AMERICAN 
JOURNAL OF BOTANY 
Vol. VII January, 1920 No. i 
THE INJECTION OF CHEMICALS INTO CHESTNUT TREES^ 
Caroline Rumbold 
The rapid spread of the chestnut bark disease caused by Endothia 
parasitica (Murr.) A. and A. in the eastern part of the United States during 
the past ten years and the resultant appeals for help from owners of orna- 
mental chestnut trees and of chestnut orchards, reluctant to lose their 
trees, were the reasons for this experimentation. 
As a rule the fungous diseases of plants are such that the application *of 
sprays, crop rotation, fertilizers, and sanitary methods of cultivation pre- 
vent or hold them in check. This disease, however, like many others to 
which trees especially are subject, can not be treated in this way. The cause 
of the sickness is iu a part which can not be reached by any outside applica- 
tion of medicine, fertilization of the soil will not help, nor will sanitation 
prevent, at least in many parts of the eastern states. 
The customary method of keeping such a disease in check has been to 
cut away and burn the diseased parts or the entire trees. The money value 
of the individual trees caused discontent with this method. 
Experiments on tree injection were undertaken as a possible remedy. 
It was believed that from its nature this treatment could not be applied to 
forest trees. Only such trees as had a definite commercial or aesthetic 
individual value would repay the requisite cost and trouble. 
History of Plant Injections 
The idea of introducing foreign substances into plants is two centuries 
old. In 1709 Magnol (cited by Sachs, i) introduced colored solutions 
into plants in order to find through what channels the sap passed. These 
first injections were made by placing the cut stems of leaves, twigs, or 
flowers in the solutions. McNab (2) was the first to put lithium into trees. 
He used caesium as well. About this time Pfitzer (3) injected salts of thal- 
^ The Pennsylvania Chestnut Tree Blight Commission was responsible for the starting 
of this experimental work in 1912; Investigations in Forest Pathology, Bureau of Plant 
Industry, for its continuation in 1913-1914 and in part for its continuation until 1918. 
The University of Pennsylvania furnished laboratory facilities, greenhouse, and many 
supplies. To Mr. Harold Peirce of Philadelphia, Secretary of the Commission, belongs the 
credit that these experiments were continued to their present stage. 
