News & Press: Legislative/Regulatory News

EAB in Marathon County, Wisconsin

Monday, October 23, 2017   (0 Comments)
Posted by: James Calkins, MNLA Regulatory Affairs Manager

MNLA Regulatory Update – New Emerald Ash Borer (EAB) Infestation Documented in Marathon County, Wisconsin; County Added to Quarantined Area


Just a little more than a month after emerald ash borer (EAB; Agrilus planipennis) infestations were identified outside previously quarantined areas in five other Wisconsin counties (Chippewa, Green Lake, Marinette, Waupaca, and Waushara Counties) and one Minnesota county (Martin County), EAB has been identified in Marathon County in north central Wisconsin.  The new infestation was found by a tree care professional on private property located along the Wisconsin River in the Town of Rib Mountain just west of Wausau, Wisconsin.  In response to this new EAB infestation, Marathon County has been added to the list of quarantined counties in the state by the Wisconsin Department of Agriculture, Trade, and Consumer Protection (DATCP).  Marathon County is located in central Wisconsin and is bordered by Wood and Portage Counties, previously infested and quarantined for EAB, to the south and contiguous with the quarantined counties in the southern half of the state.  Although scattered infestations have been found in the northern regions of the state, EAB has not yet been documented in the adjacent counties to the north, east, and west of Marathon County.  As we all know, EAB is a serious threat to ash trees growing in designed landscapes and native ecosystems and Minnesota Nursery and Landscape Association (MNLA) members located in Wisconsin and that work in Wisconsin will want to be aware of this expansion of the EAB quarantine.


The announcement of the Marathon County infestation and quarantine are available on the DATCP website at  A list of confirmed EAB infestations in Wisconsin by county, municipality, and date of confirmation is also available on the DATCP website at as is a map of the Wisconsin counties quarantined for EAB at


Including Marathon County, 47 of Wisconsin’s 72 counties (65%), including all of the counties in the southern half of the state, are now under quarantine for EAB.  Although this is a depressing statistic, it is 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, including most of the area in the quarantined counties, remains EAB-free, as a majority of the quarantined counties only have small, isolated EAB infestations.  The same is also generally true for Minnesota where only 16 of the state’s 87 counties (18%), almost exclusively located in the Twin Cities metropolitan area and several counties in southeastern Minnesota, are currently under full or partial quarantine in an attempt to slow the spread of EAB in the state.  See the link to the Minnesota Department of Agriculture (MDA) website below to view a map of the EAB infestations and quarantined areas in Minnesota.


On the national level, it should be noted that the United States Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) has just added the State of South Carolina to the federal EAB quarantine list (October 13, 2017).  The federal quarantine order is available along with previous federal quarantine notices at or directly at


It cannot be overemphasized that infested firewood is considered a primary vector of EAB and may not be moved out of a quarantined county.  Better yet, firewood should not be moved around the state or even within an infested county; firewood may only be moved outside quarantined areas if it has been heat-treated to state standards and certified by the Minnesota Department of Agriculture under a compliance agreement.  Additional information about firewood in Minnesota is available at and  The Minnesota Department of Natural Resources also has firewood restrictions (


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.


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, the destructive, non-native emerald ash borer beetle has continued to spread to new areas and, as of this writing, 16 of Minnesota’s 87 counties (18%) are currently 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.  Although 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.  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, Martin, and Wabasha Counties, 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 in August of this year, quarantines have subsequently been added in ten (10) additional counties since then (2015-August 2017).  Whether this trend continues remains to be seen.


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, interactive, searchable, ArcGIS 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


Additional information about EAB in Wisconsin is available at


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 and/or Wisconsin, contact Jim Calkins, MNLA Regulatory Affairs Manager, at; 952-935-0682.

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