Emerald Ash Borer
Parker Sundquist
Figure 1: In the image above you can see extensive mining damage done by the larva of EAB. This damage restricts nutrition and water flow and will eventually girdle and kill the tree (3).
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The emerald ash borer Agrilus planipennis is a flying borer insect native to northeast China, Russia, and the Korean peninsula that feeds on North American ash trees under the species name Fraxinus (1). In EAB’s larvae stage it is responsible for extensive damage to the cambium layers of trees, girdling them and leaving them dead within 3 years of first contact if left untreated (2). In September 2013, EAB was detected in 21 US states and 2 Canadian provinces, today EAB is in 35 US states as well as 5 Canadian provinces (3,4). Understanding what EAB is and how to manage it is one of the key issues effecting urban forests around the country. What treatment options work for an urban environment and what treatment options work for a forested area or shelter belt, what is the overall lifecycle of EAB and when is it an issue for ash trees, and also what is the importance in firewood transfer in relation to how EAB is spread across the country.
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EAB Life Cycle
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Though the adult stage of the EAB is only responsible for minimal defoliation as they feed mainly on the margins of ash leaves, it is important to understand how they pick host plants to lay their 40-70 eggs (can lay closer to 200 eggs the longer they live) (5). Female adult EAB are attracted to trees that are under more stress (6). Methyl jasmonate is a chemical released into the air or by physical contact when the tree undergoes some sort of stress, female beetles are attracted to this by scent (6,7). After the adult beetle finds a host plant, the females feed for about a week before laying their eggs. The eggs are about 1 mm in diameter and gradually change from white to an amber coloration (8). They hatch about two weeks after being laid and immediately feed on the trees xylem and phloem and some of the outer sapwood leaving “s” shaped tracks in their wake, girdling the tree (2). The larva feeds from mid-summer into fall and the last grouping of larva overwinter within the bark to stay in a pupa state. Adult EAB then emerges in the early spring, leaving a “d” shaped exit wound, and reproduce about a week after that (2). Inside trees that are heavily infested by EAB, the amount of available phloem and xylem actually tends to limit larval survival. Because of this, life cycles that take place every other year are actually more common and observed in relatively healthy ash trees. In these trees larvae overwinter in the early forms of development and emerge the second spring, feeding that summer (2).
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Figures 1-4: The first image shows five EAB eggs, the coloration of these eggs differ from amber to white and are one millimeter long (8,10). The second slide is an image of the larval stage of EAB (11). This is the stage that is the most damaging to the tree as the larva feeds on the xylem and phloem layers after hatching (2). The third image is that of the pupa stage, this usually occurs during the winter with adults emerging in the early spring (2, 12). The final picture is an adult EAB which live on average about 20-23 days but can also survive anywhere from 3 to 53 days, flying in the spring (9).
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Treatment options
Insecticidal options
Due to the lack of natural predators and pest control for EAB in North America, insecticidal options are regularly used through methods of bark sprays, soil drenches, and trunk injections. Trunk injections are the most common application method for treating EAB in urban environments, but results may vary if the timing or size of injection is wrong (14). Injections are useful because they are easily mobile, and can get the insecticide straight into the xylem, taking it up the tree and into the canopy. The larva of EAB is attacked because the insecticide poisons the layers that they consume during the summer. An applicator takes a pressurized injection system such as an Arborjet®, and shoots insecticide through the small holes they have previously drilled and plugged with a semi-permeable membrane (15).
Figure 6-7: The two types of injection tools above are used for treating EAB and other pests feeding on the inner bark. The first image is a bike pump method produced by Arborjet® (23), this method can be slower than the second image which is a product also made by Arborjet® but uses pressurized air to help the flow (22). The second method can be more damaging to the tree if the pressure from the canister is set too high (16).
