d consists briefly
of determining the area of blight infection and in removing diseased
trees west of a certain line, with the purpose of preventing the western
spread of the blight.

This Commission has ascertained as accurately as possible the amount of
infection in the various parts of the state and the results are given in
a map on display here. The state is divided into two districts by a line
drawn along the western edge of Susquehanna, Wyoming, Columbia, Union,
Snyder, Juniata and Franklin Counties, which is approximately the
western line of serious blight infection. West of this line a large
portion of the state has been scouted, and the remainder will be
finished early in 1913. We have learned by experience that in the
winter, after the fall of the leaves, the best scouting work can be
done. Persistent leaves and cankers along the trunk are readily seen,
and more and better work can be accomplished than in the summer, except
when the snow is very deep.

Blight infections have been found in counties adjacent to this line:
also in Fayette County, near Connellsville, in Warren County, near
Warren, and in Elk County, near St. Mary's. These three infections were
directly traceable to infected nursery stock, and in one case the blight
had spread to adjacent trees. A large area of diseased chestnut in
Somerset County illustrates the harm done by shipping infected nursery
stock. The centre of this infection is a chestnut orchard where about
100 scions from an infected eastern orchard were grafted to native
sprouts in 1908. The percentage of infected trees in the orchard from
which the scions were obtained, according to a count made this Fall,
averages 80 per cent. Evidently these scions brought the disease into
this region, for the grafts have all been killed by the blight and every
tree in the orchard is killed or infected by disease. On adjoining
tracts over 5,400 infected trees have been cut, and there are a number
of others in process of removal, radiating in all directions from the
orchard as a center to a distance of three miles. Another infection of
143 trees was found in Elk County. It is thought that three trees at the
centre of infection were diseased in 1909, although it is possible that
one of these trees was already infected in 1908. In 1910, 27 additional
trees were infected; in 1911, 50 additional trees, and in 1912, 228
additional trees. The disease spread in all directions from the center
of infectio