12 CONTROL OF THE CHESTNUT BARK DISEASE. 
THE METHOD IN DETAIL. 
Locating advance infections (“scouting ”).—The first thing to 
be done in each State is to determine the exact range of the disease 
in that State, and particularly to locate the advance points of infec- 
tion. This is by far the most difficult feature of the entire pro- 
gram, because the work must be directed and in large measure car- 
ried out by experts; otherwise diseased trees will be left, and the re- 
sults can not be depended upon. It is best intrusted to professional 
plant pathologists or at least to botanists familiar with fungi and 
the collecting of fungi, and even these must have some preliminary 
knowledge of this particular disease. The symptoms of the disease 
are too obscure and the means of locating it too intricate to make it 
possible for a persor. without a professional knowledge of plant dis- 
eases to deal successfully with the situation, no matter how well in- 
formed in agriculture or forestry or how experienced in the care of 
trees. It is suggested that in most States this part of the work 
would be best handled by the pathologists of the State agricultural 
experiment stations. 
For assistants the pathologists having this work in charge should 
choose the best scientific observers obtainable, regardless of other con- 
siderations, but persons with some knowledge of plant pathology are 
to be preferred. College students trained in these lines are usually 
available, for the summer vacation at least, and make in many 
respects the most desirable “ scouts” for this work. But all “ scouts” 
must be carefully and individually trained by the expert in charge. 
Attention should first be directed to the advance spots of infection 
already known to exist, and when found the diseased trees should be 
destroyed or marked for destruction. No difficulty will be experi- 
enced in locating infections 2 years old or more, but the greatest diffi- 
culty will be met in locating infections of the current year. Every 
tree in the immediate vicinity of older infected trees must be carefully 
gone over. Many dubious cases will be found, and from such trees 
samples of the suspected bark must be taken and sent to some labora- 
tory for expert judgment. It is absolutely necessary to have arrange- 
ments with some laboratory whereby such work can be done and the 
results promptly reported. 
After the spots already known to exist have been delimited and 
the trees destroyed or marked for destruction, the search should be 
continued. It is best next to clearly define the location of the main 
line of advance of the disease, back of which infection is general. 
Working away from this line as a base, a complete survey of the 
remainder of the State must be made, until it is reasonably certain 
that all spots have been located. 
Scouting is best discontinued as soon as the leaves change color in 
the fall, since from October to April, inclusive, the symptoms are 
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