What Is Emerald Ash Borer Trunk Injection? (DBH Dosing Chart)
Emerald ash borer trunk injection delivers a registered insecticide into an ash tree’s vascular system to help protect it from emerald ash borer. The dose is based on the tree’s diameter at breast height (DBH) and the specific product label. There is no universal dosing chart: rates, equipment, timing, and retreatment intervals vary by product.
A tree trunk can look sound while emerald ash borer larvae feed beneath its bark. If you have found “trunk injection” or “DBH rate” in a manual, the key point is simple: the tree’s measured size helps determine the dose, but only the label for the exact product tells you how much to use and how to apply it.
I teach this as a two-part check: measure the tree correctly, then match that measurement to the current product label. A chart copied from another product may look convenient, but it can give the wrong dose.
What emerald ash borer trunk injection means
Trunk injection is a method of applying pesticide through small openings in a tree’s trunk. A suitable product is placed into the tree’s vascular tissue, which moves water and dissolved substances through the tree. For EAB, certain registered products are labeled for this use, but injection does not repair damage already done.
The emerald ash borer (EAB) is an insect whose larvae feed beneath ash-tree bark. Some EAB trunk-injection products contain emamectin benzoate, but products can differ in formulation, concentration, permitted rate, and retreatment interval. Do not transfer instructions from one brand or formulation to another.
Injection is not a cure for every ash tree. A dead tree, a severely declining tree, or one with serious structural problems may not be a suitable treatment candidate. The insecticide also cannot repair trunk decay or make an unsafe tree structurally sound. Have a qualified tree-care professional assess a tree when its condition or safety is uncertain.
Measure DBH and calculate the product dose
DBH means trunk diameter at breast height, measured 4.5 feet (1.37 meters) above the ground. It is a measurement used by many tree-treatment labels to set a dose. Follow the label’s specific rules for slopes, swelling, branching, and multiple stems, because those details can change how the measurement is taken.
For a label that gives its rate in milliliters per inch of DBH, use:
Label rate (mL per inch DBH) × measured DBH (inches) = total product dose (mL)
The label may set a maximum dose, require dilution, or give different directions for unusual trunks. Use its full directions, not just the arithmetic. Do not replace a label’s stated method with a basal-area calculation unless the label specifically calls for it.
Illustration only: hypothetical rate of 5 mL per inch of DBH. This is not a recommended or universal rate.
| DBH | Arithmetic at hypothetical 5 mL/in | Illustrative total |
|---|---|---|
| 6 in | 6 × 5 mL | 30 mL |
| 10 in | 10 × 5 mL | 50 mL |
| 12 in | 12 × 5 mL | 60 mL |
| 18 in | 18 × 5 mL | 90 mL |
| 20 in | 20 × 5 mL | 100 mL |
| 24 in | 24 × 5 mL | 120 mL |
These numbers show only how multiplication works. Use the 5 mL rate only if the current label for the exact product authorizes it. Check maximum doses, dilution directions, multi-stem rules, and any size limits before calculating or applying product.
Product selection, DBH measurement, and applicator safety
Choosing an EAB treatment starts with the label, not a dose chart found online. Confirm that the pesticide is registered for the site and target, then check whether you may apply it yourself. State or local rules may require a licensed or otherwise qualified applicator.
Before selecting a product, confirm the ash species and treatment goal. Inspect the tree’s canopy, trunk, root-zone conditions, and overall decline. EAB injection depends on the tree having functioning vascular tissue and adequate uptake; a tree in advanced decline may not respond as hoped. Injection also does not address structural hazards.
Measure DBH at the height and in the way the label specifies. If the trunk is on a slope, swollen, forked, or made up of several stems, do not assume the usual single-trunk method applies. Use the label’s directions or ask a qualified applicator to determine how the product’s rate should be calculated.
Wear the personal protective equipment (PPE) listed on the label. Follow its directions for protecting people, water, and nearby plants, as well as for handling, storage, spills, and disposal. If the directions are unclear or the tree does not fit the label’s measurement rules, pause and seek qualified advice rather than guessing.
Label-compliant EAB injection in the field
A safe application follows the product label and the injection-system instructions from start to finish. Those instructions govern the permitted seasonal window, dose, injection method, port locations and spacing, drill bit, depth, pressure, and rate. These are product- and system-specific details, not universal settings.
A practical sequence is:
- Identify and inspect. Confirm the tree is ash and review its condition, trunk integrity, root-zone stress, and site access. Decide whether treatment is suitable before preparing product.
- Verify and calculate. Read the current label for the exact product. Confirm the application rate, maximum dose, dilution, method, applicator requirements, seasonal window, and retreatment interval. Record the DBH and calculation.
- Prepare the equipment. Wear required PPE. Inspect and calibrate the injection system as its instructions require. Use only the specified drill bit and settings.
