Pernicious garden weed #749875 - Ask Extension


Pernicious garden weed #749875

Asked May 14, 2021, 9:32 AM EDT

What is this weed taking over my garden? We carefully pulled it up last fall by the roots and it's back with a vengeance.

Baltimore City County Maryland

Expert Response

This looks like Mugwort, a tenacious weed (as you have experienced) that can be challenging to eradicate because of its ease of reproduction from the smallest of left-behind root fragments. More information is available here:

Here are a few other photos for comparison, though most show more mature plants blooming or going to seed:  As you can see from the map, it is unfortunately found throughout our state.

While usually the method of last resort, systemic herbicide use here may be warranted as the simplest, most efficient, and most effective approach to killing it off. Even so, more than one application may be needed before the colony finally succumbs. Such products are non-selective, meaning any plant (desirable or otherwise) will be damaged by exposure, so apply carefully or find a way to shield desired plants from spray. To limited the quantity of herbicide needed, and to reduce risk from over-spray, you can pull or cut down all that you can first, and treat what re-sprouts since it will be low to the ground. As with any herbicide, follow label instructions regarding dilution (if needed), re-treatment intervals, weather restrictions, and so on.


Mira Talabac Replied May 14, 2021, 12:46 PM EDT

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