Not all scientists disagree with Prince Charles' criticism of GM crops and intensive agriculture (EDP, August 14). I have a PhD in Plant Genetics and consider Prince Charles' comments anything but "ill
informed".

The Green Revolution, with its introduction of hybrid seeds, intensive irrigation and chemical fertilisers and pesticides, brought a brief period of increased crop yields. However, in areas like the Punjab in
India, this has led to water-logged and unproductive soils. Many have left the land. Remaining farmers are deeply in debt.

GM crops have been introduced in a similar top-down way, in many cases to boost the sale of herbicides. In Argentina, an increase in soya production has led to deforestation and pollution of groundwater as the use of the herbicide glyphosate has increased a massive 180 fold since
the introduction of herbicide-tolerant GM crops. Resistant weeds mean that older, more toxic herbicides are being used for the first time since the 1980s. Even in richer nations, like the United States and Canada, farmers are facing numerous problems. The supply of non-GM seeds is often restricted and farmers who wish to save their own non-GM seed find that it has been contaminated and are then sued by the biotechnology companies. These farmers may well be "really astute
businessmen who would not have anything foisted upon them" but this has done them no good whatsoever.

We need to work with small farmers whose techniques are not only preserving biodiversity and genetic variability but often growing more food per acre than larger farms. The recent UN International Assessment of Agriculture (IAASTD), which was carried out by 400 leading agronomists and scientists with the World Bank's help, concluded that science and technology must be combined with traditional knowledge, working with communities on localised solutions. It found no conclusive
evidence that GM crops increase crop yields or are the single answer to global hunger.