Last year fifty-four trees were injected; 15 with salts of the heavier
metals; 5 with formaldehyde; 12 with stains; 22 with alkalies, and the
remainder with water. An attempt was made to inject two trees with
canker extract, but the solution would not go into the trees.
On June 7, 1913, results of observations on these trees injected last
year were made as follows:
To date, the injections of the salts of the heavier metals, (copper,
zinc, barium), appear not to have killed the trees, although they
mutilated them. Those injected with the copper salts suffered the most.
Inoculations made on these trees after they were injected have taken,
and the cankers forming are larger than those on the check trees. Of
the five trees injected with the formaldehyde, two are alive, but
mutilated. Inoculations on these trees have formed cankers larger than
those on the check trees. Most of the trees injected with stains have
been cut down, for observation. None were killed, however, by the
injection. The trees injected with water are in good condition with the
exception of one tree infected with a canker, which is now girdled. The
only unusual sign about the tree is the large amount of suckers at its
base.