JOURNAL OF mm RESEARCH 
Voh. VIII Washington, D. C., February 19, 1917 No. 8 
ARSENICAL INJURY THROUGH THE BARK OF 
FRUIT TREES 
By Deane B. Swingle, Botanist and Bacteriologist, and H. E. Morris, Assistant 
Botanist and Bacteriologist, Montana Agricultural Experiment Station 
INTRODUCTION 
The economic aspects of our interest in the effects of arsenical com¬ 
pounds upon plant life have come to center largely about three conditions 
that have developed as a result of recent commercial practices, (1) the 
injury to vegetation by arsenic from smelters, (2) the injury to foliage 
and fruit by arsenical insecticides, and (3) the possible injury to fruit 
trees through the bark of the crowns and roots by the corrosive action of 
arsenicals that have accumulated there as a result of spraying. 
In the year 1909 we began at this Station an extensive investigation to 
determine, so far as possible, all the effects of arsenical compounds upon 
vegetation. The scope of this work is far-reaching, including the effects 
of practically all known compounds of arsenic on many different species 
throughout the plant kingdom. The studies have so far been largely 
physiological, but it is evident that much chemical work also will be 
required to solve some of the problems involved. 
This paper takes up only one phase of the investigation, but as our 
work on that is practically complete and it is of immediate interest to 
orchardists, entomologists, and pathologists, the results are being pub¬ 
lished in advance of the rest, on which much more work will be required. 
A preliminary report (10) ,* embodying our first year's work on this subject, 
was published in 1911. 
After fruit trees have been sprayed with improperly prepared arsenical 
insecticides, it has occasionally been noted that the bark of the twigs has 
been more or less injured, but in such cases the damage to leaves and 
fruit has been so severe as to attract much greater attention. This is 
but natural, for, as the fruit is more resistant to this injury than the leaves, 
and as the bark is even more resistant than the fruit, it is evident that 
any arsenical mixture that could be recommended as doing only moderate 
damage to the leaves would have no visible effect whatever upon the bark.. 
1 Reference is made by number to “Literature cited,” p. 317-318. 
(283) 
Journal of Agricultural Research, 
Washington, D. C. 
hf 
Vol. VIII, No. & 
Feb. 19,1917 
Key No. Mont.—4 