If done correctly with the right amount of pressure at injection, the tree should suffer minimal injuries and the uptake should be steady (16). On cloudy cool days the tree takes up the insecticide much slower than that of a hot sunny day due to the trees rate of transpiration (15). In order to give the tree the correct amount of insecticide, you have to first find the DBH (diameter at breast height) of the tree. Insecticides like Tree-Age, a chemical used for EAB (14), will have a DBH to mL chart somewhere on the packaging to show you the recommended amount of chemical per inch of DBH. When using the active ingredient emamectin benzoate, 2-4 years of total protection from emerald ash borer will be provided (16). Pricing for EAB injections is usually done by diameter inches because that also tells you the amount of chemical that will be used. Let’s say that as an example the pricing is 10 dollars per diameter inch (on average the pricing varies from 7-16 dollars per diameter inch (17)), and you have a large ash tree at 30 inches DBH. In theory you would only have to treat it once every three years at about 100 dollars per year. This may seem like a lot of money up front but the overall costs of environmental benefits lost and possible property damages could be much greater.
Biological Options
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Biocontrol is a long-term management technique that is used for pest that have generally been established for more than five years, cannot be eradicated, and cause significant ecological, environmental, or economic damage (18). Forms of biocontrol work best in areas of high density and quantity of host trees. Areas like shelter belts and forests work well with control options such as the release of non-stinging parasitic wasps (19). These two species, Spathius agrili Yang and Tetrasticus planipennisi Yang, are known to prefer the late instar larva of EAB (20). Spathius agrili Yang first finds the host plant by detecting the ash tree through compounds emitted by the tree, the wasp then detect the EAB larva through feeding vibrations within the trees bark (21). The female wasps tend to only lay eggs in the larva that has yet to been parasitized, this can be detrimental to an EAB colony (21). Tetrasticus planipennisi Yang is also known to prefer late instar larva of EAB, but can have more issues finding the hosts in the first 27 hours (20). Either wasp
Non-Treatment options |
Figure 8: This is an image of Spathius agrili Yang, the non-stinging parasitic wasp of EAB (24).
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Though treatment options are fairly obtainable and reasonably priced, leaving the selected ash trees untreated is also an option. EAB will kill a healthy ash tree in 3 years if left untreated (2). this means that if left untreated, in order to avoid possible damages or injuries from dead tree debris, the other option would be a removal/replacement strategy. Lincoln, NE, is currently one of the cities in North America choosing this approach (25). The strategy used when selecting trees for removal is based on their diameter at breast height (DBH) or trees that are already injured or declining, and it also includes trees that are placed in poor locations such as under power lines or within close proximities to houses/public areas (25). The city of Lincoln, according to its community forestry website, had 112,400 public trees in 2017 (25). Of those 112,400 public trees, 14,150 are ash trees. That is approximately 12.6% of the total canopy cover for Lincoln’s public urban forest. At a removal rate of 1,050 ashes per year with a replacement ratio of 1:1 (1,050 trees replaced per year as well) (25), the city of Lincoln should have approximately the same canopy cover now in 2019, right? The fact is that the trees that were removed had various diameters and overall sizes, according to the same website, the removed trees could vary from less than 14 inches in diameter up to greater than 18 inches in diameter (25). When you replace the same amount of trees that you remove, you lose canopy cover just based on the size difference between newly planted trees and established yet removed trees.
The option of removals and replacements can effect the total canopy cover of that city as well as be financially strenuous. In a study done with a 25 state land base focused from Detroit, IL, and an estimated 17 million trees, of the 38 million that were ash, needing to be either treated, removed, or replaced due to EAB, warranted a calculated average cost of $10.7 billion (26).
The option of removals and replacements can effect the total canopy cover of that city as well as be financially strenuous. In a study done with a 25 state land base focused from Detroit, IL, and an estimated 17 million trees, of the 38 million that were ash, needing to be either treated, removed, or replaced due to EAB, warranted a calculated average cost of $10.7 billion (26).
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If you take that same operating cost and apply it to the city of Lincoln, you get that each tree will cost about $630, which means the city of Lincoln could spend 8.9 million dollars in total for its 14,150 ash trees (25). In order to combat this, though the city is not treating ash trees, they will offer free vouchers for residents wanting to keep their trees alive in a program that is called Adopt an Ash (25). Clicking the image to the right provide more details on this program. Ultimately, no treatment turns into possible damage and lack of benefits for the area as the years go on.
