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Pest SolutionsPESTS + WEEDSUSING PESTICIDES OR HERBICIDES?
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Horsetail
Field horsetail (Equisetum arvense), giant horsetail (E. telmateia), scouring rush (E. hyemale)
Updated Oct 27, 2024
Make a Positive Identification
- Horsetails (Equisetum spp) grow in moist areas throughout the Pacific Northwest.
- They have jointed stems with feathery "foliage" that resembles a bottle brush. Most also grow fertile stems topped by a cone-like, spore-producing structure.
- All parts contain silica, which makes them rough to the touch.
- Horsetail spreads vigorously via rhizomes. In places where it is not wanted, it can be very difficult to get rid of.
Species: Horsetail
"Equisetum arvense" by douneika is licensed under CC BY-NC-SA 2.0
Horsetails and scouring rushes often grow in dense patches along stream banks, roadsides and irrigated areas. Plants spread underground with robust rhizomes and tubers. They thrive with full sun and moist soil. After plants are established they will tolerate seasonally dry soil. Horsetail is toxic to livestock when they eat large quantities or eat it regularly.
Species: Horsetail
Shaun Winterton, Aquarium and Pond Plants of the World, Edition 3, USDA APHIS PPQ, Bugwood.org
The jointed stems of horsetails grow distinctive thin leaves in whorls at each joint.
Species: Field horsetail
"Common Horsetail, Field Horsetail - Equisetum arvense" by tlhowes2012 is licensed under CC BY-NC-SA 2.0
Field horsetail (Equisetum arvense) grows cream-to-tan colored fertile stems in spring to early summer. They are unbranched, leafless and up to 12 inches tall. At the top is a cone-like structure that produces spores. These stems die after spores are released.
Species: Field horsetail
"equisetum arvense" by M. Martin Vicente is licensed under CC BY 2.0
The vegetative stems of field horsetail grow later in spring after the fertile stems. Vegetative stems are green, hollow, and grow up to 2 feet tall. They support whorls of delicate branches. These stems die with the onset of winter.
Species: Giant horsetail
"Giant Horsetail, Equisetum talmatiea" by born1945 is licensed under CC BY 2.0
Giant Horsetail (Equisetum talmatiea) is similar to field horsetail. The sterile stems with whorls of thin branches can grow up to 5 feet, sometimes taller. The leafless, fertile giant horsetail stems can grow up to 18 inches tall.
Species: Scouring rush
"Equisetum hyemale Tatton 1" by Photograph by Mike Peel (www.mikepeel.net). is licensed under CC BY-SA 4.0
Scouring rush (Equisetum hyemale) grows one type of stem rather than two. They are dark green, leafless, hollow, and segmented. Stems often grow to 1/2 inch diameter and up to five feet tall. Most scouring rush stems produce a spore-bearing cone structure at the top. These cones resemble field horsetail cones.
Look-Alikes: Tules, Bulrushes, Reeds, and Rushes
Species:
"Wood River Wetland" by BLM Oregon & Washington is licensed under CC BY 2.0
- Tules, Bulrushes, Reeds, and Rushes are common in wet areas around the Pacific Northwest.
- Similar to horsetail and scouring rush, many of these species have round, coarse green stems. They grow in dense patches.
- Unlike horsetail these plants are not toxic. They provide poor nutrition to livestock and may be difficult to control.
- They often support high-value wetland habitat in the Pacific Northwest.
Species: Tule and Bulrush
Troy Evans, Great Smoky Mountains National Park, Bugwood.org
- Tule and bulrushes (Schoenoplectus sp.) are in the sedge family.
- Common tule grows 3 to 10 feet tall. They are generally evergreen, with coarse textured, round, green stems. The stems have a spongy interior.
- Mature plants grow clusters of brownish flowers near the tops of stems.
Tolerate if possible
Common tule provides important resources to native organisms. It usually does not require control outside water conveyance structures. Control methods are similar to methods for horsetail.
Species: Rush (Juncus sp)
"Juncus swath meets wildflower meadow - geograph.org.uk - 867055" by C Michael Hogan is licensed under CC BY-SA 2.0
- Rushes (Juncus sp) grow smaller than common tule. They grow in bunches, up to 5 feet tall. Most species are much shorter.
