Saturday 9 September 2017

Elimination of nettles and ground elder: victory declared

Ground elder almost gone in just over two years
(scroll down to find nettles)
 Just demonstrating using pure water!
I am standing on ground that 28 months ago was solid ground elder
For some peculiar reason my original post under a similar title has been read 40,000 times. It would seem that many gardeners have trouble with these weeds! My original project spawned a continuing series of posts about Cathi’s grass verge and this will serve as a weedy update for those of you who have skipped the details of developing this garden feature.

This looked like the picture below 16 months ago
Note the sneaky self seeded nettles too
As to nettles I claimed victory before the end of the first season. The strong stands of nettles were completely killed by the first two or three applications of glyphosate and/or MCPA. (MCPA  bought as Agritox is particularly effective against nettles)
As I explained at the time nettles will always be with us as new ones develop from seed and join the pantheon of weeds from seed that will always need repeated attention. Even now In my own garden I often spot a nettle that has sneakily infiltrated a tall plant. It gets immediate attention with whatever tool I have in my hand be it border spade, fork, trowel or secateurs. I even enrol my hankie to pull it or for small ones more bravely use my bare hand. I even slide in with my boot. 
It will have seeded  from an earlier intruder I have missed!

A week before Open Day and I spot this
I hold no truck for those foolish people who grow nettles on purpose in the misguided and largely discredited belief that they provide unique habitat for rare butterflies and moths. When did you last see any caterpillars on your nettles?
For that matter when did you notice a shortage of nettles? I just cannot believe anyone should want to grow them. 
In another context growers of wild flowers denude their soil to reduce the vigour and discourage weeds such as nasty nettles. The only good thing about having nettles is when they take over a garden it does indicate high fertility!

Ten years ago I replaced the farmer's verge of nettles with helianthus so loved by the bees
My claim for eliminating ground elder is bit of a cheat in that the two year period in which I claim to have slayed it includes several months of its third Summer season of growth and even now some are still there. I make my claim that although by Summer 2017 some remain it is no extra inconvenience to my routine and very speedy weed control. Other than myself no one sees any there. It is weak and sparse and easily targeted. 

The problem of ground elder

I have previously stated that it is one of gardeners’ worse weeds.This is a little unfair as it is not particularly unattractive and does not stand out as a weed. Introduced by the Romans it is edible ground cover. A dear lady who managed a cemetery garden in Bath put a label on it and it was generally admired. As a complete ground cover it does the job very well especially if mown or strimmed after flowering -
even under shrubs…..

The variegated form looks rather nice
As my articles illustrate it takes a few years to get rid of ground elder by repeated spraying but it eventually goes. The real problem is when gardeners try to chop it out. The fine long lived roots are very insidious and intimately infiltrate between the roots of perennial plants and traditional cultivations spread it all over. Innocent gardeners donate infested herbaceous perennials to friends and bingo they have a new weed. They only start to notice when the ground elder starts to take over. and then it’s too late.
The reasons not to chop it are even more subtle than I have already suggested. I have explained that if it has been cut into small pieces and gardeners have failed to pull it all out - as they inevitably do - that chopped pieces rejuvenate erratically and new and for spraying necessarily well developed leaves cannot easily be treated. In this unhappy situation you need to leave it alone for several months of its growing season before you can spray it. When I was a weed control trouble shooter my easiest clients who needed elimination of such as couch grass were those who'd given up completely and intact weed abounded. Couch was nearly all eliminated after my very first spray. For those who had faffed around it took very much longer.
No the real problem is the distribution of small pieces of root. Any new plantings over the first three years might meet severed ground elder roots and be intimately infiltrated. A year or two later the herbaceous clump is more weed than plant. (It is much easier to control under shrubs)

It regenerates in almost exactly the same place
A key thing that has now only belatedly dawned on me is that the intact sprayed ground elder clumps not only still receive translocated herbicide even when some leaves have been missed but that more significantly repeatedly regenerating new shoots appear in more or less the same place. (At first there might be little terminal extension). This knowledge is what has enabled me to plant between groupings of ground elder in as early as the second year and Cathi’s verge was beautiful with Autumn planted Spring bulbs in that very first new season.  
In Cathi’s border it has been very easy to spray the very obvious ground elder.(As well as the rest of the weeds that come from seed). Even where some are actually under her plants, still intact they are easily targeted with an accurate squirt.

More tricky to spray but easy with a body contortion and a low pressure directed squirt
I end with a small confession. I have claimed that I completely eliminated all the strong two foot high monoculture of ground elder that completely covered the third of an acre village plot ten years ago. For all practical purposes it was gone by the third year. (In the second and third year it had been temporarily clothed with expendable annual flowers).
In truth a few ground elders had been missed. As my routine weed control is knapsack spraying it has not mattered a jot. Even now I occasionally find one - even two or three - small and subtly hiding, When spotted I spray it - as I do routinely for seeded weeds.
There is absolutely zero ground elder in my own garden! 

Fortunately ground elder does not come back from seed!

