Forestry
EMERALD ASH BORER
In the last year the quarantine area surrounding the initial discoveries of the Emerald Ash Borer has widened to now include the entire Northeastern Illiois area.
February 29, 2008 tree removal update
Forestry staff has tagged 399 ash trees for removal due to the infestation of the EAB. Of this total, 231 are on public property (including all the remaining ash trees in Lovelace Park), 140 are on private property, and we are awaiting survey results on 28 trees to determine public or private ownership.
Inspections have taken place on all public ash trees north of Simpson Street the entire width of the City. All private ash trees have been inspected north of Central Street, as well as those north of Simpson Street and west of McCormick Boulevard. Staff is currently inspecting all private ash trees that are north of Simpson Street and east of McCormick Boulevard.
Forestry crews will be completing the 73 ash removals in Lovelace Park on Feb. 29; 27 ash trees were removed from the park in 2007. Beginning the first week of March, we will begin to remove the infected ash trees from the public parkways. Barring any significant increase in the number of infected trees, we expect to complete the remaining public removals by the end of March or early April.
Staff continues to monitor the status of any possible State funding assistance opportunities on a weekly basis. To date, there have been no new programs announced, nor any funding provided for grants or loans on the State level.
The Illinois Department of Agriculture has produced this newsletter with updated information on the Emerald Ash Borer (pdf). They also have designated a Web site with information specific to Illinois' fight against the Emerald Ash Borer: www.ILLINOISEAB.com
Other resources are the Morton Arboretum Web site and www.emeraldashborer.info
Background
In July 2006, the Illinois Department of Agriculture (IDOA) confirmed the Emerald Ash Borer (EAB) was located in Evanston. The infestation was discovered by a City of Evanston Parks/Forestry Division employee while assisting in an extensive survey initiated as a result of an infestation in Wilmette. Beetles were found in seven trees located in Lovelace Park, located at Gross Point Road at Thayer Street in the far northwest area of Evanston. In addition, the Emerald Ash Borer was discovered in a tree on private property on the east side of Gross Point Rd. at Thayer St.
The Emerald Ash Borer is a destructive, non-native pest that feasts on ash trees. It is a small, metallic-green beetle native to Asia. Its larvae burrow into the bark of ash trees, causing the trees to starve and eventually die. While the beetle does not pose any direct risk to public health, it does threaten the tree population. Since the Emerald Ash Borer was first confirmed in the Midwest in the summer of 2002, more than 20 million ash trees have died.
Evanston has over 4,000 ash trees on its parkway and in its parks, which is about 12% of the City’s 33,000 public trees. Additionally, there are thousands of ash trees on private property in Evanston. Ash trees were widely planted in the city and in much of northeast Illinois because they are fairly inexpensive and generally quite tolerant of soils and climate in this area.
In 1999, the City of Evanston created a policy whereby any tree species that made up more than 10% of the overall population would no longer be planted on public property. This means the City has not planted any new ash trees since 1999. This effort to further diversify the overall tree population was specifically aimed to minimize the effects of an infestation.
Evanston residents with questions can call the Evanston Parks/Forestry Division at 847.866.2912 or send an email to forestry@cityofevanston.org.
In order to increase public awareness of this problem, the City offers the following information:
Where did the Emerald Ash Borer Come from?
The Emerald Ash Borer is an exotic insect pest from Asia. It was first discovered in the U.S. in 2002 in southeast Michigan. Since that time, this tree destroyer has also been detected in Indiana, Ohio, Maryland and Ontario, Canada.
Prior to its discovery in the U.S., the Emerald Ash Borer was found primarily in Korea, China, Japan and other East Asian countries. In the U.S. thus far, this pest has been known to attack all native ash trees, specifically White, Green and Blue ash; it does not attack Mountain ash and likely not European ash.
How do I know if my tree is an Ash?
Ash trees have several green leaflets per leaf stem, usually 7. The leaflets are located directly across from each other with one leaflet on the end. The leaf shape is “lanceolate,” which means they are much longer than wide, broader below the middle and tapering to the top. If the tree in question is on public right-of-way (parkway) in Evanston, its species may be verified by a call to the Parks/Forestry Division at (847) 866-2912, since all such trees have been inventoried.
What is the EAB's lifecycle?
The Emerald Ash Borer adult is a dark metallic green beetle only about 1/2” in length and 1/8” in width. Adults are only present from mid-May to late June, when they feed on the leaves of ash trees. Soon after they emerge, the adults lay eggs on the trunk and branches of ash trees. After about a week the eggs hatch into larvae which then bore into the tree. It is this larval stage that does the major damage. Larvae are creamy white in color, can grow up to an inch long and are found under the bark of the trees. These larvae tunnel and feed, creating S-shaped galleries. This tunneling cuts off the food and water supply to the tree, causing it to die. Later in the year, the larvae pupate and overwinter under the bark. New adults emerge the following May. Their emergence holes are very small (only 1/8”) D-shaped holes and can occur just about anywhere throughout the tree.
What are the symptoms?
Infestation of EAB can be difficult to detect until the branches of the tree start to die. Usually the leaves on the upper third of a tree will start to thin, and the branches will begin to die back. This is usually followed by a large number of shoots or branches arising below the dead portions of the trunk. Additional evidence of infestation includes the tiny D-shaped exit holes on the branches and the trunk. Distinct S-shaped larval feeding tunnels may also be apparent under the bark.
How does EAB Spread?
It is thought that the beetle arrived in the U.S. from Asia in the early 90s, but it was not positively identified until 2002. It is believed that the larvae hitched a ride across the borders traveling in wooden pallets. Once arriving in the United States the insects emerged as adult beetles and the cycle of devastation began. The EAB is an excellent flier and can travel fairly far distances in search of food and egg-laying sites in ash trees. Additionally, pockets of EAB outbreaks have been linked to the movement of firewood and ash tree nursery stock out of infested areas.
Who is fighting the beetle?
Because this insect has such great potential to decimate both forests and urban tree populations, national and state agencies are working together to stop the spread of EAB. These agencies include the USDA Forest Service, APHIS (Animal and Plant Health Inspection Service), and the various state Departments of Agriculture. In Illinois the lead agency is the Illinois Department of Agriculture (1-800-641-3934). Unfortunately, very little information on the beetle is available from its native region, and limited control management recommendations exist to date. Research on various insecticides is being conducted, and some are quite promising. However in new infestations, the goal must be complete eradication of every single Emerald Ash Borer. Thus in these areas, infested trees as well as surrounding healthy trees are declared a “Public Nuisance” and removal of these trees is required by law.
Fortunately in Illinois, a wide variety of organizations and agencies concerned about our urban and forest trees have had an “Illinois Emerald Ash Borer Readiness Plan” in place since 2004. This plan was compiled by the Morton Arboretum’s Community Trees Advocate and it outlines a plan for a coordinated and prompt response by all involved parties.
Steps residents can take
- REFUSE TO MOVE FIREWOOD OR PURCHASE ASH WOOD - Use only local firewood (even when traveling), and burn the wood on site or leave it when you move on. Especially, don’t bring firewood or logs from other states, or any areas that may become quarantined in Illinois, to Evanston. Do not purchase any firewood containing ash wood until further notice.
- CARE FOR ASH TREES- Call the Parks/Forestry Division if a public ash tree seems sick or needs maintenance. Care for private trees routinely, using ISA-certified arborists when hiring tree care companies.
- PLANT FOR DIVERSITY- Do not plant ash trees. Plant underutilized tree species instead.
PARKS/FORESTRY & REC 
Forestry
Emerald Ash Borer