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A Guidebook on Invasive Pests and Winnipeg Trees: Detection, Prevention and Preparedness TREES Winnipeg The Coalition to Save the Elms

A Guidebook on Invasive Pests and Winnipeg Trees: Detection, Prevention and Preparedness

Trees Winnipeg (Coalition to Save the Elms) Winnipeg Canada, 2019 Trees Winnipeg is a non-profit organization founded in 1992 in response to the heightened threat of Dutch elm disease to Winnipeg's extraordinary American elms. Our mission is to protect, preserve and promote the urban forest and urban environment and to accomplish this by: o

Offering programs that raise public awareness about the value and benefits the urban forest provides.


Providing education and training opportunities to the arborist community and the general public.


Collaborating with like-minded organizations and community groups on projects that encourage public involvement, tree protection, tree planting, and similar activities.


Table of Contents 1.0 Introduction: ................................................................... 1 2.0 Tree Identification Guide: .............................................. 2 2.1 American Elm Identification Guide: .......................... 2 2.2 Ash Identification Guide: ........................................... 3 3.0 Invasive Pests in our Community: ................................. 5 3.1 Dutch Elm Disease (DED) ......................................... 5 3.2 Emerald Ash Borer (EAB) ......................................... 7 3.3 Cottony Ash Psyllid (CAP) ...................................... 10 4.0 How to Protect our Trees: ............................................ 12 Appendix A: ....................................................................... 16 Glossary: ............................................................................ 17 Acknowledgements: ........................................................... 18 References: ......................................................................... 18 Photo and Image Credits: ................................................... 19


1.0 Introduction: Winnipeg’s Urban Canopy has been mostly comprised of monocultures where single tree species have been planted. This makes the canopy more susceptible to invasive pests and threats by limiting the distance required to travel to infest/infect the next tree. At the time of writing, approximately 58% (25% elms; 33% ash) in Winnipeg's public canopy are threatened by invasive pests. The pie chart below (fig 1) demonstrates the composition of Winnipeg’s canopy on November 19, 2019.

Above: Figure 1

Winnipeg’s urban canopy is at risk from Dutch elm disease (DED), emerald ash borer (EAB), and cottony ash psyllid (CAP). This field guide contains information about the main invasive pests which are currently a threat to Winnipeg’s urban forest. It is designed to be an informative resource to help identify trees that are at risk, and how to detect, prevent and prepare for invasive pests. 1

2.0 Tree Identification Guide: This section contains information on the common urban trees which are currently threatened by invasive pests in Winnipeg.

2.1 American Elm Identification Guide: Winnipeg’s urban canopy is defined and identified through its large population of American elms.

Form: often has an umbrellalike canopy, almost as wide as the tree is tall (fig 2) Leaf: Oval or with a pointed tip, with a doubled toothed edge. The base of the leaf where it connects to the stem is asymmetrical (fig 3) Buds: Alternate arrangement, brown and pointed (fig 4) Bark: Dark grey-brown, deeply grooved in older trees, often easily broken off (fig 5 and 6)

Clockwise from top left: figure 2, figure 3; figure 4; figure 5; figure 6.


Some elms have been bred to have resistance to DED, including Discovery elm, Prairie expedition, etc. These elms may have some resistance but can still be infected by DED. Siberian elms are the most resistant to DED and will rarely be infected.

2.2 Ash Identification Guide: There are several Ash tree species found in Winnipeg. Most commonly found in our landscape are green ash, black ash, and Manchurian/Mancana ash). Although several characteristics between the species can vary slightly, the following characteristics are common between all species: Compound leaves: 5 to 11 leaflets on a single petiole arising out of a single bud (fig 7) Leaflet shape: serrated, oblong, and pointed (fig 8) Buds: Opposite arrangement, two buds will arise side by side on a twig (fig 9)

Top: Figure 7 Middle: Figure 8 Bottom: Figure 9


Defining Characteristics: Black ash: Form: slender, narrow, and has an open canopy (fig 10) Bark: soft, with corky ridges which are easily rubbed off by hand (fig 11)

Green ash: Form: cylindrical-shaped crown (fig 12) Bark: greyish-brown and displays a diamond pattern on mature trees (fig 13)

Manchurian ash: Form: oval shaped to round and the canopy is dense (fig 14) Bark: grey and smooth when young, cracks form with age (fig 15)

Top left: figure 10; Top right: figure 11 Middle left: figure 12; Middle right: figure 13 Bottom left figure 14; Bottom right: figure 15


Back and green ash are difficult to tell apart, however green ash leaflets (fig 16) are directly attached to the petiole. Black ash leaflets (fig 17) are attached to the petiole by a petiolule. It should be noted that mountain ash, a common ornamental species is not susceptible to EAB or CAP, as it is not a true ash tree.

