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Injecting Trees: Micro vs. Macro Injections

The spring season is upon us and the trees are ready to start leafing out and uptaking all kinds of nutrients from their environment. This big uptake will help them push out new growth and put on some new growth rings as well. With the growth spurt comes the threat of pests and diseases that love munching on that supple new growth and possibly infecting the leaves and needles of your clients' trees! So, what is your plan for helping them care for their trees this coming season?

Depending on the type of pest or disease, you might be looking to do some sort of injection to the tree to help get chemicals into its vascular system. The chemicals that flow into the vascular system can help protect the tree from insects, mites, and nematodes, as well as diseases that can kill a tree in as short as one growing season once the infection has set in. But what kind of injection system is best for what you need to do to better care for trees?

Two Types of Injection

There are two types of injection systems we are going to discuss today. The first is Micro-Injection and the second is Macro-Injection. Both have the same purpose: to get chemicals into the nutrient moving system of the tree, but each have differences that will help you properly treat the respective tree with the proper techniques, as well as the proper dosage. One thing to keep in mind about injecting trees is the fact that damage is done to the cambial tissue of the tree because of the necessary drilling or probing of the tree. This should be weighed in the decision to inject or possibly use other forms of treatment, such as bark sprays, soil drenches, or foliar sprays.'


Micro-injection systems use a small injection needle that is placed into a port that is inserted into the tree. This injection port is placed in a small hole that is drilled into the cambial layer through the xylem and phloem. This port acts as a check valve, meaning that it will let the needle pass through it, but once the injection has taken place, no chemicals will be released past the valve. This helps keep the chemicals safely in the tree and not dripping into the environment.

Micro-Injections work great for treating trees with insecticides, miticides, and antibiotics. Micro-injections only inject a small amount of chemical and water into the tree's vascular system so the chemicals are not always getting to every single part of the tree. Knowing which equipment works best for each ailment is something to keep in mind when building your PHC knowledge.


Macro-injections use the same ports, but there are many more placed around the root flare of the tree. The point of a Macro-injection is to inject a higher volume of water and chemicals into the tree's vascular system so it can be spread through the entire canopy and into new growth. Since Macro-injections introduce such a higher volume of water and chemicals into the tree, they are very useful in treating vascular wilts such as Dutch Elm Disease or Oak Wilt.

Macro-injections use a sort of IV system that is place around the root flare at multiple locations. Once all the necessary hoses are connected, chemicals and water are placed in a tank and are pressurized with a pump. This allows the solution to be pushed into the tree as it is uptaking other minerals. It looks just like you have the tree hooked up to multiple IVs!'

A Little Knowledge Goes a Long Way

The biggest thing to help you with understanding which tool is correct for the job is knowledge. By researching and learning as much as you can on the subject of Plant Health Care and Integrated Pest Management you are sure to give your clients a clear and concise answer to any of their tree health problems. Looking into training programs like the Plant Health Care Technician certification through TCIA may be a great place to start!'

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