- They have evergreen, round, green stems with soft interior structure.
- Mature plants grow clustered, brownish flowers from the side of the stem near the top of plants.
Tolerate if possible
Rushes provide important resources to native organisms. They usually do not require control outside water conveyance structures. Control methods are similar to methods for horsetail.
Horsetail Benefits
- Horsetail provides structure and nutrient cycling to plant and insect communities.
- People enjoy eating young horsetail shoots, but should not eat too much. Thiaminase is found in the shoots. Eating too much thiaminase will cause vitamin B1 deficiency.
- Horsetail is harvested by many Indigenous groups for medicinal and edible uses.
- Horsetail has been used in the past for scrubbing and cleaning pots. This gives it the other common name of scouring rush.
Horsetail Risks
- Horsetail grows in dense stands. It can block waterways and contribute to flooding and silting.
- In water conveyance systems it requires action.
- Horsetail is toxic to livestock. Its presence in hay products and forage is intolerable.
- Horsetail can be a nuisance in landscapes and lawns.
Risk Card
Does it cause harm?
Adults & Children
Low
Property
Low
Pets
Some
Annoyance
Some
Environment
None
Action Optional
Action Optional
If you have horsetail growing on your property where you can’t tolerate it, take action to control it.
Do I need to take action?
- Yes. If horsetail is growing in an area that you don’t want it to grow, then take action.
- No single method will completely control an established horsetail patch. Prevention is the best control.
What if I do nothing?
If your area is moist and sunny and horsetail is present, it will thrive if you do nothing.
Prevent Horsetail
Ohio State Weed Lab , The Ohio State University, Bugwood.org
Avoid introducing horsetail into your landscape
Only use clean imported soils and planting materials.
Watch for and remove new growth
- After you dig out horsetail or treat it with herbicide, rhizomes may grow new shoots.
- Look for new growth emerging in early spring and throughout the growing season.
- Stop spore formation by destroying the fertile stems before they mature.
- The best horsetail control is to prevent it from getting established. Monitor your property each year. Take action as needed.
Maintain conditions unfavorable to horsetail
- Horsetail prefers acidic and wet soil conditions with full sunlight.
- Well-drained, shady conditions with higher pH will discourage it.
Maintain healthy planting or turf areas to provide competition
- Apply nitrogen fertilizer to boost growth of grass and other desired plants. This will help to prevent horsetail establishment.
- Horsetail doesn't respond much to nitrogen. It will be shaded out by rapid growth of the other plants.
Solutions for horsetail
Early Detection and Rapid Response
Look for horsetail on your property every year and take action as needed.
Physically Remove Plants and Non-Chemical Options
- Cut stems near the ground and dig out rhizomes and tubers.
- Horsetail growth is reduced when water is limited. Inspect and fix water leaks. To minimize horsetail in your landscape or lawn reduce irrigation and promote drainage.
Herbicides (Weed Killers)
- Herbicides provide some control of horsetail when used according to the label instructions.
- All horsetail species stems have a thick, waxy surface. This reduces herbicide effectiveness.
- Consult a pest control specialist for guidance when controlling horsetail with herbicide.
Monitoring and Follow-Up
Return to the area and look for regrowth.
NEED HELP?
Consider a licensed pest control company. Learn How to Hire a Pest Control Company.
Your local Extension Specialist in Oregon and other states can suggest other methods.
Jump to
| Method | Does it work? | Is it safe? | Recommendation |
|---|---|---|---|
A Physical removal |
Effective |
Low risk |
Recommended |
B Smother or Shade |
Somewhat effective |
Low risk |
Recommended |
C Control Using Herbicides |
Somewhat effective |
Moderate risk |
Use if Necessary |
|
D If Using Herbicides, Protect Yourself & Minimize Risks
|
A
Physical removal
Non-Chemical Method
"2015.04.09_14.40.21_DSCN2242" by AndreyZharkikh is licensed under CC BY 2.0
Physical removal
Recommended
- Reduce horsetail infestation by hand-pulling.
