428 
Journal of Agricultural Research 
Vol. V, No. io 
Mexico : 
On Quercus (?).—Jalapa, Charles L. Smith, No. 146 Central American Fungi, in 
1894 (No. 4709, Herb. Lloyd). 
From the foregoing data it will be noted that the following trees are 
attacked by the disease caused by S', subpieatum: Q. allba , Q. coccinea , 
Q . lyrata , Q. marUandica , Q. michauxii , Q. minor , Q. pains iris, Q. phellos , 
Q. prinns , £. rubra, Q. texana , 0 . velutina , 0 . virginiana , Quercus spp. ? 
and Liquidambar styraciflua (?). 
CONTROL OF THE HONEYCOMB HEART-ROT CAUSED BY STEREUM 
SUBPILEATUM 
The honeycomb heart-rot caused by 5 . subpileatum is one of several 
important heart-rots of oaks in the United States. Suggestions made 
for its control will apply more or less to all of these. The fact that 
apparently oaks of all ages are susceptible to this rot, provided they 
are old enough to have formed heartwood, must be taken into consid¬ 
eration when discussing methods of control. The only practicable 
method of control known which can be applied to the forest as a whole 
is to prevent, so far as possible, the infection of the trees. This can 
be done (1) by eliminating, so far as possible, all forest fires, since they 
produce wounds on the butts of the trees through which the fungus 
enters; (2) by preventing the formation of the fruiting bodies (sporo- 
phores) of the fungus which produce the spores. These spores are the 
direct agents for infecting the trees through dead branches and fire 
scars. 
The only method at present known by which the development of the 
sporophores of this fungus can be prevented is the destruction of all 
diseased timber which contains this rot. In lumbering tracts of oak 
all unsound or diseased trees should be cut, the parts that can be used 
removed, and the cull logs and dead trees burned, since this fungus 
fruits most abundantly on old logs and on dead fallen timber. Many 
trees under the present methods of lumbering are left standing because 
they have heart-rot in the butt. If cut down, these trees would usu¬ 
ally be found to contain enough lumber to pay for the cost of opera¬ 
tion. Such a procedure will lead to a better and closer utilization of 
our gradually decreasing supply of oak and insure a healthier future 
forest. 
Special emphasis should be placed on the fact that the rot produced 
by 5. subpileatum can continue to grow in a tree after it is felled, and 
that every cull butt, log, or tree left on the ground in a lumbering oper¬ 
ation will later bear an enormous number of sporophores of this fun¬ 
gus which will discharge annually millions of spores for many years. 
In the interest of the health of the future forest, it is therefore of the 
utmost importance that all of these cull logs and trees be destroyed. 
