Showing posts with label invasive species. Show all posts
Showing posts with label invasive species. Show all posts

Monday, June 6, 2011

Profile on Invasives: Garlic Mustard



It’s in season…. It’s invasive…. It’s sooo hard to get out of your garden...It's Garlic Mustard (Alliara petiolata)


Where does it grow?

This invasive plant likes moist forest conditions, wooded stream banks, floodplain forests, roadsides, and trail edges.


Why is it so bad?


It dominates the ground layer of plants where it grows and reduces the forests' natural ability to regenerate.


Garlic Mustard may also seriously harm one of Muskoka's species at risk, the West Virginia White butterfly. When the butterfly lays eggs on Garlic Mustard, the eggs will hatch but the young will not feed on the mustard and die. For a species whose habitat is in short supply, this is a serious problem! Learn more about the West Virginia White butterfly.

What does it look like?


Garlic Mustard grows from 13-120cm tall and stays green year-round. The stem has alternating leaves that are rounded in their first year (a photo here) but afterwards are jagged and pointy. When crushed, they produce a strong garlic smell.


In the second year, it produces flowers which are small (6-7mm), with four white pedals and are produced on a single stalk in May and June. In late July and August a small, oblong, black seed is produced. A single plant can produce up to five thousand seeds that germinate the following spring. This plant spreads like wildfire!

But don't mistake it for:


Phlox (various types): looks similar but the pedals are more rounded and there are five of them, not four.


Dame's Rocket: also looks similar but flowers can be pink or purple in addition to white. This plant also has a pleasant, fresh, floral, fragrance- not a garlic smell! The photos below are Dame's Rocket.


Both photos above are Dame's Rocket, NOT Garlic Mustard! They look soooo similar! But this one smells much nicer and can be white, pink, or purple.


How does it spread?


Unknowingly, humans and our pets can capture seeds on hair, fur, clothes,

shoes and bike tires, carrying them to new places


where the conditions are right and the seeds literally put


down their roots. It can also be spread by wild animals.





What can you do?





  • Look before you leave! After a hike, thoroughly brush off your clothing and shoes. Give your pet a brush before leaving the trail too! Garlic Mustard seeds can be carried in mud so rinse your shoes, pets, and bikes off before leaving.




  • Learn to detect this species early in its establishment, avoiding larger more labour intensive control efforts down the road.

  • Be carefule if you pull it out!



    • It can easily be pulled by hand in light, moist soils, but only for a small number of plants. This must be done over 5 successive years to ensure the seedbank is exhausted. Doing this with larger infestations could result in actually compounding the problem by encouraging the seed to spread

Have you found Garlic Mustard on your property? Look here for more tips on how to manage.

Report an invasive species: call the Invasive Species Hotline at 1-800-563-7711

Monday, May 30, 2011

Profile on Invasives: Giant Hogweed

Giant Hogweed

Heracleum mantegazzianum


This post marks the beginning of the "Profile on Invasives" series of the blog.

I will post in detail about some of the invasive species most commonly found in Muskoka.

Do you have a suggestion for a species you'd like to see covered?

Let me know by leaving a comment below!

What is it?
Giant Hogweed is a biennial or perennial plant, flowering only once in its lifetime and reproducing only by seed. Plants forming rosettes to 1m high the first year; in the second year, either sending up a flowering stem, or remaining vegetative and producing a very large rosette of huge leaves, these including their petioles, up to 2m high, and flowering in the third year. As it goes through these stages, its' appearance changes (see photos below).

Giant Hogweed grows for 3-5 years and 4-5 metres tall before flowering. Flowering occurs from June to August, at which point the seeds are released. Once the seeds are released the plant dies. Seeds are dispersed by wind, water and humans, and can survive in the soil for 7 years. Each plant can release between 20,000 to 100,000 seeds, resulting in high rates of spread.

Where does it grow?
Giant Hogweed grows in moist environments, generally near streams, lakes and ponds.
Why is it dangerous?
Giant Hogweed competes with native species for light, and can change the composition and reduce the diversity of native plant communities.

Giant hogweed contains a clear, watery, toxic sap. When this comes into contact with human skin it reacts with sunlight which results in severe burns on the skin within 15 minutes of exposure. The burns are extremely painful as evidenced in the photos below.


The sap is also carcinogenic and teratogenic, meaning it can cause cancer and birth defects. If the sap gets in your eye, the chemical in it can singe the cornea and cause temporary or permanent blindness.
What is the District of Muskoka doing about it?
On May 26th, Moose FM reported that the "Township of Muskoka Lakes is doing what it can to protect residents from the dangers of Hogweed. At a special council meeting last week, council directed staff to take action to eliminate Giant Hogweed from public land. This includes the use of pesticides and warning signage in known areas. The resolution will now go to District Council, where councillor Brad Burgess will ask to speak to members about undertaking a similar resolution district wide." Stay tuned...
What should you do if you find giant hogweed?


  • DO NOT touch the plant!

  • DO NOT try and control the plant yourself; contact a pest control expert or your town/municipality

  • Report your sighting to the Invading Species Awareness Program

  • Keep children and pets away from the plant

  • Help stop the spread of invasive plants of all kinds by removing seeds, fluff, plant material from your clothing, shoes, pets, and bikes before leaving a natural area.

  • Should you touch Giant Hogweed, wash the affected area immediately with soap and cool water. Avoid sunlight and seek medical attention.

Similar Plants


Giant Hogweed has a similar appearance to a few other common plants in Muskoka:


More Information and Photos