This is the full article I wrote for Garden News magazine this week. Unfortunately during the editing process some key words got left out of the magazine article I submitted so I’m pleased to be able to put the full one up here complete with links. The key phrase that got left out was ‘higher than the 25 point mark’. As you read on you’ll notice how important this phrase is!
I’m sorry the blog hasn’t had much going on recently. Hope to get back into the swing of it next week when I get back from London. Remember the Look Both Ways gig on sunday (see previous blog) if you’re in Central London.
The Truth About Organic Gardening is the arresting title of a new book I ‘picked up’ whilst browsing the cyber shelves of an on-line bookstore recently. The books author – Jeff Gillman, a professor of horticultural science at the University of Minnesota in the US (though don’t let the US bit put you off) – answers a few questions I’ve been thinking about recently?
Namely: Is it better horticultural practice to follow a mixture of organic and non-organic techniques than remain a slavish devotee to one system or the other? Do ethical beliefs get in the way of practical common sense? If I wanted to use chemical controls (I don’t in case you’re wondering) are some safer to use than others? If I did use chemicals and wanted to reduce my dependence on the most dangerous could I switch to something less harmful?
What’s good about Jeff Gillman, apart from the clear easy to read writing style he uses, is his refusal to take one side or the other. He looks objectively at both systems and draws his conclusions from scientific study rather than ideological belief.
The good news for organic gardeners is that organics comes out on top on most counts as being a sensible, scientifically acceptable gardening practice, with many years of study backing up what people like me say in columns like these. What we do works, and it works for sound scientific reasons. There’s no muck and magic (as the saying used to go) about it.
The gist of his argument is that organic techniques such as composting, the use of green manures, cover crops and intercropping (something I’ll talk about in a future article), the emphasis on biodiversity, the use of natural predators and the design of sensible planting regimes where pest problems are avoided or much reduced are all good for gardening; they should be adopted by all gardeners, because they are more skilful, make gardening easier and provide better results.
So far so good! When it comes to the use of pesticides however he argues organic science has failed to deliver. In his opinion organic standards allow the use of some pretty harmful pesticides, some potentially more dangerous than the chemical alternatives.
Measuring the dangers of pesticides is complicated. To make it easier for us Jeff Gillman uses a scale devised in America called the Environmental Impact Quotient (EIQs). This measures the risk to the farm worker or gardener, the risk to the consumer and the risk to the environment of various pesticides, herbicides and fungicides. Although we have different standards to the US the EIQs are good for making an at-a-glance comparison between different pesticides, helping you to make a sensible decision about which products you will buy. The higher the EIQ the more dangerous the product is. You wont find EIQ’s on product labels but you can get them from the internet (see below) or from Jeff’s book.
Under UK organic standards – organic gardeners are allowed to use Pyrethrum (EIQ of 18), Insecticidal soap (EIQ of 19), rapeseed oil (EIQ of 27.5), Bordeaux mixture (EIQ of 47.8), Sulphur (EIQ of 45.5) and up until this month Derris (EIQ of 33 although Gillman thinks it should have a higher (and therefore higher risk) rating). By comparison popular chemical controls include Glyphosate (EIQ of 15.3), 2, 4 D (EIQ between 15 and 20), imidacloprid (the active ingredient in Pravado Ultimate Bug Killer amongst others: EIQ of 34.9) and bifenthrin (the active ingredient in Bug Free and Bug Clear amongst others: EIQ of 87.8).
To give you an idea of how risky these products are Jeff Gillman suggests that you should shy away from using any pesticide that carries an EIQ higher than the 25 point mark – organic or not; and only use these once all other options have been exhausted.
And I suppose this is the point of good organic practice. It has a built in precautionary principle that non-organic styles do not: to use pesticides as a last resort. What Jeff Gillman’s book reinforces is the idea that we should not just switch from one bottle marked non organic to another marked organic but change our gardening habits from the ground up.
The Truth About Organic Gardening, Jeff Gillman
EIQ’s available from http://www.nysipm.cornell.edu/publications/eiq/
List of approved pesticides from http://www.pesticides.gov.uk/psd_databases.asp
Independent information about pesticide risk from The Pesticides Action Network, www.pan-uk.org, 020 7065 0905.