BASSWOOD DISEASES 103 



White Sapwood-Rot 



Caused by Collybia vclutipes Curtis 



This sapwood-rot is occasionally found in basswood, horse- 

 chestnut and other deciduous trees. The sapwood becomes 

 soft and decayed, and the decline and death of the tree gradually 

 results. Injuries in the bark caused by woodpeckers and other 

 birds are often found to predispose the trees to attack. The 

 sporophores of the causal fungus emerge in dusters from 

 wounds in the bark. They are small toadstools, with yellow 

 or brownish tops and gills. The bases of the stems are cov- 

 ered with a dark brown velvety growth of hairs. For the gen- 

 eral life history and control of the wood-rot fungi, see page 64. 



Reference 



Stewart, F. C. Trunk rot. ?CoUybia velutipes Curt. (Horse ciest- 

 nut). In Notes on New York plant diseases, 1. New York Agr. 

 Exp. Sta. Bui. 328 : 361. 1910. 



Southern Root-Rot 

 Caused by Ozonium sp. 



A great variety of plants in the South, including many trees, 

 are attacked by a root parasite, which is peculiar in that no 

 spores- of any type have been found and it is known only by the 

 mycelium. Cotton and sweet potatoes are among the field 

 crops seriously affected. Several kinds of trees, especialh- bass- 

 wood, elm, Cottonwood (poplars) and mulberry, are known to 

 be attacked and the roots killed. Plum trees and closely re- 

 lated species and varieties are more or less immune. The second- 

 ary SATnptoms are those which accompany any root-rot. The 

 leaves wilt and die when tlie roots are no longer able to function 

 in furnishing sufficient water and food materials. The roots 

 are iuA-aded by the mycelium and the living tissues are killed. 



