284 
Journal of Agricultural Research 
Vol. VIII, No. 8 
HISTORICAL REVIEW 
In 1907, Whipple (11), then Field Horticulturist of the Colorado Ex¬ 
periment Station, in discussing certain rootrots and crownrots that came 
under his observation, suggested that the more destructive one which 
“ seems to work exclusively in the Ben Davis and Gano * * * may 
be due to arsenic collecting about the crown of the tree and killing the 
bark.” As he did not carry on extended experiments to prove arsenic 
to be the cause, and as he suggests that there is some evidence that the 
disease is infectious, the affected trees being often in groups, this brief 
note did not arouse much interest. 
The next year, however, Headden (5), Chemist of the Colorado Experi¬ 
ment Station, sounded a note of warning to the effect that we would do 
well to use moderation in applying arsenical compounds to fruit trees for 
the control of the codling moth and other insect pests and that it would 
be better, indeed, if these insecticides could be replaced by others not 
containing arsenic. He offered evidence to show that in Colorado at 
least much damage was being done by the arsenicals collecting about the 
crowns of the trees and killing the bark there and eventually the trees 
themselves, and that, too, in considerable numbers. If we sift from his 
bulletin the evidence upon which he bases his belief that arsenic is respon¬ 
sible for the killing of the trees in question, we may briefly state it as 
follows: 
1. The trees are dying from injury to the bark on the crowns and 
bases of the roots, and the cause has not been previously found, though 
a search for parasites has been made by other members of the Colorado 
Experiment Station staff. 
2. The trees have been sprayed with arsenicals, sometimes in excessive 
amounts, and these have accumulated in the soil, especially close around 
the crowns. 
3. It is a fact quite generally accepted that solutions of arsenicals are 
poisonous to plants. 
4. Pure water will, to some extent, bring lead arsenate and other 
so-called insoluble compounds of arsenic into solution, and if the alkali 
salts frequently found in Colorado soils are added to the water the 
arsenicals are dissolved to a much greater extent. 
5. Arsenic in considerable quantity was found in the soil under the 
trees and in the injured trees themselves. 
6. A tree known to have been badly injured by sodium arsenite poured 
into an irrigation ditch near it presented symptoms similar in some 
important respects to the many dying trees under discussion. 
In a later bulletin (6) he strengthens some of these points of evidence, 
but emphasizes the fact that, while the alkali salts make the arsenicals 
more soluble and are doubtless of importance in some orchards, they are 
not at all necessary to bring a portion of the arsenic into solution, and in 
