The principal obstacle met in applying sanitation methods for the
control of the chestnut blight is the high cost of locating spot
infections. The cause of this lies in the great extent of territory
which must be covered, and difficulty in securing competent and
reliable scouts at reasonable salaries. Experience has proved, however,
that thorough scouting can be done at a moderate cost under efficient
supervision. Rapidity and efficiency in scouting vary with the size
and density of the stand, the proportion of chestnut, the topography
and location of the tract, and the prevalence of blight. The records
of the Chestnut Tree Blight Commission show that between October 3 and
June 30, 1913, it required 11,651 days of labor to scout 738,881 acres
of timber, notify timber owners of infections found, and supervise the
work of removal. This is at the rate of 63.41 acres per man per day,
with the average of 2.07 infections found, and 1.49 infections removed
per man per day. The average day, (not including time consumed in
going to and returning from work), consisted of 8.2 hours spent in the
field, .4 hour lost on account of rain, and .4 hour lost on account of
sickness and leave. With thoroughly experienced and practical men under
competent crew leaders, an average of 100 acres or more per day can be
covered, unless the spot infections are very large and numerous. In
thick infection, one man can make thorough tree to tree examinations of
from 2 to 5 acres, depending on the character of the timber. However,
on the basis of past experience, it appears to be more practical
and economical to locate the boundaries of the spot infection, and
eliminate all of the chestnut trees within and immediately adjoining
the spot infection, instead of eradicating only the diseased trees.
This plan reduces the amount of tree to tree inspection required, and
one man should be able to scout at least 50 acres per day, even when
spot infections are numerous. It has been found that a crew of two or
more men can accomplish more and obtain better results than in the case
of men scouting alone, except in a country where the woodlots are very
small and scattered.
In scouting, rapid and thorough work depends upon the experience and
capability of the crew leader. The size of the crew depends on the
character of the timber to be scouted and the ability of the crew
leader to handle men. Except in a very heavily timbered area, three men
constituting a crew will usually accomplish more than a larger crew.
There is an added advantage in a small crew in that two or three men
can find accommodations near to their work where a larger number of men
cannot, and must consequently spend more time on the road to and from
work. In large tracts of woodland, the best plan is to establish a camp
as headquarters for several crews. A camp is too expensive for a small
crew, but for a number of men it is economical, and has the advantage
of keeping the men close to their work.
The tracts must be scouted systematically. The best plan is to go back
and forth parallel to the backbone of the ridges, each man inspecting
a strip 50 to 100 feet wide. In large bodies of timber four or five
men can work together advantageously, each man being separated by the
distance best adapted to viewing all the trees in the strip between
himself and the men on either side of him. The man on the outside marks
the edge of the strip either by breaking branches on the underbrush
of species other than chestnut, or by marking tree trunks with yellow
lumber crayon. Unless eradicated as found, diseased trees are located
by pacing to the strip boundary at right angles and marking a tree on
the line with crayon to indicate the location of the diseased tree.
If a cutting-out crew closely follows the scouting crew, there is
less waste of time and effort than where the scouting crew attempts
to eradicate the infections as found, unless infections are very few
and limited to single trees. With the cutting-out crew following the
scouting crew, there is the additional advantage that they may locate
diseased trees missed by the first crew.
The greatest aid to efficient scouting is a pair of good field glasses.
They often make it unnecessary to climb doubtful trees, and are of
further usefulness in the hands of an experienced scout, because they
enable him to locate many diseased trees from a high point of land or
from tree tops. In such cases compass sights are taken on the diseased
trees, and an assistant is dispatched to locate them. Such scouting,
however, cannot entirely take the place of more detailed examination.
[Illustration: Thorough scouting for the blight is necessary.]
It has also been demonstrated that more and better work in scouting can
be done in the fall and winter, after the leaves have fallen. In August
and September the majority of new infections become plainly visible on
isolated trees, but in dense woods the foliage makes it difficult to
locate small infections. After the leaves have fallen, however, more
light is admitted, and a scout can see for comparatively long distances
through the bare tops, even in dense woods. The dead leaves on girdled
branches are conspicuous throughout the winter and early spring, and
where cankers have not yet girdled the parts, the increased light
makes them much more prominent than in summer. Winter scouting has the
disadvantage of fewer hours of daylight and occasional loss of a day
or two on account of snow storms that tend to hide the cankers on the
trunk and branches. If the snow becomes very deep it is not easy to
examine the bases of the trees sufficiently, and the snow also greatly
interferes with the proper treatment of the blighted trees.
In the work done by the Commission, the law required that the owner
of diseased trees be notified to remove them within 20 days. A map
or written description giving the location of the diseased trees on
the tract, was also required by law. On private land the scouts kept
field notes on the location of all diseased trees, blazed each tree to
the wood and marked a serial number on it with black lumber crayon;
on the side opposite from the blaze, a yellow manila tag was attached
to the tree. These tags bore a printed notification that the tree to
which one was attached must be cut in 20 days, with directions for
treatment and a warning against starting forest fires; they also bore
the serial number of the tree, the name of the scout, and the date
when attached. In this way the trees were easily identified later when
approached from any direction, and by means of the “location sheet”
giving the direction and distance of each diseased tree from some fixed
point, it was not difficult to find the trees. The “location sheet”
was made out in duplicate, one copy being handed to the owner of the
tract, with a written request to remove the trees within the 20 days
granted by law. The duplicate copy was sent to the field office, the
scout retaining his note book. Some system of this sort is necessary
when the cutting out is not done by the scouting force, but it is
cumbersome and very expensive. Frequently, it required more time to
fulfill the requirement of the law than would have been necessary to
treat properly the diseased trees on a tract. Much time was consumed
also in very detailed inspection of the trees around a blight center,
so that apparently healthy trees would not be cut, since the law
provided that healthy trees ordered to be cut, must be paid for. Not
only was this very detailed scouting a waste of time in the light of
recent investigations, but it resulted in decreased efficiency of
control because so many of the trees permitted to remain, in reality
were infected. Although no disease could be found on them at the time,
the disease developed fully after the spot was treated, necessitating
several re-examinations before all infections could be removed.