Has EAB arrived on the west coast now?

southsoundtree said:
What will that mean about injectable and soil drench treatments?
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I’d say consider to start recommending preventative treatment soon in your area, I’d expect it to spread fast along the I5 corridor. I’m more than bummed about the native Oregon species, Seattle has a shit ton of ash, I have a spattering. I’d assume it’s kinda like a wildfire, we don’t have continuity (outside denser populated areas) so once it wicks down (or up) I-5 the spread will slow and be more pocket by pocket.
 
First recorded EAB was in Detroit...that's 100 miles north of where I am along I-75, so wasn't long before it hit here. What we realized pretty quickly, was once it was "found" to be in trees in a given area, it had been there for 3+ years. Detection has probably improved over the last 20 years...but if it's "known" to be within 30-40 miles and there is a contiguous Ash host population between that infestation and you, I'd assume you have it and its time to start treating.
 
I'm an hour and a half east of Detroit and our ash were wiped out long ago. Took down the last dead one on my property 10 years ago. We were treating with that neem oil stuff, Treeazin. Seemed to work for a while, until it didn't. I hope there's better stuff available nowadays, I stopped following it long ago after they were all gone. Ash used to be a good 10% of the forest around here, it was a terrible hit. Actually pushed down the firewood market there was so much supply.

Now these past couple years I have hundreds of saplings coming up everywhere I look and I just can't figure out how all these seeds have laid dormant for this long. It's just amazing. Life finds a way...
 
Does AI get these numbers correct:

Estimated Vulnerable Ash Trees by County​

CountyEstimated Vulnerable Ash Trees (Low)Estimated Vulnerable Ash Trees (High)
Snohomish2,7398,217
King7,59022,770
Pierce3,0699,207

  • Low estimate assumes ash trees make up 1% of total urban trees.
  • High estimate assumes ash trees make up 3% of total urban trees.
  • These estimates reflect the number of ash trees that could be killed if EAB becomes established, as up to 99% mortality is expected in infested areas.

Percentage of Trees at Risk​

  • Nearly all ash trees (Fraxinus spp.) in the PNW are at risk.
  • In areas where EAB infestation becomes established, up to 99% of ash trees can be killed within a decade.
  • This risk applies to both native Oregon ash (Fraxinus latifolia) and non-native ash species planted in urban and suburban settings.

Context: Ash Trees in the PNW​

  • Ash trees make up a small percentage of the total tree population in the PNW. For example, in Portland, ash trees account for about 1% of the city’s tree canopy, with higher concentrations in riparian and wetland areas.
  • The EAB does not threaten other tree genera; its impact is almost exclusively on ash species.

Summary Table​

Category% of All Trees in PNW% of Ash Trees at Risk from EAB
All Trees (Total)100%—
Ash Trees (Fraxinus spp.)~1–3% (varies by area)Up to 99%
Non-Ash Trees~97–99%Not at risk

Key Points​

  • EAB threatens nearly 100% of ash trees in the PNW, but ash trees represent a small fraction of the region’s total trees.
  • The broader forest and urban canopy will be affected primarily where ash is a dominant or ecologically significant species, such as in riparian corridors and wetlands.
  • Other tree species in the PNW are not at significant risk from EAB.
 
Muggs said:
I'm an hour and a half east of Detroit and our ash were wiped out long ago. Took down the last dead one on my property 10 years ago. We were treating with that neem oil stuff, Treeazin. Seemed to work for a while, until it didn't. I hope there's better stuff available nowadays, I stopped following it long ago after they were all gone. Ash used to be a good 10% of the forest around here, it was a terrible hit. Actually pushed down the firewood market there was so much supply.

Now these past couple years I have hundreds of saplings coming up everywhere I look and I just can't figure out how all these seeds have laid dormant for this long. It's just amazing. Life finds a way...
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That is music to me guy. Years ago in a corporate life I led, we lived in Whitby, ON on White Ash Dr - all the houses had a concession line of huge (what else?) white ash trees at tha backs of the yards. They were magnificent, but if you look now, all of them are gone. A true disaster frankly. From the oaks and elms in Winnipeg and Edmonton to the trees you folks have in Ontario and down south, trees do make the neighbourhood for me anyway. Cheers and stay safe out there .
 
tree_luv said:
Does AI get these numbers correct:

Estimated Vulnerable Ash Trees by County​

CountyEstimated Vulnerable Ash Trees (Low)Estimated Vulnerable Ash Trees (High)
Snohomish2,7398,217
King7,59022,770
Pierce3,0699,207

  • Low estimate assumes ash trees make up 1% of total urban trees.
  • High estimate assumes ash trees make up 3% of total urban trees.
  • These estimates reflect the number of ash trees that could be killed if EAB becomes established, as up to 99% mortality is expected in infested areas.

Percentage of Trees at Risk​

  • Nearly all ash trees (Fraxinus spp.) in the PNW are at risk.
  • In areas where EAB infestation becomes established, up to 99% of ash trees can be killed within a decade.
  • This risk applies to both native Oregon ash (Fraxinus latifolia) and non-native ash species planted in urban and suburban settings.

