Crop protection chemicals

The synthetic insecticides, fungicides, and other anti-parasite chemicals are a very different story. I write as a scientist who has spent his entire career trying to find satisfactory alternatives. However, it is still essential to retain objectivity.

On the one hand, crop protection chemicals have been getting steadily safer and more effective. Before 1940, the only available insecticides consisted of compounds of lead, arsenic, mercury, and cyanide. As soon as DDT became available, the use of these very dangerous compounds was abandoned. Since then, the efficiency of insecticides has increased and the application rates have been greatly reduced. A similar story is true of fungicides, some of which used to be compounds of mercury. There has been a steady improvement in crop protection chemicals and this improvement is likely to continue.

On the other hand, we now use crop protection chemicals costing billions of dollars a year and, in spite of this, we lose more than twenty percent of our crops to pre-harvest parasites. And most of these chemicals are 'unstable', in the sense that they are within the capacity for micro-evolutionary change of the parasite, and their effectiveness then breaks down to new strains of the parasite (see 10.6). These chemicals are also hazardous to both people and the environment. However, if the use of crop protection chemicals were to stop tomorrow, most of the people in the world would starve. We must be realistic. Crop protection chemicals may be a bad thing, but they are also essential, at least until we develop adequate levels of horizontal resistance in our crops.

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