HomeMy WebLinkAboutItem 09
Date: November 19, 2018 Item No.
ORDINANCE AMENDING TITLE 4 OF LAKEVILLE CITY CODE CONCERNING SHADE
TREE EPIDEMIC PEST CONTROL AND APPROVAL OF THE EMERALD ASH BORER
MANAGEMENT PLAN AND SHADE TREE PEST CONTROL POLICY
Proposed Action
Staff recommends adoption of the following motion: Move to approve A) an ordinance
amending Title 4, Chapter 4 of the Lakeville City Code concerning shade tree epidemic pest
control; B) a summary ordinance for publication; and C) the Emerald Ash Borer (EAB)
management plan and shade tree pest control policy.
Overview
Emerald Ash Borer’s (EAB) appearance in Lakeville has prompted actions by the City to both inject
ash trees and remove ash trees to reduce the spread of the beetle within the community. The
proposed ordinance is focused on the discovery and abatement of EAB, Oak wilt, and Dutch elm
disease within the community. It provides a means for inspection on both public and private
property.
The proposed management plan and policy outline best practices to discover those ash trees likely
to be infested, the best methods for control of EAB, proper and systematic removal and disposal
of infested trees, and mechanisms for biological control. They additionally provide options for
reforestation in a manner that would improve species diversity.
Together these items provide a structured approach to addressing the discovery and abatement of
EAB and other shade tree pests and diseases. The ordinance provided support to staff in dealing
with and controlling EAB and other infestations. Staff recommends approval.
Primary Issues to Consider
• Why is this ordinance necessary? Dutch elm disease, Oak wilt, and EAB are examples of
pathogens and infestations that can devastate shade trees if not recognized and treated in a
timely manner. The focus of the ordinance is to allow for that early recognition and control.
Supporting Information
• The ordinance, summary ordinance, management plan, and policy are attached.
Financial Impact: $0 Budgeted: Source:
Related Documents (CIP, ERP, etc.): CIP
Community Values: Good Value for Public Services
Completed By: Neil Normandin, Interim Public Works Director
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ORDINANCE NO. ___
CITY OF LAKEVILLE
COUNTY OF DAKOTA, MINNESOTA
AN ORDINANCE AMENDING TITLE 4,
CHAPTER 4 OF THE LAKEVILLE CITY CODE CONCERNING SHADE TREE
EPIDEMIC PEST CONTROL
THE CITY COUNCIL OF THE CITY OF LAKEVILLE, MINNESOTA ORDAINS:
SECTION 1. Title 4, Chapter 4 of the Lakeville City Code is amended in its entirety to read as
follows:
4-4-1: DECLARATION OF POLICY:
Trees provide many environmental, economic and aesthetic benefits to the public. The health of
the trees in the City of Lakeville is threatened by shade tree pests of an epidemic nature. The loss
or poor health of trees growing upon public and private property substantially depreciates the value
of property within the city and impairs the safety, good order, general welfare and convenience of
the public. The Council intends to address pests of an epidemic nature, defined as having a
widespread occurrence directly associated with a high mortality of a tree species. In addition to
and in accordance with Minn. Stat. §§ 89.001, 89.01, and 89.51-.64, the provisions of this section
are adopted as an effort to prevent, control and/or slow the spread of these serious shade tree pests
in an orderly and systematic approach in order to reduce the loss of tree benefits to the community
4-4-2: JURISDICTION:
The city shall have control of all boulevard (street) trees, shrubs, and other plantings now or
hereafter in any street, park, public right-of-way or easement, or other public place within the city
limits, and shall have the power to plant, care for, maintain, remove, and replace such trees, shrubs,
and other plantings.
4-4-3: DECLARATION OF A SHADE TREE PEST:
The Council may by ordinance declare any vertebrate or invertebrate animal, plant pathogen,
parasitic plant or allied organism in the community threatening to cause significant damage on an
epidemic level to a shade tree or community forest, as defined by Minn. Stat. § 89.001, to be a
shade tree pest and prescribe control measures to effectively eradicate, control, or manage the
shade tree pest, including necessary timelines for action as recommended by the Minnesota
Department of Agriculture and the University of Minnesota Extension.
4-4-4: PUBLIC NUISANCES DEFINED:
The following shade tree pests occurring within a defined control area on public or private property
are a public nuisance:
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A. Any living or dead ash tree, or part of it including logs, branches, stumps or firewood harboring
emerald ash borer, Agrilus planipennis Fairmaire in any life stage;
B. Any living or dead red oak tree, or part of it including logs, branches, stumps or firewood
infected with oak wilt Bretziella (form. Ceratocystis) fagacearum to any degree with the capability
of producing a spore mat;
C. Any living or dead elm tree or part of it including logs, branches, stumps or firewood infected
to any degree with the Dutch elm disease fungus Ophiostoma novo-ulmi or any non-infected elm
wood with intact tight bark that will harbor any of the elm bark beetles including but not limited
to Scolytus multistriatus, Scolytus schevyrewi, and Hylurgopinus rufipes;
D. Any living, dying or standing tree, wood or plant part infected with any vertebrate or
invertebrate animal, plant pathogen, parasitic plant or allied organism in the community
threatening to cause significant damage to other trees on an epidemic level as defined by Minn.
Stat. § 89.001.
4-4-5: SHADE TREE PEST NUISANCES ARE UNLAWFUL:
It is unlawful for any person to permit any public nuisance as defined in this section to remain on
any premises the person owns or controls within the city. It is unlawful for any person to transport
any infested or infected plant material determined to be a shade tree epidemic pest unless
prescribed by the city forester or designated tree inspector, including the sale of or dispersal of
firewood found to be infested. The nuisance may be abated as provided in this section.
4-4-6: CITY FORESTER:
The Council may appoint a city forester who is a Minnesota Certified Tree Inspector to coordinate
the activities of the city relating to the control and prevention of damage by shade tree pests. The
city forester will recommend to the Council the details of any program for the declaration, control,
and prevention of shade tree pests. The city forester is authorized to enforce or cause to be enforced
the tasks incident to such a program adopted by the Council. The term “tree inspector” includes
any person designated by Council or the city forester to carry out activities authorized in this
section.
4-4-7: ABATEMENT OF SHADE TREE PEST NUISANCES:
In abating a nuisance, defined under Section 4-4-3 of the City Code, the organism, condition, plant,
tree, wood, or material identified as injurious on an epidemic scale to the health of shade trees shall
be removed or effectively treated to destroy and prevent as fully as possible the spread of the shade
tree pest. Such abatement procedures shall be carried out in accordance with the control area and
control measures prescribed by The City of Lakeville Shade Tree Pest Control Area and Control
Measures Policies (“Policies”). Movement or transportation of infested wood or materials must
comply with the Policies.
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4-4-8: REPORTING DISCOVERY OF SHADE TREE PEST:
Any owner or occupier of land or any person engaged in tree pruning or removal who becomes
aware of the existence of a public nuisance caused by a shade tree pest as defined under Section
4-4-3 shall report the same to the city.
4-4-9: REGISTRATION OF TREE CARE FIRMS:
Any person, firm, or corporation that provides tree care, tree pruning, or removal of trees, limbs,
branches, brush, or shrubs for hire must be registered with the Minnesota Commissioner of
Agriculture under Minn. Stat. § 18G.07.
4-4-10: INSPECTION AND APPLICATION OF CONTROL MEASURES:
A. The city forester or designated tree inspector is authorized to inspect premises and places
within the city to determine whether shade tree pests exist thereon and to investigate all reported
incidents of shade tree pests. The tree inspector is authorized to take all reasonable measures to
prevent the maintenance of public nuisances and may enforce the provisions relating to abatement
in this section. Diagnosis of shade tree pests will be made by the presence of commonly recognized
visual symptoms and signs; and occasionally by tests when recommended by the commissioner of
the Minnesota Department of Agriculture or the commissioner of the Minnesota Department of
Natural Resources; or other reliable means.
B. The city shall notify the entire community by two means of communication such as the city
website and official newspaper when seasonal inspections for shade tree pests are about to
commence. In addition, the tree inspector shall knock on the door before entering private property
for the purpose of inspecting or abating nuisances. If the owner, resident, or other person in control
of the property does not answer the door, the property owner shall be provided with the opportunity
to schedule an inspection or abatement within a reasonable time period. If the inspection or
abatement is not authorized by the property owner within such reasonable time period,; the tree
inspector may take appropriate legal measures to gain authorization for entry.
C. No person, firm, or corporation shall interfere with the tree inspector or with anyone acting
under the city forester’s authority while engaged in activities authorized by this section.
4-4-11: STANDARD ABATEMENT PROCEDURE:
Except as provided in Sections 4-4-12 and 4-4-14 of the City Code, whenever a tree inspector
determines with reasonable certainty that a public nuisance, as described by this ordinance, is being
maintained or exists on premises in the city, the tree inspector is authorized to abate a public
nuisance according to the procedures in this section.