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How to hire an Arborist
Step 1. Identify that the job requires an arborist
- Jobs that require the use of a chainsaw or any work that is above your head should be done by a professional arborist
- Jobs that require the use of pesticides or insecticides should be done by an arborist
- Jobs that are being used in legal disputes (hazard trees on property lines) should be done by an arborist
- Any job that requires more than hand pruners and possible climbing, should be done by an arborist
Step 2. Choose the correct arborist for the job
- Tree care companies will usually have a plant health care specialist and a trimming specialist that you can call out to give a bid on the project
- Plant health care specialists are who you should call if there is something eating your tree, some sort of fungus, or any other overall tree health impairment
- Trimming specialists should be called for annual pruning cycles, house or sidewalk clearance, and also tree removals
Step 3. Look for the correct certifications
- The two main arborist certification organizations in Nebraska are the International Society of Arboriculture (ISA) or the Nebraska Arborist Association (NAA)
- Any arborist that is ISA or NAA certified is trained in safety, tree health, and efficiency for tree related work
- You can find local certified arborists through either of their websites listed below:
ISA
NAA
Step 4. Gather multiple opinions and bids
- Different arborists complete the same job in unique ways using different tools or techniques
- Pricing may be different but the lowest price doesn't always guarantee the best deal, there may be measures certain arborists take to keep the process healthier for the tree or safer for the workers that consequently raises the price of the job
- The best arborist for the job is the arborist that takes all factors, obvious or not, into consideration for the final bid
Step 5. Selecting the arborist
- ISA or NAA certified
- Choosing the correct specialist (trim specialist or plant health care)
- Listen to multiple bids from different companies
- Select the bid that seems the safest for the tree and the workers
- The lowest price bid may not always be the best deal in the long run
This video is another good tool to use to better understand the importance of selecting the correct arborist for the job!
- Jobs that require the use of a chainsaw or any work that is above your head should be done by a professional arborist
- Jobs that require the use of pesticides or insecticides should be done by an arborist
- Jobs that are being used in legal disputes (hazard trees on property lines) should be done by an arborist
- Any job that requires more than hand pruners and possible climbing, should be done by an arborist
Step 2. Choose the correct arborist for the job
- Tree care companies will usually have a plant health care specialist and a trimming specialist that you can call out to give a bid on the project
- Plant health care specialists are who you should call if there is something eating your tree, some sort of fungus, or any other overall tree health impairment
- Trimming specialists should be called for annual pruning cycles, house or sidewalk clearance, and also tree removals
Step 3. Look for the correct certifications
- The two main arborist certification organizations in Nebraska are the International Society of Arboriculture (ISA) or the Nebraska Arborist Association (NAA)
- Any arborist that is ISA or NAA certified is trained in safety, tree health, and efficiency for tree related work
- You can find local certified arborists through either of their websites listed below:
ISA
NAA
Step 4. Gather multiple opinions and bids
- Different arborists complete the same job in unique ways using different tools or techniques
- Pricing may be different but the lowest price doesn't always guarantee the best deal, there may be measures certain arborists take to keep the process healthier for the tree or safer for the workers that consequently raises the price of the job
- The best arborist for the job is the arborist that takes all factors, obvious or not, into consideration for the final bid
Step 5. Selecting the arborist
- ISA or NAA certified
- Choosing the correct specialist (trim specialist or plant health care)
- Listen to multiple bids from different companies
- Select the bid that seems the safest for the tree and the workers
- The lowest price bid may not always be the best deal in the long run
This video is another good tool to use to better understand the importance of selecting the correct arborist for the job!
ISA vs. NAA
Any time a chainsaw is needed or tree work that is above your head, an arborist should be hired to do the job. Hiring someone with the correct qualifications and safety procedures will make the job go much more smoothly and the risk of damages or injuries will drop significantly. There are two main types of qualifications you should look for in Nebraska when hiring an arborist. The Nebraska Arborist Association (NAA) and the International Society of Arboriculture (ISA) both certify arborists for hire, but differ in the qualifications needed and the locations at which the certifications hold true (27).
The ISA has a multi leveled application process that begins with a minimum of 3 years of full time work in arboriculture and/or a degree in arboriculture or a related field, followed finally by an exam that is provided by multiple ISA chapters around the country and the world. When the arborist is certified through the ISA they need to continue to learn about trees in order to keep their certification, this is because the industry is changing techniques or guidelines as we learn more about tree biology and how each species reacts to management (27). In a three-year period an ISA certified arborist can either have CPR and first aid training, computer based training, take college courses, chapter events, tree climbing championship events, or read published articles to obtain Continuing Education Units (CEU) (27). ISA’s way of rewarding further research and personal studying is an important factor to consider when hiring an arborist, theoretically an ISA certified arborist is the most up to date version of an arborist one could hire.
