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Tree Care

Dutch Elm Disease Management

COMMUNITY INVOLVEMENT

Community Action: The Elm Guard Program

As municipal resources decline, community action is essential in the fight to preserve the elms. Elm guard groups are active in many communities throughout Manitoba. These groups learn about the disease, how to detect DED and contact municipal officials to report suspected diseased or dying trees.

Introduction - Community Action

Elm Tree in the FallThe fight against DED is not a lost battle. In Manitoba we have shown that with sufficient government funding and commitment by the people, we can protect our mature elm populations. As well as educating ourselves about DED, especially learning about the signs of the disease and what to do about it, we should care for our elms to prevent the disease from occurring in the first place.

The greatest incidence of DED occurs on private property. In Winnipeg, it is estimated that over 80% of DED occurs in our yards. In rural areas, the problem is the same. Shelterbelts have been especially hard hit by DED Despite the greatest efforts of municipalities, DED management programs cannot prevent the destruction of private trees. Homeowners can and must do their part to protect their elms.

Many homeowners spend time and money on the flowers and grass in their yards. Trees are often left to fend for themselves. Dead wood on elm trees accumulates and becomes a breeding site for the elm bark beetle. DED then strikes and often spreads to public street elms resulting in greater losses of DED despite the effort of municipal DED management programs.

A common argument against taking care of our trees is that the cost is too great. It is true that it can be a fairly expensive proposition to prune mature trees. However, one must remember that the cost of pruning should be amortized over a number of years. Pruning is only required once every 7-10 years or as required from storm damage, for instance.

The cost of watering and fertilizing is minimal if done properly. Trees enhance property values and also reduce energy costs. Healthy trees are worth the investment.

Advantages Of An Elm Guard Group

By working with your neighbours in an elm guard group you can:

  • Street lined with Elm TreesObtain group rates (perhaps 10-20% reduction in costs) for pruning and tree care from tree service firms
  • Organize a basal spray program to control the elm bark beetle. (You provide authorization for the City to enter your property and the Forestry Branch will treat the base of your elms free of charge.) Get your neighbours involved too!
  • Attend workshops and learn how to care for the trees in your own backyard.
  • Plant trees at neighbourhood parks and playgrounds. (Make sure you obtain authorization from the appropriate local officials.) Information is available from the Coalition to Save the Elms and local officials on funding opportunities to purchase trees.
  • Band trees for cankerworm control on Labour Day. Make sure to remove the bands by the May long weekend.
  • Help preserve the character of your neighbourhood.
  • Get to know your neighbours and make new friends!

The Elm Guard Program: Roles and Responsibilities

Learn how to identify American elms, detect DED, identify hazard elms (more than 50% dead), and spot elm firewood.

Divide your neighbourhood or area into assigned territories. Survey your assigned area one to two times per week during the period of mid-June to mid-August. Don't forget back lanes, parks and riverbanks. During your surveys:

  1. Look for the Symptoms of DED
  2. If the tree shows signs of DED, loosely tie flagging tape (supplied by the Forestry Branch) around the trunk for identification, fully complete the "Elm Guard Request for Sample" form and immediately provide it to the elm guard coordinator who will convey the information to the Forestry Branch.
  3. The Forestry Branch will then examine and if necessary, tag the tree for future identification. In Winnipeg, if the elm has DED or is deemed a hazard tree, it will be removed by the city. If you live in a rural area, check with your municipal office to see if your town has a DED management program and cost-shared arrangement with the province.
  4. Check firewood piles for elm wood. Elm wood is distinguished by bark that is dark grey/brown in colour, has broad intersecting ridges and a rough flaky appearance. The bark cross-section has alternate brown and beige layers - a feature distinctive to elms.
  5. If you see someone pruning an elm tree between April 1st and July 31st, report it to the city's Forestry Branch or the local Natural Resources officer. It is illegal to prune elms during this period as the fresh wounds are attractive to the elm bark beetle which spreads DED
  6. If you are on holiday during the summer, please ensure that you have a back-up person or neighbour to patrol your assigned area.

For more information about the elm guard program please contact Trees Winnipeg at 204-832-7188, or the City of Winnipeg's Tree Line at 311 or the Manitoba Conservation official in your area. The Provincial Tree Line phone number in Winnipeg is 204-945-7866.

