SOS Elms Coalition
Tree Care guide

Why worry about your elm?
What is your elm tree worth?
What is Dutch Elm Disease?
Tree Care Made Easy - Watering, Fertilizing, Pruning
Pruners and other Resources


Why worry about your elm?

Dutch Elm Disease can infect all types of elms in Saskatchewan.  American, Siberian & Manchurian elms are all susceptible and must be treated equally. American elms are the most common shade tree found in the older neighbourhoods of Saskatoon.  In fact, there are as many as 100,000 in the city.  American elms are native to Saskatchewan and therefore ideally suited to our cold, harsh climate.  They can live for 250 years or more in our urban setting, providing beauty and shade for generations to come.

American elms have a characteristic “umbrella” shape when seen in profile, growing to 23 metres (75 feet) in urban conditions.  The canopy of  mature trees will often meet across a street creating an   attractive “tunnel” of branches and leaves.  Its dark green leaves are oval in shape and asymmetrical (having halves that are not even in size and shape) at the base. The leaf edges are double-toothed.
 
 

American Elm leaf
Leaf of an American Elm
Siberian Elm leafLeaf of a Siberian Elm

Siberian elms (often called Manchurian elms) are less graceful and majestic than the American elm.  A hardy, weedy, and relatively short lived species, the Siberian elm can have a variety of forms depending on location and pruning – from a shrubby hedge to a single tree.  Their leaves are similar to, but smaller than, those of the American elm. Siberian elms are fast growing, typically reaching heights of 12 m (40 ft).  They are unpopular with gardeners as they produce an abundance of seed and their branches break easily.  They are less likely to die from DED, but can be a source of infection.
 

What is your elm tree worth?

In terms of Real Estate it is estimated that a mature American elm is worth at least $3,600.  This doesn’t even begin to take into account the many other benefits of trees, such as shade and wind protection, as well as the beauty and clean air they provide.

Properly planted trees can cut air-conditioning and heating bills by 10-15 percent.  Studies have shown that a mature urban forest increases property values by 5-20 percent, improves residents’ health and well-being, and can even reduce crime rates!  If you’re a nature lover, consider the habitat that trees provide for songbirds and other animals.  There are a multitude of  reasons to save our urban forest.  It costs as much as $1000 to remove a tree and as little as $250 to prune it.  Why not keep your tree healthy and alive for you and your grandchildren to enjoy – it makes good financial sense.

What is Dutch Elm Disease?

Dutch Elm Disease (DED) is a fatal fungal disease that can kill an American elm in as few as three weeks.  It is spread by the native elm bark beetle that feeds and breeds in elm trees. Elm bark beetles are tiny, about the size of a pinhead, and can be present without you noticing them. The disease is spread as beetles that are infested with the sticky DED spores move from tree to tree.  Control the beetle and you can control DED!

DED was first identified in the Netherlands and northern France in 1919.  It was actually brought to Europe from the Dutch East Indies during the late 19th century.

The first infections in North America were observed in the United States in Ohio in 1930.  In Canada, the disease was first reported in  Quebec in 1944.  Since then DED has spread to almost everywhere that elms grow.

The first reported case of DED in Saskatchewan occurred in Regina in 1981.  While the situation there is under control for now due to a very effective DED program, other  areas of the province have not been as lucky.  Manitoba has had DED since 1975.  The disease spread rapidly from there into eastern Saskatchewan in the 1990s.  This spread has largely occurred along natural corridors of wild elms, such as the Souris River Valley.

Unfortunately, DED can move very quickly. All it takes is someone transporting infested elm firewood to a disease-free zone.  This is likely what happened when DED was discovered in Davidson in 1999.  DED is now within an hour’s drive of Saskatoon!

DED is almost here and everyone, young and old, must be ready to lend a helping hand.  Are you ready to join the fight to save our elms?  With your help we can win the battle and we will have elms to enjoy for years to come!

Can you recognize DED?

DED causes elms to shut down their water-conducting vessels so one of the first signs of the disease will be a branch in the upper canopy of an elm with leaves that wilt, turn brown and shrivel in early summer.  They often remain on the tree for the full season.  If the disease strikes later in the summer, leaves will usually wilt, turn yellow and fall prematurely.

If you see an elm with the symptoms of DED call the City of Saskatoon at 975-3300.  The Pest Control Officer will take samples of the suspicious branches and send them away for testing.  If the sample is positive for DED, the tree will be removed and buried in a designated area of the landfill.  The quicker this happens the better!

You are responsible!

