What are Trunk Injections?

Updated: Jul 14

Written by: Brad Hill, Hoppe Plant Health Care Manager, certified arborist WI-1235A


At Hoppe Tree Service we care for plants with different types of insect issues and diseases as well as abiotic disorders caused by poor soils, weather and animals. The specific problem with the plant drives how and when we perform certain treatments, and which will provide the best, longest-lasting results. In many situations a direct trunk injection is the best solution.



Types of Trunk Injections

There are two types of trunk injections, macro and micro. This refers to the volume of the water and product required to ensure proper protection. Both types are injected low on the trunk at the root flare and into the tree’s vascular tissue which will translocate the product into and throughout the tree.


Micro injections are a good delivery method for insecticides such as emamectin benzoate that protect ash trees from the emerald ash borer, birch trees from bronze birch borer and oak trees from two-lined chestnut borer. Macro injections introduce a larger volume of water and product into the tree and canopy and are effective for treating vascular diseases like Dutch elm disease, oak wilt and sycamore anthracnose.


How Trunk Injections are Performed

If a direct trunk injection is prescribed for your tree a trained, certified and licensed technician will follow these general steps:

  • First, he or she will make sure the measurement of the tree is accurate and up to date. This will ensure that the tree gets the proper dosage required for the treatment.

  • After mixing the product, the technician will drill multiple holes, depending on the size of the tree, evenly spaced at the base at the root flare and into the vascular system.

  • He or she will then insert the tapered tips into the drilled ports and pressurize the system and check for any leaks. The pressure is only to get the product to the tip - the tree does the rest of the uptake. Think of it as the tree getting an IV of medicine with multiple injection sites.

Watch how John, one of our Plant Health Care Team members and a licensed pesticide applicator, explains the steps for trunk injections for treating emerald ash borer.




Micro injections can occur in a matter of minutes and a macro injection might take several hours.

These treatments are performed once the leaves have fully emerged and can be done until the appearance of fall color change. They also provide two to three years of protection. If possible, it is best to take preventative measures against susceptible trees with protective injections, but therapeutic injections can prove successful once an insect or disease issue is present.



Untreated vs. Treated: The untreated ash tree at left has lost most of its leaves due to emerald ash borer. The tall ash on the right is thriving after trunk injections to treat for EAB.


If you have concerns about the health of your trees, contact Hoppe. One of our team of certified arborists will inspect your trees to identify any issues and recommend a course of treatment that our plant health care technicians will perform. If you do have a tree with an insect issue or disease, trunk injections give you options!

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