A. The tree inspector will notify in writing the owner of record of the premises that a public
nuisance exists and order that the nuisance be terminated or abated. The notice may be given in
person or by mail. Failure of any party to receive the mail does not invalidate the service of the
notice. A copy will be on file at the City offices.
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B. The notice of abatement shall state that unless the public nuisance is abated by the owner, it
will be abated by the city at the expense of the owner. The notice shall specify the control measures
to be taken to abate the nuisance and provide a reasonable amount of time to abate the nuisance.
The notice will also state that the owner has the right to appeal the determination that a public
nuisance exists by submitting a request in writing to the city clerk within seven (7) days after
service of the notice, or before the date by which abatement must be completed, whichever comes
first.
C. If no timely appeal is submitted, and the control measures prescribed in the notice of abatement
are not complied with within the time provided by the notice or any additional time granted, the
tree inspector or designated person shall have the authority to obtain permission from the owner
or individual in control of the property or other legal authorization, enter the property and carry
out abatement in accordance with the notice of abatement.
4-4-12: HIGH-COST ABATEMENT:
If the tree inspector determines that the cost of abating a nuisance will exceed $3,000 based on a
reasonable, good faith estimate, the written notice referred to in Section 4-4-11 must provide that
if the nuisance is not abated within the reasonable amount of time provided, the matter will be
referred to the City Council for a hearing. The date, time, and location of the hearing must be
provided in the notice.
4-4-13: APPEAL PROCEDURE:
If the city clerk receives a written request for a hearing on the question of whether a public nuisance
exists, the City Council shall hold a hearing within fourteen (14) calendar days following receipt
by the clerk of the written request. At least three (3) days’ notice of the hearing shall be given to
the individual who made the written request for the hearing. The Council may modify the
abatement notice or extend the time by which abatement must be completed. Each owner, agent
of the owner, occupant, and lienholder of the subject property or properties in attendance, if any,
shall be given the opportunity to present evidence at the hearing. After holding the hearing, the
City Council may issue an order requiring abatement of the nuisance.
4-4-14: ABATEMENT PROCEDURE IN EVENT OF IMMINENT DANGER:
A. If the tree inspector determines that the danger of infestation to other shade trees is imminent,
and delay in control measures may put public health, safety, or welfare in immediate danger, the
tree inspector may provide for abatement without following Section 4-4-11 or 4-4-12. The tree
inspector must reasonably attempt to notify the owner of the affected property of the intended
action and the right to appeal the abatement and any cost recovery at the next regularly scheduled
City Council meeting.
B. Nothing in this section shall prevent the city, without notice or other process, from immediately
abating any condition that poses an imminent and serious hazard to human life or safety.
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4-4-15: RECOVERY OF COST OF ABATEMENT; LIABILITY AND ASSESSMENT:
A. The owner of premises on which a nuisance has been abated by the city shall be personally
liable for the cost to the city of the abatement, including administrative costs. As soon as the work
has been completed and the cost determined, the city clerk or other official shall prepare a bill for
the cost and mail it to the owner. Thereupon the amount shall be immediately due and payable at
the office of the city clerk.
B. After notice and hearing, as provided in Minn. Stat. § 429.061 (which may be amended from
time to time), the city clerk shall, on or before Sept. 1 next following abatement of the nuisance,
list the total unpaid charges as well as other charges for current services to be assessed under Minn.
Stat. § 429.101 against each separate lot or parcel to which the charges are attributable. The City
Council shall then certify the charges against the property to the county auditor for collection along
with current taxes the following year or in annual installments as the City Council may determine
in each case.
4-4-16: PENALTY:
In addition to any penalties provided for in this code if any person, firm, or corporation fails to
comply with any provision of this section, the City Council or any official designated by it may
institute appropriate proceedings at law or at equity to restrain, correct, or abate the violation.
4-4-17: SEVERABILITY:
Should any part or provision of this ordinance be declared by a court of competent jurisdiction to
be invalid, the same shall not affect the validity of the ordinance as a whole or any part thereof
other than the part held to be invalid.
SECTION 2. This Ordinance shall be effective immediately upon its passage and publication.
ADOPTED by the City Council of the City of Lakeville, Minnesota this ____ day of
_______________, 2018.
CITY OF LAKEVILLE
BY: _______________________________
Douglas P. Anderson, Mayor
ATTEST:
____________________________
Charlene Friedges, City Clerk
199700v1
CITY OF LAKEVILLE
DAKOTA COUNTY, MINNESOTA
SUMMARY ORDINANCE NO. 2018-____
AN ORDINANCE AMENDING TITLE 4,
CHAPTER 4 OF THE LAKEVILLE CITY CODE CONCERNING SHADE TREE
EPIDEMIC PEST CONTROL
NOTICE IS HEREBY GIVEN that on November 19, 2018, Ordinance No. 2018-___
was adopted by the City Council of the City of Lakeville.
NOTICE IS FURTHER GIVEN that, because of the lengthy nature of Ordinance No.
2018-___, the following summary of the ordinance has been prepared for publication:
Ordinance No. 2018-___ amends City Code Title 4, Chapter 4 concerning shade tree
epidemic pest control management to address pests of an epidemic nature, defined as having a
widespread occurrence directly associated with a high mortality of a tree species. The provisions
of the Ordinance provide regulations to address prevention, control and/or slow the spread of
these serious shade tree pests through an orderly and systematic approach in order to reduce the
loss of tree benefits to the community. The Ordinance defines certain public nuisances related to
shade tree pests and declares such shade tree pests as unlawful within the City. The Ordinance
provides for inspection, application of control measures, and an abatement procedure.
A printed copy of the whole ordinance is available for inspection by any person during
the City’s regular office hours or on the City’s website.
APPROVED for publication by the City Council of the City of Lakeville, Minnesota this
19th day of November, 2018.
CITY OF LAKEVILLE
By: ________________________________
Douglas P. Anderson, Mayor
ATTEST:
________________________________
Charlene Friedges, City Clerk
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City of Lakeville
Emerald Ash Borer Management Plan
EAB infested ash – Oak Shores Park, Lakeville, MN January 2018
November 14, 2018
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Table of Contents
Page
Purpose……………………………………………………………………………………………….4
Introduction………………………………………………………………………………………….4
Current Emerald Ash Borer Status in Lakeville…………………………………………………….7
Tree Inventory and Ash Tree Population…………………………………………………………...7
Program Administration and Impact……………………………………………………………….8
Public Outreach and Education……………………………………………………………………..9
Management of Ash Trees with Best Management Practices …………………………………….10
1. Monitoring and Inspection………………………………………………………………...12
2. Insecticide Use……………………………………………………………………………...13
3. Ash Tree Removal…………………………………………………………………………..16
a. Proactive Structured Ash Removal………………………………………………...16
b. Poor Condition Ash Removal: City Projects……………………………………....18
c. EAB Infested Ash Removal: City Property………………………………………...18
d. EAB Infested Ash Removal: Private (non-City) Property ………………………..19
4. Biological Control…………………………………………………………………………..22
Ash Wood Disposal………………………………………………………………………………...22
Management of Ash Trees During Planning and Development Review…………………………23
Reforestation and Canopy Replacement…………………………………………………………...24
1. Public Property Reforestation……………………………………………………………...25
a. Park, Facility, Utility.…………………………………………..................................25
b. Boulevard…………………………………………………………………………...25
c. City outlots, conservation areas, woodlands/open space…………………………26
2. Private Property (non-City) Reforestation………………………………………………...27
Conclusion………………………………………………………………………………………….28
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Figures and Tables
Page
Table 1: City of Lakeville Tree Population and Ash Count ……………………………………….8
Figure 1: Percentage of Counties Infested with EAB by Years of Infestation……………………10
Figure 2: As the Number of Dead Ash Trees Goes Up, Management Options Go Down………12
Table 2: City Ash Trees Eligible for Injection of Emamectin Benzoate…………………………..15
Table 3: Private Ash Trees Eligible for Injection of Emamectin Benzoate……………………….16
Table 4: Boulevards: Recommended Minimum Targets of Proactive Ash Removals……………17
Table 5: Parks: Recommended Minimum Targets of Proactive Ash Removals………………….17
Table 6: Facility and Utility: Recommended Minimum Targets of Proactive Ash Removals…...18
Table 7: Infested Ash Tree Removal Guidelines on Unmaintained City Property………………19
Table 8: Infested Ash Tree Removal Guidelines on Unmaintained Private Property……………20
Figure 3: Runoff Volumes will Increase Based on the Percent of Impervious Surface…………..24
Table 9: Reforestation and Canopy Replacement Recommended Targets………………………26
Maps
Map 1: USDA Cooperative Emerald Ash Borer Project Distribution in the United States………..5
Map 2: City of Lakeville Confirmed EAB Infestation Areas 2017………………………………….7
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Purpose
The purpose of the City of Lakeville Emerald Ash Borer Management Plan is to minimize the
significant fiscal and environmental impacts of emerald ash borer (EAB). The loss of over 12,000
ash trees, about 9.5% of all trees in Lakeville will have a noticeable effect on home values, quality
of life and the environment over the next two decades if it is not managed properly. The most
effective way to handle the EAB in Lakeville will require a mixed approach including tree
preservation by injection, tree and stump removals, replanting and adding additional staff to
assist with handling the pest in a systematic way. The EAB Management Plan is consistent with
the City’s vision statement which seeks to offer “…exceptional parks, trails and recreational
opportunities;” in addition to “…safe neighborhoods; and responsive and cost-effective public
services together (to) create a place we are proud to call home.”
