PRESENT STATUS OF CHESTNUT BARK DISEASE. 51 
Observations and experiments seem to bear out the statement that 
it is very improbable that any method of spraying can interfere with 
the growth of the fungus if it has once established itself in the inner 
bark, but it may be of considerable importance in preventing the 
development of spores which come from other trees or from other 
parts of the same tree. 
It has already been demonstrated that the crotches of branches 
and enlarged bas of sprouts are very susceptible to infection because 
they are favorable places for the lodgment of water, dust, spores, etc. 
In a large majority of cases infections are definitely known to have 
originated at.a point where the outer bark had been injured in some 
way, leaving the inner living bark exposed, or where the entire bark 
over a more or less limited area had been stripped from the tree or 
cracked and split away from the wood. Certain injuries which are 
known to have afforded entrance for the disease have been of such a 
nature that they might easily be overlooked, while others have been 
quite obvious, even to the careless observer. Among the latter may 
be mentioned broken limbs, split limbs, branches which have been 
carefully cut but not properly treated with tar or paint, bruises from 
hames, plows, and cultivators; also poor grafts and diseased grafting 
scions. Among the former may be included bruises from boot heels, 
climbing spurs, holes made by borers and other insects, knife and saw 
cuts, and frost cracks, 
Almost the only treatment that can at present be safely recom- 
mended as surely retarding the spread of the disease to a greater or 
less extent is one which will never be of practical use except in the case 
of orchard trees or certain valuable ornamental trees. It consists 
essentially in cutting out the infected branches or areas of bark and 
carefully protecting the cut surfaces from outside infection by means 
of a coat of paint or tar. This cutting must be thoroughly done and 
the bark of every infected place entirely removed for a distance of at 
least an inch (where the size of the branch permits) beyond the 
characteristic, often fan-shaped, discolored areas produced by the 
growing fungus in the inner bark. All small infected twigs or 
branches should be cut from the tree, the cut being made well back 
of the diseased area. A pruning knife with an incurved tip, a hollow 
gouge, or any other clean-cutting instrument will serve for cutting 
out diseased spots. So far as the exigencies of the case will permit, 
all borers’ holes should be cut out. It has been repeatedly observed 
in the field that infection often starts where borers are at work, or 
even at the old holes made by them. The paint or tar may be applied 
by means of a good-sized brush, care being taken to cover every part 
of the cutting. Treatment should begin, or observations at least, at 
ihe base of the tree and the fact ascertained whether the disease has 
141—v 
