Résumé
In the last décade, two main types of staggered targeted control (STC) have been désigned by CIRAD in francophone Africa in collaboration with national research institutions. In the first in Benin, Cameroon and Guinea, spray calendars are used with five or six applications at fortnightly intervals. Formulations and doses dépend on the pests present during scouting on the day before spraying. -In the second in Burkina Faso pre-1996, Mali and Togo, the basic calendar programme is applied with a pyrethroid-organophosphate mixture at half the usual dosage and scouting six days after spraying. Further spraying is performed on the next day if a threshold is passed. Special procedüres dépend on the country (phytosanitary ecoregions, risk of a particular pest related to the growing season, sampling procedure, plant organs or pests observed). Decision-making procedüres, spraying thresholds and products and doses may vary according to these féatures, and STC programmes match country pest conditions. Ecological and economic benefits include a 40-50% reduction in chemical control, lowering costs by CFAF 10, 000 to 15, 000 per ha. Better knowledge of pest biology and damage and better crop monitoring give 100-200 kg/ha seed-cotton where STC is applied. Many identified constraints remain, including problems of the status and payment of specialized scouts among growers. The real cost of products may form a serious constraintfor single active substance formulations. (Résumé d'auteur)