Use a funnel over the nozzle or spray against a piece of cardboard used to shield the shrubs. Add food coloring or spray die to see where you are getting the stuff. Accidentally sprayed areas can be washed off if necessary.

I don't think it's that great for horsetail, in fact I know of farm fields where it looks like they might be using glyphosate and getting MORE horsetail because of it (by killing off the competition). They're spraying something that produces similar visual effects to glyphosate, anyway.

For herbicides that are recommended for horsetail...

Here is a link that might be useful: PNW Weeds-Control of Problem Weeds - hogweed to jimsonweed

Roundup just kills it from the ground up. It will come back from the root. I have been pulling it for 20 years in my flower beds and haven't found anything that kills it. It's the worst weed there is.

A Coal Age relict, the only plant growing on parts of the Tacoma smelter site.

I solved the horsetail problem several years ago using Finale - purchased because the sign in our local garden center on the display read 'actually kills horsetail and blackberry' :) I treated not only what was popping up in my own garden and sidewalk strip of lawn, but the patch in the public area on the corner, and it hasn't reappeared.

I pulled the horsetail first, then got down low and either spritzed or painted (disposable foam brush)newly emerging regrowth. It took a little attention for more than one season, but the end result was horsetail gone, with very little product used. Same type application worked for blackberry - pull, cut, dig as best possible, then treat new growth.

Here is a link that might be useful: Finale

Having repeated the pesticides class for the 4th time at PCC, I won't forget the instructors words that RoundUp is not reliable to eradicate horsetail.

It will have an effect, and timing is the key.

Horsetail is naughty to get rid of. I remember putting a serious dent in some patches by spraying RoundUp when the foliage was grown and expanded, and clean of dust. But I also put down Casoron in the same area as a preemergent to kill cell division of new tips that would grow.

You may be looking at a 2 or 3 season project for control.

For that FINALE, the technical sheet download was revealing.

Finale was shown to be toxic to aquatic life. I'd estimate that the label will warn against use by bodies of water and streams.

The Lethal Dosage number was LD50, which, if that doesn't require a commercial license to purchase, is only 1 or 2 toxicity points shy of needing a license.

The most hazardous pesticides have LD50 ratings from 1 to 49 or 1 to 50.

So this Finale is either a Danger label herbicide or 1 number shy of the Danger label requirement.

It may do the job well, but it's a brutal enough chemical to be very careful with for safety and environmental reasons.

The label says that Finale kills only the green parts of the plant, not the root. It does not translocate, like Roundup. Horsetail has a diabolical network of underground stems. So Finale must be killing it by simply removing its leaves, so that the plant can't make food. If that's true, then you have to keep spraying the regrowth (as Morz8 did) or you have to kill the regrowth with Casoron (as mdvaden did).

It occurred to me that you can do the same thing without herbicides: just tear out every shoot that you find before it becomes big enough to feed the root system. If you are cleaning out a small area, this might be the easiest, safest approach. Or, if you are starting a new garden, try using black plastic to deprive the shoots of sunlight for a few weeks. Or rototill several times over the course of a summer.

Also, the label warns that there is some residual soil action which can kill bulbs. This, combined with the toxicity issue, makes me unenthusiastic about this product. Also, on page 6, the label says it should be applied by professionals only (unless I've misinterpreted that point).

This plant has underground stems over a wide area, so you can't kill it by destroying a couple of shoots. You will have to destroy shoots in a wide perimeter around your garden. Flowerfan2, maybe that's why you are not able to kill it.

It is very informative to learn that Roundup will be of no use and Finale is the better option. This weed has taken over about 1000 sq foot of my yard. It has appeared first in 2004, when we tried to pull out the roots. It reappeared with double force in 2005. I have spend long hours in 2005, removing the top growth by shearing off with scissors just the green portion of the growth in the hope of choking the food supply. However, it came back this year with equal strength and is begining to spread to my neighbor's yard.
I have read that rototilling causes it to multiply.

All the non-chemical options have been tried. I am concerned about the chemical use but at this point but the problem is going beyond control. If Finale is the next obvious option then it will be proper if some licensed persons to do this task considering environment safety. I would like to find out how to contact such experts here in Portland. Any information or help is appreciated.

Lazygardener I don't even know if a commercial operator would normally have this in their products, no license is required for application or I wouldn't have had it.

The label has the same precautionary statement as Roundup, do not apply directly to water - It was on the same shelf as Roundup and I compared labels before purchasing. Premixed pump spray, nothing to measure so nothing to wash or rinse of a concentrated form. Same price.

