Injection of chemicals directly into the sapstream of trees has been used for over three decades.  Various techniques have been used with varying degrees of success.  The methods have been used for treating insect pests, fungal and bacterial diseases and for nutritional supplementation.  MACROINFUSION.  This technique involves infusing relatively large amounts of fluid containing the active ingredients diluted with water in most instances(as much as 50 gallons in very large trees). Holes are drilled through the bark and into the xylem (active sapwood) at multiple points around the base of the tree, often into the root flares at and below ground level.  Infusion tubing is attached and the fluid is infused, in amounts up to several gallons.  The fluid gradually moves upward and diffuses outward to saturate many of the active tissues with active chemicals.  This method is very effective for Dutch Elm Disease prevention, using Arbotect, a fungicide.  It has been used to control other fungal diseases, such as anthracnose and oak wilt and for nutritional deficiency such as iron chlorosis.  We use this technique to provide Dutch Elm Disease protection for up to three years with one infusion.  The charge for this treatment is usually $20 to $25 per trunk diameter inch.  See picture to left of infusion tees placed and tubing attached. MICRO-INJECTION.  This technique uses fewer holes, often somewhat higher on the tree and much less chemical.  At each injection point, from 1 to 10 milliliters of concentrated active ingredient is injected and spreads upward into the tree tissues.  We have tried this technique and have been unhappy with the results and dismayed by the technical problems we have encountered.  In some instances, we have observed bark separation and injury to the cambium (growth) layer under the bark.  In addition, the tissue levels of active ingredients is much lower, resulting in poor actual results (poor or no control of the target insect or disease).

MICRO-INFUSION WITH THE TREE I.V.   This technique was developed by Arborjet a few years ago and found to be very effective in controlling Hemlock Woolly Adelgid in eastern states.  More recently, it has been tested extensively for treatment and prevention of Emerald Ash Borers.  Several holes are drilled, but fewer than either technique discussed above.  Arborplugs are placed and infusion needles are placed into them, after which the product is infused from the Tree IV using low pressure applied by a hand pump. See picture to right. We have been using the Arborjet system for four years.  We have treated hundreds of ash trees and have had excellent results preventing and treating ash borers.  We have used the system for scale treatment, for fungal disease prevention and for nutritional treatments. This year we will have an exciting new chemical for use in the tree IV.  Emamectin benzoate has been tested by Michigan State University and found to give 99 to 100 per cent control of Emerald Ash Borer larvae and adults for at least two years with one injection.  It should also prove to give long lasting control of leaf miners, some other leaf-eating insects and larvae.  We hope it will also control the mites that cause leaf galls on maples and flower galls on ashes.

QUICKJET INJECTOR.  The newest method for infusing chemicals into trees is the Quickjet injector.  This tool was developed by Arborjet and we had the privilege of doing some of the testing of the prototype.  It will be helpful for smaller dosages of certain chemicals and in trees that take the treatment chemicals better.  The needle is similar to the infusion needles of the tree IV and the chemical is infused through arborplugs. See picture to left.  Unlike the micro-injection discussed above, the injection is deeper into the active sapwood, rather than into the cambium layer, and no bark separation or cambial damage is observed. The charge for micro infusion using either the tree IV or the Quickjet varies from $5 to $15 per trunk diameter inch.