Gabriele Stoll
Natural Crop Protection in the Tropics
Letting Information Come to Life
Methods of Field Protection
Principles of preventive crop protection
Important advances have been made during the past decade in the development of Integrated Pest Management (IPM) concepts, both at the technical level and in training methodology. However, there are quite diverse interpretations of what IPM is. These are due to differences in backgrounds, attitudes and intentions.
 This book is not about IPM. It is a resource book on  non-chemical crop protection practices, addressed particularly to smallholders and organic farmers. It attempts to make maximum use of local knowledge and resources, and to enrich these with external knowledge and scientific know-how. The experience of recent decades has made it clear that singular crop protection measures have their limitations and their costs and that crop protection must be viewed from a holistic perspective.
 Smallholders work under conditions of great agro-ecological diversity, often exposed to adverse conditions such as erratic rainfall, soil erosion and nutrient depletion which can affect the crop’s ability to tolerate or resist pests. Moreover, the farmers live in diverse and often adverse socio-economic situations and may have production goals which differ from purely market-oriented goals. Thus it is clear that appropriate crop protection strategies for small farmers can only result from a thorough understanding of the natural, technological and socio-economic conditions and their interrelationships. In these situations it is decisive that farmers understand the principles of crop protection and adapt, rather than adopt, promising pest management techniques to their situations.
 Preventive crop protection must be the first step. Managing the farming system towards a high degree of self-regulatory mechanisms which reduce the need for curative crop protection is the most intelligent and rewarding way to cut down expenses. Expenses for crop protection include at the individual household level time, money and health, while at the community and national levels they may include water pollution, reduction in pollination, loss of biodiversity, foreign exchange, and public health.

Preventive crop protection practices are employed to counteract the nature and behaviour of the pest, to encourage the activity of natural enemies or antagonistic organisms or to strengthen plants to resist or tolerate pests and diseases. To practice preventive crop protection successfully, knowledge of biological factors such as the soil, the plants, the pests and their natural enemies as well as the agro-ecosystem and the farming system are all essential in order to develop site-appropriate crop protection strategies. Discussion of much of this is outside the scope of this book. Nonetheless, the following presentation outlines some of the basic principles.

More information in this chapter about:

1. Knowledge of agro-ecosystems
2. Healthy plants and healthy soils
3. Natural rhythms and optimal planting season
4. Crop rotation
5. Mixed farming and diversification
6. Host plant resistance and tolerance
7. Managing natural enemies
8. Field sanitation
9. Social aspects