Trees serve as part of the City’s green infrastructure: they clean the air, slow down and absorb
stormwater, reduce erosion, save electricity by reducing air conditioning costs, enhance property
values and provide habitat for wildlife. One figure provided by the Minnesota Shade Tree
Advisory Council (MnSTAC) states the loss of all urban ash trees in the state will lead to 1.7
billion gallons of water entering our stormwater systems annually. A proactive and structured
approach to managing the City’s ash population will distribute the impacts over 10-15 years and
help ensure an orderly response while maintaining as many tree benefits as possible. The City’s
plan will be guided by the best management practices issued by the top three agencies
researching EAB in the state; the Minnesota Department of Agriculture, the Minnesota
Department of Natural Resources and the University of Minnesota. Since research is ongoing,
management practices will be modified if new strategies are recommended.
Introduction
Emerald ash borer (Agrilus planipennis Fairmaire) is a non-native invasive beetle that was
discovered in the Detroit, Michigan area and Windsor, Ontario in 2002 after ash trees began to
die. It was most likely introduced to North America on wood packing materials originating from
Asia. Scientists believe it could have been introduced as early as 1990, so the insect had over ten
years to build its population without any proactive management. Since that time, EAB has spread
to at least 31 states.
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Map 1: USDA Cooperative Emerald Ash Borer Project Distribution in the United States
In May of 2009, EAB was first confirmed Minnesota when it was found in a St. Paul
neighborhood. Most recently, within Dakota County, EAB was found in Eagan in 2014, Apple
Valley in 2016, and Lakeville in 2017.
The emerald ash borer adult is very small from 3/8-1/2 inches long, and the immature stage
(larvae) is about one inch long. Due to its small size, and its inconspicuous location under the
bark, it can be difficult to detect in the early stages and typically infests a tree for 3-5 years before
visible signs and symptoms appear. During that time, one generation of beetles can emerge from
an infested tree each year and fly to nearby ash trees. Emerald ash borer spreads about one to two
miles per year, which is the average flight distance of an adult beetle. The insect has spread faster
than one to two miles per year due to human movement of firewood, nursery stock and other ash
products.
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Ash trees are killed when EAB larvae (the immature stage) feeds under the bark of ash trees,
disrupting the tree’s ability to transport water and nutrients throughout the tree. The adults feed
on ash leaves but are not the primary driver of tree mortality. Emerald ash borer has killed
hundreds of millions of ash trees where it becomes established. According to the state’s
Department of Natural Resources, Minnesota has 2.65 million ash trees in communities, and
about 1.1 billion ash trees in total growing in forests and communities, the most of any state in
the country. The USDA Forest Service EAB website states “…emerald ash borer is the most
destructive invasive forest insect ever to have invaded North America.” Ash trees were frequently
the default replacement for elm trees lost to Dutch elm disease in the late 1970’s and 80s. They
traditionally survive in soil conditions that many other trees cannot and are selected for difficult
growing sites. According to the Minnesota Shade Tree Advisory Committee, EAB is “…more
destructive than Dutch elm disease, which required a state investment of $500 million to
combat.” Currently, there is no funding available from the state of Minnesota to communities
like Lakeville to tackle this pest.
Beyond existing as a threat to forest health and canopy cover, emerald ash borer becomes a
public safety issue because the insect accelerates the wood drying that would normally happen as
a tree dies. Due to the wood properties of ash, the trees become incredibly brittle and hazardous
when succumbing to EAB. As trees become more dangerous to remove, there are fewer options
for safe removal by appropriately trained staff and contractors. This is a relevant issue for private
property tree owners in addition to the City. There is a direct relationship between the risk
associated with removing a tree and the cost when contractors are hired to remove an infested
tree. As the EAB population builds in a community, tree death increases and accelerates, often
referred to as the “death curve” because it is an exponential relationship. Although it is not
currently possible to eradicate EAB once found, there are research-based control measures that
can slow and flatten out the “curve” to spread tree losses and costs over time, which will be
proposed for implementation in the plan.
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Current Emerald Ash Borer Status in Lakeville
The first infested tree was confirmed in October 2017 near Cedar Avenue and 160P
th
P Street West.
In December 2017, the Minnesota Department of Agriculture (MDA) and City staff surveyed a
little over half of the City in a radius around the infested tree to determine the extent of
infestation. Due to the number of infested trees found, proximity to the Apple Valley infestation
and the extent of wood pecker activity on the infested ash trees found, MDA staff believe the City
of Lakeville infestation began in approximately 2014. Like every other community where it has
been found, EAB was difficult to detect here until the larvae population was big enough to attract
woodpeckers. There were about 85 infested trees that were located during the survey, most of
which are growing on private property in front yards.
Map 2: City of Lakeville Confirmed EAB Infestation Areas in 2017
Tree Inventory and Ash Tree Population
In 2017, a City-wide tree inventory was completed to assess the total number of ash trees on
public boulevards, facilities, utility sites, parks, and select trail corridors. Trees were inventoried
in the mowed, maintained (non-wooded) areas using a geographic positioning system (GPS)
within a geographic information system (GIS) so that data can be updated and tracked
electronically. At this time, the City does not have an inventory or estimate for the number of ash
trees growing in the wooded sections of park land, City owned conservation areas, or outlots but
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will budget for that project once higher-use areas such as parks and streets have started
implementing BMPs.
The boulevard and private property trees were inventoried with a statistical sample that estimates
the total number of trees achieving a 95% probability and a relative error of 10% or less, based on
a method described in the Journal of Arboriculture, the scientific journal of urban forestry and
the discipline of arboriculture. This is a cost effective, accurate and industry-approved way to
estimate the City’s exposure and anticipated budget scenarios required to handle EAB. The trees
growing on the City-owned lands of parks, facilities, and utilities were all inventoried if they were
found in a maintained area.
Table 1: City of Lakeville Tree Population and Ash Count Maintained Areas Only
Categories Ash
Trees
Other Tree
Species
Total Trees Ash as a %
of Total
(rounded)
City-owned Tree Population
Boulevard (street) trees* 1,790 7,695 9,485 19%
Parks 688 3,094 3,782 18%
Facilities 60 494 554 11%
Utility Properties 1 162 163 <1%
Total City-owned 2,539 11,445 13,984
Private Property
Single-family, Multi-Family,
Schools, and Commercial all
included*
9,943 107,442 117,385 8.5%
Total Inventoried City & Private 12,482 118,887 131,369
*statistical sample inventory
Program Administration and Impact
The Public Works Department will take the lead role to implement the EAB plan and associated
program. Specifically, the City Forester and Public Works Director will work collaboratively with
the Parks and Recreation Department Director and associated staff to implement the best
management practices (BMPs) to handle emerald ash borer and ash trees throughout Lakeville.
The City Forester will ensure City ordinance requirements related to EAB infested trees on
private properties are enforced as recommended by the City Council.
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Implementing the proposed EAB management plan will spread out the financial and staffing
requirements over a ten to fifteen-year period but will still require significant additional City
resources. EAB management has financial and staffing implications that will exceed the City’s
current Public Works (Street, Forestry) and Park allocations.
Public Outreach and Education
The City will proactively communicate about EAB through the website, cable, social media and
the official newspaper. The City hosted a public presentation in December 2017, which was
filmed and is available online. Beyond information sharing, the City Forester or her
representatives will proactively connect with businesses, the school district, and residents to
ensure best management practices become more well known. In addition, the City Forester and
assigned representatives will give presentations to smaller groups, such as homeowners
associations or neighborhood groups regarding EAB best management practices. From
September 2017 through August 2018, the City has a GreenCorps member assisting with EAB
outreach and planning efforts. City events such as the Earth Day Watershed Clean up, the
Annual Tree Sale, and residential site visits will be an opportunity to educate the public about
emerald ash borer. The City Forester will also attend events such as the Lakeville Landscape &
Home Expo to reach a wider audience. In March 2018, the City is partnering with the Minnesota
Department of Agriculture to host a free EAB Field Workshop for the community at Oak Shores
Park and will continue to leverage those opportunities to amplify outreach efforts.
