Mugging the Mugwort

Mugwort plants in blackberry patch

Some weeds are just misplaced flowers, and some are just plain impossible.

One of the impossible weeds at Meadow Glenn is mugwort (Artemisa vulgaris).

Some of mugwort’s common names range from the descriptive to truthful. 

“Chrysanthemum weed” is descriptive. Mugwort’s leaf shape and aroma somewhat resemble those of garden chrysanthemums. “Felon weed,” however, tells the real story. What this weed does to gardens is nothing short of criminal because once it’s established in a garden, it is next to impossible to remove or kill completely.

Mugwort was well established at the south end of our house when we moved here 14 years ago. Knowing nothing about the weed, I cut, hoed, dug, and pulled mugwort during the spring and summer months for several years. In an additional fit of ignorance, I planted a blackberry bed where I had just dug out mugwort. Now, years later I still fight mugwort in our blackberry bed every spring and summer. It’s the weed that just keeps growing.

Mugwort's 'persistent' underground stems

Weeds of the Northeast (1997 edition), the handy reference work by Uva, Neal, and DiTomaso, hints why my past battle plans have failed: “Rhizome fragments [underground stems] can be transported by cultivation or with infested balled and burlapped nursery stock, topsoil, or composted organic matter. … Its persistent rhizomes make mugwort difficult to control in perennial crops. It is also well adapted to mowing and cultivation and is relatively tolerant of most herbicides.”

In the past, every time I tried to dig or hoe mugwort, I broke up the weed’s underground stems or rhizomes. If a plant had four rhizomes and I broke each into three pieces, I likely ended up with 12 new plants.

That’s why a premium crop of mugwort grows in our blackberry patch. But enough is enough, and I’ve decided to get serious about eradicating this plant pest. Mugwort often survives selective, broadleaf herbicides such as 2,4-D. It’s time to use the ultimate weapon, glyphosate, a non-selective herbicide that kills most plants.

The University of Maryland Master Gardener Handbook explains that glyphosate “stops growth by interfering with amino acid synthesis. Growing plants slowly turn yellow and stop growing, and the entire plant eventually turns brown and dies. Glyphosate is quickly bound to organic matter and has no residual activity in the soil….”

Yes, I’m going to use glyphosate on the mugwort, but I’m not going to spray with abandon. One reason is that I don’t want to risk having the herbicide drift onto my blackberry plants. Another is that I try to use a minimal amount of pesticides of any sort.

Weeded bed awaits new mugwort sprouts

On Monday I took my Cape Cod weeder and uprooted all the mugwort I could in our blackberry patch. On the surface, the bed’s looking good now. But as I weeded, I could hear underground stems snapping, so I know that in a week or two, new mugwort plants will be sprouting from each of those fragments. I plan once a week to check for mugwort sprouts and then spray the emerging leaves with glyphosate.

After all these years of battling mugwort, will I finally win the battle in 2011?

That’s my plan.