212 Ww. V. AGR. EXPERIMENT STATION [Bulletin 137 
to the one which causes this disease is known to occur in 
Europe. He published a careful description of the disease and 
its behavoir in 1906. 
His work was followed by a great deal of discussion as to 
the cause and importance of the disease, and meanwhile the 
chestnut trees were dying by thousands and tens of thousands. 
The Office of Forest Pathology at Washington, D. C., has 
devoted considerable time to the study of this disease, especial- 
ly as to its manner of spreading, distribution, and methods 
of control. 
Pennsylvania was the first state to give the matter serious 
consideration and more will be said of their work under an- 
other heading. 
DESCRIPTION. 
The disease may attack a tree of any age, and any part of 
the tree. It is caused by a-fungus, and this seems able to 
start its growth only in wounds of some sort, but when we 
consider the squirrels, insects, and birds which may make 
small wounds through the bark it is easy to see that there are 
numerous points of entrance. ; 
It finds conditions most favorable for its growth just be- 
tween the bark and the wood. Once started, it spreads rapidly 
and soon girdles the part upon which it is growing. It is this 
characteristic of girdling which makes it especially destruc- 
tive. Only a small amount of tissue is actually invaded by the 
fungus, but the entire tree, limb, or twig is killed beyond that 
point. When a twig or limb is diseased, the spores or fruit- 
ing bodies of the fungus are washed down toward the trunk, 
which soon becomes infected and girdled. 
The disease is most noticeable during late spring and sum- 
mer. During this period, the recently killed or dying limbs 
are easily detected from some distance, on account of their dis- 
colored foliage. The leaves on a diseased branch turn to a 
reddish brown color, and finally wither, but they have a ten- 
