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Emerald Ash Borer (EAB) Quarantine Update

Friday, September 15, 2017   (0 Comments)
Posted by: Jon Horsman

New EAB Infestations Reported in Minnesota and Wisconsin


Emerald ash borer (EAB; Agrilus planipennis) adult; in Minnesota, EAB adults emerge from infested ash trees from May until August leaving behind small (1/8”), D-shaped exit holes in the bark of the tree (Photo Credit: David Cappaert, Michigan State University,

Nearly six months after the last new infestation in Minnesota was confirmed in early March, several new infestations of emerald ash borer (EAB) outside previously quarantined areas have recently been reported and confirmed in Minnesota and in Wisconsin; one in Minnesota and five in Wisconsin.  The latest find in Minnesota is in Martin County on the Iowa border in south-central Minnesota (confirmed on August 22 and reported on August 23).  In response to this new EAB infestation, the Minnesota Department of Agriculture (MDA) has added Martin County to the list of quarantined counties in the state as an emergency quarantine with a formal quarantine to follow.  Including Martin County, 16 counties, almost exclusively located in east-central and southeastern Minnesota, are now under full or partial quarantine to slow the spread of EAB in the state.  Sadly, because the Martin County infestation is removed from the other known EAB infestations in Minnesota and Iowa, the MDA believes the Martin County infestation is the result of someone moving infested ash as firewood or in some other form.  Infested firewood is considered a primary vector of EAB and should not be moved around the state; burn firewood where it is 


The announcement of the Martin County EAB find and resulting quarantine can be accessed on the MDA website at  The proposed quarantine language for Martin County is also available at  For those interested, a public meeting to discuss the discovery of EAB and the EAB quarantine in Martin County will be held on Wednesday, September 20, 2017, from 5:30 to 7:30 p.m. at the Martin County Courthouse (201 Lake Avenue, Fairmont, MN 56031; Room 103).  Additional information is available at


In addition to the Martin County infestation in Minnesota, five new EAB infestations have recently been confirmed in Wisconsin (August 22-30).  As reported by the Wisconsin Department of Agriculture, Trade and Consumer Protection (DATCP), the affected counties include Chippewa, Green Lake, Marinette, Waupaca, and Waushara Counties.  With the exception of Chippewa County (northwestern Wisconsin) and Marinette County (northeastern Wisconsin), these counties are located in east-central Wisconsin and are surrounded by counties with confirmed EAB infestations.  With these new finds, 46 Wisconsin counties, including the entire southern half of the state, are now under quarantine for EAB.  It is, however, important to note that, with the exception of the far southeastern corner of the state and a few of the counties bordering Minnesota in the southwestern part of the state, most of Wisconsin remains EAB-free, as most of the quarantined counties only have small, isolated infestations.  The same is also generally true for Minnesota.  Additional information about EAB in Wisconsin is available at


History of EAB in North America and Minnesota


Native to east-central Asia, emerald ash borer (EAB; Agrilus planipennis; Coleoptera: Buprestidae) was first documented in North America in 2002 in southeastern Michigan (Detroit area) and has since spread to 30 states in the Eastern, Midwestern (including Minnesota), and Mountain regions of the United States and the far southern portions of two Canadian provinces (Ontario and Quebec). Capable of attacking healthy trees, hundreds of millions of ash trees (Fraxinus spp.) have already been killed in infested areas and all three species of ash native to the Upper Midwest and Minnesota are susceptible to attack – white ash (Fraxinus americana), black ash (Fraxinus nigra; most common in northern Minnesota and the most numerous species in the state), and green ash (Fraxinus pennsylvanica; also called red ash; the most widely distributed species in the state and the most commonly planted species in designed landscapes).  As a result, it is estimated that as many as one billion ash trees could be at risk in Minnesota alone.


Emerald ash borer (EAB; Agrilus planipennis) feeding gallery and larva; EAB larvae create serpentine galleries just under the bark and are susceptible to foraging by woodpeckers and woodpecker damage to ash trees, most often observed during the winter and early spring, can be a sign of a possible EAB infestation (Photo Credit: David Cappaert, Michigan State University,

In Minnesota, EAB was first documented in Ramsey County in 2009 (May); EAB was also confirmed in Hennepin and Houston Counties the same year and all three counties were subsequently quarantined by the Minnesota Department of Agriculture (MDA).  Winona County was added to the list of quarantined counties in 2011.  Since then, this destructive, non-native beetle has continued to spread to new areas and, as of this writing, 16 of Minnesota’s 87 counties (18%) are subject to complete or partial quarantines in an attempt to prevent the spread of emerald ash borer in the state.  Fifteen (15) counties are covered by complete quarantines including Anoka (2015), Chisago (2015), Dakota (2014), Dodge (2016), Fillmore (2015), Goodhue (2017), Hennepin (2009), Houston (2009), Martin (2017), Olmsted (2014), Ramsey (2009), Scott (2015), Wabasha (2016), Washington (2015), and Winona (2011) Counties.  A partial quarantine (established in September 2016 and formalized in March 2017) is also in effect for southeastern St. Louis County.


