Guidance on Nimblewill

Question: I have Nimblewill creeping in from surrounding yards. I have been fighting the battle with Tenacity, but new areas just pop up. I have been applying 2-3 treatments 2 weeks apart as directed. Also using a surfactant. Areas that appeared to die off have come pack now at the end of summer, although the had not appeared once I applied as stated above. Is there anything I can do?  I am attaching photos. The first 2 photos are current/after several applications in different months of Tenacity. The last photo shows Tenacity’s affect during early application. 
Thank you very much in advance. I am in Livonia, if that matters in any way.

responder: The Question Asker Replied September 08, 2024, 9:00 PM EDT
response: Adding a few more photos in June and July showing Tenacity application. Thank you.

responder: Thank you for your question!   Laura S.      Michigan State University Extension Advanced Master Gardener Volunteer You may also contact the toll free MSU Extension lawn and garden hotline at 1-888-678-3464 with your gardening questions or visit www.migarden.msu.edu for Smart Gardening resources. Replied September 08, 2024, 11:32 PM EDT
response: Hello Diana Before I send this along to our weed expert, to confirm ID, please attach one or two more pictures of the nimblewill plant itself.  Take a small section dug up, laid out on a plain background, and photograph it from 8 inches away or so.   Spread out the stems and leaves  so we can see how they are arranged on the stem. Include a seedhead if possible.  It helps to put a coin or something beside it to give a sense of scale.  I attached a similar picture of nimblewill as an example of what is needed. Also, if you do not yet have them, here are Purdue’s and MSU’s Turf weed entries for nimblewill.  https://www.canr.msu.edu/ipm/diseases/nimblewill?language_id= https://turf.purdue.edu/nimblewill/

responder: The Question Asker Replied September 09, 2024, 10:00 AM EDT
response: Thank you for your prompt reply. Please find the attached photos. On Sun, Sep 8, 2024 at 11:32 PM Ask Extension <<personal data hidden>> wrote:

responder: The Question Asker Replied September 09, 2024, 10:06 AM EDT
response: Sorry. Sent before I finished attaching. Thank you!On Sun, Sep 8, 2024 at 11:32 PM Ask Extension <<personal data hidden>> wrote:

responder: Erin Hill, PhD  Replied September 13, 2024, 10:50 PM EDT
response: Diana, unfortunately using Tenacity for control of nimblewill and creeping bentgrass is not always effective in just one season. It is better at suppression than actual control.   More often the recommendation is to kill the area completely using the broad spectrum herbicide glyphosate. It will likely require to applications and you would need to wait to ensure it worked before planting new grass.   When using products containing glyphosate there are a few important points to consider. First, as with any pesticide, 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 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. Fourth, glyphosate alone can take up to 14 days to show full activity under ideal growing conditions. Retreatment of the area may be needed depending on the degree of infestation. Glyphosate is most effective for perennial control in the fall but can be applied anytime the plants are actively growing (temperatures consistently above 50F). For woody species, periods of heavy sap flow in the spring may not be effective times to treat. Finally, glyphosate is getting harder to find in the consumer market (i.e., big box stores) and Roundup brand products have been changing their active ingredients (even though the labels look similar) and moving away from glyphosate. Roundup Super Concentrate as of the summer of 2024 still has glyphosate only as the active ingredient. There are also generic glyphosate products available at stores like Tractor Supply Company. 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).

responder: The Question Asker Replied September 17, 2024, 7:58 AM EDT
response: Thank you very much for your guidance and information. Once I have killed it off, what is the best course to prevent continuous infiltration on all sides from my neighbors. Fencing is prohibited by city code.  This is my main concern, since as I watched it creep in over the last 2 years, and managed to get those areas under control, a new area crops up. It has been frustrating for sure. Thank you, again. I really appreciate any additional input you can provide.On Fri, Sep 13, 2024 at 10:50 PM Ask Extension <<personal data hidden>> wrote:

responder: Erin Hill, PhD  Replied September 17, 2024, 1:43 PM EDT
response: Without the neighbors also controlling this plant or fencing or some other type of barrier to prevent stolons from growing into your property, this is a tough situation. Putting in mulched ornamental beds would create a border, but that is costly and requires its own maintenance. You might be able to actively suppress it with the Tenacity once you've killed off your current encroaching plants and replanted, but this is going to continue to be a battle. The easiest solution may be to accept that something green is growing even though it might not be aesthetically ideal.    I am sorry I don't have better news.