Soil Treatments Drenching & Injection
Imidacloprid is applied to the soil around the tree and taken up by the root system. Imidacloprid can be purchased under, trade names such as Bayer Advanced Tree & Shrub Insect Control, Merit, Touchstone, Zenith, and Lesco. Soil applications should be made in the spring (March to early June) or fall (mid-September to mid-November) Avoid applications to frozen or waterlogged soil, but the soil should be moist It can take 30 days for the chemical to get into the tree and can provide protection for up to 2 years. Soil applications are made the following ways:

Soil Drenching
This treatment option involves the mixing the appropriate amount of imidacloprid with water and pouring the mixture around the tree, normally directed to the root zone near the base of the tree. Take necessary precautions to prevent runoff. You should rake back any heavy leaf litter or mulch on top of the ground before making the application. Return the leaf litter or mulch after the application is made. This it not a preferred method for stream bank trees.

Soil Injection
This treatment option involves the injection of the chemical into the ground with a soil injector. A tool called a Kioritz ® soil injector is commonly used. This tool may be purchased for around $300. Inject the product six to twelve inches out from the tree’s base. Evenly space a minimum of 4 injection holes around the tree. This treatment can be used on stream bank trees provided you have good soil conditions. Treat the side of the tree away from the stream. Do not apply if surface water is present around the tree.

Trunk & Stem Injection
In this systemic treatment, imidacloprid is injected into the trunk of the true. This application is normally recommended for trees growing in poor soil conditions and would include very rocky or wet areas. Stem injections should be made by a professional arborist. Specialized equipment is needed. Soil treatments should be favored when possible due to tree wounding around the injection site and the higher cost