I think there might be a bit of confusion here - I admit to being thoroughly perplexed by mdvadens comment's, as my understanding of Finale is the same as Morz8's - an OTC non-selective herbicide available for purchase pretty much anywhere that sells such products.

Googling turned up two tradename Finale's - one manufactured by AgrEvo for open use and the second manufactured by Bayer, which seems to be restricted to commercial use. Both have WARNING labels (moderate toxicity) compared to RoundUp's CAUTION label (slight toxicity). Equisetum (mare's tail, horsetail) was listed as a controlled weed by Finale - too many different RoundUp formulations with rather generalized target information to get much from them.

My experience is that either CAN help control this very troublesome weed but it will take more effort than just applying a herbicide. Repeated applications will be necessary and I'd not expect very thorough control for at least a couple of growing seasons.

My personal view would be to attempt the RU method first, as it does have systemic properties Finale does not. Root control of horsetails is equally as important as the topical application - leaving the roots alive (as Finale's method of action would allow) is not much of a control, IMO :-) Combining this use with Casoron (which I'd avoid like the plague) would make some sense in open, infested areas, but Casoron (also non-selective) works by inhibiting the growth of root tips, so I'd certainly avoid using in an onamentally planted area.

And while it is not a listed method of application and therefore not entirely legal, I'd opt for painting full strength (concentrate) RU on the horsetail shoots rather than spraying. Drift of non-selective herbicides is nearly impossible to control and the direct painting method limits the amount of product that comes into contact with the soil. Finale tends to be highly soluble and will move through the soil easily, increasing the risk of groundwater contamination and affecting aquatic life.

Regarding root control - there have been a number of studies of horsetails done over the years. The persistance of this species is rather remarkable (they were present with the dinosaurs, so obviously highly adapted to a broad range of sitautions). One theory that has been put forth is that the root system is somehow interconnected - the roots of horsetails in one area are attached to those in neighboring areas. How much of this is true is debatable, as the spread of this plant is just as easily accomplished by the seeding of blowing spores. At any rate, controlling the plant in your own garden may be a moot point of neighbors don't or if allowed to grow unchecked in open, public areas.

Gardengal, thanks for the input, I may have added to the confusion by providing the wrong link? I didn't realize more than one product could have the same name.

I just came up from the basement with my container, and it reads Finale, Farnam Companies Inc. 1% glufosinate ammonium, 99% other ingredients. Large block letters on the front "Kills the Roots". But then it's been a few years since I've had any horsetail to treat; this container isn't anything recent and I couldn't say if the label may have changed.

I have just spoken to a gentleman from the local yard maintenance. He has suggested that horse tail roots do usually go don;t more that a foot in to the soil. Digging out the roots from the 1st foot of the soil. It may be a labor intensive process considering the spread. He mentions that chemicals may not help.

-lg

This may be totaly off the point, or to the side of it, but when I bought my cottage in southeast portland, the septic tank inspector came, and after I had spent a whole sunday digging a criss cross grid in my back garden in the freezing January rain to locate the stupid tank,(the folks who owned it had rented it out for years, retired to arizona and said they didnt remember exactly where it was but they had been cool landlords, and offered me a fantastic deal, so....) the guy accepted my 75$ inspection/permit thing, looked around for a few seconds, signed off and started to leave. I asked him how come he didnt need to look around any more than that(all that rediculous digging was still making me cross) and he said, "I dont see any horse tails, and thats a pretty good sign that its still doing ok" I have no idea if he was kidding, but its given me a new way of looking at little ditches full of horse tails....

Gardengal...

(First, I hate not being able to edit these posts, as I missed puttng the 50 after the LD50 number. Finale's chemical is an LD50 of 50).

So, here's what I was saying in different words.

All pesticides are rated on a "kill 50% of a rat population - consistently".

Caution chemicals have LD50's from 500 on up to infinity.

Warning chemicals - more lethal range - have LD50's from 50 to 499.

DANGER chemicals - most lethal range - have LD50's from 1 to 49.

Most restricted chemicals that need a commercial license, are in the 1 to 49 range. So, Finale's chemical, at 50, is one digit away from the DANGER label.

Some chemicals - say aquatic stuff - have LC #s for "Lethal Concentration". Most herbicides on the shelf are LD for "Lethal Dosage".