- Completely remove the tops about 2 weeks after each emergence. This will eventually weaken the plants.
- Continue pulling every year as horsetail re-sprouts.
- Maintaining a healthy planting or turf area to provide competition can help to prevent horsetail establishment.
| Does it work? | Effective It is hard to permanently control horsetail. They have a high level of food reserves stored in the rhizome. |
| How much effort? | High effort It may take several years of dedicated pulling to completely kill horsetail. |
| What's the risk? | Low risk |
| Possible risk of exposure or harm from chemicals | NONE |
Ohio State Weed Lab , The Ohio State University, Bugwood.org
B
Smother or Shade
Non-Chemical Method
Master Gardener Volunteer, Oregon State University
Smother or Shade
Recommended
- Horsetail will eventually die out if it doesn't get enough sunlight.
- Cover with inorganic mulches such as plastic, commercial “weed barrier” fabrics or roofing paper. The horsetail cannot penetrate it, and the mulch will block sunlight.
- Organic mulches don't work. Horsetail will grow through even deep layers of loose organic mulches like bark or wood chips.
- Reduce vigor and growth with shade from plants or synthetic shading fabric.
| Does it work? | Somewhat effective |
| How much effort? | Moderate effort |
| What's the risk? | Low risk |
| Possible risk of exposure or harm from chemicals | NONE |
"Allotment" by scary_mary is licensed under CC BY-NC-ND 2.0
C
Control Using Herbicides
Chemical Method: Use with caution
Chameleonseye, iStock
Control Using Herbicides
Use if Necessary
Read the label carefully on combination products. Make sure the product is suitable for your specific situation.
| Does it work? | Somewhat effective
|
| How much effort? | Moderate effort
|
| What's the risk? | Moderate risk
|
| Possible risk of exposure or harm from chemicals | El uso de herbicidas conlleva cierto grado de riesgo. El riesgo más bajo se presenta con el uso de métodos alternativos. You may be exposed to an herbicide if you:
Follow directions closely to reduce risk. |
Some herbicides are available for home use. A few are listed below. These active ingredients, used in a mixture or individually, are suggested chemical treatments to control horsetail. Look for these chemical names in the “Active Ingredients” section of product labels.
- 2,4-D + Dicamba
- MCPP-P
- Triclopyr
- Sulfentrazone
- Ammonium salts of fatty acids
- Dichlobenol (pre-emergent)
Suggested active ingredients are from the Pesticide Information Center Online (PICOL) Database. They are permitted for HOME use in Oregon. Read the label for application directions and effectiveness information.
ONLY professional pesticide applicators can use Restricted-Use Pesticides (RUP) that may be more effective. For larger stands of horsetail contact a licensed pesticide applicator with experience controlling horsetail.
Herbicide Application Tips
- Most of these ingredients will damage most plants and grasses. Don’t let the spray contact plants you want to keep.
- All horsetail species stems have a thick, waxy surface. This reduces herbicide effectiveness.
- The site where the horsetail is growing will affect the herbicide product choice. Products are registered for use on different sites.
- Read the label carefully. Make sure the product is suitable for your specific situation.
- Monitor the area and repeat treatment each year, as needed.
- Consider consulting a pest control specialist when controlling horsetail with herbicide.
Herbicide Application Requirements for Aquatic Areas
- Aquatic-use products may not be approved for Home Use in your area.
- Consult a licensed pesticide applicator or your local university extension agent before purchasing or using an aquatic herbicide product.
- Herbicides applied over or near a water body must be registered for aquatic use.
- Treating horsetail near aquatic areas requires specialized skills. This ensures the herbicide is applied effectively. It also protects waterways.
Horsetail often grows near water. Consider hiring a licensed pesticide applicator to manage horsetail in aquatic areas. Contact your county Weed Control program for herbicide application information for riparian areas. Find contact information here: County Weed Control Programs
If Using Herbicides, Protect Yourself & Minimize Risks
Chemical Method: Use with Caution
FangXiaNuo, iStock
Why is it important to read herbicide labels?
- They have detailed information on how to use the product correctly and legally.