The historic trend demonstrates that EAB related tasks often outstrip public resources and staff
during the peak years of EAB infestation. Tasks include public property ash tree inspections and
removals, private property tree inspection requests, ordinance/code compliance and questions.
Educating the public aggressively must be a priority to manage expectations and so they can use
self-help during the peak years to handle infested ash trees appropriately before they become
public safety hazards.
The Minnesota Department of Agriculture (MDA) and Natural Resources (DNR) have
community outreach in place to discourage the movement of firewood throughout the state,
including brochures, billboards, advertisements, and vehicle inspections. In addition, a statute
restricts the movement of unapproved firewood onto DNR owned land and a state and federal
quarantine restrict movement of firewood of any hardwood tree species into a non-quarantined
county.
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The City Forester and staff responsible for managing EAB will continue to attend workshops and
seminars to stay current with new strategies to manage the pest. Staff will also coordinate
management with neighboring cities and agencies when appropriate to improve the management
of EAB.
Management of Ash Trees with Best Management Practices (BMPs)
When EAB was first found in Michigan, several management strategies were attempted and
failed. Since that time, several research-informed strategies have emerged and are now industry-
accepted best management practices (BMPs) for reducing the costs and preserving tree value
during the peak of EAB infestation. Minnesota has done better overall, than many of the initial
states due to aggressive management, education, outreach, quarantines, sanitation and cold
weather.
Figure 1: Percentage of Counties Infested with EAB by Years of Infestation
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The option of “doing nothing” is not an accepted option for this pest because it will guarantee a
faster buildup of the beetle population and result in the steep ash tree death curve. An accelerated
rate of ash tree deaths affects City and private property-owner budgets in a dramatic way while
reducing aesthetics and losing the benefits that ash trees provide to Lakeville. In addition, the
“doing nothing” option costs more over a shorter period and provides a significant risk to public
safety because of the exponential relationship between the beetle population and ash tree death.
All of the EAB cost-calculators and modelling software indicate that focusing solely on tree
removal and replanting is the most expensive option. Since Michigan was the first state where
EAB was found, tree managers did not know they were in the middle of a building EAB
population. Many of the small communities were faced with spending millions of dollars in less
than five years to handle thousands of dying ash trees because they had no time to plan and
implement management to spread the “death curve” over time. Preservation by injection was not
an option for many of the earliest infested communities because the tree canopies showed more
than thirty percent dieback, and the research to support the treatments had not yet occurred.
Instead of a “doing nothing” approach, the City should proactively monitor and inspect for the
pest on City and private property, use trunk injected insecticides to preserve high value ash and
suppress the EAB population, encourage private (non-City) property owners to proactively treat
their high value ash, engage in structured removals of poor/fair condition ash trees on public
property before infestation, remove EAB infested trees when they are found, and consider
participating in biological controls if they become available. There is an inverse relationship
between time and management options, meaning the more time that goes by, the more trees die,
and the options to manage EAB through structured removal, insecticides, removal and
replacement decrease (Figure 2). This section describes each of these management practices
accepted by the three main agencies researching EAB in Minnesota and how they apply to the
City of Lakeville.
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Figure 2: As the Number of Dead Ash Trees goes up, Management Options go Down
U Best Management Practice 1: Monitoring and Inspection
The most efficient way to detect EAB in a tree is visual inspection for woodpecker activity in the
mid to upper canopy of ash trees during the winter months. Woodpeckers fleck off the outer
darker bark while looking for EAB larvae. As the woodpecker works, the inner, lighter bark is
exposed (referred to as “blonding”) and dime sized oval holes appear along branches. Early in
the infestation, October through April should be used to survey the City’s ash trees for signs of
woodpecker activity. Late February/March is the most prolific time for identifying infested trees.
Many of the woodpecker holes reveal galleries that can be seen from the ground, but binoculars
may also be used. As the infestation progresses, the City may need to shift to year-round
surveying and inspecting to keep up with the volume of trees showing woodpecker activity
indicating EAB.
The area of most intensive inspection should start near known-infested trees and work out in a
radius from each of those points. Typically, a state-Certified Tree Inspector is hired or appointed
to focus almost entirely on tree inspections during the period required for EAB inspections on
City and private property. In addition, all field staff who work on trees need to monitor for new
EAB pockets throughout the City. Street and Park Department staff have already been trained on
EAB but there will be additional opportunities offered each year by the City Forester and outside
agencies to ensure they have the knowledge and capability to assist in finding newly infested
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trees. In addition, a more specialized chainsaw training will be offered so crews can learn how to
assess an infested ash tree and determine if it is safe to drop.
U Best Management Practice 2: Insecticide Use
Insecticides are very effective in controlling insect populations when they are applied properly at
the correct time of year in the appropriate dose (rate). There are several insecticides that are
registered to kill EAB in ash trees. The method advocated by the City is the trunk injection of
emamectin benzoate using the current industry standard injection system that has efficacy data
supporting its use on trees ten inches or greater in diameter. The applied injection is systemic, so
the tree takes up the insecticide in its xylem tissues (water conducting system). The insecticide is
injected where the root system and trunk interface, is pulled upward by the tree, spreads through
the canopy in all the fine branches and can be detected inside the tree tissues and leaves. The
insecticide has a two-year efficacy period, with early research indicating it might be possible to
stretch treatments to every three years. According to the USDA Forest Service EAB website in
February 2018, emamectin benzoate was “…found to be the most effective product and provided
two to three years of nearly complete EAB control. All EAB adults fed leaves from trees treated
with emamectin benzoate died within four days and larval densities were reduced by 99%
compared to untreated trees”. The insecticide is toxic to EAB larvae and adults upon ingestion.
According to a handout created by the University of Minnesota and two other universities
detailing Frequently Asked Questions Regarding Potential Side Effects of Systemic Insecticides Used
to Control EAB, emamectin benzoate is “..derived from a naturally occurring soil bacterium, has
been registered for more than ten years as a foliar spray to control pests in vegetable and cotton
fields…and similar products are used in veterinary medicine as wormers for dogs, horses and
other animals.” Since the insecticide is injected into the tree, it minimizes the non-target effects.
The trunk injection can be performed on a tree 8-10 times for the price it would cost to:
• Remove the tree
• Grind the stump
• Replace the tree
At the end of the 20-year treatment cycle, a tree and all its benefits to the community have been
preserved. Based on an analysis of the City’s tree inventory, the average diameter of a high quality
public property ash tree is about 16-inches in diameter. According to the National Tree Benefit
Calculator, a 16-inch diameter green ash tree growing a Lakeville yard provides an overall benefit
of $157.00 per year and in a City park, that same tree provides benefits of $126.00 a year. The
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benefits or “ecosystem services” that the ash trees provide include reductions in stormwater,
electricity, natural gas, and carbon dioxide along with improved air quality, and property values.
When there are thousands of ash trees lost during a short period of time before a canopy can
rebound, the lost benefits can compound. One example of that effect occurred in one of the first
communities hit by EAB in Westland, Michigan. According to a study by Deborah McCollough
published in the January-March 2012 International Journal of Pest Management; the removal of
Westland’s 3,000 municipal ash trees killed by EAB “led to a 33% increase in outdoor water
consumption, which subsequently caused the regional water authority to levy a 10% surcharge on
the City.”
The systemic trunk injected insecticide can be compared to an insecticide spray staying on the
surface of the tree, which would only remain effective for a matter of weeks until it breaks down
due to sunlight and/or rain. Another less-preferred option is another systemic insecticide; the soil
drench/soil injection or trunk injection of imidacloprid (both professional and homeowner
formulations) which have per-acre use limits. The use limits restrict the number of
trees/diameter inches that can be treated per acre. In addition, it should not be applied within 25
feet of a water body or storm drain in the street due to runoff concerns. Although the flowers of
ash trees are wind pollinated (not visited by pollinators such as bees), soil applied imidacloprid
can kill pollinators if there are nearby flowering trees, shrubs, and plants (which would also take
up the insecticide). There is also a formulation of trunk-applied imidacloprid, but it has been
found to be less effective than emamectin benzoate under heavy EAB infestation and must be
applied yearly which is less convenient.
