"weed" w rhizomes and tubers

Asked September 3, 2019, 3:07 PM EDT

I live in Detroit in a residential neighborhood. I have a back yard that was planted to grass seed over 10 years ago and which has been diligently maintained through hand weeding (always to the root) and never with chemical pesticides or weed killer. A healthy lawn will, by its nature, crowd out unwanted growth, and this has been my experience: I have been relatively weed free, with average maintenance, for several years. Six weeks ago I noticed a plant, or weed, I had never seen before, mostly restricted to the lawn. To my great dismay it has an aggressive rhizome root system: pulling by hand, with a hand weeder, is nearly impossible as the delicate tuber where the shoot meets the rhizome stem underground is like balsa wood, super delicate. I have been using a garden shovel and must dig deep under the plant to get at it, approx a foot diameter of lawn around the plant. One tiny plant, approx 5 inches tall, had a rhizome root extending, literally, 3 feet in two opposite directions! I have looked online and cannot identify or figure out a way to eradicate. Rhizomes will spawn other plants, but most are simply appearing on their own. I have saved samples in water.

Wayne County Michigan

4 Responses

I believe what you are seeing here is tree of heaven (Ailanthus altissima). It is an introduced tree species in Michigan. This species can reproduce by seed and root sprouts. Even seedlings can produce horizontal roots that can produce additional sprouts. If you have any larger tree of heaven plants nearby or in a neighbors property, then that could be a source. If not, then it likely appeared by seed deposition. If there are nearby parent trees I am afraid that you will continue to see shoots appearing from these horizontal roots.

Treatment using a herbicide will likely be more effective than hand removal due to the root system. Is that something you are interested in? If so, there are selective herbicides that could be used to affect only the tree sprouts and not the grass. Please respond and I will provide more information.

Thanks a lot Erin for the response. Yes, my continuing research after my initial email to you was leading me in the direction of this tree. What a nightmare! Upon boundary inspection, I see my neighbors property has a medium sized example. We are cooperative neighbors so I will attempt to eradicate that source as well as any other sprouts. My limited research does indicate herbicide as most effective, partly for the reason you mention above. I would love more information, and thanks in advance.


Once you eradicate the source, here are some herbicide recommendations.

In a lawn setting the active ingredient triclopyr would work well to control the tree seedlings while not harming the grass. This can be found in products such as BioAdvanced Brush Killer Plus. Triclopyr is active on broadleaf plants and it can persist in the soil for up to several months, so it is not recommended for ornamental or vegetable garden areas. The seedlings can be cut near the soil surface and the herbicide can be painted on the cut (within 5 minutes). The herbicide will be taken up into the root and rhizome system to help achieve a complete kill. Depending on your infestation level you may need to repeat this over time on other newly emerging seedlings to fully kill the underground system. Remember with any pesticide application it is critical to read and follow all labeled instructions for maximum effectiveness and environmental and personal safety.

Another option would be to use a glyphosate product (such as Roundup Weed & Grass Killer, among others), though this will harm the grass nearby. Similar to the triclopyr you can utilize a “cut stump” treatment. Instructions for this are explicitly stated on the product Roundup Super Concentrate. When using products containing glyphosate there are a few important points to consider. First, as with the triclopyr, remember to read and follow all labeled instructions. Second, glyphosate is a broad-spectrum herbicide, meaning it will injure or kill other plants contacted during the application, so care is needed to avoid green plant material, exposed roots, and injured bark of desired plants. Third, glyphosate is relatively safe in the environment when used as labeled. It adsorbs strongly to soil in most cases (i.e. clay and organic matter), allowing even sensitive crops to be planted shortly after application; meaning no carry-over issues are expected. Retreatment of the area may be needed depending on the degree of infestation. Finally, be sure that the product you choose has only the active ingredient glyphosate or glyphosate + pelargonic acid. Products with additional active ingredients may have other unwanted effects and may delay the planting of other plants in the coming season(s).

Both triclopyr and glyphosate are most effective for perennial control in the fall (now) but can be applied anytime the plants are actively growing (temperatures consistently above 50F).

Erin thank you again. I will get right on this. It's a big help.

sincerely, Greg