The NAA is an arborist certification process that takes place in Nebraska only (28). The certification is given to people who have either passed the NAA arborist school or who have had two years of experience in arboriculture (28). NAA certification is less strenuous than that of the ISA and in fact uses the ISA’s same code of ethics. NAA certified arborists are certified to get the job done safely and efficiently but the ISA has more of a research based approach that keeps arborists up to date with the most current and understood management techniques.
The ISA has a multi leveled application process that begins with a minimum of 3 years of full time work in arboriculture and/or a degree in arboriculture or a related field, followed finally by an exam that is provided by multiple ISA chapters around the country and the world. When the arborist is certified through the ISA they need to continue to learn about trees in order to keep their certification, this is because the industry is changing techniques or guidelines as we learn more about tree biology and how each species reacts to management (27). In a three-year period an ISA certified arborist can either have CPR and first aid training, computer based training, take college courses, chapter events, tree climbing championship events, or read published articles to obtain Continuing Education Units (CEU) (27). ISA’s way of rewarding further research and personal studying is an important factor to consider when hiring an arborist, theoretically an ISA certified arborist is the most up to date version of an arborist one could hire.
The NAA is an arborist certification process that takes place in Nebraska only (28). The certification is given to people who have either passed the NAA arborist school or who have had two years of experience in arboriculture (28). NAA certification is less strenuous than that of the ISA and in fact uses the ISA’s same code of ethics. NAA certified arborists are certified to get the job done safely and efficiently but the ISA has more of a research based approach that keeps arborists up to date with the most current and understood management techniques.
References
1. Ryan D. DeSantis, W. K. (2013). Modeling the effects of emerald ash borer on forest composition in the Midwest and Northeast United States. General Technical Report (GTR) , n/a.
2. Daniel A Herms, D. G. (2013). Emerald Ash Borer Invasion of North America: History, Biology, Ecology, Impacts, and Management. Annual Review of Entomology, 13-30.
3. Daniel A. Herms, D. G. (2014). Insecticide Options for Protecting Ash Trees from Emerald Ash Borer. Ohio: The Cooperative Emerald Ash Borer Program.
4. Network, E. A. (2019, 10 1). Emerald Ash Borer Information Network. Retrieved from Emerald Ash Borer Information Network: emeraldashborer.info
5. Wei Xia, D. R.-H. (2004). Emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), in China: a review and distribution survey. Acta Entomologica Sinica, 679-685.
6. Deepa S. Pureswaran, T. M. (2009). Host Selection and Feeding Preference of Agrilus planipennis (Coleoptera: Buprestidae) on Ash (Fraxinus spp.). Environmental Entomology, 757-765.
7. Deborah G. McCullough, T. M. (2009). Emerald Ash Borer (Coleoptera: Buprestidae) Attraction to Stressed or Baited Ash Trees. Environmental Entomology, 1668-1679.
8. Leah S. Bauer, R. A. (2003). Emerald Ash Borer Life Cycle. Research and Technology Development Meeting, 8.
9. Haleigh Ray, J. L.-K. (2019, September n/a). Featured Creatures: Emerald Ash Borer. Retrieved from Featured Creatures: Entomology and Nematology : entnemdept.ufl.edu
10. Cornell University . (2019, n/a n/a). Invasive Pests: Emerald Ash Borer. Retrieved from Cornell Cooperative Extension: Albany County : albany.cce.cornell.edu
11. Entomological Society of America. (2016, October 24). Emerald Ash Borer May Become a Problem for Olive Growers. Retrieved from Entomology Today: Brought to You by the Entomological Society of America: entomologytoday.org
12. Watchel Tree Science. (2018, August 9). Borer in Wisconsin. Retrieved from Watchel Tree Science inc.: healthytrees.com
13. Garpiel Group. (2019, August 1). Emerald Ash Borers Attacking Ash Trees, Resulting in Millions Lost. Retrieved from Garpiel Group: The Blog: garpielgroup.com
14. Deborah G. Mcullough, T. M. (n/a). Evaluation of Trunk Injections for Control of Emerald Ash Borer. Emerald Ash Borer - Chemical Control, 38.
