The pinkish cones on fertile horsetail shoots are called strobil.
Considered a living fossil, horsetail (Equisetum arvense) is one of the oldest plants on the planet, primarily because it is one of the toughest to get rid of. Horsetail has an airy, fernlike look, upright like a bottle brush, with wiry, leafless 6-inch to 2-foot stems as well as shoots tipped with a cone that produces the plant's reproductive spores. Occasionally planted on purpose in gardens down to U.S. Department of Agriculture plant hardiness zone 2 for use as filler in flower arrangements, in basketry or herbal medicine, the plant spreads not only by spores, but through rhizomatous roots that, when broken, can form new plants from the tiniest piece. Eradicating the horsetail plant is a long-term project.
What Not to Do
When you're faced with a patch of horsetail growing where you don't want it to, don't start yanking or digging. When you don't get the whole root -- and you won't, some are reported to be more than 10 feet long -- more plants appear. Tilling the plants under garners the same results. Smothering the plants with black plastic or other mulch is not effective either, as horsetail thrives when conditions are wet, dark and low on oxygen. Sprouts emerge when the plastic or mulch is removed no matter how long the plant has been covered.
Chemical Control
Recommendations on chemical control of horsetail are mixed, with some experts saying that herbicides are only effective when applied numerous times, as the plants can resprout from the roots multiple times. Monsanto, the maker of glyphosate-based herbicide Roundup, says that because the plant has a high silica content and a waxy exterior, it just doesn't absorb herbicide well, though small infestations can be controlled by injecting the herbicide into the stems of the plants. University of California-Davis Extension advises use of 2-4,D, dichlobenil and chlorsulfuron, while University of Minnesota Extension recommends triclopyr when the plant is not in water.
Mechanical Control
While not a quick solution, horsetail can be controlled by eliminating top growth repeatedly and preventing spores from germinating. Cut off the green growth above ground on horsetail plants whenever it appears, and the plant eventually dies out. When you have a patch of horsetail that you are cultivating on purpose, you can control its spread both by repeatedly removing shoots in areas where you don't want them and by removing the shoots that produce the spore-filled cones. Do not compost the cones or any roots, though the green foliage of a horsetail plant is said to speed decomposition in a compost pile, and a tea made by steeping the plant's greenery in water can be used as an anti-fungal spray on plants susceptible to powdery mildew and blackspot.
Cultural Control
The most effective, though uncommon, approach to eliminating horsetail is to alter the conditions in which the plant is growing, to make the site inhospitable to horsetail. Horsetail thrives in wet conditions, so improve drainage by filling in low spots that hold water and install drainage ditches or small swales or dry streambeds to divert water. The plant also prefers poor, infertile soil so boost its nutrient content with chemical fertilizer or organic compost, aged manure or fish emulsion. Raising the soil's pH is a key element in a horsetail-control plan as well, since the plant prefers acidic soil. Add agricultural lime to the soil two weeks before or after the fertilizer for best results. Though it may take up to five years, the plants will go away on their own using this tactic. Keeping the greenery and spore cones cut hastens success.
Good Luck with your Horsetail elimination!
Marianne
Comments
Post a Comment