Issue No. 12, Article 9/June 10, 2005
Field Horsetail Biology and Control
We receive many calls and e-mails throughout the year about how to control field horsetail (Equisetum arvense). This plant is typically found in and along roadsides and around the outside edges of a field. It thrives in well-drained, acidic, sandy soils and full sun.
Reproductive stage of horsetail.
This perennial plant is native to North America and is one of a few plant species that have survived since the dinosaurs. Field horsetail is also called scouring rush, bottle-brush, snake-grass, and horsepipes. Many of these names come from the earlier use of this plant as a scouring pad to clean pans, act as sandpaper, and polish metal (Mitch, 1992).
Field horsetail is quite easy to identify in the vegetative stage, as it resembles a small evergreen, while in the reproductive stage it looks like a stovepipe with segments that snap apart. The rhizome and tuber system of this plant may extend to 6 feet deep and has internodes approximately 4 to 5 inches apart. This system then can spread from one rhizome stem to cover an area of 2.5 acres over a six-year period (Cloutier and Watson, 1985).
As previously mentioned, there are two forms of this plant, the vegetative and the reproductive. Both forms can be found in the field at the same time. The vegetative stems emerge late in the spring and look like bare pine trees or a horsetail (hence the name). The stems are green and erect to somewhat prostrate, reaching up to 2 feet in length. The stems are grooved and have many branches, ranging from 2 to 4 inches long, with black tips.
The reproductive stage is typically found before the vegetative stage. In this stage, the plant resembles a stovepipe. The stem is solitary, with no branches or leaves, and is light brown to dark green in color. The joints of the stem are dark brown and rigid, with a papery sheath covering the joint. Field horsetail stems can grow to be over 30 inches tall. Fertile stems have a dark brown cone on top of the plant. This cone is where the spores are produced. Once the fertile horsetail stem has produced spores, the aboveground portion will die.
Field horsetail can reproduce by spores, rhizomes, or tubers. Very little is known about spore production as it relates to this plant. However, we do know that the multiple means of reproduction contribute to why this plant is difficult to control.
The best way to control field horsetail is to not let it become established. This is easier said than done; although by cleaning off equipment, improving drainage systems, and having the right fertility program, establishment can be slowed or prevented. Horsetail does not respond to nitrogen, so fertilization to increase the ability of the pasture or crop to compete with field horsetail is also beneficial. Using narrow-row soybean is also beneficial in suppressing field horsetail because of canopy closure occurring prior to its emergence.
Tillage and cultivation work well to destroy the top growth and delay reestablishment; however, it will take many years to deplete the field horsetail of resources.
Few herbicides have any effect on field horsetail. In field crops, Beacon (primsulfuron) and repeated applications of MCPA can give some suppression. Python (flumetsulam) and Dual II Magnum (S-metolachlor) applied preemergence provide some residual control of field horsetail, whereas glyphosate applications have very little to no effect. In noncrop areas, diclobenil (Casaron), clorsulfuron (Telar), and sulfometuron (Oust) are labeled for applications. Be sure to read and follow the label prior to using any of these herbicides for control of field horsetail.
In conclusion, field horsetail is a very easy plant to identify but very difficult to control. Control measures should include a combination of tactics, including preventing the establishment and spread of field horsetail along with crop competition and tillage.
Cloutier, D. and A. Watson. 1985. Growth and regeneration of field horsetail (Equisetum arvense). Weed Science 33:358-365.
Mitich, L. 1992. Intriguing World of Weeds: Horsetail. Weed Technology 6:779-781.