2020-051 Emerald Ash BorerDate: May 15, 2020 Report No. 2020-51
INFORMAL STAFF REPORT
TO MAYOR AND CITY COUNCIL
SUBJECT:
Emerald Ash Borer confirmed in the City of Denton
BACKGROUND:
Emerald Ash Borer (EAB) is an invasive exotic beetle native to Asia that was first discovered
near Detroit, Michigan in 2002. EAB is responsible for the death of millions of ash trees across
the country due to larvae feeding on the inner bark of the tree and disrupting a tree’s ability to
circulate and process water and nutrients. Trees are usually infested 2 – 3 years before showing
signs of decline.
Since it was first detected in Michigan, the beetle has spread to 35 States and 6 Canadian
provinces. As of December 2018, the Texas A&M Forest Service confirmed reports of EAB in
Tarrant County (northwest of Fort Worth). EAB has infested and killed ash trees in the Eagle
Mountain Lake area and now it has been identified in Denton.
DISCUSSION:
On Thursday May 7, 2020 the Urban Forester met with a homeowner in the Villages of Carmel
neighborhood who had concerns that his ash trees might have EAB. After meeting with the
homeowner, he was waiting to cross the street and noticed a bug land on a leaf of an ash tree. With
the assistance of the homeowner he was able to capture the bug and place it in ziploc bag. Upon
further investigation he had a strong notion that the bug was an adult EAB beetle. He informed the
homeowner that the Texas A&M Forest Service (TFS) would be contacted to get a second opinion.
Later that day he emailed pictures to Courtney Blevins, Urban Forester with the TSF. Courtney
replied that he thought the diagnosis of EAB was right and requested a meeting to pick up the
specimen the next day and send it to the TFS entomologist for positive identification.
On Friday May 8, 2020 the Urban Forester received a call from Allen Smith Entomologist with
the TFS who used the pictures to confirm the specimen is an EAB beetle. For it to be official the
specimen would have to be sent to a lab in Michigan for positive identification. Allen stated once
we receive positive identification, Denton County will be quarantined by the Texas Department of
Agriculture (TDA). This means that a protocol will be in place to reduce of the spread of the EAB.
TDA will also have to inspect and approve our wood waste recycling equipment/program at the
landfill to verify we are compliant with standards for processing EAB wood waste products for
resale. Mr. Smith also stated that there would be a meeting with communities, agencies and
businesses in Denton County that will be affected by the quarantine. Both Allen and Courtney
have offered their assistance to help the City of Denton deal with this pest.
The State of Denton Urban Forest 2016 report calculated Denton’s urban forest to consist of about
4% (138,000) ash trees including public and private properties. Ash represent the eighth most
populous tree in Denton, most of which are located on private property, natural areas and near
riparian areas. As a part of Davey Resource Group’s work on the Urban Forest Master Plan
Date: May 15, 2020 Report No. 2020-51
(UFMP) a street tree (tree within the street right-of-way) count was performed on 10% of public
streets. Using this data, it was extrapolated that Denton has approximately 20,850 street trees
(between the curb and sidewalk). Utilizing data above it has been calculated the approximate
number of ash street trees is 834.
About 70% of City properties maintained by Parks and Recreation have been inventoried for ash
trees. A total of 59 ash trees have been inventoried, with most locations having only two or less
ash and the majority of those being less than 12 inches DBH, (Diameter by Breast Height). The
highest concentration of ash trees are in Lake Forest Park and Sequoia Park.
Standard industry options for managing EAB are:
1. Proactively remove the tree and replant with a non-ash species.
2. Treat ash via trunk injections or soil drench to allow for systematic removal and
replacement over time.
3. Commit to a preventative treatment program for the life of the tree.
Staff has the following recommendations:
On city maintained property:
1. Treat high profile ash greater than 14 inches DBH in maintained area, currently 2 ash are
recommended for treatment.
2. Proactively remove and replace all other ash in maintained areas over the next year.
Street trees:
1. Distribute educational materials to property owners informing them about EAB and their
options as stated above to address the EAB.
2. Explore options for replacing street trees.
Development Projects
1. Amend the Denton Development Code to list ash as a non-protected tree.
CONCLUSON:
While treatments can begin after infestation, generally by the time EAB is detected the infestation
is too far-gone (less than 50% of crown remaining) for treatments to be effective. Depending on
the insecticide used, treatments are required annually or biennial. Please see the following websites
for additional information.
http://www.emeraldashborer.info/
https://www.aphis.usda.gov/aphis/maps/plant-health/eab-storymap
https://www.aphis.usda.gov/aphis/ourfocus/planthealth/plant-pest-and-disease-programs/pests-and-
diseases/emerald-ash-borer
STAFF CONTACT:
Haywood Morgan
Date: May 15, 2020 Report No. 2020-51
Urban Forester, Parks and Recreation
Haywood.Morgan@cityofdenton.com
REQUESTOR:
Staff Initiated
PARTICIPATING DEPARTMENTS:
Parks and Recreation Department
STAFF TIME TO COMPLETE REPORT:
Parks and Recreation Department 7 hours