314 Journal of A gricultural Research voi. viii, no. 8 
that almost the entire top of the tree is killed. In the former case, there 
were no general symptoms of injury during the course of the experiment. 
In the latter case, with nearly all the smaller branches killed and 
streaks running down the larger limbs and trunks, the few remaining 
branches grew vigorously and the foliage appeared perfectly healthy 
and normal. As a result of so many branches being killed, many buds 
pushed out below, making succulent water sprouts. It is well recog¬ 
nized that most of the arsenic absorbed through wounds in the bark 
may be deposited in the wood and bark that are killed and not carried 
extensively through the tree. That some is carried into the unkilled 
portions is shown by analyses made by the chemistry department of 
this Station. The work of Headden has established beyond question 
that considerable amounts may be taken up from the soil before the 
tissues are actually killed. All things considered, we think it doubtful 
if general systemic poisoning has occurred to any considerable extent as 
a result of orchard spraying, though we have no reason to believe that 
it can not be produced experimentally. 
SIGNIFICANCE OF RESULTS 
The results of the foregoing experiments are of interest chiefly in 
relation to the pioneer work done by Headden, of the Colorado Agri¬ 
cultural Experiment Station, on the crown injury to fruit trees in Colo¬ 
rado and elsewhere and the relation of spraying for codling moth to this 
injury. Headden’s work was reviewed in the opening pages of this 
paper, arid certain points of strength and of weakness in his evidence 
were pointed out. 
In this contribution we have shown that arsenical compounds used 
for spraying can penetrate the corky layer of the rough bark and cause 
a corrosion and killing of the inner bark and produce symptoms similar 
to those described by Headden. The symptoms we have produced should 
.be closely compared with those found in Colorado. They are alike in 
several respects: (1) The bark is killed and discolored in a localized 
area at and extending out from the point in contact with the arsenic; 
(2) the wood underneath the dead bark is discolored in an irregular 
region growing smaller toward the center of the tree (if there is no black- 
heart from winter injury) and up and down from the point of injury; 
(3) the dead bark, if in contact with moist soil, becomes darker, more or 
less disintegrated, and friable; (4) the fruit on trees with corroded crowns 
may become small and highly colored; (5) in early fall the foliage may 
take on a distinctly purplish color. There are two points of difference: 
(1) There is a marked tendency for longitudinal dead streaks to be 
formed as a result of artificial treatment; (2) we have never produced 
corroded crowns that were quite so dark in color or quite so friable in 
texture as those on some of the injured trees in Colorado. 