15. Kuhns, M. (2011). Getting Chemicals into Trees Without Spraying . Utah Forest Facts , n/a.
16. Joseph J. Doccola, D. R. (2011). Tree Wound Responses Following Systemic Insecticide Trunk Injection Treatments in Green Ash (Fraxinus pennsylvanica Marsh.) as Determined by Destructive Autopsy . Arboriculture and Urban Forestry , 6-12.
17. TriCity Tree Doctor . (2019, n/a n/a). Emerald Ash Borer. Retrieved December 25, 2019, from Tri-City Tree Doctor: tree-doc.com
18. United States Department of Agriculture Forest Service. (2019, 7 31). Emerald ash borer: Biological Control of the Emerald Ash Borer. Retrieved from United States Department of Agriculture Forest Service, Northern Research Station: nrs.fs.fed.us
19. Houping Liu, L. S. (2003). Exploratory Survey for the Emerald Ash Borer, Agrilus Planipennis (Cleoptera: Buprestidae), and its Natural Enemies in China. The Great Lakes Entomologist, n/a.
20. Michael D. Ulyshen, J. J. (2010). Interactions between Spathius agrili (hymenoptera: Braconidae) and Tetrastichus Planipennisi (Hymenoptera: Eulophidae), Larval parasitoids of Agrilus planipennis (Coleoptera: Buprestidae). Biological Control, 188-193.
21. Xio-Yi Wang, Z.-Q. Y.-H. (2010). Host-seeking behavior and parasitism by Spathius agrili yang (Hymenoptera: Braconidae), a parasitiod of the emerald ash borer. Biological Control, 24-29.
22. Arborjet. (n/a, n/a n/a). QUIK-jet AIR Kit. Retrieved December 31, 2019, from Arborjet: Revolutionary Plant Health Solutions: arborjet.com
23. Arborjet. (n/a, n/a n/a). Tree I.V. 2-Pack Kit. Retrieved December 31, 2019, from Arborjet: Revolutionary Plant Health Solutions: arborjet.com
24. Wickens, A. (2008, Nov 19). Spathius agrili. Retrieved from The Ecological Impacts of the Emerald Ash Borer: sites.google.com/site/emeraldashborer1
25. Lincoln Parks and Recreation. (n/a, n/a n/a). Emerald Ash Borer. Retrieved December 31, 2019, from Lincoln Parks and Recreation: Community Forestry, FUNdamental to Vibrant Neighborhoods: Lincoln.ne.gov
26. Kent F. Kovacs, R. G. (2010). Cost of potential emerald ash borer damage in U.S. communities, 2009-2019. Ecological Economies, 569-578.
27. International Society of Arboriculture . (2020, n/a n/a). ISA: Credentials . Retrieved from International Society of Arboriculture : isa-arbor.com
28. Nebraksa Arborist Association . (n/a , n/a n/a). NAA statewide certification program . Retrieved 1 9, 2020, from Nebraska Arborist Association : nearborists.org
2. Daniel A Herms, D. G. (2013). Emerald Ash Borer Invasion of North America: History, Biology, Ecology, Impacts, and Management. Annual Review of Entomology, 13-30.
3. Daniel A. Herms, D. G. (2014). Insecticide Options for Protecting Ash Trees from Emerald Ash Borer. Ohio: The Cooperative Emerald Ash Borer Program.
4. Network, E. A. (2019, 10 1). Emerald Ash Borer Information Network. Retrieved from Emerald Ash Borer Information Network: emeraldashborer.info
5. Wei Xia, D. R.-H. (2004). Emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), in China: a review and distribution survey. Acta Entomologica Sinica, 679-685.
6. Deepa S. Pureswaran, T. M. (2009). Host Selection and Feeding Preference of Agrilus planipennis (Coleoptera: Buprestidae) on Ash (Fraxinus spp.). Environmental Entomology, 757-765.
7. Deborah G. McCullough, T. M. (2009). Emerald Ash Borer (Coleoptera: Buprestidae) Attraction to Stressed or Baited Ash Trees. Environmental Entomology, 1668-1679.
