OBSERVATIONS ON THE EFFECT OF GROWTH-STIMULATING COMPOUNDS ON THE HEALING OF WOUNDS ON APPLE TREES

Wounds were made at various times of the year on the trunks and large branches of apple trees with a 1 in. bit and treated with a number of organic compounds in lanoline paste. The healing of these wounds was followed through two growing seasons by tracing and measuring the area of exposed wood at different times after wounding.
Callus growth was practically confined to the summer months. Development of callus was improved by applications of lanoline, and the lanoline effect could be further enhanced in the early part of the first growing season following treatment by the addition of certain growth-stimulating compounds including 4-chloro-3:5-dimethylphenoxyacetic acid and 2:4-dichlorophenoxyacetic acid. Indolyl-3-butyric acid probably also caused some stimulation. After the period of initial stimulation the rate of callusing was approximately the same on treated as on untreated wounds.