Giant horsetail (E. telmateia
) is similar to field horsetail but is taller and more robust, with sporebearing cones that are 4 inches long compared to the 1 ½-inch-long cones of field horsetail. Field horsetail can also be confused with the related scouring rush (E. hyemale
)—although scouring rush differs in that it does not have the two different stem types. Instead, the stems of scouring rush are all fertile and resemble the fertile stems of horsetail except that they are green and have two black bands at their joints. Scouring rush also seems to encroach into more drier sections of agriculture fields, this may be due to a higher water table or underground moisture in those zones.
All horsetail species are considered toxic to livestock (particularly horses), but are low in palatability and rarely eaten unless fed with hay. Field horsetail thrives in acidic, poorly drained sandy or gravelly soils and full sun. Although it is considered a wetland plant, it can also be found in drier areas.
Control of horsetail and scouring rush is similar, so this document will focus on horsetail management. Because horsetail does not respond to nitrogen fertilization and wants sunlight, its growth can be suppressed through the use of a fertility program and competitive cover crops. Other control options that have met with some success include use of inorganic mulches and weed barrier fabrics. Improving drainage in the area can also be helpful.