You may want to consider leaving the horsetail if it's growing in a riparian zone. They are a benefit in more fragile ecosystems such as riparian zones and wetlands. The deep roots act as nutrient pumps in wetlands, transporting phosphorus, potassium, and calcium to the soil’s surface where other plants can then access them, boosting the overall vitality of the ecosystem. Horsetail’s adaptability to low-nutrient environments as well as its tolerance of salinity mean it can handle the “stressful soil” that many other plants cannot survive.

Areas where you might want to control this 'difficult to control' plant are areas where livestock might be present, as it is potentially toxic to livestock, particularly horses. Or if it is present in a garden bed located away from a riparian area. Control will be difficult and requires a multi-pronged approach over multiple seasons.

Altering moisture availability by improving surface and subsurface drainage will help with control, but you will need to deplete the energy reserves of the rhizomes by removing the stems every 2 weeks during the growing season. This process can take 3 to 4 years to achieve success. Combining with chemical control can help with control.

Glyphosate is most effective for perennial control in the late summer to early fall when plants will translocate the most to their root system, but it can be applied anytime the plants are actively growing (temperatures consistently above 50°F). Be sure that the product 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).

If there is visible water located near the site at the time of application or it is along the shoreline of the Great Lakes or Lake St. Clair, a permit is required prior to making an herbicide application; contact the Michigan Department of Environment, Great Lakes, and Energy (EGLE) Aquatic Nuisance Control Program Staff at<personal data hidden> for more information. Also, a list of approved aquatic herbicides needs to be consulted on the Michigan EGLE website (https://www.michigan.gov/documents/deq/wrd-anc-approvedherbicides_445623_7.pdf). Ingredients in nonaquatic products may be toxic to fish and other aquatic organisms.

All of this information including more details on this topic can be found in Dr. Erin Hill's article, published this year:

https://www.canr.msu.edu/resources/field-horsetail-a-plant-as-old-as-time