In summary, the trunk injection of emamectin benzoate is preferred to other trunk injections,
spray or soil-applied insecticides because:
• Research data indicates it is the most effective to kill EAB
• It can be done every-other year
• It is a restricted-use pesticide so only state licensed pesticide applicators can use it
• The insecticide is injected inside the tree, reducing the chance that children, pets or other
wildlife will encounter it while playing in a yard or park
• Since it is inside the tree, it would not runoff in the soil or overland to lakes, creeks, or
other water bodies
Many cities use trunk (stem) injected emamectin benzoate to:
• Preserve high value good condition trees on a 20-year plan (10 injections)
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• Preserve fair condition trees that are providing a unique aesthetic to a street corridor, or
park where other trees would be hard to establish
• Stage tree removals in parks or boulevards by keeping fair/poor condition ash trees from
dying and becoming hazardous while cities move through a structured removal plan
• Create a “herd immunity” effect; there is early research indicating the more trees are
treated, the slower the insect population grows in the community
• Encourage property owners and other non-city properties including commercial, multi-
family and the school district to preserve their ash trees and slow down widespread tree
mortality and canopy loss, at least until newly planted trees can establish. Staff will
consider offering a City-sponsored bid and a bulk-treatment program at no additional
cost to the City which would be available to any entity in the City (town home
associations, single family, etc.)
Based on the City-wide tree inventory completed in 2017, the following ash trees are eligible for
injection:
Table 2: City Ash Trees Eligible for Injection of Emamectin Benzoate
Category of Property Total Ash Trees Ash Eligible for Injection
Boulevards 1,790 1,273*
Parks 688 471
Facilities 60 38
Utility Properties 1 1
TOTALS 2,539 1,783
*statistical sample inventory was completed for trees in the boulevard, final number may vary based on
actual field inspection, this number represents the maximum possible based on size class of 10” diameter or
greater
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Table 3: Private Ash Trees Eligible for Injection of Emamectin Benzoate
Category of Property Total Ash Trees Ash Eligible for Injection
Front & Back Yard 9,943 6,500*
*statistical sample inventory was completed for trees on private property, final number may vary based on
actual field inspection, this number represents the maximum possible based on size class of 10” diameter or
greater
U Best Management Practice 3: Ash Tree Removal
Ash trees that are found to be infested with EAB at any time of year should be removed during
the next possible non-flight (dormant) time of October-April to eliminate a hazardous tree
condition and to reduce the beetle population. Wood must be chipped into 1-inch by 1-inch
sections to kill larvae and prevent them from maturing. Ash trees that are in fair or good
condition with less than one-third (30%) of the canopy affected on City or private property
would be eligible for removal exemption if they are treated with emamectin benzoate within the
next available growing season, and when pesticide application records are remitted to the City.
The City will adopt a proactive program where at any given time during the EAB non-flight
period, ash trees will be marked and removed in a series of ash reduction programs:
a. Proactive Structured Ash Removal
b. Poor/Fair Condition Ash Removal during City projects
c. EAB Infested Ash Removal for Sanitation and Hazard Prevention – City Property
d. EAB Infested Ash Removal for Sanitation and Hazard Prevention – Private Property
a. Proactive Structured Ash Removal
Proactive structured ash removal would call for the removal of trees that may not yet be infested
on City boulevards and maintained areas of parks, facilities and utility properties. The purpose of
this BMP is to spread out the cost and number of removals over a 10-year time instead of waiting
for them to die, overwhelming City crews and budgets. The trees would be smaller than ten
inches in diameter (ineligible to inject), in conflict with infrastructure, or in poor or fair
condition with significant structural defects. It might also include reducing the number of ash
trees on a City property or boulevard that has an excess of that species planted, with other
established trees nearby to readily fill the canopy.
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Based on tree inventory data, City departments can follow some recommended ash removal
targets to ensure staff and budgets (if contractors are needed) are not overwhelmed. Most of the
structured removals are front-loaded ensuring ash that do not meet injection criteria are
removed before they start showing signs of infestation, making them safer to remove and less
likely to become a public safety risk. Adjacent residents whose boulevard ash trees are planned
for removal would be notified by mail in advance regarding the planned work. Since City parks
have so few trees to remove, it is recommended they are handled within the first five years of the
program to make space for replanting. Since trees are living, dynamic organisms, they change so
some trees originally slated for injection may be moved to the “remove” list if they succumb to
storm damage or otherwise become less desirable to treat. These numbers provide a baseline to
work from.
Structured Ash Removals on City Property:
Table 4: Boulevards: Recommended Minimum Targets: Proactive Structured Ash Removals
by Year
5-year increments Number of trees to remove each
year
Totals
2018-2022 69 345
2023-2027* 35 172
TOTAL 517
Table 5: Parks: Recommended Minimum Targets: Proactive Structured Ash Removals by
Year
5-year increments Number of trees to remove each year Totals
2018-2022 43 217
2023-2027* 0 0
TOTAL 217
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Table 6: Facilities and Utility: Recommended Minimum Targets: Proactive Structured Ash
Removals by Year
5-year increments Number of trees to remove each year Totals
2018-2022 4 to 5 22
2023-2027* 0 0
TOTAL 22
*by this point in time, most of these trees are likely to show some signs of infestation so the removals are
front-loaded to reduce the number of infested trees
b. Poor Condition Ash Removal during City projects
During certain City infrastructure projects such as street reconstruction, any poor or fair
condition ash trees will be removed if they do not meet the requirements for preservation by
injection. The trees in this group overlap with the ash population that would be slated for the
structured removal program. Since there are usually tree removals associated with planned
Capital Improvement Project, removing poor and fair condition ash as part of the project would
be a way to efficiently and cost-effectively accomplish the goal of ash reduction, and ensure staff
and contractors are not working around a tree that would eventually be removed anyway. This
would be accomplished by the City Forester, Engineering and Construction Services working
collaboratively on an approach.
c. EAB Infested Ash Removal for Sanitation and Hazard Prevention: City Property
The City will be monitored and inspected throughout the year for EAB infested ash trees. During
the insect’s dormant (non-flight) period of October through April, infested trees will be marked
and removed by City staff or contractors. Trees in high use areas such as parks and boulevards
should be prioritized first for removal to reduce public risk due to hazardous tree conditions.
Infested trees on edges of City outlots, conservation areas, and open space will be removed at the
discretion of the City Forester or her representatives to follow best-management practices
(BMPs) within budget and time constraints. Currently, the City does not have a comprehensive
inventory or estimate of the number of ash trees growing in City outlots or conservation areas.
As estimate may be obtained as time and budgeted funds are available. In general, infested trees
found in deep wooded City out lots or conservation areas that will not impact public safety or an
adjacent private property will not be removed. The reason for this is twofold: damage to adjacent
natural resources often exceeds the overall environmental benefits of removal, and the costs and
staff time associated with the volume of removals will likely exceed budget constraints. If an ash
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tree becomes infested within a City owned natural area of any kind, it will be removed only if it is
within 75-100 feet of a developed/utilized area of any property type. This practice does not
provide optimum sanitation to reduce EAB but acknowledges the reality of staff and budget
constraints and places a realistic focus on those trees will most impact public safety. Ash tree
mature heights range from 65-80 feet tall. The following guidelines will be utilized in the field to
determine if an infested ash tree would qualify for removal:
Table 7: Infested Ash Removal Guidelines on Unmaintained (naturalized) City Property
Infested Ash Tree is Located on this
Category of City Property
Infested Ash Tree will be Marked for Removal
within:
Unmaintained area Adjacent to a City Trail 75 Feet
Conservation Area, Outlot, or Natural Area
Adjacent to a Public or Private Street
100 Feet
Conservation Area, Outlot, or Natural Area
Adjacent to a Maintained Park, Facility, or
Private Property
100 Feet
d. EAB Infested Ash Removal for Sanitation and Hazard (High Risk) Prevention: Private
Property
The almost 10,000 ash trees growing on private property will also be monitored and inspected
throughout the year for EAB infested ash trees. Although the City does not seek to encourage
removals during the flight period of May-September, door hangers could be left for residents
during that time if wood pecking consistent with EAB symptoms are detected. This might
encourage a resident to have the tree injected or to prepare for the tree inspector to return in the
winter and potentially mark the tree for removal. In addition, removal during the “flight period”
may be warranted if the tree has an imminent risk of failure which would impact a target such as
a home or the street. This type of public service would be dependent on staffing levels. During
the insect’s dormant (non-flight) period of October through April, infested trees will be marked
by a City tree inspector and removed and paid for by the resident. If the property owner does not
act in the time designated on the City notices, the City would request a quote from a private tree
contractor to remove the tree and invoice and/or place all costs on the property owner’s taxes as a
special assessment.
Lakeville has a Shade Tree Epidemic Pest Control Ordinance in Title 4, Chapter 4 of the City
Code to allow for the described program to occur, and for infested trees to be declared a
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“nuisance” requiring abatement. Abatement measures would include tree removal and
appropriate disposal of wood. Although it is new program to the City of Lakeville, Shade Tree
Disease Control Programs have been underway controlling oak wilt, Dutch elm disease and EAB
in other nearby cities including Apple Valley, Eagan, and Burnsville as well as other comparable
cities throughout the metro area including Eden Prairie, Minnetonka, Plymouth, and St. Louis
Park. Many of these cities have had a program for decades.