Left: figure 16 Right: figure 17

3.0 Invasive Pests in our Community: 3.1 Dutch Elm Disease (DED) DED has devastated elm populations around the world. It was first recorded in Canada (in Quebec) in 1944. DED entered Manitoba via diseased elm firewood from the United States and was found in Winnipeg in 1975. DED is a vascular disease Above: figure 18 caused by a fungal infection. The fungal infection causes the tree to block it’s vascular tissue, preventing water and nutrient uptake, ultimately killing the tree. The fungus is spread through root grafting and by elm bark beetles (fig 18). Elm bark beetles pick up fungal spores as they feed on new twigs and bore into the bark to lay their eggs.


DED Signs and Symptoms: DED can progress quickly and symptoms that indicate DED include: 1.

When the bark is peeled away staining is present (fig 19) 2. The tree has flagging, the presence of brown shrivelled leaves that remain on the tree (fig 20) 3. Branches near the top of the canopy experience dieback (fig 21) 4. Sudden wilting or drooping of the leaves on one or more of the major branches

Top left: figure 19; Top right: figure 20 Bottom: figure 21


DED is manageable, this has been proven by Manitoba having the largest population of American elm trees in North America. This is thanks to the collaborative effort between the Provincial and Municipal governments, private industry, the academic community, and the general public. Provincial and Municipal governments take part in the DED Management Program. The program is currently ongoing and includes DED surveillance, removing infected trees, elm pruning, public education, research, and tree planting. Rapid removal is key to the success of our elm trees to ensure that DED is kept at manageable levels, preserving our canopy for future generations. Note: Tanglefoot sticky tree bands do not prevent DED. If applied correctly they mitigate cankerworm infestations.

3.2 Emerald Ash Borer (EAB)

Above: figure 22

EAB (fig 22) is an invasive pest originating in Asia and was confirmed in Winnipeg fall 2017. Since, its introduction to North America, EAB has decimated millions of hectares of ash trees. EAB has killed up to 99% of a local ash population within 10 years

of discovery. Note: EAB cannot be eradicated once found. EAB is not manageable. The larva from the wood-boring beetle feed on the tissue below the bark, creating S-shaped galleries underneath, disrupting the flow of nutrient and water resulting in the death of a tree. All ash trees, regardless of species, size or health are at risk of dying from EAB.


At the time of writing, there are ~101,000 public ash trees, on boulevards and parkland, however, more than double that number of trees are found on private property. There are ~256,000 on private property and in natural areas. Ash trees found on private and naturalized areas will not be managed by the City of Winnipeg. With the Majority of ash trees located on private property this means that there will be a direct impact on property owners. Cost to private property owners will include the cost of prevention if chosen, removal, and cost to replace lost trees. The best time to create a plan for your ash tree is now. As an ash tree is infested by EAB, the wood will become brittle and structurally unsound, increasing the safety risk to property, public, and tree care professionals. The removal cost of an infested ash tree will be significantly more due to the increased danger and need for specialized equipment and training. EAB signs and symptoms: EAB is very difficult to detect, it can take 3 to 5yrs for an ash tree to show signs and symptoms of EAB infestation. Possible signs and symptoms that could indicate EAB infestation include: 1. S-Shaped galleries underneath the bark (fig 23) 2. Unusually heavy seed crops (fig 24) 3. Epicormic shoots emerging from the trunk of the tree (fig 25) 4. The presence of canopy dieback (fig 26) 5. Woodpecker damage can be seen as holes and/or blonding (fig 27) 6. Cracks present on the trunk of the tree (fig 28) 7. D-shaped exit holes created by the adult beetle emerging from the tree once mature (fig 29) 8. Feeding notches from adult beetle (fig 30)


Top (left to right): figure 23, figure 24 Middle (left to right): figure 25, figure 26, figure 27 Bottom (left to right): figure 28, figure 29, figure 30


Due to the difficulty of detection and the aggressive nature of the beetle, Winnipeg will lose most of its ash trees. Homeowners and private property owners will need to make a management plan to mitigate the impacts.