More about nettles

I fear I might have been little coy about eliminating nettles. Because it is so easy for me to get rid of them with MCPA (Commercial source Agritox) and given an initial clear run free of garden plants in both Cathi’s verge and Lyndi’s field very sturdy nettles were completely eliminated with two or three sprays over four months in the first season. (Remember for MCPA which is also a constituent in many amateur lawn weedkillers a ’clear run’ includes nettles growing in a grass field)

This neglects nettles’ ability to freshly and rapidly reassert themselves from seed. Although all the nettles were completely killed in my other project in Lyndi’s field, now in the second year you will still find some! I go to spray in Summer once a month. In a quarter of an acre it is very easy to miss some small seeded nettles and in such a large area it is easy to miss a few on my next visit too! It might be after ten weeks when I find luxuriant clumps. (her old paddock is very fertile after all those horses). By then the nettles are almost seeding! Worse my regular spray is glyphosate which against nettles is not as effective as MCPA. (Please don’t embarrass me by asking whether you can legally mix glyphosate and MCPA together).

I shall just keep pegging away until the nettle seed is out of the system. Most will very soon be gone as I practice zero cultivation and I do not bring buried weed seed to the surface. But you never get rid of them all. Overall the project is going very well.

How effective is glyphosate against nettles?
Undoubtedly sprayed at the right rate and frequency it will eventually kill them but I am in denial as to how ineffective routine glyphosate spraying can be!

I remember when I was hired to manage an old walled  kitchen garden free of established perennial weed but that by neglect of the necessity to prevent weeds seeding for in this case the last hundred years the soil weed seed population was phenomenal. Poor Paul  - who I taught to spray out the regular crop of emerging weed seed. He was concerned that annual nettles were persisting. What should he do? …. (Annual nettle Urtica urens is distinct from the more common perennial kind).

When I was writing my original post on nettles and was checking out a few things on the net I found some references to folk routinely spraying rough weedy areas with glyphosate and claiming that it seemed to encourage nettles! Clearly their spray was not strong or frequent enough and killing competing vegetation gave nettles a free run. I wondered if the victims were rich enough to be foolishly using amateur ‘ready to use spray’. 
I don’t actually know how strong these ready made solutions actually are. I imagine very weak!

I thought I should find out what strength of glyphosate is responsibly recommended to kill nettles. The net is very opaque when we home  gardeners seek information as to how to use professional glyphosate in our garden and I found no references suggesting nettles might be ‘difficult’. It is ironic that when searching google for recommended dilutions for nettles I found Roger Brook at the top of page two.

My previous experience suggests that 1 in 50 dilution of 360g/l commercial product is sufficient. But what if in my haste I fail to achieve complete cover (but as ever best short of wasteful ‘run off) or if a complacent gardener sprays regeneration too late? (or even too soon!)
I think if I wanted to be sure to get rid of it now I would use dilution 1 in 40 which I would make up with 250 mili-litres of product dissolved in ten litres of water in my 15 litre sprayer. (A full sprayer is too heavy for me)

A problem with MCPA
You might conclude that if you have nettles in a paddock, on waste land or under hedges and trees you might prefer MCPA. I went to the Agritox website to read about dilutions and to my amazement I found the weasel words ‘not approved’ for knapsack sprayers’. What on earth does ‘not approved’ mean? There are many things in this world that I disapprove of and they still carry on. Why should MCPA be plastered over tens of thousands of acres of grassland and cereal crops with huge tractor mounted monsters and applied in amateur products to almost everyone’s lawns and yet knapsacks, those most accurate of all sprayers be not approved for applying MCPA?
If these things bother you the sister professional product  24D is ‘approved’ for knapsack spraying. Virtually identical to MCPA and used as alternatives or mixed together they have been used for selective weed control in cereals, grassland and lawns for the last fifty years. 24D bought as similarly priced Depitox kills nettles very well.
It amuses me to think that when I ordered some 24D thirty years ago my supplier substituted MCPA as if it were identical and I have used Agritox in my knapsack sprayer ever since.
A new nettle project

Although I look after Cathi’s garden I have not been concerned with the strong clumps of nettles in her fields where her fifteen soay sheep and her two rheas graze. I am about to start a demonstration in a one acre field

Spike hates the nettles
This Spring Cathi had her nettles ‘professionally’ spot sprayed. Unfortunately the usual story, they were not sprayed again. By now the old nettles have completely regenerated and new young plants have come from seed. It is normally necessary to respray at least on one further occasion perhaps about ten weeks later. This is when new strong growth has occurred and before it can consolidate and recover or new nettle seedlings get going.
The pictures below represent a necessarily new start.

Sprayed five months ago and look what happened!
On the roadside of the fence I have now sprayed with 1 in 50 glyphosate. In the fields I used 1 in 75 MCPA made up by dissolving 150 ml in ten litres of water 
Typical patchy distribution of nettles. Perhaps the ministry would have Cathi hire a tractor?
She might use a watering can or a hand sprayer but a carefully directed knapsack is ideal. Perhaps the ministry would prefer Cathi to use an amateur lawn weedkiller or would that be illegal?
I intend to completely eliminate the nettles in one of her fields. I will update this post to show how things proceed and I will take care not to exceed Ministry regulations that dictate maximum doses per unit area per year.
It took me twenty minutes to spray the nettles with a 1 in 75 dilution.

Watch this space!

Links to related posts

My original post on nettles and ground elder project
Prologue to second year of project
Report on first year

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