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A: There are those who suspect Wildflower Center volunteers are the culpable and capable culprits. Yet, others think staff members play some, albeit small, role. You can torture us with your plant questions, but we will never reveal the Green Guru's secret identity.

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Ask Mr. Smarty Plants is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.

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Thursday - June 11, 2009

From: Golden Valley, MN
Region: Midwest
Topic: Non-Natives
Title: Control of invasive non-native Alliaria petiolata (garlic mustard)
Answered by: Nan Hampton

QUESTION:

What can I do to control garlic mustard that has moved into my wild area and what should I plant to combat this aggressive plant? Ostrich ferns, Pagoda dogwoods and emerald hemlocks have been recommended.

ANSWER:

Alliaria petiolata (garlic mustard) is an invasive introduced European species that is on numerous Federal and State Noxious Weeds lists. The Plant Conservation Alliance recommends removing the entire plant (roots included) when the population isn't too large and you want to protect desirable native plants from possible harm from herbicides.  With larger populations cutting the plants right above ground level before seed set is another possibility.  This will have to be continued throughout the growing season to keep the plants from going to seed.  In either case, the plants should be removed from the area and destroyed.  If the population is very large, it can be controlled with careful application of glyphosate herbicide.  Please read the details of control measures in the Plant Conservation Alliance link.

Of the three possiblities for a plant to combat the garlic mustard— Tsuga canadensis (eastern hemlock), Cornus alternifolia (alternateleaf or pagoda dogwood), and Matteuccia struthiopteris (ostrich fern)—I would think that the ostrich fern would be most effective.   First of all, the hemlock and dogwood are relatively slow growing and require space between plants to grow—a ground space that the garlic mustard would happily occupy.  The ostrich fern plants can grow close together and; indeed, the ostrich fern is not recommended for small spaces because it is aggressive and tends to take over.  You certainly could have the ferns growing under and around either or both trees above if you would like to have the trees.


 

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