DISEASES OF SHADE AND FOREST TKEES. 115 



let, which is widely distributed throughout Xorth America. 



The fungus usually gains entrance through 



\v mid-, hut some authorities claim that it will SJJ?" 



arrack uninjured roots. It causes a decay of 



the routs, thus cutting off the supply of water and food from 



the -nil and eventually causing the death of the tree. In 



tin- mots and surrounding soil will be found the so-called 



slim- strings" hard black strands of the fungus which 



branch and interlace, draw nourishment from the decaying 



Fig. 43. Armillaria mellea. Parasitic on the 



roots of many trees. (Courtesy of 



New York Botanic Garden.) 



\v< . d, and finally give rise to the fruiting bodies. The fruit- 

 ing bodies, a form of mushroom (Fig. 43) appear to grow 

 from the soil, are honey colored, the upper surface viscid and 

 s p. -eked with white; the gills of the lower surface white and 

 giving off great quantities of spores; the stems are swollen 

 at the base and have a distinct ring below the umbrella 

 shaped top. 



Treatment. 



Xewly cleared land in which this disease is prevalent 

 should not be set to trees of any kind. When the disease 



