112 SHADE TREES. 



only in the northern part of the United States. 



White rot. . . 



It gains entrance to living trees through 

 wounds, causing a white heart rot. It has been reported on 

 maples, oaks, elm, basswood, willow and ash. 



Polystictus vesicolor (L.) Fr. (see below) is the cause of 

 a soft heart rot of the catalpa. The disease starts in the 

 center of the trunk or branch, causing the wood to turn pale 

 and finally a straw yellow color. The diseased wood becomes 

 soft and pithy and easily broken. The disease can usually 

 cataipa ^ e ^cognized by the holes which are formed 



heart rot. where diseased branches have been broken off. 

 Trees in the open are not so likely to be attacked as those 

 grown in crowded conditions which result in the natural 

 dying of the lower branches. 



Treatment. 



Careful pruning and treatment of wounds will prove ample 

 protection for shade and ornamental trees. 



SAP ROTS. 



The sap rots are the cause of considerable losses, and al- 

 though it is impossible to draw a sharp line of distinction 

 between those which are parasitic and those which are sapro- 

 phytic, the majority of the sap rot fungi must be considered 

 primarily saprophytes. Among the most important are the 

 following : 



The sap rot caused by the fungus (Polystictus versicolor 

 (L.) Fr.) is a true saprophyte, except on -the Catalpa (see 

 above), and attacks cut and fallen timber of many kinds. 



Although more of a saprophyte than a para- 

 Destroys . * y 

 posts, poies site, the wide distribution and great abundance 



of this fungus demands that it should receive 

 some attention in this publication. It is especially destruc- 

 tive on railroad ties, posts and poles. It grows in the sap 

 wood, causing a decay and eventually forming its charac- 



