1International Potato Center, Peru; 2FAO Intercountry Programme on Rice IPM; 3PROINPA, Bolivia; 4Oregon State University, USA

Background and objectives
In industrialized countries, rice blast and potato late blight are managed primarily through the intensive and precise use of fungicides. For several reasons, farmers in developing countries have particular difficulty in managing these diseases. Fungicides are often unaffordable or otherwise inaccessible, and/or applied under conditions that are dangerous to human health and the environment. It is difficult to understand a system when one of the key components is invisible. Information about plant diseases and their management is not readily available. Appropriate selection and management of resistant varieties can allow farmers to stabilize their yields with minimum use of fungicides, but this requires that farmers have access to knowledge and to crop genetic diversity. This talk will briefly describe two ongoing efforts to help resource-poor farmers improve their decision-making through training and participatory research on the biology of plant disease and the factors that affect epidemics.

Results and conclusions
A season-long training programme on management of rice blast disease was developed and implemented in a collaboration involving farmers' groups, the Vietnamese national program, the FAO's Inter-country Programme on Integrated Pest Management in Rice and the International Rice Research Institute. The 'Farmers' Field School' (FFS) model of participatory training and research was used. The curriculum involves various discussions and learning activities, including simulation and field experiments on the effects of varieties, varietal mixtures, nitrogen levels, plant density and fungicide. The farmers readily adopted experimental methods and used them to improve their disease management strategies.

Phase I of the programme (1994-96) involved development, testing and improvement of the curriculum based on the experience of the farmers and trainers in central Vietnam. Phase II, currently in progress, involves expansion of participation, further refinement of the curriculum, and selection of new resistant varieties. Between late 1994 and mid-1997, the programme expanded dramatically, to involve >2000 farmers in north, central and southern Vietnam. Based on their observations through the FFS, farmers reduced seeding and nitrogen rates. Farmers' groups and the National Institute for Plant Protection conducted parallel, multi-year tests of the varieties introduced through the FFS, and two blast-resistant varieties were released. Phase III will involve the improvement and diversification of rice varieties in Vietnam.

In 1997, a similar effort was undertaken to address the problem of potato late blight (LB). The season-long FFS curriculum again involves learning activities and field experiments. Because the biology of the two pathosystems is quite different, little of the rice blast curriculum could be used as a basis for the LB curriculum. The current version of the curriculum includes field experiments on variety-by-fungicide interactions; humid-chamber experiments to understand pathogen biology and aetiology, and pathogen-variety-fungicide interactions; and small field experiments designed by farmers to test their own hypotheses. The results of the first pilot effort in Cajamarca, Peru, will be presented.