Caring for Your Yard


Environmental Awareness

Weed Inspection: Why We Do It & What You Need to Know

Alberta is extremely susceptible to invasive species. Some species are looking to get a foothold in our waterways and others are looking to invade our productive agricultural land. For this reason the Weed Act was proclaimed in 1907 and has existed in some form for the last 108 years, making it one of Alberta’s oldest pieces of legislation. Its latest revision, (proclaimed in June 2010) listed 46 prohibited noxious and 29 noxious weeds requiring either eradication in the case of prohibited noxious or the control of noxious weeds. This revision showed an increased focus on new invasive plants that most had assumed weren’t even in Alberta yet.

To assist landowners/occupants in the identification and control of these legislated weeds, your Town Council appoints a number of weed inspectors annually. One of their main goals of this program is to create awareness about these new invasive weeds and why they must be controlled or eradicated.

Weed Report Vs. Weed Notice

Should a weed inspector discover a noxious weed, they will write up a Weed Report and inform the landowner of the weed infestation. This is not a Weed Notice. A Weed Report is offered as an informational tool to encourage landowners to control the weeds in question and /or contact the Weed Inspector to learn more about the plants’ management and control.

A Weed Notice, on the other hand, is a legal document under the Alberta Weed Control Act. A Notice will be issued if a landowner has repeatedly failed to control the weeds identified on the Weed Report or in the case a Prohibited Noxious weed is discovered, a Weed Notice must be written. A Weed Notice is a document that, if unattended to, will lead to the municipality taking action to control/eradicate the weeds in question with the landowner still responsible for the cost of the control.

Under the Act, Weed Inspectors “may enter at any reasonable hour on land or premises, and inspect the land or premises or any crops, hay, etc.,” excluding the dwellings on the premises. For more information on the weeds in your municipality, please visit the Alberta Invasive Species Council:

Weeds Door Hanger

Black Knot


“Inspect your trees”

Black Knot occurs naturally and is caused by a fungus, Apiosporina morbosa. It is a widespread and serious problem in this area. The disease infects Mayday, Chokecherry, Pin Cherry and members of the Prunus family, and can lead to the eventual death of the tree if proper control measures are not taken. The disease becomes more serious with each growing season.

BlackKnot 2   BlackKnot 1

The disease is very visible this time of year. Thickened, black knotty material is seen on twigs, branches, fruit spurs, and occasionally on the trunk. These knots continue to grow each season, eventually killing the branch, by restricting water and nutrient flow.

The best defence is to begin with resistant varieties. Check your local garden centre for recommendations. The first step in disease control is eradication. Prune out all knots and signs of infection as soon as they are noticed. Make pruning cuts at least 8 inches below the swollen, black area. To prevent the spreading of the fungus, dip pruning tools in a 10 percent bleach solution between cuts. Destroy infected branches by burning or complete disposal. Trees that are completely infected should be removed and burned to avoid spreading infection. Keep trees healthy by providing adequate moisture and nutrients.

Do not place infected plant material in the yard waste pickup, composter or use as mulch or store as firewood.

Black Knot Fact Sheet


Aspen and Poplar: Bronze Leaf Disease in Alberta

Bronze Leaf Disease (BLD), caused by the fungus Apioplagiostoma populi, is a disease affecting Poplars, primarily Swedish Columnar Aspen, 'Tower' poplar and poplar hybrid clones.

What are the symptoms?

Typically, symptoms appear in later summer (early-mid August) or early fall (September) and may be relegated to only a few branches or leaves. Browning or reddening begins at the margins of the leaves and then progresses inward, however the leaf stem and veins may remain green for some time. Leaves on an entire branch may be infected and can remain on the tree throughout the winter and are noticeable. Tree death can occur in 3-5 years.

Can the disease be controlled?

There is no chemical control for this fungus, only early detection and treatment to reduce spread and save the tree. Keep your trees healthy by providing adequate moisture and nutrients.