Context: Ash Trees in the PNW​

  • Ash trees make up a small percentage of the total tree population in the PNW. For example, in Portland, ash trees account for about 1% of the city’s tree canopy, with higher concentrations in riparian and wetland areas.
  • The EAB does not threaten other tree genera; its impact is almost exclusively on ash species.

Summary Table​

Category% of All Trees in PNW% of Ash Trees at Risk from EAB
All Trees (Total)100%—
Ash Trees (Fraxinus spp.)~1–3% (varies by area)Up to 99%
Non-Ash Trees~97–99%Not at risk

Key Points​

  • EAB threatens nearly 100% of ash trees in the PNW, but ash trees represent a small fraction of the region’s total trees.
  • The broader forest and urban canopy will be affected primarily where ash is a dominant or ecologically significant species, such as in riparian corridors and wetlands.
  • Other tree species in the PNW are not at significant risk from EAB.
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Yes, I’d say that’s pretty accurate. I’d even guess king county (Seattle) is on the higher end of the range given.
Personally on the emotional side what breaks my heart is the native Oregon ash which is mostly limited to Oregon. We do have some populations in Washington but not like oregon
 
levi r said:
Wow. Our urban canopy was more than 20% ash when EAB came to town.
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Some areas (streets or close to entire neighborhoods) are pure ash Seattle.
Not sure if I’m reading it correctly but SDOT (Seattle dept of transportation) data suggests ~5k ash street trees. I’m not totally clear but there maybe ~200k ash total (or that’s just the number of street trees)
Check the map where entire street are lined in them then a general spattering.

This is likely the highest numbers in King county but it’s a heavily populated area
Maybe folks smarter than I can filter ash on the GIS
seattlecitygis.maps.arcgis.com

Story Map Series

This story map was created with the Story Map Series application in ArcGIS Online.
seattlecitygis.maps.arcgis.com seattlecitygis.maps.arcgis.com

The AI county estimate low end was 7k ash in the county, - Seattle’s street trees and that only leaves 2k ash throughout the remainder of the county. This is how I’m basing my estimate being on the higher end of the AI scale.
 
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evo said:
Yes, I’d say that’s pretty accurate. I’d even guess king county (Seattle) is on the higher end of the range given.
Personally on the emotional side what breaks my heart is the native Oregon ash which is mostly limited to Oregon. We do have some populations in Washington but not like oregon
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Good to know AI is somewhat accurate... having it calculate all 3 PNW states paints a much larger issue:
"Based on available data and regional estimates, here are the estimated numbers of vulnerable ash trees in Washington (WA), Oregon (OR), and Idaho (ID), reflecting the risk from Emerald Ash Borer (EAB):
Key Points for Estimation
  • EAB kills up to 99% of ash trees (Fraxinus spp.) once established.
  • Ash trees are a small fraction of total trees but are ecologically significant, especially in riparian and urban areas.
  • Estimates below use ranges based on urban and natural forest inventories, regional reports, and the proportion of ash in the tree population.

Estimated Vulnerable Ash Trees by State​

StateEstimated Vulnerable Ash Trees (Low)Estimated Vulnerable Ash Trees (High)
WA2 million4 million
OR2.5 million4.5 million
ID200,000400,000

Methodology and Context
  • Washington (WA):
    • Ash is present in riparian zones and urban forests, especially Oregon ash (Fraxinus latifolia).
    • The estimate reflects both natural and planted ash populations statewide.
  • Oregon (OR):
    • Oregon ash is a dominant riparian tree, especially in the Willamette Valley and western Oregon.
    • The state has the largest natural population of Oregon ash in the PNW, with significant numbers in both wild and urban settings.
  • Idaho (ID):
    • Fewer native ash stands, but some presence in riparian corridors and urban plantings.
    • Numbers are much lower than WA and OR due to limited natural range.

Notes​

  • These figures are estimates; actual numbers may vary depending on recent inventories, local planting practices, and the extent of natural stands.
  • The vast majority of these trees are at risk of mortality once EAB becomes established, as no effective eradication has been achieved elsewhere.
  • Losses will be most severe in riparian areas and urban forests, where ash is a key component of the ecosystem and urban canopy.
Summary:
Roughly 2–4 million ash trees in Washington, 2.5–4.5 million in Oregon, and 200,000–400,000 in Idaho are at risk of being killed by Emerald Ash Borer once it becomes established in the Pacific Northwest. These numbers reflect both natural and urban populations and underscore the significant ecological and management challenges ahead."

Recent OSU research predicts a 2x-3x increase in PNW wildfires over the next 3-5 years due to climate change alone. With 5-10 million ash trees expected to die in the next 5-10 years, the wildfire outlook is grim.

