Why We Never Use Trunk Injections

Protecting a Tree Should Not Begin With Drilling Into It

Many arborists and tree companies use trunk injections. Eric Putnam BCMA Inc. does not use trunk injections under any circumstances because we consider the practice inherently damaging and potentially deadly to trees. Every trunk injection requires drilling through the protective bark and directly into the living cambial and vascular tissues. The tree must then expend energy to compartmentalize each individual injection wound. These wounds do not simply disappear after the chemical has been introduced.

How Injection Damage Develops

Creating Direct Entry Points Into Living Tissue

Injection ports are typically installed near the base of the trunk. This area connects the trunk to the tree’s structural root system and is commonly exposed to moisture, soil organisms, fungal spores, bacteria, and other sources of disease pressure.

Even when the drill bit and injection equipment are disinfected, the tree’s bark cannot be made sterile. Fungal spores, bacteria, organic debris, and other microorganisms present on or within the bark can be carried directly into the newly drilled hole. Once one or more of these contaminants enter the injection wound and become established within the living tissue, the tree may no longer be able to successfully close or compartmentalize (CODIT) the wound. The injection site can then remain an active pathway for internal decay, vascular disruption, and continued fungal or bacterial colonization.



Reusing equipment from tree to tree creates an additional risk of transferring pathogens between properties and individual trees.

The Long-Term Effects of Repeated Injections

Based on our long-term field experience, more than half of repeatedly injected trees may experience serious decline or mortality within approximately five to ten years.

Repeated injections can lead to internal decay columns, localized cambial death, vascular disruption, fungal colonization, and the eventual failure of the tree to close or compartmentalize the accumulating wounds.



Unfortunately, the connection between the injections and the later decline is rarely acknowledged. By the time the tree begins showing extensive decay, vascular disruption, cambial dieback, or structural deterioration, the decline is often attributed to drought, insects, age, disease, or another secondary factor.

Research behind our approach

Repeated wounds in American elm. Dissection of 80 elms found discoloration associated with injection wounds. Trees injected over successive years sometimes had severe internal injury. (Discolored and Decayed Wood Associated with Injection Wounds in American Elm | Arboriculture & Urban…)

The injected material matters. In small American elms, chemical treatments produced larger columns of discolored wood than water injections; the studied fungicide was particularly injurious. (https://auf.isa-arbor.com/content/isa/11/5/137.full.pdf)

Some injury is hidden from view. In preliminary observations of injected maple and ash, external bark cracks understated the extent of cambial injury found through dissection. (https://www.nrs.fs.usda.gov/pubs/jrnl/2005/ne_2005_smith-k_003.pdf)

Application method affects visible wounds. Among 365 treated green ash trees, trees treated with a sealed plug system had more observed external wounds than those treated with an open system. Many wounds in the sealed group were associated with improper plug application. (https://www.rainbowecoscience.com/content/pdf/tree-injection-research/TI-Research-Observation-External-Wounding.pdf)

Injected material affects wound response. In five-year-old sweet orange trees affected by citrus greening, oxytetracycline injections led to slower wound closure and more internal discoloration than water injections. Wound response also varied by injection location and season. (https://link.springer.com/article/10.1007/s00468-023-02440-2)

Drilled and drill-free injection in sweet orange. In two trials involving young sweet orange trees affected by citrus greening, the drill-free system caused more trunk injury than the drilled system under the methods tested. The systems delivered different antibiotic doses, so this should not be presented as proof that drill-free methods are generally more damaging. (https://www.mdpi.com/2311-7524/11/8/976)

Injected formulation and trunk injury. In two trials involving citrus-greening-affected ‘Valencia’ orange trees, a formulation containing an adjuvant was associated with wider and longer wounds and more bark cracking, without improving antibiotic performance. Oxytetracycline treatments also improved fruit yield and quality. The authors could not isolate the effect of pH from the effect of the adjuvant. (https://www.mdpi.com/2079-6382/15/9/892)

* Disclaimer: This does not apply to Oak Wilt, which might require trunk injections *