Treatment guide
Emerald ash borer treatment: rates per inch of DBH
What to inject or drench, how much per inch of trunk, when in the year it works, and how often you come back. Emamectin benzoate, imidacloprid, and dinotefuran, with worked doses for the tree sizes you actually see.
pest
Emerald ash borerAgrilus planipennis
A flatheaded borer whose larvae feed in the phloem under the bark, cutting off water and nutrient transport. Untreated ash in an infested county are usually dead in three to five years. The beetle is a regulatory pest in most states; check your state's quarantine before moving ash wood.
Symptoms (the tree's response)
- Crown dieback starting at the top
- Canopy thinning
- Epicormic sprouting on the trunk and main limbs
- Bark splitting over galleries
Signs (the organism itself)
- D-shaped exit holes, about 1/8 inch
- S-shaped larval galleries under the bark
- Woodpecker flecking (blonding) on the upper trunk
- Adults on foliage, May through August
Common hosts: Green ash (Fraxinus pennsylvanica), White ash (Fraxinus americana), Black ash, Blue ash, Every other Fraxinus, White fringetree (Chionanthus virginicus), an alternate host
Timing window
4 active monthsOrganism active
Preventive treatment
Curative treatment
Trunk injections move best when the tree is transpiring and before adults emerge, so April into May. Fall soil applications (October) also work for preventive imidacloprid and dinotefuran. Do not inject a tree that has lost more than about half its canopy; there is not enough live phloem to carry the product.
Treatment options
Product, rate, delivery, timing
Rates below are per inch of trunk diameter at breast height unless the row says otherwise. The registered label wins over anything on this page.
TREE-äge G4 (Arborjet)
- Active ingredient
- Emamectin benzoate 9.7%
- Rate
- 5 to 10 mL per inch DBH by pest pressure; the app puts a 22-inch ash at 115 to 180 mL (about 5.2 to 8.2 mL per inch)
- Delivery
- Trunk injection
- Timing
- April to June, tree actively transpiring
- Frequency
- Every 2 years
TREE-äge R10 (Arborjet)
- Active ingredient
- Emamectin benzoate 4%
- Rate
- Per label; ready-to-use, so roughly two and a half times the volume of G4 per inch for the same active
- Delivery
- Trunk injection
- Timing
- April to June
- Frequency
- Every 2 years
Mectinite (Rainbow Ecoscience)
- Active ingredient
- Emamectin benzoate 4%
- Rate
- Per label, by DBH
- Delivery
- Trunk injection
- Timing
- Spring before adult emergence, April to May
- Frequency
- Every 2 years
IMA-jet (Arborjet)
- Active ingredient
- Imidacloprid 10%
- Rate
- Per label, by DBH
- Delivery
- Trunk injection
- Timing
- March to May
- Frequency
- Annually
Xytect 2F (Rainbow Ecoscience)
- Active ingredient
- Imidacloprid 21.4%
- Rate
- Per label, by DBH; the label steps the rate up at 15 inches DBH
- Delivery
- Soil drench or soil injection
- Timing
- Early spring as soon as soil thaws, no later than the first week of May, or late summer into fall
- Frequency
- Annually
Transtect 70 WSP (Rainbow Ecoscience)
- Active ingredient
- Dinotefuran 70%
- Rate
- 2 to 4 g per inch DBH
- Delivery
- Soil injection, soil drench, or basal bark spray
- Timing
- Spring to mid-summer, trees actively growing
- Frequency
- Annually
- TREE-äge G4 (Arborjet): The one to reach for over 25 inches DBH or under heavy pressure. Only option in the library that carries two seasons.
- TREE-äge R10 (Arborjet): No mixing. Slower uptake on big trees because of the volume.
- IMA-jet (Arborjet): Budget option. One season of protection, so the client is paying for a visit every year.
- Xytect 2F (Rainbow Ecoscience): Takes 30 to 60 days to move into the canopy. Preventive only, on healthy trees under 25 inches DBH.
- Transtect 70 WSP (Rainbow Ecoscience): In the tree in two to three weeks, so it is the pick when a client calls in June. Bark spray version translocates through the bark on accessible trunks.
