Perspective on Pathology Diversity is the Spice of Life One impact of the 1947 Agriculture Act - more research, more food - was that I didn't have to look for a job. The expansion of the Plant Breeding Institute (aided by Richard Macer) easily made room for me - and later for my two other ex-Presidential friends and colleagues, Roy Johnson and Peter Scott. We enjoyed exciting days, helping to provide some of the tools for a phenomenal increase in agricultural production. However, we did begin to recognise some, but certainly not all, of the danger signs of this mammoth environmental change - I remember, for example, long discussions on the wisdom or otherwise of the 1964 Seeds Act, designed to protect the breeder and to provide royalties. Now we see one of the consequences of commercialised breeding within an industrial ised agriculture: massive monoculture and the accelerating erosion of genetic resources. Monoculture and mixtures Some of the work that I have been involved in, particularly in Zürich, helped to reveal one effect of this trend. Monoculture of cereal varieties, and, even more so, of disease resistance genes, has led to the selection of a trans-national pathogen population; distinct "islands" of the pathogen population, separated because of the previous relatively small and diverse host populations, simply disappeared. The pressures from such massive inter-linking of pathogen populations helped rapidly to wipe out the effectiveness of many resistance genes. One simple alternative that John Barrett and I tried to push, in the teeth of accelerating industrial agriculture, was the use of variety mixtures. After a brilliant but short-lived beginning, it failed in Britain. But I am still pushing this approach, because, properly done, it is simple, cheap, effective, reliable, stable, requires no inputs and has shown great effectiveness elsewhere. Aha, I can almost hear the cries from some quarters - here comes Bio-Wolfe again with his tired old mixtures. However, I tend to follow Max Planck's cynical conclusion - "a new scientific truth does not triumph by convincing its opponents and making them see the light; but rather because its opponents eventually die and a new generation grows up that is familiar with it" (Fisher, 1978). Genetic engineering What is being offered to deal with such side-effects of monoculture? Breeding and pesticides, of course, but today, in addition, we have the prospect of genetic engineering. Now, all scientists agree that molecular biology is amazing for the new insights that it gives us into the structure of living organisms. And it provides the most excellent tools for biological research - indeed, I look back with great pleasure to the way in which Dick Flavell persuaded us to be among the first to use those tools for our population studies. But genetic engineering as it is applied to plant breeding in its modern business framework is, in my opinion, just not acceptable. Why? Because many of the characters currently available have only dubious relevance to agriculture (there's always jam tomorrow), and all are being pushed in ways that promote monoculture still further, to the detriment of agricultural systems and the environment. Moreover, the entry of the products of genetic engineering into the market seems now to be moving beyond the control of our democratically elected representatives. Because of the high costs of investment, and thus the need for a large and rapid return, it seems doubtful to me, whether genetic engineering will ever be able to contribute sensibly to agriculture; certainly not in the foreseeable future. Fortunately, there are other ways. For example, the use of materials derived from genetic engineering has been banned, worldwide, by the organic agriculture movement. This may seem an extreme position to some, but it does offer a demo cratic alternative. Indeed, for this and for many other reasons, I have gradually come to the conclusion that organic systems are the only way to encourage a sound way forward in agriculture. Organic farming and plant breeding Of course, there are problems. For example, by eschewing genetic engineering, the organic movement may eventually cut itself off from all new varieties developed from mainstream breeding as genetic constructs spread among these programmes. This means that breeding programmes directed primarily to organic production need to be extended and strength ened. If this can be done (funding?), there could be many advantages - for (almost) the first time, breeding would be carried out under organic conditions selecting for characters of prime importance to organic agriculture. We might also see the development of methodologies that are now closed to conventional breeding (e.g. population breeding and selection for mixed cropping) and a wider range of crops under consideration. I believe that we are now at a crossroads. On the one hand, if we follow the direction of mainstream agriculture towards even more intensification and monoculture (e.g. through genetic engineering), can we provide enough food not only now, but forever more? Based on current performance, I have serious doubts. On the other hand, can an organic approach do the job? Better sustainability is beyond doubt, but the principal criticism from the mainstream is that a major shift to organic production will mean reductions in yield and an inability to provide enough food. I believe this to be wrong, on at least three counts. First, in a paper to the Farm and Food Society in 1995, Lawrence Woodward stated ". . . that the question of feeding the world organically has less to do with the technical ability of organic farming to produce adequate nutrients and is more about systems of distribution, markets, finance and political structures". Second, when I look at that technical ability of organic farming to produce, I find that overall output from an organic enterprise, and particularly from a small and intensively managed unit, is already high. Thirdly, and most importantly, we need to compare the returns (what returns?) on the immense amount of funding that has gone into molecular-based agricultural research and compare them with the returns that could have accrued from investing that money in organic research in an environmentally-sensitive framework. One such investment that I am personally in the process of making, albeit on a small scale, is to try to maximise the use of functional diversity in a range of organic agroforestry systems, in Suffolk. The objective is to throw monoculture completely into reverse and to maximise the positive interactions that can occur among trees, crops and naturally occurring plants, animals and microorganisms. Further considerations here are the extent to which such systems might contribute to an increase in rural employment - and to putting some of the culture back into agriculture. My only problem is that, to follow my 80 year tree rotation, I need to find some way of staying around for a long time . . . gene therapy . . . ? Martin Wolfe
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