What should I do?

If you find one or more of your trees has Bronze Leaf, remove the diseased leaves and infected branches 10-12 inches from the infected area into healthy wood, place in a sealed bag—sealed bags prevent spores from being released and spreading infection—and take to a landfill. Trees that are completely infected should be removed and burned to avoid spreading infection. Do not place infected plant material in the yard waste pickup, composter or use as mulch or firewood.

Be on the look out and check your Swedish Columnar Aspens and Tower Poplars for Bronze Leaf Disease yearly.


Dutch Elm Disease Awareness Week: June 22- June 28


The Society to Prevent Dutch Elm Disease (STOPDED) would like to make sure Albertans are informed about Dutch Elm Disease (DED) and how it can prevented with Dutch Elm Disease Awareness Week recognized annually throughout Alberta.

American elms are planted extensively in Alberta and have throughout the years become the tree of choice for the Prairies with good reason. These giants with their height and broad vase- shaped canopies have given them tremendous esthetic value. They are tough, can endure extreme heat, cold and drought, yet retain incredible beauty. However, all elm species that grow in Alberta have an Achilles heel—DED, a deadly fungus. This fungus clogs the elm tree's water conducting system, causing the tree to die in a short period of time. The fungus is primarily spread from one elm tree to another by elm bark beetles.

During DED Awareness Week, take a moment and find out how you can help save our elms.

How do I know if my tree is infected?

Leaves on a DED-infected elm will wilt or droop, curl and become brown. This appears in mid-June to mid-July. Leaves on trees infected later in the season usually turn yellow and drop prematurely. Leaf symptoms are accompanied by brown staining under the bark. All suspicious elms must be tested in a lab, a service STOPDED funds.

Monitoring for the beetles is done annually throughout the province by STOPDED. The smaller elm bark beetles have been found throughout the province in low numbers and now the banded elm bark beetle is found in larger numbers throughout the City of Medicine Hat and area. For this reason we must be even more vigilant.

What can I do?

  • Be aware of the Alberta elm pruning ban between April 1and Sept. 30. The beetles are most active at this time and can be attracted to the scent of fresh tree cuts, possibly infecting a healthy elm.
  • Keep your elm trees healthy and vigorous.
  • Water elms well from April to mid-August. To allow the tree to harden off for the winter, watering should be stopped mid-August followed by a good soaking or two before freezeup.
  • Only between Oct. 1 to March 31, remove dead branches and trees as they can provide beetle habitat.
  • Dispose of all elm wood immediately by burning, burying or chipping.
  • Report all suspect trees to the DED Hotline at 1-877-837-ELMS. A confirmed DED tree must be removed immediately to prevent further spread.

What shouldn't I do?

  • Do not transport or store elm firewood at any time! DED and the beetles are declared pests under the Alberta Agricultural Pests Act making it illegal to do so.
  • Do not transport elm firewood into Alberta! Firewood is confiscated at all the Alberta-Montana border crossings.
  • Do not prune elms between April 1 and Sept. 30.

To report a DED suspect elm tree or for more information, call the STOPDED hotline at 1-877-837-ELMS or check out the website at

Our elms are a treasure that we cannot afford to lose.




Invasive Weeds to Watch For

Oxeye Daisy, Canada

The Oxeye Daisy stands out prominently in the landscape, as there are no native white-flowered daisies in Alberta. Often perceived to be a ‘pretty’ wildflower, is actually an aggressive invader. It is a perennial that spreads primarily by seed, but also by shallow, creeping roots. The greatest impact of this plant is on forage production in pastures and meadows. Cattle avoid oxeye daisy and so any pasture infested decreases forage available for grazing. Horses, sheep and goats, however, will readily graze oxeye daisy and can be used in companion grazing situations to control oxeye daisy. Dense stands of oxeye daisy can decrease plant diversity and increase the amount of bare soil in an area.