During the early infestation, all removals would need to take place by early April, so that staff
would have time to take enforcement by a City designated contractor by May 1P
st
P, the earliest
possible date EAB adults mature and start to fly. When the City’s infestation is so advanced that
EAB infestations are covering the City, the program would shift to minimizing public safety risks
from dying trees instead of minimizing the risk of spreading EAB. At that point it may become
necessary to mark and require the removal of infested ash trees throughout the entire year to
keep up with hazardous tree identification. Conditions will be monitored by the City Forester
with assistance from the Minnesota Department of Agriculture and other Minnesota cities who
have experience with later-stage infestations.
Like the City property guidelines, infested ash trees growing in “unmaintained” deep wooded
lots, wetland edges, or agricultural lands that will not impact public safety or an adjacent private
property will not be marked for removal unless they meet specific distance criteria:
• Infested trees growing within developed/utilized portions of a parcel will be marked.
• Infested ash trees within 100 feet from a developed/utilized portion of a private property
parcel, maintained City park, City/private street will be marked.
• Infested ash trees within 75 feet from a City trail will be marked.
Table 8: Infested Ash Removal Guidelines on Unmaintained (naturalized) Private Property
Infested Ash Tree is in an Unmaintained
Area on Private Property
Infested Ash Tree will be Marked for Removal
within:
Adjacent to a Private Property Maintained
area (same property owner or another)
100
Adjacent to a Maintained City Park, Public
or Private Street
100
Adjacent to a City Trail 75
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To assist residents with the requirement to remove infested ash trees; the following are some
programs that should be implemented:
• Continue to inspect ash trees by request when they are reported to be showing
signs/symptoms of EAB
• Offer workshops or neighborhood meetings to share information
• Give a “Frequently Asked Questions” information sheet in every infested tree notification
letter to guide residents through the process and provide detailed assistance on the City’s
website.
• Consider an “extension” of time for property owners having 75 diameter inches or more
marked on their property at one time, which could be applied to commercial properties,
homeowner associations or public entities such as the school district.
• Consider a nuisance abatement agreement or other agreement which would authorize the
City to send their designated contractor to remove an infested tree if the property owner
communicated an inability to remove the tree in the time established by the City. The tree
would in many cases, get removed ahead of the removal deadline without the additional
administrative burden of certified letters. This type of program would be useful in
situations where an individual loses a job, experiences a death in the family, or for an
individual on a fixed-income due to retirement status or disability.
The following are some program that could be considered for implementation over time:
• Solicit a private property tree removal bid from professional tree contractors to offer as an
option for residents to remove their trees. This would save the resident the time and
hassle of getting their own bids, but there would be no guarantee that it would be the least
expensive option which would be communicated. It could also serve as a “consumer
protection” option when people do not have to time to investigate whether a contractor is
properly insured or licensed by the state.
• To assist residents in finding a reputable tree contractor, consider licensing tree
companies at the City-level. This was done at one time in Lakeville’s history, and is
common in neighboring cities. The City would need to determine a mechanism for
enforcement other than Forestry staff. Currently Minnesota Statutes Chapter 18G.07
requires companies and person conducting tree care activities to be registered with the
commissioner, and a searchable database is available to the public, however no liability
insurance information is collected. Another option would be a voluntary list whereby
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contractors could submit their insurance information and basic company information to
be included on a list as a resource for residents distributed by the City. The City licensing
or the resource list would not constitute a recommendation to residents, but a starting
place to ensure the contractor is not a “fly by night” type operation and that they carry
basic liability insurance.
Best Management Practice 4: Biological Control
Another option for EAB management on parcels of land 40 acres and above or in densely ash
populated corridors is called biological control. The Minnesota Department of Agriculture is the
lead agency that implements biological control of invasive species throughout the state.
According to that agency, biological control is defined as using “…natural enemies to bring EAB
populations into balance and reduce damage.” It is the only management option that can be
applied at the forest landscape level. It is being deployed in southeastern Minnesota in remote
natural areas where infested trees cannot be destroyed such as along the river.
There are three types of parasitoid wasps released in Minnesota. Two species attacks the larval
stage of EAB under the ash bark. The other species kills EAB eggs that are in bark crevices. These
wasps are small like gnats and do not harm humans. They were selected by the US Department of
Agriculture’s Animal and Plant Health Inspection Service (APHIS) and Forest Service and tested
extensively to ensure that they will not negatively impact other species or the environment.
APHIS rears these biological control agents at a specialized facility in Brighton, MI and provides
them to states with EAB infestations.
Currently, the City of Lakeville does not have any forest land that would meet the requirement
for biological control but will remain open to any new or emerging options that would reduce the
environmental and economic burden of this pest.
Ash Wood Disposal/Utilization
The strategies used to dispose of ash wood must meet the current Minnesota Department of
Agriculture (MDA) quarantines, which are established by county. Dakota County is under a
quarantine. The quarantine prohibits removing any of the following from a quarantined county
into a non-quarantined county:
• The emerald ash borer (Agrilus planipennis),
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• Ash trees (Fraxinus spp.), ash limbs and branches, ash stumps and roots, ash
logs, ash lumber, ash chips, ash bark chips, and
• Firewood of any hardwood (deciduous) species.
Wood and wood chips from tree removals and pruning by City crews is being deposited in the
Central Maintenance Facility (CMF) yard and removed by the Shakopee Mdewakanton Sioux
Community (SMSC) Organics Recycling Facility at no cost to the City. They create compost,
mulch, and use the wood as renewable fuel at Koda Energy, a joint energy initiative between
SMSC and Rahr Malting in Shakopee.
The City should implement:
• A contract that would guarantee removal of all wood by May 1st of each year to ensure
infested trees are removed from the City before the EAB active flight season starts.
• An analysis of current space for wood waste versus future needs. An alternate waste
disposal site could be considered in the event the City’s yard is overloaded, or a
designated “back up” area at CMF where wood debris can be stored during the peak tree
removal period. Capacity needs should consider the possibility of EAB infested wood in
addition to a large-scale storm event.
The City will create a list of local wood waste disposal sites to assist residents in processing
infested trees properly.
The City should consider exploring:
• Utilizing ash wood for saw logs, which would require specific removal specifications and
working with a sawmill operation. There would also need to be space allocated in the
CMF yard for storage of saw logs.
Management of Ash Trees During Planning and Development Review
In addition to a Shade Tree Ordinance, several existing ordinances and procedures that pertain
to tree planting and tree preservation during the Planning and Development Review process
should be updated to prohibit planting ash trees, favoring ash removal for trees under ten inches
in diameter or within buffer areas adjacent to developed land. In addition, a mechanism to
require replanting after ash tree removal on commercial, industrial, or multi-family housing will
help ensure future screening and canopy in those spaces. An overall measure that would assist
with preventing a future insect/disease wiping out an entire canopy would be to require new
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developments or redevelopments provide a more defined level of species diversity for each
landscape plan that is reviewed.
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Reforestation and Canopy Replacement
According to an i-Tree Canopy analysis conducted in January 2017, the City of Lakeville’s tree
canopy covers approximately 27% of the entire City (based on 2017 aerial photography). The
i-Tree Program is a suite of peer-reviewed, online tools created by the USDA Forest Service and
several other agencies to assess and manage forests and community trees. The analysis was
conducted by the City’s GreenCorps member to determine canopy coverage in the first year that
EAB was found in the City. The i-Tree Canopy program estimates tree cover and tree benefits for
a given area with a random sampling process that allows the user to classify ground cover types.
Over time, as a community develops, natural ground cover and forest land is often lost. With the
loss of trees and canopy cover, the tree benefits are lost as well. In particular, a community loses
the valuable natural stormwater interception services of trees to the impervious surfaces of
buildings and streets which increases runoff, negatively affecting the water quality of lakes and
streams in the area. Canopy cover can be maintained or increased by proper tree planting and
care across the community. For example, even though the City of Saint Paul is an urban area,
their canopy cover was 32.5% in 2009, the first year EAB was found.
Figure 3: Runoff Volumes will Increase Based on the Percent of Impervious Surface
Higher volumes of runoff result in flooding, water pollution, and erosion. Photo courtesy of LEARN NC,
www.learnnc.org
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1. U Public Property Reforestation
It is recommended that ash trees lost on maintained City parks, facilities and utility properties
are all replaced at a one-for-one replacement. Each tree lost in those high value public spaces
would be replaced with a tree that would improve the species diversity of that property and the
entire system. Some of the ash trees slated for preservation on City property in the first six to ten
years may be removed and replaced due to changes in physical condition or to slowly reduce the
burden of treatment costs. Currently, the City has too many ash, crabapple, maple, spruce, and
linden/basswood so those species would not be favored. In general, the “10 percent rule” by Dr.
