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

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