Originally the quarantine in St. Louis County was limited to Park Point in the City of Duluth (November 2015), but was subsequently expanded to include the southeastern portion of St. Louis County including the entire City of Duluth in response to additional EAB finds.  Superior, WI (Douglas County), is also infested and was quarantined in 2013.  The remainder of St. Louis County is not currently under quarantine.  Noting that the infestations in Duluth, MN, and Superior, WI, are in areas where winter temperatures tend to be moderated by Lake Superior, these infestations are close to the larger populations of ash trees in the colder, more forested areas of both states.  As a result, depending on the actual winter temperatures experienced, we may soon learn whether these infestations will be able to expand and affect ash trees in the adjacent, colder areas where laboratory studies have suggested EAB populations may not be able to reach tree-killing levels as a result of the winter temperatures typically experienced in these regions.  It should also be noted that, with the exception of the City of Duluth and the recent find in Martin County, the current EAB infestations in Minnesota are limited to the Twin Cities metropolitan area and the southeastern corner of the state.


Fortunately the spread of EAB in Minnesota has been slower than what has been experienced in other infested areas and the new finds in Dodge and Wabasha County, and the expanded quarantines in Goodhue and St. Louis Counties are the only new areas that have been added to the Minnesota EAB quarantine in 2016 and so far this year (2017).  Of course, this may change as this is a time of year when new finds are common as a result of woodpecker activity focused on EAB larvae in infested trees.  Although the spread of EAB and the number of trees that have been lost in Minnesota have been atypical compared to the more easterly infestations in other states, it is possible that EAB is beginning to spread more quickly.  Beginning with the first EAB finds in Minnesota in 2009, six (6) counties were quarantined during the first six years (2009-2014) of the Minnesota invasion, but, including the most recent find in Martin County, quarantines have subsequently been added in ten (10) additional counties since then (2015-August 2017).  Whether this trend continues remains to be seen and larger, healthy, ash trees that have noteworthy landscape value and provide valuable social and ecosystem services (e.g., shading and temperature reduction, reduced stormwater runoff, cleaner air, improved human health and well-being, and carbon sequestration) in landscape settings can be effectively protected with properly-applied systemic insecticides.


In addition to the Douglas County (Superior), WI, infestation, and the new isolated infestations in Chippewa and Marinette Counties, EAB infestations have also been found in other areas in Wisconsin.  These areas include an isolated infestation in Sawyer County (the neighboring county to the southeast of Douglas County), an isolated infestation in Oneida County (Rhinelander; another cold hardiness test location in USDA Cold Hardiness Zone 3), and all of the counties in the southern half of the state south of a line from Hastings, MN, in the west to Green Bay and the Door Peninsula in the east and including all of the border counties with Minnesota (Buffalo, Trempealeau, La Crosse, and Vernon).  Including the most recent detections, 46 of Wisconsin’s 72 counties (64%), including all of the counties in the southern half of the state, have documented EAB infestations and are under quarantine.  The initial confirmation of EAB in Wisconsin was in Washington County, located in the southeastern corner of the state, in 2008 (August).  Emerald ash borer is also present in Iowa (mainly the eastern and southern counties) and a few counties in east-central Nebraska.  The Minnesota and Nebraska infestations, plus infestations in a small number of counties just across the state borders in eastern Kansas, Oklahoma, and Texas, and an isolated infestation in Boulder County, CO, are currently the western-most infestations in North America.  In Canada, the EAB infestation is currently limited to extreme south-central Quebec and southeastern Ontario and an isolated infestation in the Thunder Bay, Ontario, area approximately 45 miles northeast of the Minnesota border.  The introduction of EAB in North America, which likely occurred in the early 1990s, was a human-mediated event and, more recently, the long-distance and initially-isolated infestations of EAB in the Minneapolis/St. Paul metropolitan area, the Duluth/Superior area, Rhinelander (WI), the Kansas City (MO/KS) metropolitan area, and the southwestern Arkansas/northern Louisiana/northeast Texas region, and in Boulder County (CO), were almost certainly human-mediated introductions.  Along with other control efforts, all concerned must be constantly diligent and take great care to avoid moving EAB-infested materials, including firewood, to non-infested areas to slow the spread of this devastating insect pest.


Selected Links to Additional EAB Information


General information about the Minnesota Department of Agriculture (MDA) emerald ash borer (EAB) program and links to more specific information about EAB in Minnesota are available on the MDA website at


The text of the Minnesota EAB quarantine (Version 11; May 9, 2017) is available at  The quarantine addresses the use and movement of regulated materials which include the insect itself (all life stages); all plants and plant parts of the genus Fraxinus, including nursery stock, scion and bud wood, logs, branches, stumps, and roots, chips and mulch (composted or not); firewood of any non-coniferous species, and other materials deemed to be a risk for the spread of EAB by the Minnesota Commissioner of Agriculture.


A new ArcGIS, interactive, searchable, online map of specific EAB finds and generally infested, quarantined, and biocontrol areas in Minnesota is available at


A summary of the status of EAB in Minnesota, along with information about some of the activities being pursued by the MDA to better understand and track EAB in the state, are available at


A map of the Wisconsin counties quarantined for EAB and a list of confirmed, EAB infestations by location in Wisconsin are available at and, respectively.


And finally, additional information regarding the status of EAB in North America is available on the Emerald Ash Borer Information Network website at and from the United States Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) at



If you have questions or comments regarding this EAB quarantine update or the status of EAB in Minnesota, contact Jim Calkins, MNLA Regulatory Affairs Manager, at; 952-935-0682.

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