Horsetail Control

Question: I have Horsetail growing along a ditch on my property. I have tried 24D and Glyphosate with little success. However, I am not sure I am using the correct ratio of those chemicals. If those herbicides can control it, what ratio of chemical to water should I be using? I am using a small 1.5 gallon hand sprayer.

Is there any other herbicide that might work? If so, what ratio of chemical to water would you recommend for the herbicide?

Thanks for your help!!

responder: Erin Hill, PhD  Replied June 21, 2023, 1:48 PM EDT
response: Dealing with horsetail is always a tough situation as you are finding...here's a little more on why that is... Horsetail (Equisetum arvense) is a native, perennial, spore-producing fern with a prolific rhizome system that can grow to a depth of 6-10 feet or more. Field horsetail has two stem forms. The reproductive form appears as erect, unbranched, white to brown fruiting stalks (stems) which emerge in early spring and bear terminal spore-releasing cones (this is the version seen in your photos). Vegetative stems are green, branch in whorls and give the plant a bottle-brush appearance. These stems emerge later in the spring and should not exceed 2 feet in height. Field horsetail is a common plant/weed of shores/wet areas, landscapes, orchards and nursery crops. It is often found in areas of poor soil drainage or where the water table is high. It can also grow particularly well in sandy, gravely soils or neutral or slightly basic soils. Once established, field horsetail can tolerate many habitats.   Chemically treating the plant with herbicides is problematic because of the biology of the plant. The high silica content of the stems limits herbicide absorption and extensive root system often results in regrowth. Field horsetail is tolerant to most herbicides used in the landscape. Residents have had some success with repeated applications of glyphosate (the active ingredient found in Roundup Weed and Grass Killer, and other generics). As far as the rate goes, you're not permitted to use a higher rate than what is listed on the label. To give further advice about the rate I would need to know the exact product that you have as the percentage of the active ingredient, glyphosate, varies by product. I would also check for any environmental hazard statements with regards to applying this product near water...if there happens to be water in the ditch.   You can find some other suggestions for other herbicides from Iowa State University Extension in the following article: https://crops.extension.iastate.edu/encyclopedia/equisetum-biology-and-management  Be sure to read and follow all labeled instructions if you try something different to ensure that it is intended for this situation and to ensure maximum personal and environmental safety. Beyond herbicides there are some mechanical strategies, but they are not simple and some are probably not suited to your area. Here's what I usually include in reports for smaller, isolated areas...Mechanical control options include hand pulling shoots and what rhizomes/roots you can dig up. Plants can spread if rhizomes are chopped and not removed, therefore try to get as much as possible and dispose of in the trash, not in compost. By mechanically removing the parts you can get to you may be able to starve the extensive root system over time, but it will require constant vigilance over several years. This may also be achieved by repeated mowing, which may work in your case. A combination of mowing and herbicide application may also be helpful. You could experiment with spraying on freshly mowed material to see if you get better control due to the entry points created in the plants from mowing. If soil removal is an option, soil would need to be removed to 6 feet or more. If that is not possible, placing a geotextile fabric in a shallowly excavated area before back filling with new soil would prevent rhizomes from entering the bed. Fabric must be placed on the bottom as well as the sides of the hole. If this plant is found in a neighboring area that is not controlled/removed, reintroduction can be expected.  I'm sorry I don't have better solutions for your situation. Please let me know if you have any questions.

responder: The Question Asker Replied June 23, 2023, 7:47 AM EDT
response: Hi Erin,Thank you so much for the very detailed response in regards to my questions. Your explanation helped me better understand why this weed is so difficult and challenging to control.I do like your recommendation of mowing + chemical control and will pursue this direction. Hopefully this will address the problem or at least limit the weed expansion.Thanks again!Bob Kartanys    On Wednesday, June 21, 2023 at 01:48:27 PM EDT, Ask Extension <<personal data hidden>> wrote:

responder: Erin Hill, PhD  Replied June 27, 2023, 1:09 PM EDT
response: Bob, good luck and let me know how it goes (<personal data hidden>).  Sincerely, Erin