Invasive Weed Watch: Garlic Mustard

Be on the lookout for this eager grower.

This non-native, Alliaria petiolata, brought over by pioneers as a culinary and medicinal herb, is on Tree Canada‘s list as a Tree Killer. How does it kill trees? By escaping cultivated gardens long ago and moving into wild areas. It colonizes rapidly in forests, and shades out native tree seedlings. It interferes with soil funghi, upsetting the ecosystem, and further harming existing trees. It has no predators. Deer are not crazy about it, and tend not to eat it. Plants make thousands of seeds, so it spreads and spreads. In my walk this morning I saw many stands of it in the wild areas of the park. It’s all over Toronto.

In addition to trees, it is threatening many native woodland flowers, like wood poppy, trilliums and asters. In turn, wildlife and insects are adversely affected as they lose their food and natural habitat. Garlic mustard is toxic to butterflies. If a butterfly lays its eggs on a plant, the eggs hatch, but larvae will not feed on it, so they die.

If you see it in your garden, rip it out by hand. Try to get rid of it before it goes to seed. It’s not enough to dig this up and throw it in the compost pile. Bag and throw it out with the garbage. The seeds can remain viable in the soil for five years, so it will take a while to eradicate it from a garden, if you have it.

If you find yourself with a big bag of garlic mustard, you can save some for eating. The leaves, roots and flowers are edible. One of the most popular ways to use the leaves is in pesto. I’ve heard it’s very tasty. I haven’t had time to make it though, I’m too busy ripping it up.


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