528 SPECIAL PLANT PATHOLOGY 



eased trees seems to be the only efficient method of checking the spread 

 of Polyporus siUphureus. 



Honeycomb Heart-rot {Stereum subpileatum, W. H. Long).— The 

 pocketed, or honeycomb, heart rot has been found on the following. 



Fig. 190. — Cross-section of a living post oak tree rotted by Polyporus sul- 

 phureus. {After von Schrenk. Hermann, Bull. 149, U. S. Bureau of Plant Industry, 

 pi. iv, 1909.) 



nine species of oa.ks: Quercus alba, Q. lyraia, Q. marilandica, Q. Michauxii, 

 Q. minor, Q. palustris, Q. Icxana, Q. velutina and Q. virginiana.^ 



The first indication of this honeycomb heart-rot in white oak is a 

 slight discoloration of the heartwood, which assumes a water-soaked 

 appearance, which may extend from i to 6 feet beyond the actual decay. 



* Long, W. H.: A Honeycomb Heart-rot of Oaks caused by Stereum subpileatum, 

 Journal of Agricultural Research V; 421-428, Dec. 6, 1915. 



