CHESTNUT BARK DISEASE. . 7 
trates the bark to the wood of the chestnut tree, killing the 
invaded tissues, but does not enter into the wood to any appre- 
ciable extent nor does it affect directly any part of the tree 
other than that with which it comes in contact. The tree or 
branch is killed only when the disease goes completely around 
it, thus girdling it and stopping the flow of sap to the parts 
above the infected area. : 
The mycelium or vegetative part of the fungous plant grows, 
as has been stated before, in and beneath the bark and the spores 
are borne in characteristic red-brown or orange-colored pus- 
tules. These are seen dotting the surface of the cankers on 
smooth bark and thickly clustered in the crevices of rough bark. 
The spores are the bodies by which the organism perpetuates 
itself and are borne on the fruiting pustules in countless num- 
bers. There are two forms of these spores, one of which is 
borne in the summer and the other in late fall and winter, both 
being capable of infecting chestnut trees under the proper con- 
dition. So small are the summer spores that 8,000 of them placed 
end to end equal an inch in length. The chestnut blight fungus 
does not so far as known injure any other kind of tree nor does 
it usually attack a tree unless the bark has been injured or the 
tree is in a weakened condition. It has, however, been found to 
a very limited extent on a few oaks, but never doing any appre- 
ciable injury. 
REMEDIES TRIED. 
At present there are no sure remedies known for this dis- 
ease, because the fungus grows wholly within the tree, only 
its fruiting pustules appearing on the surface, thus making it 
very difficult to control the disease by spraying even if it were 
practicable to do spraying in a chestnut forest. Other methods 
of control have also proved unsuccessful. 
Spraying. It has been claimed that spraying with Bordeaux 
mixture will prevent trees from becoming infected, which it 
doubtless would if the tree had no wounds in the bark and 
could be covered completely with the mixture at all seasons of 
the year. But this is nearly impossible and surely impracti- 
