Pressurized injection of aqueous solutions into tree trunks

A more precise analysis of the factors limiting pressurized trunk injection using dye solutions, a growth retardant (daminozide, succinic acid 2,2dimethyl hydrazide) and a my cobacteriostatic agent (tetracycline) has been completed. This included methods of drilling injection ports, influence of port diameter, depth, and pressure system. Results of these investigations suggest that trunk injection of aqueous solutions is feasible in many angiospermous species. Injected solutions moved up and down the 1- and 2-year old xylem into major scaffold and secondary branches, into terminal bud tissues of elongating shoots and secondary and tertiary lateral roots. Depending upon species, injection rates varied from 200 to 1800 ml/min at 14.08 kg cm^?2 through injection ports 0.63 cm in diameter and 5 cm deep. Inhibition of stem elongation in Prunus persica var. nectarina (Ait.) Maxim and Prunus persica L. ‘Johnson’ and ‘Loadel’ trees was obtained with 5 to 50 g daminozide/tree, using 0.5 to 5% solutions. Tetracycline-induced remission of “pear decline” was achieved with 100–800 mg dosages depending on tree size. Dormant-season injections were effective for controlling growth and/or pear decline.