- Place and inject. Put ports only at label-specified locations, spacing, and depth. Apply at the stated pressure and rate. Stop if a port leaks, fails to accept product, or the system behaves abnormally; do not compensate by forcing product into the tree.
- Close out. Account for product used. Clean equipment and handle rinse water, containers, and leftover product exactly as the label directs.
Do not improvise port spacing or drill depth based on a chart for another product. If an application cannot be completed as directed, stop and consult the label, system instructions, or a qualified applicator.
Injection-system inspection, calibration, and cleaning
An injection system delivers a measured amount of product through ports in the trunk. The device may use a particular method or operating pressure, so its instructions matter alongside the pesticide label. A system that leaks, is poorly calibrated, or does not accept product normally can make the application unreliable.
Before use, inspect the system for damage and check its calibration according to the manufacturer’s directions. Confirm that the parts, drill bit, and operating settings match the product’s instructions. Do not assume a device used with one product is suitable for another.
During application, watch for leaks, blocked ports, or unexpected resistance. Stop if the equipment behaves abnormally; do not increase pressure or alter the method unless the instructions specifically direct you to do so. Afterward, clean the equipment and manage rinsate and containers as the label requires.
Real-world calculation scenarios: what a DBH chart can and cannot tell you
A DBH chart can help with arithmetic once the correct label rate is known. It cannot tell you whether the tree is eligible, whether the product is legal for that site, or how to position and operate the injection system. The examples below are hypothetical scenarios, not treatment recommendations.
| Scenario | What the DBH math shows | What still must be checked |
|---|---|---|
| A single-trunk ash measures 10 inches DBH | At a hypothetical 5 mL/in rate: 50 mL | Whether that exact product label allows the rate and dose |
| A single-trunk ash measures 20 inches DBH | At the same hypothetical rate: 100 mL | Maximum dose, dilution, and any size limits |
| A tree has several stems | No universal total can be stated from one stem measurement | The product label’s multi-stem measurement and dosing rules |
| A large ash is severely declining | A calculated dose does not show that treatment is suitable | Tree condition, vascular function, and professional assessment |
The main lesson is that a correctly multiplied number can still be the wrong dose if the rate or measurement method does not match the label. Treat the chart as arithmetic support only.
Treatment records, follow-up, and seasonal planning
Good records let you verify what was applied and plan the next check. Write down the tree ID, DBH, product name and lot, label rate, total dose, date, and applicator. Keep the current label and any application notes with the record.
Apply only during the product’s permitted seasonal window. Uptake depends in part on functioning vascular tissue and transpiration, so timing and tree condition matter. Do not assume that a treatment can be applied at any time of year or that every product shares the same schedule.
Follow the product label for retreatment timing; do not repeat an application early just because symptoms remain. Monitor the canopy and tree condition, and seek an assessment if decline continues or the tree presents a safety concern. Injection cannot reverse advanced decline or fix structural defects.
Frequently asked questions
These answers clarify common questions about EAB trunk injection and DBH dosing. The pesticide label remains the controlling source for product rate, application method, timing, and safety directions; the same DBH measurement can lead to different doses for different products.
What is emerald ash borer trunk injection?
It is a method of placing a labeled insecticide into an ash tree through trunk ports so the tree can move it through its vascular tissue.
How do I calculate an EAB injection dose from DBH?
For a label rate stated in mL per inch, multiply that rate by the DBH measured as the label directs. Check the label’s maximum dose and other instructions.
Is there one universal mL-per-inch rate?
No. Rates vary by product and formulation. A rate from another brand, product, or label revision is not a safe substitute.
Where do I measure DBH?
DBH is generally measured 4.5 feet (1.37 meters) above ground. Follow the product label for slopes, swelling, branches, and multiple stems.
Can I use the hypothetical 5 mL-per-inch chart?
Only if the current label for your exact product authorizes that rate and the tree fits its directions. The chart is an arithmetic example, not a recommendation.
Can I inject a dead or severely declining ash?
Do not use injection as a substitute for removal or risk management. A dead or severely declining tree may not take up treatment, and injection does not fix structural hazards.
Are injection-port spacing and drill depth standard?
No. Port locations, spacing, drill bit, depth, pressure, and application rate depend on the product label and injection-system instructions.
When should an ash tree be injected?
Use only the seasonal window listed on the product label. Timing and uptake vary with the product and tree conditions.
Can I apply the injection myself?
That depends on the product label and state or local rules. Use a qualified applicator where required, and do not proceed if you cannot follow the directions safely.
What should I do if a port leaks or will not accept product?
Stop and check the label and equipment instructions. Do not force product or change pressure or port placement unless the instructions specifically allow it.
How often should treatment be repeated?
Follow the exact product label’s retreatment interval. Do not assume another product’s schedule applies.
(This article was written by one of our staff writers, Evan Bradley. Visit our Meet the Team page.)