The LD50 rating does not reflect other issues like carcinogenic. For example, Amitrol, an herbicide sometimes used by roadsides and in fields that turns foliage a pretty pink, has a fairly high LD50 rating: not high in toxicity, but a very big number. It would seem safe. But it's restricted since it can cause cancer of the petuitary gland. It used to be a "Caution" chemical, until a lot of highway workers and the sort, started to get cancer. Then it was put on the restricted list. Prior to that, it was known that it caused cancer in certain mammals.

This is part of the reason that I dropped my Pesticide Consultant and Applicator license in Oregon, to downgrade my herbicide use to personal use at home instead of commercial.

There is too much that's unknown yet. For example, an administrative person with the Oregon Dept. of Agriculture, said that there is no information about how the residue of several herbicides interact in the human body.

And even with gloves and respirators, there is always some minor contact with herbicides and insecticides.

So, I'm not afraid of them. But after years of professional applicating and college classes on the subject, I see no need to handle volumes of pesticides anymore when there are other things to do like water features and pruning.

Oh..yes..

You can buy on the shelf, non restricted. That's basically LD50's of 50 on up. So that's why Finale is on the shelf; as are others with LD50's from 50 and upward.

According to label info I downloaded, it reported an LD50 for oral toxicity of 2030, dermatological toxicity of 1390 and an inhalation toxicity 3.73 after 4 hours. You can see where this was confusing as these numbers didn't match what you reported at all.

It became even more confusing when I discovered two separate manufacturers with the same tradenamed product - one really must be careful of the info they pull from the 'Net :-) A bit more hunting determined that Scott's sold Finale USA to Farnam Companies in 1999. How Scott obtained this product from AgrEvo Environmental Health was not disclosed nor was the apparent subsequent sale/transfer to Bayer Crop Science, for which they received EPA approved registration for Finale in August of 2000!! More info than I wanted to know, not enough to feel really comfortable with, too much time spent hunting down reliable info and not really any help at all in controlling the OP's horsetail problem.

I understand about the pesticide licensing. I too hold a Pesticide Consultant's license, obtained for reasons related to my job and business - just didn't feel comfortable (or legal) purchasing any type of pesticide for resale or providing recommendations for them without it. Having said all that, I decline to use anything other than what are considered organic or biocontrols myself but still need to keep up to speed to intelligently inform others and answer questions.

lazygardener, my comment about rototilling needs to be taken in the context of the paragraph that it was in. I was brainstorming ways to keep the horsetail from manufacturing food. One way is to keep rototilling often enough that the plant can't make new shoots. These plants are not supernatural; if they don't have food, they will eventually die. There are two reasons it may take a long time. One, the underground stems may have a lot of food stored in them. Two, the plant may have green shoots far from your garden that you haven't found yet.

In your case, the rototiller approach is not practical, since your landscape plants are already in.

I killed a whole field of these plants, but it was ages ago, and I don't remember all the details. I do remember that part of the fix was Amitrole T. I don't think I would do that again. Too toxic.

Gardengal...

My source was good. I think I was reading too late at night.

In fact, the MSDS sheet download from the Bayer company link provided in an earlier post, shows that Finale has an Oral LD50 of...

3,570

That's from the Finale Material Safety Data Sheet pdf download.

If that's the case, it's probably safer than a lot of beverages.

The link earlier in this thread has several downloads for Finale.

And double check my data on that. There I was reading that fine print in the late evening again !!!

I have learnt that the correct chemical to use is
a combination of RU Pro and Crossbow. 2 ounces of RU concentrate and Crossbox each, mixed with 1 Gal water plus some soap water is the combination most yard professionals would use. I am not sure where Crossbow can be purchased from and how safe it would be to use it. It may be necessary to destroy few of my perennials also since it may not be easy to separate them from the weed that easily. Around the shrubs I have been told to remove the weeds manually and later spray as weeds reappear. In the open areas, simply spray liberally and on the grasses use Crossbow only.

-lg

Crossbow is available on the shelf now - isn't it?

If anyone is near Jacksonville (I'm in Ruch), Oregon, and you just need a few ounces, feel free to send an email.

I must have half a gallon of Crossbow left. The label fell off, but I recall mixing 1 oz. per gallon. I'm sure it's label is online too.

Anyhow, I have not used any of it in 2 years, and would be glad to share a few ounces here and there.

All the chemical talk is depressing me. I always look at a good digging-out session as my aerobic excercise--no gym membership necessary.
Here's an excerpt from an article by Ann Lovejoy. Even if you do go the poison route initially, the following sounds like good advice for lasting control. Good luck!

