 



Diseases of Economic Plants 



large set of small fruits, and in the following season few 

 flowers, deficient growth, and small leaf development and 

 perhaps chlorosis. In cases where only a few roots are 

 diseased the evident effects may be limited to the correspond- 



FiG. 25. — Clitocybe upon apple. After Wilcox. 



ing side of the tree. Several years may elapse between the ap- 

 pearance of the first symptoms and final death. The roots, 

 one or all, of trees well advanced in disease show decay, de- 

 pendent in character upon the causal fungus. Several dif- 

 ferent fungi cause root-rot (see p. 370). Among those most 

 common on fruit trees are: Clitocyhe parasitica Wil. A 