Worked examples
Dose per tree
TREE-äge G4, moderate pressure
22″ DBH
147.5 mL total, 12 injection sites at about 6 inch spacing, 12.3 mL per site (from the PHC Rx calculator)
TREE-äge G4, low rate
18″ DBH
90 mL total at 5 mL per inch, 9 sites
Transtect 70 WSP, soil injection
30″ DBH
60 to 120 g at 2 to 4 g per inch
Want the number for the tree in front of you? Use the tree injection rate calculator.
Which product, for which tree
Under 25 inches, healthy, preventive: imidacloprid drench in spring or fall is the cheap route, but you are back every year. Over 25 inches, or anything with visible dieback, or a county with heavy pressure: emamectin benzoate by trunk injection, every two years. Client calls in June with a tree they just noticed: dinotefuran, because it is in the canopy in three weeks instead of two months.
The research behind the two-year interval is Smitley, Doccola, and Cowles in Arboriculture & Urban Forestry 36(5), 2010: a single emamectin benzoate injection at 0.2 g active ingredient per inch gave two to three years of control on street trees up to 18 inches. McCullough's group at Michigan State repeated it at larger diameters. That is why the calendar in PHC Rx puts the retreat at 24 months instead of 12.
What the label check will catch
EAB is on every one of these labels, so the pest check passes. Where a prescription fails in the app is usually timing (a soil drench scheduled for July when the label wants it in the ground by early May), reapplication interval (an annual product going in at 8 months because the client got nervous), or delivery method (dinotefuran as a bark spray on a tree the label limits to soil application at that size). Each of those shows as a warning before the client sees the prescription, and you can override with a written reason.
Label check
1 warningLast application was 14 days ago. Proceed with a documented override, or reschedule.
When not to treat
- More than 50 percent canopy loss. Injection needs live phloem to move the product. Recommend removal and say why in writing.
- A tree the client will not commit to for six or more years. One emamectin injection is a two-year decision; a program is a decade.
- Ash within a few hundred feet of untreated ash in an active infestation, if the client wants a one-time fix. It will be reinfested.
- Quarantine violations. Treating is fine; moving the firewood is not.
Pricing the job
Most companies price EAB injections per inch of DBH, with a minimum per visit. The PHC Rx default for trunk injection is in the $10 to $25 per inch range, set per company in service pricing. A 22-inch ash at $15 per inch is $330 every two years. Product cost for that tree on TREE-äge G4 is well under a third of that, which is why EAB programs are the most profitable line most PHC divisions run.
FAQ
Questions arborists ask
What is the emamectin benzoate rate per inch of DBH for emerald ash borer?
For TREE-äge G4 (9.7%), the label runs 5 to 10 mL per inch of DBH depending on infestation pressure. The research standard behind the two-year interval is 0.2 g of active ingredient per inch. A 22-inch ash at a moderate rate works out to about 147 mL in the PHC Rx calculator. Always confirm against the label in hand.
What is the imidacloprid rate for emerald ash borer?
Imidacloprid soil products like Xytect 2F are dosed per inch of DBH with the rate stepping up for trees at or above 15 inches; the label carries the exact figures. It is preventive only, best on healthy trees under 25 inches, and it needs 30 to 60 days to reach the canopy, so it goes in by early May or in fall.
When is the best time to treat for emerald ash borer?
April into May for trunk injections, before adults emerge and while the tree is moving water. Fall works for preventive soil applications. Summer treatments are for dinotefuran, which moves fast enough to matter.
How often does an ash need to be treated?
Every two years on emamectin benzoate. Every year on imidacloprid or dinotefuran. The calendar in PHC Rx schedules the retreat visit when you record the application.
Can a tree with dieback still be saved?
Usually, if it has kept more than half its canopy. Past that, the phloem is too damaged to carry a systemic. Write down the canopy estimate at the time of the assessment; it is the number the client will ask about later.
Where do these rates come from?
The PHC Rx species library and rate calculator, which are built from the product labels for TREE-äge, Mectinite, IMA-jet, Xytect, and Transtect. When you write a prescription in the app, the rate is checked against the label again. The label wins.
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