Biocontrol with parasitoid wasps (such as Tetrastichus planipennisi and Oobius agrili) is already being implemented in Oregon as part of a biocontrol response to EAB. The risk of biocontrol causing its own issues is minor compared to what the EAB has in store for PNW's forests if nothing significant is done to combat it.
 
tree_luv said:
Good to know AI is somewhat accurate... having it calculate all 3 PNW states paints a much larger issue:
"Based on available data and regional estimates, here are the estimated numbers of vulnerable ash trees in Washington (WA), Oregon (OR), and Idaho (ID), reflecting the risk from Emerald Ash Borer (EAB):
Key Points for Estimation
  • EAB kills up to 99% of ash trees (Fraxinus spp.) once established.
  • Ash trees are a small fraction of total trees but are ecologically significant, especially in riparian and urban areas.
  • Estimates below use ranges based on urban and natural forest inventories, regional reports, and the proportion of ash in the tree population.

Estimated Vulnerable Ash Trees by State​

StateEstimated Vulnerable Ash Trees (Low)Estimated Vulnerable Ash Trees (High)
WA2 million4 million
OR2.5 million4.5 million
ID200,000400,000

Methodology and Context
  • Washington (WA):
    • Ash is present in riparian zones and urban forests, especially Oregon ash (Fraxinus latifolia).
    • The estimate reflects both natural and planted ash populations statewide.
  • Oregon (OR):
    • Oregon ash is a dominant riparian tree, especially in the Willamette Valley and western Oregon.
    • The state has the largest natural population of Oregon ash in the PNW, with significant numbers in both wild and urban settings.
  • Idaho (ID):
    • Fewer native ash stands, but some presence in riparian corridors and urban plantings.
    • Numbers are much lower than WA and OR due to limited natural range.

Notes​

  • These figures are estimates; actual numbers may vary depending on recent inventories, local planting practices, and the extent of natural stands.
  • The vast majority of these trees are at risk of mortality once EAB becomes established, as no effective eradication has been achieved elsewhere.
  • Losses will be most severe in riparian areas and urban forests, where ash is a key component of the ecosystem and urban canopy.
Summary:
Roughly 2–4 million ash trees in Washington, 2.5–4.5 million in Oregon, and 200,000–400,000 in Idaho are at risk of being killed by Emerald Ash Borer once it becomes established in the Pacific Northwest. These numbers reflect both natural and urban populations and underscore the significant ecological and management challenges ahead."

Recent OSU research predicts a 2x-3x increase in PNW wildfires over the next 3-5 years due to climate change alone. With 5-10 million ash trees expected to die in the next 5-10 years, the wildfire outlook is grim.

Biocontrol with parasitoid wasps (such as Tetrastichus planipennisi and Oobius agrili) is already being implemented in Oregon as part of a biocontrol response to EAB. The risk of biocontrol causing its own issues is minor compared to what the EAB has in store for PNW's forests if nothing significant is done to combat it.
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Just a Wild Ass Guess. I’d expect Wa state to be the lower end of the estimate and OR to be the higher end.
Nevermind the other adverse issues, such as shading streams and salmon spawning.
 
I had customers near EAB ground zero for Toronto and on one street built late 60's it changed from tree-tunnel covered over street to all new planted about 8 footers, both curb and lawn trees. One guy moved in new-build and said it looked just like when the subdivision was built, virtually no tree cover.

I used to have the map of the relatively handful of city blocks infected I saved from the newspaper. Within some years it spread city to city and then to cottage country.

IIRC the bugs prefer other ash species over green ash, so there's more chance for treating/saving green ash. Talking a year or two extra time even for trees on the same street.
 
After going through an ash extinction event here from about 2018-2022, here’s my advice.

Identify the most beautiful majestic ashes and treat them. Like 2-5% of the total population of ashes.

Remove all the other ash trees while they are safe to climb and rig. Compile all the wood and turn it into lumber. (Makes for a particularly great floor).

You can leave the short ones though. (Not such valuable lumber, easy flops when they need to be removed, and also a greater chance of survival)

Do not wait until they are half dead or dead.
 
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Stumpsprouts said:
After going through an ash extinction event here from about 2018-2022, here’s my advice.

Identify the most beautiful majestic ashes and treat them. Like 2-5% of the total population of ashes.

Remove all the other ash trees while they are safe to climb and rig. Compile all the wood and turn it into lumber. (Makes for a particularly great floor).

You can leave the short ones though. (Not such valuable lumber, easy flops when they need to be removed, and also a greater chance of survival)

Do not wait until they are half dead or dead.
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(Bold hi-light mine). Good article on ASH tree decay process hazard in Lilley, Christopher Ash to Ashes: Don't Be Part of the Process TCIA Magazine Volume 36(6) June 2025 pp 20-25 FYI Cheers
 
Those were released pretty quickly after Emerald Ash Borer was discovered to be a widespread pest. The initial researchers who are very optimistic said that they would not stop the continued mass killing of ash trees. Their vision then, and as I understand it remains, that in the long term there will be a balance where the parasitoids will kill enough EAB that Ash may remain a (limited) part of the ecosystem.
 
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