LEGISLATION

In 1980, the Dutch Elm Disease Act was proclaimed to prescribe programs and measures for the control of DED in Manitoba. The main features of the Act and Regulations include:

  • The prohibition of pruning American elm between April 1st and July 31st (when the elm bark beetle is actively seeking new breeding material)
  • The prohibition of stored elm wood.
    The proper disposal of elm wood by burial, chipping or burning
  • The right of entry and inspection: appointment of inspectors with specific powers such as the right to enter properties to conduct inspections and carry out control procedures.
  • The requirement of possessing a Manitoba Arborist license when engaged in commercial activities relating to the care of elms.
  • Penalties for contravention of the Act: a maximum fine of $5,000.

For further reference, the Manitoba Dutch Elm Disease Act is available online here.

PREVENTATIVE MEASURES

Basal Treatment
NOTE

Basal TreatmentThe City of Winnipeg has requested that Trees Winnipeg stop taking individual basal spraying request applications from members of the public from this date forward. Over the last two years, the City has re-focused the program to spray trees along riverbank areas within the City of Winnipeg. Normally, these riverbank areas are where Dutch elm disease and the Elm bark beetle populations are the highest. It is believed that focusing limited resources in these areas is the most efficient and effective way to control Dutch elm disease in Winnipeg.

Furthermore, the City informs Trees Winnipeg that those registrations Trees Winnipeg has collected in the past will receive the lowest priority for spraying. These registrations will be sprayed only if time and resources permit. The reasons for this change are as mentioned above.

Should residents have any questions about this change, please call The City’s Customer Service Center at 311.

As well as removing their breeding material, elm bark beetles can be controlled with insecticides. A registered insecticide containing the active ingredient chlorpyrifos is most effective in controlling overwintering beetles for up to 2 years.

Research has shown that chlorpyrifos breaks down quickly in sunlight while retaining its chemical effectiveness deep in the fissures of the bark. If applied properly, there should be little spray drift.The spray is applied to the lower 25 cm of the tree. The chemical will prevent adult beetles from overwintering in the tree and is applied every two years. Effectiveness also increases with the number of trees treated. The beetle population can be reduced by more than 98%.

In Winnipeg, the city sprays all boulevard and park elm trees to reduce the elm bark beetle population. You too, can have the the base of your elms in your own yard by registering in the Basal Spray Program with the Coalition to Save the Elms. The basal spray application is done from August to October by the City of Winnipeg.

In Winnipeg the City will apply the basal treatment, at no cost to the homeowner. The Coalition to Save the Elms volunteers work with the City obtaining signed authorization forms from homeowners allowing access to their property. Homeowners, living in close proximity to rivers where the disease is often concentrated, should take advantage of the opportunity to have their elms treated by the city. But for the treatment to be most effective it is helpful to spray as many elms as possible. Obtaining the support of your neighbours will be of great value for everyone.

In rural municipalities, elm trees are treated by the municipality only if that municipality participates in the DED Cost Sharing Agreement Program managed by Manitoba Conservation.


Elm Tree Sanitation

Sanitation is the removal of all identified diseased and hazard elm trees as soon as possible after detection. It also includes the removal or treatment of remaining stumps.

To prevent the spread of DED to healthy trees, it is essential to remove diseased, dying and dead elms. These trees are ideal breeding material for the elm bark beetle.

Elm firewood is a perfect breeding site for the beetle. It is also the perfect means of transporting DED from place to place. Detection and proper disposal of elmwood is especially important.

Fungicide Injections

Fungicide InjectionsThe injection of fungicides into elm trees is another method of protection against DED The fungicide is injected into the vascular system of the tree circulating throughout the trunk, branches and crown.

The chemicals Alamo and Eertavas are currently registered for use in Canada.

There are two types of injection: root flare and trunk injection.

Root flare injection is more commonly used. Holes are drilled through the bark into the wood around the base of the tree. The injector heads are inserted into the holes and the chemical is injected. Injections can be done at any time of the growing season. For the greatest protection, injection should be done when trees are in full leaf before the end of June.

