Let’s start with a bit of pedantics. Horsetail (Equisetum arvense) and Mare’s Tail (Hippuris vulgaris) are two different plants. The first, although often called, incorrectly, “Mare’s Tail”, is a pernicious, invasive generator of swearing when it pokes its head up on our allotments or in our gardens. The latter, although it looks similar, is an aquatic plant. In this post I’m looking at ways in which I’ve managed to control, and, ultimately, eradicate Horsetail.

You’ll have to bear with me for the first bit as were I to simply tell you “method 1” for dealing with Horsetail, I would arguably be inciting you to commit a criminal offence. So, instead, I’m telling you how I found, by sheer accident, a way that worked.

I bought my present house as a new-build back in 1991. It was built on what had been farmland. Anyone who has bought such a property has probably noticed the appearance of horsetail about ten years after purchase when the roots that were buried under a mound of builders’ rubble and wotnot managed to grow enough to break surface. One side of my property abuts a now disused railway embankment. My plans to create a vegetable patch on that side of the house were thwarted by the waterlogging of ground caused by run-off from that embankment. I solved that problem by levelling off and paving the ground (now the location of a garden shed, greenhouse, barbeque and outdoor dining area) and building a soakway along the boundary to divert this run-off. As an aside, I discovered, during this process, that my side fence had been erected a couple of feet inside my boundary so I gained a fair bit of garden as a result.

Now one of the annual (or more frequent) jobs that you acquire along with large areas of paving, or decking, is that of dealing with algae. In my case, algae would appear more on the blocks of the soakway wall than in the paving itself. Being an anti-chemical chap, I initially dealt with the algae with a mix of jet washing and scrubbing. Meanwhile, Horsetail had appeared in one patch of the gravel of the soakway. Digging it out was not a practical option so I just pulled as much of it out as I could and waited for it to regrow, as it always did.

One day, I was asked to try out an algae killing chemical. This was in the days before many of today’s products had reached the market. I duly loaded up a sprayer (a 2-litre pop bottle with a pressure head) and sprayed the blocks. I couldn’t help also spraying the gravel on the soakway and the Horsetail shoots growing through it which duly died within about 48 hours. Some 15 years later, the soakway remains Horsetail-free. But a couple of years later, a patch of horsetail appeared through a gravel pathway elsewhere in the garden. I still had some of the algae-killing stuff so I tried spraying with it. Same result. Horsetail has not regrown. Incidentally, whenever I’ve done this accidental spraying thing, I’ve left the stems to rot down where they are. Doesn’t take long but it does mean that whatever is doing the job is clearly reaching the roots.

But there is always a but. Horsetail occasionally appears in odd patches around the gravel paths which I prefer to paved ones. I now use modern products to deal with algae, (Wet & Forget is, I’ve found, very good).  But, at least at the specified concentrations it’s not as effective against Horsetail as the original product I trialled, accidentally of course. I still keep some of that product in case.

Whilst this solution worked (works) for areas which aren’t planted or due for planting within about six months, I still needed something for those situations where the odd shoot appeared in the middle of a cultivated area. Whilst Horsetail is susceptible to Glyphosate, it’s waxy coating makes it resistant so the usual advice is to beat the crap out of it first to break up that surface. Horsetail is brittle and when you start whacking with abandon, you’re going to break little bits off and send them flying in all directions. Which you don’t want to do, of course. So, many moons ago, I did a bit of lateral thinking (well after drinking half a bottle of Southern Comfort I would be lateral!). Spray a plant with weedkiller and it gets absorbed through the foliage and finds its way into the central communication channel of the plant and so makes its way down the stem(s) to the roots. So why not, I thought, bypass the foliage and introduce the chemical direct into the stem. Technically it shouldn’t work, I suppose, but I found that it did.

You need a needle or, more correctly, a syringe and needlestick. Your friendly pharmacist may be able to provide you with the type that diabetics use to inject insulin but they’re not strong enough. So when I took resident cat for one of his annual jabs, I asked the vet if she could sell me a syringe or two. She gave me a couple. Nice.

I use pure Glyphosate, not Roundup. I don’t like Roundup. So I cannot say whether Roundup will work as well nor whether or not it will clog up the syringe in a way that pure Glyphosate does not. Using a pipette (with tiny little graduations on it) I mix up a very small amount of Glyphosate concentrate with the appropriate small amount of water, erring if necessary on the side of making the solution a bit stronger rather than weaker. You may, of course, try pre-diluted Glyphosate. Then I suck an amount of the solution into the syringe This works best if I pull the plunger slowly.

Using a pair of scissors or snips, cut off the top of the Horsetail shoot and pop it into something so you don’t just leave it on the ground. When you look at the cut end, you need to be able to see clearly the central core of the stem. If you can’t, cut a bit(s) more off the stem off until you can. Then gently push the needle into the top of the stem by an eighth to a quarter of an inch and SLOWLY eject a small amount of the weedkiller solution into the stem. You need to do this very gently and slowly or the solution will just bubble out around the needle.

SAFETY ESSENTIALS:

1. The needlestick will come with a protective cap. Leave that in place when you’re not actually sucking solution into the syringe or injecting it into the plant.
2. The needlestick is usually packed separately from the syringe. Be careful when screwing the two bits together.
3. Make sure you don’t accidentally squirt solution in the wrong direction. A doctor or nurse will need to remove any air from the syringe before jabbing you but you don’t need to be so careful when injecting a plant.
4. If the stem won’t stay upright or still while you’re trying to inject, hold the stem WITH TWEEZERS, NOT YOUR FINGERS!
5. After use, empty the syringe then suck some plain water into it and eject it carefully to keep the needlestick unblocked. Store somewhere very safe, preferably in a box. Don’t just leave the syringe lying around on a shelf.

Sometimes the Horsetail stem will show signs of die-back within a few days but usually I repeat the injection after a week, first removing another half-inch of stem to leave a soft end. Once the stem is dead, leave it in place for at least another week to make sure that the roots are dealt with as well.

This works reliably for me though, of course, I’m usually dealing with young stems. I’ve never tried to inject a foot-high plant, nor to deal with a large area of the stuff this way. I can’t offer any warranties and I’m conscious that so many bloggers offer solutions to so many problems that don’t work. All I’m saying is that I’ve been injecting the odd bits of Horsetail that pop up in my beds and borders for over 5 years. The technique has worked for me. I know of a few others who’ve tried it and tell me it works for them too.

Good luck. Of course, if you want something historically proven, you’ll probably find some idiot selling Paraquat on Amazon or ebay. Maybe under its other name of Gramoxone. Just make sure your will’s up to date first.