"Horsetail is harder. Small areas may be cleared in a season by persistent cutting, coupled with thorough digging out of roots. Larger areas can take several seasons to clean up, but by continually cutting the tops, you eventually starve out the roots. However, two more steps are needed to keep horsetail defeated.

Horsetail is an indicator plant, telling us that somewhere on the scene is dense, damp soil that's low in oxygen and high in moisture. It's tough to get rid of horsetail in the maritime Northwest, where acidic, airless clay soils abound. To make things worse, our native soils also tend to be very low in humus, the organic material that feed soil-dwelling biota.

This is true of most rain-forest soils. Left undisturbed, these soils support an exceptional range and quantity of plants. Once the forest is cleared, the organic material is quickly used up and plants don't grow well. To improve the situation, we need to replenish the soil's organic matter so stored minerals and nutrients become more readily available to plants.

Unlike garden plants, horsetail doesn't mind lean, depleted soils. An established stand of horsetail has spreading roots that can penetrate deep into the subsoil to find what the plant needs. With roots like that, and a rebounding habit, it's no wonder that horsetail is not welcome in garden beds. The best and most lastingly effective way to get rid of established horsetail is to alter the soil situation by adding oxygen as well as humus.

Start by trenching out your pathways and lining them with crushed gravel. Paths that are lower than the surrounding beds will act like French drains, pulling excess water away from the plant roots.

By dropping the internal level of the paths even slightly, we can direct the water off the garden site. The path can remain level to the eye and foot, but the trench beneath the surface should drop about 3 to 4 inches over every 10 feet of run. At the end of the water's hidden path, plant a bio-sponge of dwarf willows, redtwig dogwoods or other water lovers that thrive in heavy, damp soil.

On heavy clay soils, it is critical to mound beds rather than excavate them. Digging out clay beds is like making bathtubs in which to drown your plants. Resist the impulse to dig; instead, build up. Today, soil scientists tell us not to double dig or till beds, which disturbs the biotic colonies. Instead, simply layer on amendments such as compost.

When fighting horsetail, compost and composted dairy manure are excellent amendments, helping to open up and nourish the soil. To build a mounded bed, layer on compost blended with topsoil or a mixture of crushed sand or sandy loam, making the mounds deep enough that you don't need to work into native soil when planting.

Mounded beds don't need boxes or edging; just shape them attractively, then mulch with 2 to 4 inches of compost and plant whatever you like. For vegetables and perennials, and even many shrubs, a foot of mounded soil is plenty.

Aerobically brewed compost teas are also great weapons against horsetail. Spraying these living teas monthly can significantly alter the nature and texture of dense clay. Even diluted, brewed teas can help combat horsetail by improving the soil. If you've got good tea, you'll notice a definite improvement within a year."

Annuka, your posting is wonderful! Most helpful and clearly written. thanks, I'm saving it.

I'm not sure I'd agree with Ann's statement. I've seen horsetail in all sorts of soil conditions, including those that were heavily amended into loose, organically rich and very well draining - in short, ideal gardening soils. And I've also seen horsetail brought into formerly uninfested gardens through the incorporation of imported "topsoil", compost or other bulk amendments.

I think relegating the problem just to specific soil conditions is a bit simplistic.

And while I personally avoid the use of any chemicals in my garden and encourage others to do so as well, sometimes that is the only practical or even slightly efficient means of control.

Sorry, I should have just posted the link. I left out this important part... cut- don't pull:

"Native colonies of horsetail should be left in place along natural streams, bogs and wetlands, where the plant is an important member of the ecological community. However, when horsetail arrives in the garden with topsoil or on another plant's roots, kill it before it multiplies.

"Happily, newly transplanted horsetail is not hard to eradicate. The trick is to dig out all the roots before they get established. If any persist, cut the shoots when they are between 6 and 12 inches high. Pulling triggers the production of new shoots, so never pull, always cut.
Waiting until the shoots are a certain size depletes the storage roots. This works especially well on immature, poorly established roots. However, it is also an important part of the program for eradicating mature, established weeds of many kinds.
The seedless tops of most weeds can go in the compost. However, never put even a tiny scrap of weed root in the compost. Bag or burn the roots, which can resprout pretty much year round."

