76 Journal of Agricultural Research voi. iii, no. i 



CONTROL OF THE PIPED ROT OF POLYPORUS DRYOPHILUS 



The piped rot caused by Polyporus dryophilus is one of several impor- 

 tant heart-rots of oaks in the United States. Suggestions made for 

 its control will apply more or less to all of these. So long as oak trees 

 are allowed to stand long past maturity in our wood lots and forests, 

 heart-rots will continue to be common. The practice of leaving uncut 

 in a lumbered area all the badly diseased trees, especially those with 

 heart-rot, is radically wrong from the standpoint of proper forest sani- 

 tation, for this practice enables heart-rotting fungi to maintain them- 

 selves in the forest while the new generation of trees slowly develops and 

 attains the age at which they form heartwood and thus become suscep- 

 tible to the attacks of heart-rotting fungi. Trees diseased with heart- 

 rot ought not to be left for seed trees wherever it is possible to leave 

 healthy ones for this purpose. In hardwood forests it is often not neces- 

 sary to leave seed trees, owing to the abundant sprout production, and 

 the presence of young trees intermingled among the more mature ones. 



Trees in the wood lot should be inspected annually, and all trees evi- 

 dently rotted at the heart should be removed. If the trunk of a tree 

 diseased with heart-rot is struck with an axe, it does not ring with a 

 clear sound. The presence of the fruiting body of Polyporus dryophilus 

 on a tree also is evidence of the presence of the piped rot and of the 

 necessity of removing the tree. Sporophores on trees should be removed 

 whenever found. 



In large forested areas it is not possible to personally inspect the trees 

 every year nor to search the forests annually for sporophores, although 

 the present prices of good white-oak lumber nearly justify the expense 

 necessary in a system of careful forest sanitation. It will certainly pay 

 in lumbering tracts of oak and other valuable hardwoods to cut out all 

 unsound or diseased trees, remove the parts that can be used, and bum 

 the remainder. Many trees under the present methods of lumbering 

 are left standing because they are decayed in the trunk near the butt. 

 If cut do\\Ti, these trees would be found to contain enough lumber to 

 pay for the cost of operation. Such a procedure will lead to a better 

 and closer utilization of our gradually decreasing supply of hardwood 

 lumber, especially of white oak. 



The destruction of all trees that are rotted in the heart in timber sales 

 will be a step far in the direction of control for these diseases of timber. 

 A new forest grown on areas lumbered with due regard to sanitation 

 will be certain to be nearly free from heart-rot. 



