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By making biodiversity the issue for accepting or rejecting genetically modified (GM) crop agronomy, the UK government has almost certainly hastened the eventual replacement of conventionally bred varieties. (625 words)

After nearly a decade of commercial use, genetically modified crops are very fully integrated into US agriculture. And one might have expected that, like air seeding, personal computers and other technology of the 1990's it would not be worthy of any special attention.

The US Department of Agriculture does, however, still question farmers in its Prospective Plantings survey on their intentions to seed genetical modified varieties of maize, soyabeans and cotton. As might be expected the process of adoption of this powerful technology is about complete. Only about 14 percent of soybeans and 24 percent of cotton acres are still seeded to traditionally bred varieties.

For maize, however, over half the US crop is still seeded to them. The reason for this partial adoption of the technology is, of course, because the traditional maize herbicide, atrazine, which has been used for decades, is particularly effective in controlling weeds.

Paradoxically, it was this "relative" ineffectiveness of herbicide resistant maize in an agronomic context that resulted in its approval for use in the UK. While the European ban on the use of atrazine after 2005 means that genetically modified maize is expected to become relatively more effective at that time, it will, therefore, become environmentally less acceptable.

It might seem that biotechnology can not win in this agronomically upside world where the better the job, the less acceptable it is.

Genetically modified oilseed rape and sugar beet have been rejected because they were relatively effective, but GM maize has been accepted because it was relatively ineffective. By doing this the UK government appears to have established the principle that genetically modified crops and their agronomy are preferred if they are grown in a manner that results in increased biodiversity. And one would suppose the same principal applies to conventional technology.

The agronomics of genetically modified varieties are particularly powerful. Hence, it should be a relatively simple task to adjust the manner in which they are grown to accommodate this second objective of biodiversity without impinging unduly on the first objective which is, of course, to provide an economic advantage by reducing unit costs of production.

Herbicides used with conventionally bred varieties are often only effective if used when weeds are at an early stage of development. Agronomically benign weed growth, which does not compete with a crop but has environmental value, can not be accommodated. There is, of course, very considerable flexibility in the application of glyphosate with genetically modified crops in terms of the stage at which weed growth can be controlled which allowa this accommodation of environmental objectives.

Further the relative impotence of conventional herbicides means they have to always be used to their full potential, whereas GM crop weed control regimes can be relaxed to accommodate environmental objectives.

The implications of this is that genetically modified varieties and their agronomy may quickly become the environmentally preferred option.

And further, under these circumstances, any government claiming to be sensitive to environmental issues will eventually need to effectively ban non-GM technology by banning the herbicides needed to support it. While the UK may have been very slow in approving the technology, it may yet get to beat the US to dumping the environmentally unfriendly conventionally bred varieties through phasing out the herbicides upon which they are dependent.

Quite where this would leave the organic movement is another matter. It does not, of course, use the herbicides that might be phased out. But it would have the challenge of maintaining its conservancy mantra while it was banning the use of environmentally favoured farming techniques.

April 19, 2004