Frank Santamour, US National Arboretum geneticist will be followed. The rule proposes no
more than 10 percent of any one species should make up the tree population, no more than 20
percent of any genus, and no more than 30 percent of any one family. An application of this rule
would be that no more than 10 percent of Lakeville’s parks should be bur oaks, no more than 20
percent should be in the Quercus (oak) genus, and no more than 30 percent should be in the
Fagaceae family (oaks, beech, chestnut). It is regarded as a rule that has some limitations, and
many urban foresters believe each percentage should be even smaller, but it is a good starting
point to work from. Percentages for City property can be viewed in the computer-based
inventory which is updated as trees are removed and planted.
Although boulevard tree planting is prohibited in most areas, there are unique corridors that are
heavily planted with ash trees. Some of the ash trees would be preserved with stem injections, but
those that are too small or in poor condition should be replaced with a diverse group of trees.
Examples of these corridors include along Ipava Avenue and Kensington Boulevard. Although
symmetry and repetition are planting concepts often implemented with traditional landscape
designs, they run in opposition with promoting species diversity. Monoculture type plantings
where one to two species are utilized increase the chance an entire space is clear cut when a non-
native disease or insect like EAB is introduced. Instead, there will be a less formal appearance in
the boulevard planting areas; shifting to more of a specimen-based arboretum style planting.
Repetition can be used, but the patterns could be more complex with a longer stretch of space
before species are repeated in the planting design. In neighborhoods where boulevard trees are
not eligible for preservation by injection and are lost in front of homes, residents may be angry
that their trees will not be replaced. It would be useful to create a budget for the Lakeville Arbor
Day Tree Sale so that the City can help reduce the cost of the trees for residents to purchase and
plant on their own property. It is currently a program that pays for itself, so the cost of the trees
for residents is usually more than wholesale, but less than retail on a per-tree basis.
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Infested ash trees lost in city outlots, conservation areas or other natural spaces would only be
replanted as part of a larger natural resource plan which would also minimize non-native
invasive species like European buckthorn and garlic mustard. This program would be a joint
Public Works collaboration between Environmental Resources and Forestry but would not be
the main reforestation focus during the peak of EAB infestation unless significant resources were
diverted.
In general, the best way to maximize the number and diversity of trees planted is to use all
available planting stock types: bare root, container and balled-and-burlap (B&B). Currently most
of the trees planted on City property are handled by contractors, but there are additional creative
ways to plant trees without driving up a planting budget. As part of the replanting plan, the City
should implement a three-year aftercare program. Stressed trees are more susceptible to diseases
and insect pests. Each tree needs to be watered and checked weekly during the growing season of
May through October for a minimum of three years to ensure the City’s investment is retained
and the tree continues to mature and provide ecosystem services and benefits. At a minimum,
one additional seasonal employee working forty hours a week should be charged with this task
when tree planting on City property commences on a larger scale. New trees should not be
planted at an increased rate unless new seasonal staff or resources are committed to ensure each
tree is watered once weekly during the growing season.
Table 9: Reforestation and Canopy Replacement Recommended Minimum Targets
Property Type Number of Trees
Removed
Replant Rate Number of Trees to
Replant
Parks, Facilities, and
Utilities
239 trees 100% 239
Boulevards 517 15%* 78
TOTALS 756 N/A 293
* Replanting in select corridors only, the City does not allow boulevard tree planting
In addition, the City should consider:
• Installing a gravel bed to maximize the use of lower cost, quicker establishing bare root
trees. A gravel bed is an above ground irrigated “box” filled with pea gravel that
encourages dense root growth. Certain species do better than others in this bed, so it
would not be an exclusive nursery solution, but one aspect to implement.
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• Utilizing existing permanent staff and adding additional specialized seasonal staff such as
Certified Tree Inspectors to assist with replanting, watering and care from May through
October of each year.
• Host a planting event in the park for residents to learn from, and use trained volunteers
to assist such as the MN Tree Care Advisors.
• Utilize Sentence to Serve (STS) and/or Institutional Community Work Crews (ICW
crews) to assist in ensuring trees stay mulched and have tree guards and watering bags on
at the appropriate time of year.
• Fund the Arbor Day Tree Sale or other tree replacement incentive program to encourage
property owners to replant trees on their property (out of the boulevard) after an ash tree
is removed from the boulevard.
U2. Private Property (non-City) Reforestation
Like City property, the private property community forest has too many spruce, crabapple, ash,
maple and arborvitae. The City needs to actively advocate for a more diverse palette of trees to be
planted by homeowners, schools, developers, and property managers.
The City has offered the Arbor Day Tree and Shrub Sale for many years, selling 200-300 trees
each year at less than retail cost. Although it is a popular program for those who are aware of it,
there is a lot more room for growth. It would be ideal to have more households or Lakeville
organizations participate, increasing the number of trees sold and planted in the community.
Forestry and Parks staff have increased promotion of the event and will continue to do so over
time. The program typically offers at least eight different lesser-known species that property
owners can chose from. The species that are already overplanted in the City such as maple,
spruce or crabapple will generally not be offered, since the purpose of the program is to increase
canopy cover as well as insect/disease resilience throughout the community forest. The program
could be expanded to encourage property owners to replant on private property after their
boulevard and/or yard tree is lost due to EAB; conversely, there could be another paradigm
introduced that would incentivize replanting on private property such as a “trade-a-tree”
program.
Commercial, Industrial and Multiple-Family parcel-owners should be encouraged to replant
after EAB infested trees are removed to improve and preserve the aesthetics of these areas in
Lakeville, and to try to recapture the tree benefits over time. The current ordinances related to
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trees may need to be amended to ensure the “conditions of approval” that the developments were
approved with are fulfilled to ensure entire parking lots or parcels are not clear cut when ash
(that are not injected) die from EAB. In some cases, ash trees will be preserved and would not
need to be replaced.
Conclusion
Emerald ash borer is a significant “predicable” natural disaster facing the City of Lakeville but
following a systematic, proactive plan and leveraging appropriate resources to respond will
minimize the fiscal and environmental impacts of the pest. The EAB Management Plan is
consistent with the City’s vision statement which seeks to offer “…exceptional parks, trails and
recreational opportunities;” in addition to “…safe neighborhoods; and responsive and cost-
effective public services together (to) create a place we are proud to call home.” and should be
implemented immediately to manage the beetle population and preserve the benefits that ash
trees provide to the community.
City of Lakeville: 10/22/2018
Page 1
Lakeville Shade Tree Epidemic Pest Control Area and Control Measures Policy
This policy provides the definitions for control areas and specific control measures related to
abating nuisances pursuant to the City Code regulating Shade Tree Epidemic Pest Control. Shade
tree pests are defined in the City Code as a nuisance. Shade tree pests of an epidemic nature are
those that have a widespread occurrence directly associated with a high mortality of a tree
species. Trees provide many environmental, economic and aesthetic benefits to the city of
Lakeville and the ordinance and policies aim to prevent, control, and/or slow the spread of
epidemic pests in an orderly and systematic approach to preserve as many of the tree benefits as
possible. The control area and measures policies may be updated when there are advances in
technology and scientific research toto reflect the recommended best management practices.
Specific timelines for required tree removals may be modified by staff based on qualifying
circumstances.
1.1 Emerald Ash Borer.
(A) Emerald ash borer, Agrilus planipennis Fairmaire is a non-native invasive shade tree
pest and is defined as an insect that infests and kills ash trees. The adults are small,
iridescent green beetles that live outside of trees from May 2nd until September 30th. The
immature stage are larvae; grub -like organisms which live and feed underneath the bark of
ash trees disrupting the tree’s ability to transport water and nutrients. The typical City
inspection period for this pest is October 1st- April 1st of each year. Inspections are linked to
the best-management practice to refrain from moving ash wood while EAB is active from
May 2nd-September 30th.
(B) Control measures that may be taken to manage and abate emerald ash borer are:
1) Use of appropriate insecticides.
Proper insecticide application can preserve ash trees ten (10) inches in diameter and
larger using stem injected emamectin benzoate (insecticide) at the appropriate rate (dose)
by a state licensed pesticide applicator at an interval prescribed by the label when the tree
has less than or equal to thirty (30) percent canopy dieback. If the tree is showing signs of
EAB and has been marked for removal or is under consideration for marking, all
associated pesticide applicator records or approved bid for the following season must be
remitted to the city forester or designated tree inspector as proof of application.
Insecticide injections on private lands are optional and, if performed, are at the
landowner’s expense. Insecticides are the only method that can be used to prevent ash
mortality and must be completed by a qualified contractor registered with the Minnesota
commissioner of Agriculture under Minn. Stat. § 18G.07.
2) Removal and disposal of trees.
