ngin - Norfolk Genetic Information Network

28 May 2002


We've received the following comment from Peter Melchett, Policy Director of the Soil Association, on Prof Chris Leaver's suggestion that:

"organic farms can never take up that much of the countryside, as they benefit from the pesticides sprayed onto neighbouring fields"


"Organic agriculture thrives because it has a cordon sanitaire of conventional crops around it. If conventional crops fall in number, the yields of organic crops will drop, making them less economic." [New Scientist May 18, 2002,]

Prof Leaver is on the Governing Council of the John Innes Centre and regularly coauthors papers in support of GM crops with Prof Tony Trewavas.


Leaver's organic claims

Stated as a fact this is total rubbish.  There is no science that we know of to support (or disprove) this speculation. However, a much more credible hypothesis would be that the opposite is true. Organic farming does not depend on 'cordon sanitaires'. In fact, organic farming depends not on eliminating diseases, insect pests or weeds, but rather on using rotations of crops, mixed crops and mixed livestock systems to reduce the incidence of these things, and on the natural good health and vitality (of animals and plants) to resist attacks.  So a well developed organic farm will have a very low level of crop diseases, insect pests and weeds, with strong animals and crops well able to resist or overcome any negative impact.

The only serious threat to this proven system of disease and weed control comes from huge, sudden surges in disease, insects or weed seeds.  These cannot be produced in a well-functioning organic system, as there are natural checks in place.  These include the presence of predatory insects, crop rotations which stop the build up of weeds or crop diseases, rotational grazing by different farm animal species which stop the development of high worm burdens, lower stocking densities which reduce the spread of disease, no artificial nitrogen fertiliser which weakens the cell walls of plants and makes them more susceptible to disease, the use of natural diets (for example grass or conserved grass for ruminants) and normal growth patterns which produce healthier animals, no routine use of medicines, and much, much more!

However, major outbreaks of crop and animal diseases, insect pest attacks and the development of new weed problems are all well-known characteristics of conventional agriculture, regularly produced by conventional systems - and chemicals and medicines are applied (often routinely) to deal with the problems. Conventional systems, with for example continuous cropping of combinable crops, or very large numbers of one livestock species often kept together in confined housing or on heavily stocked land, provide the ideal conditions for major breakdowns in health, the sudden multiplication of insect pests, and the development of resistant weed species.  Only when conventional farming ends completely will organic farming be free of this threat.

Peter Melchett
Policy Director, Soil Association
Bristol House, 40-56 Victoria Street, Bristol, BS1 6BY
for more on organic BS:

ngin bulletin archive