Characteristics of sapwood discoloration in three broadleaf tree species initiated by different trunk-injected insecticides

Abstract

Potential concerns for adverse effects of trunk injection on tree health have arisen because of the injury caused by injected holes and chemical injections. There are, however, few previous reports evaluating injury formed in sapwood. In this study, we investigated the size of sapwood discoloration following injection of 4 or 2 insecticides to the trunks of Cerasus × yedoensis, Platanus × acerifolia, and Liriodendron tulipifera. The insecticide D, containing organic solvents, initiated the discoloration more than 500 cm above the injected holes in C. × yedoensis, and more than 100 cm above them in P. × acerifolia. At the height of the injected holes, it presented large cross sections of the discoloration. Meanwhile, the discoloration was largest by the insecticide B and smallest by the insecticide A among 3 insecticides using water as a solvent although they were appreciably smaller in comparison with the insecticide D. Our study revealed that the discoloration following trunk injection was largely affected by the solvents and its sizes were different among the tree species.