Crop Loss Appraisal

Press, 2 September 1977, Page 17

Crop Loss Appraisal

There were no reliable figures for losses in crop production on a global basis, but it was possible to estimate that it was of the order of 20 to 30 per cent, Dr Clive James, a plant pathologist in the plant production and protection division of the Food and Agriculture Organisation in Rome, said this week.

A specialist in crop loss appraisal, Dr James was at Lincoln College this week as the guest of the Australian Plant Pathology Society at a workshop to examine ways of measuring the development of diseases in crops.

Crop losses that occurred in developed or industrialised countries, he said, were very much lower than in developing or third world countries. Thus the losses in production due to pests in rice were very much more substantial than the global figure. In Brazil, for example, losses in production in the 3.5 M ha wheat crop could be up to 50 per cent in value terms.

These losses occurred, said Dr James, in spite of the fact that substantial amounts of money were being spent on pesticides in both the deeveloped and developing countries — he put the value of the world pesticide market at about SIO.OOOM (U.S.), with that for fungicides being worth about SIOOOM. Dr James said that crop loss data was necessary to determine the extent of the loss so that the farmer could decide how much he should spend on control measures, and also so that policy formulators and decision makers on a national basis could decide on the most effective use of resources of manpower and money.

It also represented a way of looking at the adequacy of existing control techniques and indicating future requirements.

Crop loss appraisal could be dons by both experimental and survey methods — the experimental part involved characterising the relationship between the amount of disease and the resulting loss of production and

knowing this then surveying the actual crops to assess disease levels and using this information to quantify the losses in production. Within national plant protection programmes, Dr James said he believed that these surveys should be continuous because the situation was a dynamic one and continually changing. They enabled changes that were taking place to be monitored and problems identified at an early stage so that there was maximum time for problem solving. The Food and Agriculture Organisation, he said, had been interested in this since 1967, when it convened a conference of all member Governments. This conference looked at the available methodology or means of assessing crop losses due to pests, weeds and diseases, and a major finding was that little methodology was in fact available and the main recommendation was that member Governments should develop these methods to facilitate progress in putting into figures or quantifying production losses. Since then F.A.O. had established an international programme in crop loss appraisal. Workshops had been held to bring to the notice of plant protection specialists means that were available for doing this. It was an area not covered by any course in a university so that it was necessary to distribute information to such people throughout the world. Thus one of the objects of the workshop he had been attending at Lincoln was to do this for people in Australia and New Zealand.

The Lincoln workshop was attended by more than 60 persons, including 27 from overseas.

One of the greatest needs, said Dr James, was to standardise methodology. At the moment he said that people working in this area in different countries tended to speak different languages so that in many cases it was difficult. if not impossible, to make comparisons between countries.