All wood more than one (1) inch in diameter or three (3) inches in circumference from
the removed ash tree must be disposed of within the timeline provided by the City by
City of Lakeville: 10/22/2018
Page 2
chipping into (1) inch or less in two (2) dimensions (two (2) of three (3) measurements-
length, width and thickness-must be one (1) inch or smaller) or by hauling to a wood
waste facility following all current Minnesota Department of Agriculture (MDA)
quarantines or guidelines, established on a county basis. The stump from such removed
trees must not extend more than three (3) inches above the ground or, if taller, must be
completely debarked. Tree removal is required within thirty (30) days of inspection and
first notification of nuisance. Individual extensions up to two weeks will be approved on
a case-by-case basis depending on site factors such as trees requiring utility line
clearance. If a tree has thirty (30) percent dieback or less and the property owner is
interested in injecting the tree, an extension of June will be permitted when a
homeowner-accepted bid from an MDA licensed pesticide applicator is submitted to
Forestry staff.
(C) Definition of control areas. The control area for emerald ash borer is defined as:
All lands within the boundaries of the City are considered the control area. Whenever a
nuisance as defined in City Code is found to exist within any developed/utilized portions of
any parcel regardless of zoning or within one hundred (100) feet of such developed/utilized
areas of any property or within 75 feet of any paved City trail that may lie within non-
maintained naturally wooded areas on private property or City property, the tree will be
considered within the control zone.
1.2 Oak Wilt.
(A) Oak wilt disease is a shade tree pest and is defined as any living or dead tree, log,
firewood, limb, branch, stump, or other portion of a tree from any oak species of the genus
Quercus existing within the control area that has bark attached and that exceeds three (3)
inches in diameter or ten (10) inches in circumference and contains or can produce to any
degree a reproductive structure (fungal spore mats) of the fungus Bretziella (form.
Ceratocystis) fagacearum. The typical City inspection period for this pest is June 1st-
September 30th during leaf-on conditions when symptoms may appear.
(B) Control measures that may be taken to manage and abate oak wilt disease are:
(1) Installation of a root graft barrier.
A root graft barrier can be installed to prevent the underground spread of oak wilt
disease. The City may assist in marking the proposed location of the root graft barrier to
assist the landowner. The barrier disrupts transmission of the fungus within the shared
vascular systems of trees sharing a common root system. The barrier is created by
excavating or vibratory plowing a line into the soil to break shared roots. The most
effective depth is sixty (60) inches with a vibratory plow. On difficult sites, a trencher
may be used to achieve a minimum of forty-two (42) inches depth between any oak tree
infected with oak wilt disease and each nearby and apparently healthy oak tree within
fifty (50) to one hundred (100) feet of the infected tree. Although it is the best method to
prevent the underground spread of oak wilt, the root graft barrier may be impossible to
City of Lakeville: 10/22/2018
Page 3
install because of the presence of pavement or obstructions such as a steep slope, septic
system or utility lines. Root graft barriers on private property are optional and if
performed, are at the landowner’s expense.
(2) Use of fungicide.
Fungicides (propiconazole) may be effective in preventing the above ground formation of
oak wilt symptoms when injected into the stem (trunk) of living red oak trees that do not
already show symptoms of oak wilt disease. They may also be used therapeutically for
trees in the white oak group once they have been found to have oak wilt disease (bur and
white oaks). Fungicide injections on private lands are optional and, if performed, are at
the landowner’s expense. Injections must be repeated every two growing seasons for
several cycles to protect the trees and must be completed by a qualified contractor
registered with the Minnesota commissioner of Agriculture under Minn. Stat. § 18G.07.
(3) Removal and disposal of trees.
The City will mark for the removal of diseased red oak trees that have the potential to
produce spores of the fungus Bretziella (form. 16TCeratocystis) fagacearum.16T If the site
permits it, the landowner or adjacent property owner’s planned root graft barrier(s)
should be installed first. Tree removal is required by November 15th of each year
following notification. Due to the complex control measures associated with oak wilt,
individual extensions will be approved on a case-by-case basis once a treatment plan has
been adopted by the property owner, approved by the city forester or designated tree
inspector and depending on site factors such as trees requiring utility line clearance. In
no case will the tree be removed later than April 1P
st
P of the year following infection. The
stump from such removed trees must not extend more than three inches above the ground
or, if taller, must be completely debarked. All wood more than three (3) inches in
diameter or ten (10) inches in circumference from such removed trees must be disposed
of by hauling to a wood waste facility, debarking, chipping, or by splitting into firewood,
stacking the firewood, and immediately covering the woodpile with unbroken four (4)-
mil or thicker plastic sheeting that is sealed into the ground with soil until October 30th
of the calendar year following the calendar year in which the tree was removed. A mil is
a thousandth of an inch and refers to the thickness of the plastic required to provide an
adequate barrier for disease transmission. The edges of the cover must be buried or sealed
to the ground by the City deadline provided. Wood chips from infected trees may be
stockpiled or immediately used in the landscape and are no longer a disease risk.
(C) Definition of control areas. The control area for oak wilt disease is defined as:
All lands within the boundaries of the City are considered the control area. Whenever a
nuisance as defined in City Code is found to exist within any developed/utilized portions of
any parcel regardless of zoning or within 100 feet of such developed/utilized areas of any
property or within 75 of any paved City trail that may lie within non-maintained naturally
wooded areas on private property or City property, the tree will be considered within the
control area.
City of Lakeville: 10/22/2018
Page 4
1.3 Dutch Elm Disease.
(A) Dutch elm disease is a shade tree pest and is defined as a disease of elm trees caused by
the fungus Ophiostoma novo-ulmi, which is transmitted by grafted elm roots underground
and by elm bark beetles including but not limited to: Scolytus multistriatus, Scolytus
schevyrewi, and Hylurgopinus rufipes. A diseased elm tree includes any living or dead tree,
log, firewood, limb, branch, stump, or other portion of a tree from any species of the genus
Ulmus existing within the control area defined that has tight bark attached and that exceeds
three (3) inches in diameter or ten (10) inches in circumference and could contain bark
beetles, and/or provide an area for beetle reproduction or any spore or reproduction of the
fungus Ophiostoma novo-ulmi. The stump from such removed trees must not extend more
than three inches above the ground or, if taller, must be completely debarked. The typical
City inspection period for this pest is June 1st-September 30th during leaf-on conditions
when symptoms may appear.
(B) Control measures that may be taken to manage and abate Dutch elm disease are:
(1) Use of fungicide and therapeutic pruning.
Fungicides may be effective in preventing Dutch elm disease when injected into living
trees that do not already show symptoms of Dutch elm disease. In rare cases, a tree may
be saved by therapeutic pruning of the diseased branch(es) if there is greater than ten (10)
feet of clear, non-stained non-diseased sapwood between the wilting branch and the main
stem/trunk in addition to a fungicide application. Proof of treatment must be remitted to
the city forester or designated tree inspector within the time given to abate the nuisance
and must be completed by a qualified contractor registered with the Minnesota
commissioner of Agriculture under Minn. Stat. § 18G.07. Pruning and fungicide
injections on private lands are optional and, if performed, are at the landowner’s expense.
(2) Removal and disposal of trees.
Prompt removal of diseased trees or branches reduces breeding sites for elm bark beetles
and eliminates the source of Dutch elm disease fungus. All dead or dying elm trees must
be removed within 30 days of detection and first notification from April 1st through
October 31th. Dead or dying elm trees or wood with tight bark detected from November
1st through March 1st must be debarked, burned or removed by April 1st. Diseased trees
and wood not promptly removed will be removed by the City at the landowner’s expense.
All wood more than three (3) inches in diameter or ten (10) inches in circumference from
such removed trees must be disposed of at a wood waste facility or by debarking,
chipping, or by splitting into firewood, stacking the firewood, and immediately covering
the woodpile with unbroken four (4)-mil or thicker plastic sheeting that is sealed into the
ground with soil until October 30th of the calendar year following the calendar year in
which the tree was removed, or by burning before the removal deadline provided by the
City. A mil is a thousandth of an inch and refers to the thickness of the plastic required to
provide an adequate barrier for disease transmission. The edges of the cover must be
City of Lakeville: 10/22/2018
Page 5
buried or sealed to the ground by the City deadline provided. Wood chips from infected
trees may be stockpiled or immediately used in the landscape and are no longer a disease
risk.
(C) Definition of control areas. The control area for Dutch elm disease is defined as:
All lands within the boundaries of the City are considered the control area. Whenever a
nuisance as defined in City Code is found to exist within any developed/utilized portions of
any parcel regardless of zoning or within 100 feet of such developed/utilized areas of any
property or within 75 of any paved City trail that may lie within non-maintained naturally
wooded areas on private property or City property, the tree will be considered within the
control zone.