Which trees should be injected? As injection is an invasive, expensive and difficult preventative procedure, only healthy high-value elms should be treated.

However, injection may also cure trees in the early stages of infection. Treating diseased trees is not recommended unless there is less than 10% infection or crown wilt present. Extensive crown wilt indicates a well-established infection that will not respond to injection. Pruning of diseased branches should be done before or as soon as possible after the tree is injected.

The effects of the fungicide last perhaps two years. Injection is a costly procedure that does not provide a cure or long-lasting resistance to DED.

Surveillance

Elm Trees Marked for RemovalSurveillance is a systematic survey of all the elms in the control area to detect both diseased and hazard (more than 40% dead) elms as well as stored elm firewood locations.

In Winnipeg, surveillance is the responsibility of the city's Forestry Branch. In most areas of the city, surveillance is carried out twice each summer. In 1996, the Forestry Branch instituted an enhanced DED control program which resulted in the weekly survey of some areas in the city. In rural communities participating in the cost-shared program, Manitoba Conservation carries out surveillance.

In Winnipeg, there are a number of elm guard groups who have been trained in the detection of DED and who assist the Forestry Branch by surveying trees in their neighbourhood.Communities such as Neepawa and Brandon also have active citizenry who keep an eye out for the signs of DED The information collected from the surveillance is then computerized and used by removal operations crews.

If you learn to spot the signs of DED in the very initial stages of the disease, and your elm is a mature high value tree, you can have it injected with a fungicide.

The use of elm as firewood is restricted by law in Manitoba. Unfortunately, many people do keep elm wood. The wood, unless debarked, is a habitat for the elm bark beetle. It is essential to recognize elm wood to help prevent the spread of DED.

If the homeowner is storing elm wood in contravention of the Dutch Elm Disease Act, a notice will be left requiring the homeowner to properly dispose of the wood.

REFORESTATION

In areas where DED is rampant, the selection and planting of alternate species of trees can be considered. species such as green ash, black ash, basswood or linden, silver maple, Schubert, chokecherry and common hackberry grow well in Volunteer Tree Plantingsouthern and central Manitoba climates.

However, the replanting of American elms is also recommended in areas where DED management programs are in place. No other tree can replace the majestic elm. While it is important to avoid planting a monoculture of tree species, it is equally important to the long-term survival of the elm that new growth be encouraged as well. Hopefully, research will find a long-term solution to DED in the near future.

RESEARCH

Extensive research into the mechanisms of DED, the habits of the elm bark beetle and the existence of naturally occurring disease-resistant strains of elms is being carried out in Manitoba and Ontario. The Coalition to Save the Elms has been instrumental in encouraging multi-level government support of promising research at the Universities of Manitoba and Toronto. With the support of the Coalition and the public, research has been funded by the City of Winnipeg, the Province of Manitoba, and the federal government.

At the University of Manitoba, research is being conducted on "field-resistant" strains of elms. Thousands of American elm seedlings are being screened by Department of Plant Science and Manitoba Conservation. Although the research looks promising, it will take time before a DED-tolerant American elm is identified.

Additional research being proposed by the University of Manitoba in collaboration with Manitoba conservation and the City of Winnipeg will look at three areas of study:

  1. Identifying more specific behavioural characteristics of the native elm bark beetle to better understand the transmission of DED fungus by the beetle,
  2. Assessing alternative chemicals to Dursban or Chorpyrifos for basal spray treatments to control native elm bark beetle, and
  3. Assessing the effectiveness of rapid removal of diseased elms.

Although the City of Winnipeg has the most successful DED management program in North America, progressive thinking in our urban forestry sector identifies that changes can be made to improve the program over the long term. This research is critical to sustaining a healthy urban forest and environment. There are still many unanswered questions about the behaviour of the native elm bark beetle and DED. Most other research in North America has traditionally focused on other species of beetle that are not prevalent here. This currently proposed research will provide the evidence needed to make more changes.

SUPPORT INCREASED FUNDING FOR THE DED PROGRAM

TREES WINNIPEG'S RECOMMENDATIONS FOR IMPROVEMENTS TO WINNIPEG'S DED MANAGEMENT PROGRAM

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