In message , Mike Armstrong
writes
Hi all,

I have a rather nasty case of horsetails. It has travelled from the
overgrown jungle of a garden next door. I realise that without
clearing it from next door I have no chance of permenantly eradicating
it, all I want to do is stop it from coming up from between my patio
paving slabs. If I pull them up then they keep coming back within
days and are 1 foot high within a week or two. They are actually
starting to cause the slabs to become uneven! Pulling them from
between the cracks is difficult as most often they just snap where
they emerge from the crack without any root coming up.

Your best value for money is probably to strim them off at ground level
and do the same to the jungle next door if you can get the owners
permission.

Chlorate under the slabs will discourage it a bit, but the stuff is very
water soluble and inclined to migrate downhill with runoff water and in
the soil.

Moving house is the simplest solution to horsetails ;-)

The 'tails are also coming up in my borders (I just keep pulling them)
and are travelling across the lawn (and patio) at about 3 metres per
year (I just mow them down). In a couple of years, my neighbours on
the other side could well start to have the same problem.

I tried Round-Up on an area of them with very little effect. I
realise that I need to 'roughen' them up a little before applying,
however the smallest amount of roughing up seems to just snap them.

You should be able to get a fair kill rate with glyphosate after
bruising the stems. But with a forest of the stuff next door you are
really up against it.

Driving slates down a couple of feet along your boundary will help a
bit. Equisetums are very deep rooted (and store a lot of energy in the
dark threadlike rhizomes) but many sideways shoots are in the top 2' of
soil.

I bought a tub of sodium chlorate as it claims to stop growth for 6
months, but having read the instructions I am actually a little afraid
of using the stuff!

It's the patio thats the big problem so my questions are :-

Is sodium chlorate going to be effective against this pest?

Marginally. I'd expect glyphosate to work better if applied right.

How best to apply it (pour it down the gaps between the slabs, spray
directly onto the weeds)?

The instruction don't say whether children/pets need be excluded. I'm
guessing that they do. Question is, for how long?

Put the weedkiller under the slabs. Otherwise the stuff will remain sat
where it was put until the next rain washes it into the soil.

How close to the grass is it safe to go?

Unanswerable it depends how much the land slopes. Chlorate weedkiller is
a simple water soluble inorganic oxidising agent that kills plants. And
as the instructions so coyly put it "may promote combustion".

Thanks for any help eradicating this beast of a weed!

You won't eradicate it. You might gain some control though.

Regards,

--
Martin Brown