8. Leah S. Bauer, R. A. (2003). Emerald Ash Borer Life Cycle. Research and Technology Development Meeting, 8.
9. Haleigh Ray, J. L.-K. (2019, September n/a). Featured Creatures: Emerald Ash Borer. Retrieved from Featured Creatures: Entomology and Nematology : entnemdept.ufl.edu
10. Cornell University . (2019, n/a n/a). Invasive Pests: Emerald Ash Borer. Retrieved from Cornell Cooperative Extension: Albany County : albany.cce.cornell.edu
11. Entomological Society of America. (2016, October 24). Emerald Ash Borer May Become a Problem for Olive Growers. Retrieved from Entomology Today: Brought to You by the Entomological Society of America: entomologytoday.org
12. Watchel Tree Science. (2018, August 9). Borer in Wisconsin. Retrieved from Watchel Tree Science inc.: healthytrees.com
13. Garpiel Group. (2019, August 1). Emerald Ash Borers Attacking Ash Trees, Resulting in Millions Lost. Retrieved from Garpiel Group: The Blog: garpielgroup.com
14. Deborah G. Mcullough, T. M. (n/a). Evaluation of Trunk Injections for Control of Emerald Ash Borer. Emerald Ash Borer - Chemical Control, 38.
15. Kuhns, M. (2011). Getting Chemicals into Trees Without Spraying . Utah Forest Facts , n/a.
16. Joseph J. Doccola, D. R. (2011). Tree Wound Responses Following Systemic Insecticide Trunk Injection Treatments in Green Ash (Fraxinus pennsylvanica Marsh.) as Determined by Destructive Autopsy . Arboriculture and Urban Forestry , 6-12.
17. TriCity Tree Doctor . (2019, n/a n/a). Emerald Ash Borer. Retrieved December 25, 2019, from Tri-City Tree Doctor: tree-doc.com
18. United States Department of Agriculture Forest Service. (2019, 7 31). Emerald ash borer: Biological Control of the Emerald Ash Borer. Retrieved from United States Department of Agriculture Forest Service, Northern Research Station: nrs.fs.fed.us
19. Houping Liu, L. S. (2003). Exploratory Survey for the Emerald Ash Borer, Agrilus Planipennis (Cleoptera: Buprestidae), and its Natural Enemies in China. The Great Lakes Entomologist, n/a.
20. Michael D. Ulyshen, J. J. (2010). Interactions between Spathius agrili (hymenoptera: Braconidae) and Tetrastichus Planipennisi (Hymenoptera: Eulophidae), Larval parasitoids of Agrilus planipennis (Coleoptera: Buprestidae). Biological Control, 188-193.
21. Xio-Yi Wang, Z.-Q. Y.-H. (2010). Host-seeking behavior and parasitism by Spathius agrili yang (Hymenoptera: Braconidae), a parasitiod of the emerald ash borer. Biological Control, 24-29.
22. Arborjet. (n/a, n/a n/a). QUIK-jet AIR Kit. Retrieved December 31, 2019, from Arborjet: Revolutionary Plant Health Solutions: arborjet.com
23. Arborjet. (n/a, n/a n/a). Tree I.V. 2-Pack Kit. Retrieved December 31, 2019, from Arborjet: Revolutionary Plant Health Solutions: arborjet.com
24. Wickens, A. (2008, Nov 19). Spathius agrili. Retrieved from The Ecological Impacts of the Emerald Ash Borer: sites.google.com/site/emeraldashborer1
25. Lincoln Parks and Recreation. (n/a, n/a n/a). Emerald Ash Borer. Retrieved December 31, 2019, from Lincoln Parks and Recreation: Community Forestry, FUNdamental to Vibrant Neighborhoods: Lincoln.ne.gov
26. Kent F. Kovacs, R. G. (2010). Cost of potential emerald ash borer damage in U.S. communities, 2009-2019. Ecological Economies, 569-578.
27. International Society of Arboriculture . (2020, n/a n/a). ISA: Credentials . Retrieved from International Society of Arboriculture : isa-arbor.com
28. Nebraksa Arborist Association . (n/a , n/a n/a). NAA statewide certification program . Retrieved 1 9, 2020, from Nebraska Arborist Association : nearborists.org