Here is a link that might be useful: Seattle PI article

This Seattle PI writer continually publishes a mix of truth and fiction, particularly when it comes to controlling weeds and other pests. She was the one who earlier maintained that horsetail could be eliminated by Blackberry & Brush Blocker, a vinegar based herbicide. This has not been backed by the experience of anyone I'm aware of, nor of any controlled trials. The linked article above, while containing some truth, includes unsubstantiated information. The studies I'm aware of show no effect of amending soil as a way to control established horsetail. Nor is there is any evidence that application of dilute compost tea will control horsetail. And her only recommended technique for controlling "false bamboo" (Japanese knotweed) is by cutting, which is a method that clearly has been shown not to work well in trials by the Nature Conservancy, and must be done every 2-3 weeks over several growing seasons to even begin to make a dent, and often only results in increasing the spread of the clump.

mdaven_of_oregon, Thanks for the offer. I will keep it in the bank right now. I am in touch with a contractor who can obtain it from his sources. I will probably end up asking contractors to do this work of relocating few perennials before spraying the RU + Crossbow mixture. There is also some additional work like a small retaining wall and sprinkler repair etc in the yard. With a new baby in the family and longer hours at work, this is my only option. Any contractor reference is welcome, I live close to Hwy26 on Bethany.

-LG

Lazygardener...

I just noticed the Beaverton in your "sig" line.

Oh how joyous it was to move from there last July, to this Valley here. (My site link is in "my page" and there's a page for our new area).

West Portland suburbs are nice though. I'd live there again when I'm out of the workforce and not in need of driving in heavy traffic. Activity-wise, I like it up there.

My family moved to Beaverton when the population was about 9,000 - 10,000 in 1963. Even in 1980, I was able to drive from Murray x Scholls Ferry (now Murrayhill) all the way to Rock Creek PCC past West Union x 185th in 15 minutes to reach my 6pm class. And half those trips were non-stop making every signal on the green.

There is a landscaper in Beaverton / Tigard.

Dan Bond

He's in the Washington County phone book - should show SW 128th in Tigard.

He's conscientious and well trained. Nobody in town has better manners than this man.

If you don't find him in the book, my email is at www.mdvaden.com

But I think you will find him.

And for trees, the best person I've found is Justin with Roots and Shoot out of Portland area. Collier is great too, but Justin is a bit less, and he's usually the one working.

Almost forgot...

Look in the White Pages, not the Yellow Pages, for Dan Bond.

I think the solution to removing horsetail permanently is to mail it to me. Then I plant it in my pond, where for some curious reason, it promptly starts to weaken and dies before winter sets in, never to return. At least that's what happened with the horsetail I planted in the pond on purpose because I think it's cool, and I wasn't too worried about invasiveness in an above-ground pondlet (about bathtub size) sitting on a cement patio. I killed it. Dead. And not because I was trying to kill it.

Lisa

Speaking of local infestations, this area has for some years now been supporting a veritable gang of gardening talking heads who do not all limit their talking (and writing) to factuality.

mdvaden_of_oregon ,

Thanks again. I will surely look up Dan Bond. If I don't
find him I will send you an email.

BTW, these days Murray x Scholls Ferry to Rock Creek PCC at 6 PM will take about 25 minutes.
The sunset hwy has become a 3 lane highway, that has been
helping us a lot.

-LG

This is a timely topic. My husband and I are hoping to transform a weedy patch at the back of our new yard into a veggie garden. The area is shot through with horsetail. I've never fought this particular foe, but here's our plan--we'd appreciate any thoughts you all have to share...

This spring, we scavenged cardboard from anyplace we could get it and laid out a layer or two of cardboard over the whole area, about 15 feet by 25 feet. The weeds were basically just trampled underneath, though we did spray some Roundup on the stray weeds poking out around the edges. (The horsetail did seem pretty responsive to the RU--no clue how far along the root system that went, though.)

We then marked out where the beds and the paths would be. Where the paths are, we laid out a few inches of bark chips on top of the cardboard.

Where the beds will be, we laid out black weedcloth, basically to hide the unsightly cardboard! Our intent is to leave the garden-to-be in this state until at least fall, maybe next spring. When we're ready to plant we'll layer several inches of Cedar Grove topsoil on the cardboard and plant directly in the topsoil.

Hopefully by then all the weeds will have been smothered, and the cardboard will be weak enough that roots of our desired plants will be able to penetrate through.

Seem like a reasonable plan? Anyone have any better suggestions?

Much obliged!

Angie Kantola

It is not a bad idea. But next year, I am willing to bet that HT will break through the card board and plastic in which you will need to be ready with RU in the spring.

-lg