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The Monday Garden
Garlic Mustard: The Invader's Edge

Issue No. 54 - April 6, 2003
by Sue Sweeney

  

The word ďAprilĒ comes from the Latin "aperire" meaning "to open".   In my zone, first come the trees, lead by red maples and elms.  Also ahead of the pack are invasives like the garlic mustard (Alliaria petiolata), growing in a wooded lot near my grocery store.

Invasive critters, like the Asian Longhorn beetle and the Norway rat, can sneak in the country but invasive plants need to entice humans into importing them.   In the case of garlic mustard, early European immigrants valued this biennial member of the mustard family because it tastes, well, like garlic.  Adding to its charm, itís high in vitamins A and C, and easy to grow in moist part-shade.   As an evergreen, itís readily available in fresh form all winter, which was a particularly good thing before supermarkets.

But being likable isnít enough.  That just gets you into the garden.  To be invasive, you have to spread fast and beat out the local competition by hogging the light, water, nutrients, and space.  Unfortunately, garlic mustardís chief competitors include our beloved spring beauty, wild ginger, bloodroot, Dutchman's breeches, hepatica, and trillium.  

Garlic mustard has infested 29 states and southern Ontario.  It does it by soaking up the rays all winter while the competition is dormant under ground.  It stays low (as pictured) through its first winter, taking advantage of the insulating snow, warmth of the earth, and winter sun.  Then it shoots up 2í to 3í, with clusters with white or pink cross-shaped flowers in May.  By July, itís gone, leaving only the upright, banana-shaped seed pods characteristic of the mustard family.

Curiously, the experts arenít sure how garlic mustard spreads.  They know you canít blame it on the birds or the wind.   While the plant makes thousands of seeds that remain viable for years, they fall close to the parent.  The white-tailed deer helps by clearing ground that garlic mustard then can take over.  But how does it move from site to site?  Best guess is animal traffic.

Getting rid of it: There are similar-flowered native plants, so first check a crushed leaf for the garlicky smell.  Then pull it up, making sure to get all of the root, or keep it cut to the ground so it canít flower.  Herbicides and fire are also used (this is a cure?).   Whatever, keep it up for at least five years.  Meanwhile donít put the roots or seeds in the compost or garbage; place them in a black plastic bag in the sun for several months to sterilize.  (Since this it what it takes to kill the stuff, you can see why garlic mustard is winning). 

Better idea: Successful invaders have fewer pests than the local competition.   Since humans are the most effective pests for garlic mustard, The Brooklyn Botanic Garden suggests we start eating it again.  See the pesto recipe from The Wild Vegetarian Cookbook at http://www.bbg.org/gar2/topics/kitchen/2002fa_garlicmustard.html.

Caution: Never to eat plants grown near a road or driveway.  Heavy metals from car exhausts poison the ground and end up in the plants for decades.  Also beware of old industrial sites, dumps and illegal dumping sites.

  
From The Monday Garden. Copyright © by Sue Sweeney. Reproduced with permission. 

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