Pesticide Use

Well my hopes for an Indian summer seem to have come to little. The south and east of Britain has had some lovely hot days but here in the north west we’ve not been so lucky.

The list of jobs to be done outside gets longer as the weather worsens. I’m fast coming to the conclusion that there’s a lot to be said for a giant polytunnel. At least I could keep dry. We moved the drying onions under cover just as the weather changed so at least they’re drying out nicely. We’ll be stringing them soon.

My cunning plan to keep the cats off our raised salad bed has backfired. I built a little frame from bamboo canes and draped some horticultural fleece over. It’s stopped them using the bed as a litter tray but they’ve found their way in and discovered it’s a lovely sheltered place to snooze away a cold afternoon.


When I first started growing, near 40 years ago, you could be forgiven for thinking that being a gardener required a degree in chemistry. For every pest and disease there was a chemical to spray and the trick of being a good gardener was to know which one to use.

It was hard to tell the difference between the garden shed and the back room of a pharmacy. We happily mixed up our sprays, adding a bit for luck, and off we went to dose our crops without the benefit of all-encompassing protective suits, respirators and goggles. Amazingly most of us survived and even enjoyed the fruits of our labour.

However, in 1962 Rachel Carson published her book Silent Spring which detailed the effects of insecticides and pesticides on the environment and gradually people have realised the dangers to themselves in pesticide residues as well as the environmental  harm that chemicals could cause.

We realised that killing both the pest and the predators of that pest was a bad idea. There would always be a few pests that survived and nature had designed them so they could recover their numbers quickly. Without those predators to keep them in check, more spraying was needed and a self-defeating circle was the result.

Move the clock forward to today and things couldn’t be more different. The chemical tools available to gardeners seem to reduce every day as more and more products are de-listed.

I have to wonder if we’re not throwing the baby out with the bathwater in all this rush to organics. Worse still, we seem to be throwing the baby out and leaving the bathwater in some ways.

As someone who has done battle with a plot infested with mares tail, I’ve tried everything. Hoeing away and trying to dig out as much of the root as you can has some effect but it’s a job like painting the Forth bridge. By the time you clear one bed, the blessed stuff is away on the one before.

Glyphosate does have some effect, but you have to re-apply it five or more times to make real inroads. This more or less takes a plot out of production for a season. There was one weed killer that worked, Amcide. Amcide is just Ammonium Sulphamate, a variation on Sulphate of Ammonia.

Most gardeners know sulphate of ammonia as a straight nitrogen fertiliser. Ammonium sulphamate is a twist on the fertiliser molecule so the plant thinks it is absorbing nitrogen but it can’t actually use it. A bit like the way carbon monoxide blocks the absorption of oxygen in red blood cells.

Because of this, the chemical is taken down to the roots of the weed and it kills the whole plant, dead. The chemical on the soil reacts with oxygen and gradually converts to its cousin, sulphate of ammonia, so after six to eight weeks you can safely re-plant in nitrogen rich ground.

Simple, effective, well understood and used safely for many years; Amcide is now de-listed. My understanding is that the manufacturers couldn’t justify the expense of all the tests required to keep it on the list.

Now it’s worth noting that the range of chemical controls available to the farmer and those with a certificate of competence is far greater than those available to the ordinary gardener. Which brings me round to aminopyralid.

Aaminopyralid is a selective weedkiller for use on pasture. It’s very cost-effective, a phrase dear to the hard-pressed farmer’s heart but it is also very persistent.

The farmer sprays his field, kills the weeds and the cattle eat the grass. Inside the cow’s stomach the grass breaks down and releases the chemical which travels through the cow or indeed a horse to end up in the manure.

The first we gardeners knew of it was when our crops failed. We all know how manure helps get a good crop of potatoes but manure with aminopyralid in just killed the crop. It also hit tomatoes, peas, beans, carrots and lettuce.

Once we realised and kicked up a fuss, online petitions and plenty of media coverage, the product was taken off the market. It was a result, but not great consolation to those looking at blighted plots they’d need a year or longer to make safe. Or those with manure piles that are now classified as toxic waste and probably going to remain so for two or three years yet.

Once the fuss in the press had died down, they quietly re-listed the products using aminopyralid with promises to better warn the farmers about the problem.

When you understand the company spent $80,000,000 bringing the product to market, you get an idea of what’s at stake. You could be forgiven for thinking it a victory of money over common sense,

So here we are – tried, tested and safe is illegal, proven nightmare for the gardener is perfectly legal. It’s a mad old world.

Posted in Allotment Garden Diary
2 comments on “Pesticide Use
  1. gee says:

    Iv seen a very interesting DVD called One Man,One Cow,One planet by Peter
    Proctor from New Zealand,it explaines how we are changing the soil structure with chemicals and we need to get back to adding more humus/manure to the soil,its the best way to improve your soil,there is no
    magic result in chemicals in the long run.
    Im old enough to remember growing crops with only Farm yard manure,but some time in the late 50s my Grandfather started useing fertilisers,such as
    Nitro chalk,with great results,the crops were doubled at the time but as the years rolled on the land needed more fertilisers to get the same result,I also noticed the soil structure changed to a soil with less worms in it.
    The DVD realy made me realise what we have been doing wrong all these years.

  2. Dave Davies says:

    You can still buy Ammonium sulphamate online from Amazon but only as use as a compost accelerator or flame retardant. You are not allowed to use it as a herbicide even though you can find the usage instructions online!

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