3.3 Cottony Ash Psyllid (CAP) CAP (fig 31) also know as, jumping tree lice is native to Eastern Europe. It was confirmed in Winnipeg in the summer of 2017 at the Forks but has spread widely throughout the city. CAP infests Black and Manchurian ash trees but does have an affinity for stressed trees. At the time of Above: figure 31 writing 14,400 ash trees could succumb to this pest. CAP is thriving in our hot summers and does not seem to be affected by the cold winters. After the CAP eggs hatch the immature insects (nymphs) feed on tree leaves sucking out the sap which results in curled up leaves and a white cottony substance to be produced. Heavily damaged leaves can have a cauliflower appearance and may result in the leaves dropping prematurely. Over time, this will result in the tree being more susceptible to other pests and illnesses, increasing its chances of dying.


CAP signs and symptoms: There are multiple indicators of CAP, they include:  thinning in the upper portion of the tree (fig 32)  browning, yellowing and curling along the edge of leaves (fig 33)  curled and deformed leaves (fig 33)  a cottony substance found within the curled leaves (fig 33)

Left: figure 32; Right: figure 33

CAP has no natural predators and Winnipeg’s ash trees have no resistance to the pest. At the time of writing, there is no effective treatment. The insects are protected under the curled leaves for the majority of their life cycle rendering insecticides in-effective. Soap/permethrin mixture may work when applied frequently and with precise timing. The window for application is very small. If you choose to consider treatment the best time to apply the soap mixture depends on the life cycle of the pest. Application during the early nymph stage, usually the first week of June and then again for the second-generation nymph the first week of July is most effective.


Due to a lack of effective treatment Winnipeg black ash and Manchurian ash are at risk due to CAP. Create a management plan with a certified arborist and discuss how CAP and EAB may impact your tree to make an informed decision.

4.0 How to Protect our Trees: Legend: DED EAB DED and EAB ALL threats

Please note that there are many overlapping preventive measures and proactive measures that citizens can do to help preserve a healthy urban canopy. The colour guide will aid in separating the action item and the corresponding invasive pest(s).

Don’t Move Firewood of ALL tree Species or Ash tree material: Transporting firewood can accelerate the spread of the invasive pests, as a single piece of firewood can decimate forest stands. Winnipeg is a regulated area by the Canadian Food Inspection Agency (CIFA). This means it is illegal to transport ash trees (whole or parts), ash nursery stock, ash logs and branches, ash lumber, wood packaging materials with an ash component, ash wood or bark, ash wood chips or bark chips, firewood from ALL tree species. All regulated items can be properly disposed of at the Brady landfill. Note: Elm firewood cannot be stored as it provides a breeding site for elm bark beetle encourages the spread of DED. Report Suspicious Trees & Symptoms: If you see a tree displaying any symptoms of EAB or DED report it! Contact Information: Within Winnipeg call 311; Within Manitoba call tree line 204 945-7866


Volunteer for Winnipeg Forest Watch Program: The Winnipeg Forest Watch Program is an opportunity to volunteer outdoors and survey neighbourhoods for invasive pests. At the time of writing the surveys are focused on the preservation of ash trees. All information collected will be given to the City of Winnipeg and play an active role in the management and preservation of our canopy. Visit: www.treeswinnipeg.org to find out more information. Tree Care & Maintenance: Regular tree care (watering and pruning) can help reduce the stress trees experience, making them less susceptible to disease. This is especially important for DED as the elm bark beetle has an affinity for stressed trees. Mulching around your tree will provide slow-releasing nutrients and aid in retaining soil moisture. Note: Elm pruning is banned in Manitoba from April 1 to July 31. Complete elm tree removals can be done at any time of year. Note: Basic tree care will not prevent the onset of EAB. Investing in ALL trees will ensure a healthy non-ash canopy remains. Caring for City-Owned Trees: If you wish to have a public tree treated or pruned at your own expense, you can apply for permission by filling out a property owner’s agreement online and hire an arborist from the City of Winnipeg pre-approved list of arborists. Please, contact 311 for more information.