Control: Mowing before bloom can reduce seed set but will not control the plant. Mowing during or after flowering will disperse seeds. Because of its shallow root system, oxeye daisy can be controlled with cultivation.

All information provided by the Alberta Invasive Species Council. For more on the various noxious and prohibited noxious weeds, please visit The AISC website.


The Difference between Scentless Chamomile, Oxeye Daisy & Shasta Daisy

Scentless Chamomile and Oxeye Daisy are both classified as noxious weeds in the Alberta Weed Act and need to be controlled. The Shasta Daisy is a common garden feature. It is a domesticated plant and is not classified as a weed, but can easily be confused with Oxeye Daisy.

The heads on all three look similar and are almost impossible to tell apart. It is the leaves you must look at to differentiate between the three.

oxeye daisy oxeye daisy leaves scentless chamomile leaves

The leaves on Scentless Chamomile are very finely divided, fern-like or carrot top looking. The leaves on Oxeye Daisy become thinner the closer they are to the stem and are more jagged. The leaves on a Shasta Daisy are jagged looking, similar to but not identical to the Oxeye Daisy leaves. The Shasta Daisy has more spoon-shaped, rounded leaves.

Oxeye Daisy is a very attractive common garden flower, does create problems when expanding beyond the garden. It can infest the grass and in no time, take over the yard or surrounding areas. The Oxeye Daisy Individual plants can produce over 500 flat, black seeds that are viable in the soil for 2-3 years or more. Seeds have no dormancy requirement and are viable upon dispersal.

We strongly recommend people to pull these plants out of their yards, bag them and perhaps replace with another white flower. If everybody does their part, this will help to create a weed free environment.


Pretty Garden Flower or Invasive Noxious Weed?

Some of our favorite flowerbed species can wreak havoc on our native environment. About 10% of the ornamental plants brought over from other countries can become invasive once placed in our ecosystem. They thrive because they do not have any predators to control their spread. Once established, their rapid growth and spread can outcompete native vegetation, damaging our natural areas.

Listed below are some common prohibited noxious and noxious weeds found in flowerbeds and landscape settings:

Himalayan Balsam

Himalayan Balsam

This shallow-rooted annual can become a real problem in riparian areas as the plant likes marshy, wet areas and grows incredibly fast, shading out all other vegetation. The seed pods explode when mature, catapulting seeds up to 6 metres away. This plant is easy to control by hand pulling before seed pods mature and should be bagged and burn.


Bighead Knapweed

Bighead Knapweed

A long-lived perennial, once established, this showy garden ornamental can take over garden beds as it is very hard to control. The plant spreads by seed, so care is need when disposing of the seeds. Herbicide, if possible, is a good option to control this plant, as digging out the roots can be laborious and take a few attempted. The removed plant parts should be bagged and burned.


flowering rush

Flowering Rush

Originally sold in garden centers as an aquatic plant for water features. Incredible invasive as this plant will take over miles of shoreline and control options are very limited. Reproduces by seed and rhizomatous roots.


yellow clematis

Yellow Clematis

This plant is a climber. Usually grown on fences or a lattice structure as the spreading vines rapidly encompass the area. This plant is aggressive once established and the puff-ball like seeds spread easily through wind and water dispersion. There are non-invasive Clematis plants available from your local garden center that can be planted instead of or to replace Yellow Clematis.


dames rocket

Dames Rocket

This perennial is a prolific seed producer, up to 20,000 seeds per plant. The flowers are very similar to a lilac bushes flower; 4 petals and can range in color from purple to pink or white. Hand pick or apply a herbicide to control this weed. 


Creeping Thistle, Canada

These spiky fellows show up every year across most of Alberta, and are aggressive and creeping. They have purple or white flowers, grow up to 120 cm tall, and are ridged and slightly hairy.

Control: Chemical application in the late fall is the most effective way of dealing with this little pest.

All information provided by the Alberta Invasive Species Council. For more on the various noxious and prohibited noxious weeds, please visit The AISC website.