Elms that are located on city property,  e.g. on boulevards and in parks, are maintained by city employees.  However, privately owned trees are the responsibility of the landowner.  It is up to you to make sure your elms are maintained for environmental and legal reasons as you are liable for any injuries or damages caused by fallen branches or dead trees.

This is what you should do:

  •  Don’t store or transport elm firewood as elm bark beetles will breed in it.  It is illegal!  One two foot piece of elm wood can hold 1,800 infested beetles.  Elm firewood must be taken to the city landfill where it will be buried to make it inaccessible for breeding.
  • Hire a professional to prune the dead or broken branches from your elm trees to get rid of elm bark beetle breeding sites. Do not prune during the pruning ban (April 1st – August 31st) when the smell from cut branches can attract elm bark beetles.
  • Band your trees for canker worms every fall when the cankerworm population is high. This will not prevent DED, but will keep your trees healthier and less likely to contract the disease.  Also, make sure to renew the sticky layer in the Spring if needed and remember to take down your bands by May 15th
  • Watch for the symptoms of DED and report any suspicious looking trees.

Tree Care Made Easy!

Many people carefully water, fertilize and cut their lawns, but never give a second thought to their trees.  Proper tree care is not much different.  Trees also need watering, fertilizing and a good pruning every now and then!

Watering:
Elms are fairly resistant to drought, however if you notice that leaves are starting to droop during periods of very hot or dry weather it may be time to get out the hose.  Infrequent, thorough soakings are better than frequent minimal watering. In the early morning, water the entire area beneath the crown of the tree with a sprinkler until at least 3 cm (1 in.) of water has been applied.  This can be measured by placing empty tuna cans under the sprinkler and watering until the cans are full.  Repeat this weekly and your tree will start to perk up!

Fertilizing:
Mature elms will benefit from a fertilizer application every two or three years.  Fertilizer can be applied on the surface of the soil or in “feeding” holes that are dug in the soil around the tree from the drip line (where the outer edge of the canopy drips onto the soil) and outward.  Fertilize in early spring before growth begins. For well established trees that are 10 cm (4 in.) in diameter or more, apply 1 kg (2.2 lb.) of fertilizer per 3 cm (1 in.) of trunk diameter using a 20:20:20 mix.  Evenly distribute the fertilizer from the drip-line and out.  After surface applications, make sure to water well.
 

Pruning

Because most elms are very large and require specialized skills and equipment to reach the top branches, it is recommended that a professional tree pruner be hired to do the work.  Someone with ISA (International Society of Arboriculture) certification is best.  Do not hire someone who “tops” trees as this simply encourages weedy, weak growth that may actually require more frequent pruning!  A listing of pruners with ISA certification is included on the last page.  Elms should be pruned every 5 to 7 years and also as soon as possible after any damage has occurred from storms, high winds or accidents.  All dead and dying limbs should be removed so that elm bark beetles do not use this wood as a breeding site. Do not prune between April 1st and August 31stwhen the smell of freshly cut branches will attract elm bark beetles to your yard. Do not keep the wood – it is illegal!  Take all elm wood directly to the city landfill where it will be buried to make it inaccessible to breeding beetles.

cross-section of an elm log

If you are pruning a smaller elm tree you may wish to consider the following pointers:

  • Prune all dead or dying branches on a regular basis to improve the tree’s health and to avoid future problems.
  • Prune to maintain the desired shape or size of the tree.
  • Prune crossing or rubbing branches to avoid further damage.
  • Prune to increase or reduce density of the tree branches.  Generally trees should be thinned to produce an open crown allowing light and air to penetrate to the interior.
Whether you are pruning a tree yourself or having someone else do the work, make sure that all pruning equipment is disinfected prior to and after each cut.  Spraying your tools with a 50:50 mixture of bleach and water or with methyl hydrate (gasline antifreeze) will prevent the spread of disease to healthy parts of the tree or to other trees.  In our climate pruning cuts should not be painted or treated in any way.  Proper pruning is more important than wound treatment for quick healing of cuts.
 

Pruners and other Resources

ISA (International Society of Arboriculture) Certified Tree Pruners located in Saskatoon

Arbour Crest Tree Services 242-8733
Arbortech Tree Services  222-0120
B & B Tree Service 221-9233
Loraas Tree Service  222-5222
Sawyer's Tree Service 244-8906
Schwinghammer's Tree Service Ltd. 244-4080
Superpro Tree Experts 931-4401
   
   

Resource People


City of Saskatoon   306-975-3300
SOS Elms Coalition 
Saskatchewan Ministry of Environment     306-933-6515
Coalition to Save the Elms
Elmcare Site
Gardenline - College of Agriculture – University of Saskatchewan

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