- They contain information on potential hazards of the product.
- They provide instructions you should follow for poisonings and spills.
- Following label instructions helps you to minimize the risks and maximize the benefits.
Key Herbicide Safety Tips
- Read the entire label front to back.
- Follow the instructions.
- Review the instructions even for brands you know.
- Only apply the product where the label says it may be applied.
- Be precise in your application. More is not better.
The Label is the Law
ALWAYS read the label before using herbicide products. The label is a legal document that provides information on how to safely use the herbicide. This helps avoid harm to human health and the environment. Using an herbicide in off-label ways is illegal. It can result in legal enforcement actions.
READ THE LABEL & Follow Instructions
It has instructions to protect you and the environment.
- Labels are different for every product and they often change over time.
- Use a magnifying glass for small print.
- Pay attention to CAUTION, WARNING, and DANGER statements.
- Pay attention to the PRECAUTIONARY STATEMENTS.
- The law states you must read and follow herbicide instructions.
Protect Yourself
Eye, skin & lung irritants
- Wear the right protective gear. This often includes chemical-resistant gloves, safety glasses, a long-sleeve shirt, pants, socks, and shoes.
- Mix outdoors or in a well-ventilated area.
- Wash hands after mixing or applying, and before eating or smoking.
- Take a shower immediately after handling herbicides.
- Wash clothes worn while mixing or applying separately from other laundry.
Protect Children & Pets
Children and pets are at risk if they eat or touch the plants before it dries.
- Keep them away during and after applying herbicides (read label for how long).
- Remove toys and pet dishes from yard before applying.
- Don’t track herbicide products into your home on shoes or clothes.
Protect Pollinators
- Apply in the early morning or evening when bees are less active.
- Kill weeds before they flower. Avoid spraying flowering plants.
- Do not spray on bees or insects.
Protect Plants You Want to Keep
- Glyphosate and similar herbicide ingredients damage both grass and broadleaf plants.
- Minimize spraying of foliage, stems, exposed roots, or the trunks of desirable shrubs or trees to avoid harm.
- Follow the label to avoid damaging the roots of trees and shrubs.
Avoid Wet, Windy, or Hot Weather
Use during favorable weather for best results.
- Don’t spray when it’s raining or when rain is expected in the next 24 hours.
- Wind causes spray to drift that can get on you and desired plants.
- Herbicides may be less effective in hot weather if the target plants are moisture-stressed.
- Some herbicides can turn into a vapor in hot weather and damage nearby plants.
Don’t Spray into Water
- It’s illegal to apply herbicides in a stream or slow moving/wetland pool.
- You need a product registered for aquatic areas. This includes waterways, ditches, drains, and other places where water collects.
Storage & Disposal
- Store in a secure area away from children.
- Don’t put unused herbicide products in the trash.
- Never pour down any drain or waterway.
- Take unused herbicides to a hazardous waste facility.
Call 1-800-CLEANUP (1-800-253-2687) to find out where to dispose of herbicides.
For the Portland metro region in Oregon, contact Metro’s Recycling Information. Call 503-234-3000, email or visit Metro’s website
More about:
About Using Pesticides on School Grounds in Oregon
If using pesticides on school grounds, there are special rules in Oregon. See School Integrated Pest Management (Oregon Department of Agriculture).
NEED HELP?
The National Pesticide Information Center (NPIC) can answer questions about pest control chemicals.
1-800-858-7378 or npic@ace.orst.edu
Consider using a licensed pest or weed control company. Learn How to Hire a Pest Control Company.
Your local Extension Specialist in Oregon and other states can suggest other methods.
Content provided by Weston Miller and Signe Danler. Pesticide safety information edited by Kaci Buhl.
Peer review facilitated by OSU Department of Horticulture.
HORSETAIL REFERENCES
Equisetum: Biology and Management
Iowa State University Extension and Outreach
Field Horsetail
Oregon State University
Weeds: Horsetails (Scouringrush) – Equisetum spp.
WSU CAHNRS and WSU Extension Hortsense
Horsetail and scouringrush (pdf)
Weed Research and Information Center, UC Davis