Fungicide Treatments: Elm tree injections are an option for those who wish to protect healthy, high-value elm trees on their property. There are a variety of products available; the treatments are most effective when applied to healthy trees and must be repeated every few years, depending on the product. These treatments should be done by a professional arborist. Insecticide Treatments: Ash tree injectable insecticides are available for those who want to try to protect high-value ash trees on their property. These treatments are most effective when applied to healthy trees and must be repeated every 2 years for the life span of your tree. These treatments should be done by a professional arborist. It is difficult to detect EAB in a tree, and other threats and stressors may be present resulting in insecticide treatments not being guaranteed to be effective. Treatment should only be used to prolong the life of an ash tree and not to save it. At the time of writing, there are 2 insecticide treatments that are available on the Canadian market TreeAzin and IMA-jetÂŽ (imidacloprid) they are relatively new to the market and have many unknowns on effectiveness and ethicality of the products. IMA-jetÂŽ is a neonicotinoid and it is not fully understood how the application will affect the environment in the long term including the impact on wildlife and beneficial insects. Make a plan: Contact a certified arborist to make a management plan for your trees. This is especially important with all ash trees. See Appendix A for an EAB Management key to help you explore the ideas behind removal, treatment or a combination of the two, prior to consulting a certified arborist.


Replace and Plant trees: When planting, consider a mix of different species and ones that do well in Manitoba. Species diversity will increase the urban canopy resilience to invasive pests. Each spring we offer our ReLeaf Tree Planting Program to promote species diversification and educate owners on proper planting techniques. Note: Elm trees are still being planted in our landscape. Plant elm trees in areas that have minimal elms to encourage species diversity. Be a tree advocate! Advocacy plays an important role in ensuring policies and plans that guide the city emphasizes protection and management of our urban forest. Contact your city councillor to address your tree concerns. A list of Winnipeg’s councillors can be found on the City of Winnipeg website (https://winnipeg.ca/council/contact.stm). To contact your city councillor please contact them through letter, email, phone, or set an appointment to speak with them in person. Tips for contacting your councillor: 1. Focused: have a clear, concise, informed and definable reason/goal you would like to discuss. This will provide your councillor with a clear understanding of the issue at hand and how it will affect their ward. 2. Clarity: ensure all questions and concerns are clearly stated. If you would like a response, ask directly and provide them with your preferred contact information. 3. Politeness: we are all passionate about our city. Ensure, you maintain a polite, positive and enthused demeanour to encourage a positive working relationship with your councilor into the future.


Appendix A:


Glossary: Blonding: the removal of the outer layer of bark by woodpeckers, revealing a distinct lighter colour Bud(s): a small protuberance the side or end of stems and branches of a plant that may develop into a flower, leaf, or shoot Compound leaves: a leaf of a plant consisting of several or many distinct parts (leaflets) joined to a single stem Dieback: a condition in which a tree starts to die from the upper portion of the canopy down, as a result of disease or pollution Galleries: tunnels that are created when larva or insects feed beneath the tree bark Leaflet: one of the blades or segments of a compound leaf Permethrin: is an insecticide Petiole: the stalk that attaches the leaf blade to the stem/branch Petiolule: the stalk that attaches the leaflet to the main stalk (petiole) of a compound leaf Root Grafting: the process of nearby trees root systems joining and continuing to grow together Staining: discolouration in the wood of elm trees infected by DED. Usually appears in as brown or red streaks. Healthy elmwood appears as a cream colour Vascular tissue: is comprised of the xylem and phloem and conducts water, mineral salts, and synthesized food substances throughout a tree or plant


Acknowledgements: This guidebook was prepared by Trees Winnipeg (Coalition to Save the Elms, Manitoba Inc.) with invaluable assistance from the City of Winnipeg. A special thanks to Trees Winnipeg’s 2019 Forest Watch Coordinator Gabrielle Neufeld for aiding in gathering information and contribution of images. Editor: Lisa Jones Reviewers: Christopher McDonald

References: Canadian Food Inspection Agency. https://www.inspection.gc.ca/ City of Calgary, Parks and recreation.

