Horticulturists Corner: Tree Injection - An Alternative To Spray
By Wayne Jewell
Transpiration involves water being drawn from the earth via tree roots and traveling by way of xylem cells throughout the tree until it reaches the leaves from which it evaporates. This is an over simplification of the process of course and there is more involved.
However, I mention this because there are times when it is just not possible and/or practical to spray a tree. Possibly the tree is too large to be sprayed or it is a windy day that could cause a spray to go off target.
An alternative solution is to have a tree “injected” by a trained professional who has the ability to acquire tree care products that are not available to the average home owner due to licensing and training requirements.
Though there are several companies that specialize in tree injection products and equipment for use in the tree care industry, one that comes to mind is the J.J. Mauget Company out of California.
Many years ago, after obtaining my state pesticide applicators license, I was sent out to the east side of Cleveland to a company called Lanphear Supply who is a Mauget distributor, for training and certification in the use of Mauget products.
Since we have many large trees at Sunset Memorial Park, this gave me an alternative to spraying and the ability to do tree injections of insecticide, fungicide, fertilizer and micro-nutrient products.
Tree injection does take some time and in fact is a much slower process than tree spraying so the decision to use injection needs to be based on the value and importance of the tree in the landscape compared to the cost of material and labor involved to do an injection. Keep in mind that the larger the tree, the more injections will be needed and thus the higher the cost to treat.
The first step is to identify the problem. In this case, I am treating an old Red Oak tree that appears to be suffering from Oak Wilt Decline. To determine how much product I will need, I wrap a measuring tape around that tree at about four and one half feet above the ground to determine the trees circumference at breast height or CBH. In this case the CBH is 9 feet 6 inches which I covert in to all inches or 114 inches. To determine how many cartridges of a product called “Fungisol” which is a tree fungicide, I divide the 114 by 6 and come up with 19 cartridges needed. I space the cartridges around the base of the tree keeping them near the root flares of the tree. Then, I drill a 11/64 inch diameter hole through the bark until I feel the bit hitting the xylem (wood) and drill another 3/8 of an inch in to the xylem. I insert a feeder tube in to the hole. Then compress the cartridge by squeezing the top and bottom of it between my two hands until it locks in to place and slip it on to the end of the feeder tube, tapping it with a rubber mallet just hard enough for the feeder tube to rupture the membrane of the cartridge to let the 4 ml of solution enter the feeder tube. Before proceeding to the next hole, I sterilize the drill bit with alcohol and then repeat the process all the way around the tree. These holes are actually about 4 to 6 inches above the ground in the root flares but not in the area between them. This is where proper mulching is important. Too many people in the industry mulch in such a fashion that they pile mounds of bark up around the tree and actually hide these root flares on large trees. It is a practice that serves no horticultural benefit and can actually cause harm to the tree. Good mulching does not hide root flares-but actually accentuates their presence and makes tree injections possible.
Once the liquid has been sucked from the feeder tube by the transpiring tree, the tubes and cartridges can be safely removed and disposed of just as any other pesticide container but without the triple rinsing requirement.
The faster a tree is transpiring water, the faster the liquid will be drained from the feeder tubes. Pressurizing the cartridge is merely to get the liquid in to the tube. After that, it is up to the tree’s natural processes to take over.
Conditions that cause rapid evaporation of water will give rapid up take in to the tree. For example, warm air temperatures, low humidity, wind and adequate soil moisture make for a faster injection and up take.
The people at the Mauget Company have a saying: “A bad day to spray is a good day for Mauget”.