https://www.calgary.ca/CSPS/Parks/Pages/Planning-andOperations/Pest-Management/Tree-pests-and-diseases.aspx City of Winnipeg, Urban Forestry Branch.

https://winnipeg.ca/publicworks/parksOpenSpace/UrbanFor estry/default.stm International Society of Arboriculture.

http://www.treesaregood.org/ Sustainable Development Government of Manitoba, Forestry & Peatlands.

https://www.gov.mb.ca/stopthespread/fis/index.html Trees Winnipeg (Coalition to Save the Elms. Manitoba, Inc.). Winnipeg Forest Watch Handbook: A Guide on Tree Health and Basic Tree Care for Homeowners. Winnipeg, Manitoba. 76pp. University of Saskatchewan, College of Agriculture and Bioresources. https://gardening.usask.ca/articlesinsects/cottony-ash-psyllid.php


Photo and Image Credits: Image:


Cover page

Gabrielle Neufeld, Trees Winnipeg

Figure 1

City of Winnipeg, Public Tree Inventory, Feb 2019

Figure 2

Steven Katovich, Bugwood.org

Figure 3

Paul Wray, Iowa State University, Budwood.org

Figure 4

Brett Marshall, Sault College, Budwood.org

Figure 5

Kathy Smith, Ohio State Extension, Budwood.org

Figure 6

City of Moosejaw, www.moosejaw.ca

Figure 7

Keith Kanoti, Main Forest Service, Budwood.org

Figure 8

Keith Kanoti, Main Forest Service, Budwood.org

Figure 9

Lisa Jones, Trees Winnipeg

Figure 10

Bylands Nurseries Ltd., www.bylands.com

Figure 11

Rob Routledge, Sault College, Budwood.org

Figure 12

Tree Time, www.treetime.ca

Figure 13

Richard Webb, Budwood.org

Figure 14

Bylands Nurseries Ltd., www.bylands.com

Figure 15

University of Minnesota, www.trees.umn.edu

Figure 16

Minnesota wildflowers www.minnesotawildflowers.info/tree/green-ash

Figure 17

Minnesota wildflowers www.minnesotawildflowers.info/tree/green-ash

Figure 18

J.R. Baker & S.B. Bambara, North Carolina State University, Bugwood.org

Figure 19

George Hudler, Cornell University, Budwood.org


Figure 20

Joesph Obrien, USDA Forest Service, Budwood.org

Figure 21

USDA Forest Services-Northeastern Area, USDA Forest Service, Budwood.org

Figure 22

Pennsylvania Department of Conservation and Natural Resources - Forestry , Bugwood.org

Figure 23

Troy Kimoto, Canadian Food Inspection Agency, Bugwood.org

Figure 24

Whitney Cranshaw, Colorado State University, Bugwood.org

Figure 25

Joesph Obrien, USDA Forest Service, Bugwood.org

Figure 26

Daniel Herms, The Ohio State University, Bugwood.org

Figure 27

David Cappaert, Bugwood.org

Figure 28

Rob Routledge, Sault College, Bugwood.org

Figure 29

Kenneth R. Law, USDA APHIS PPQ, Bugwood.org

Figure 30

Debbie Miller, USDA Forest Service, Bugwood.org

Figure 31

City of Saskatoon, www.saskatoon.ca

Figure 32

Christopher McDonald, City of Winnipeg

Figure 33

Lisa Jones, Trees Winnipeg

Back Cover page

Gabrielle Neufeld, Trees Winnipeg


To request copies of this publication, please contact: Trees Winnipeg (Coalition to Save the Elms) 1539 Waverley Street Winnipeg, Manitoba R3T 4V7 Phone: (204) 832 – 7188 Email: office@treeswinnipeg.org www.treeswinnipeg.org

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A Guidebook on Invasive Pests and Winnipeg Trees: Detection, Prevention and Preparedness  

A Guidebook on Invasive Pests and Winnipeg Trees: Detection, Prevention and Preparedness contains information about the invasive pests which...

A Guidebook on Invasive Pests and Winnipeg Trees: Detection, Prevention and Preparedness  

A Guidebook on Invasive Pests and Winnipeg Trees: Detection, Prevention and Preparedness contains information about the invasive pests which...