Rational Use of Fungicide Applications to Maximize Peanut Yield Under Foliar Disease Pressure in West Africa

In West and Central Africa, three foliar diseases—early leaf spot caused by Cercospora arachidicola S. Hori; late leaf spot caused by Cercosporidium personatum Berk. & M.A. Curtis (syn. Phaeoisariopsis personata (Berk. & M.A. Curtis) Arx); and rust caused by Puccinia arachidis Speg.— are major constraints to peanut production. Disease distribution and severity vary from region to region with yield losses ranging from 10 to 50% depending on the agroecological zone and cultivar (7,15,21,22). While the mean pod yield in West Africa is about 750 kg/ha, data from the region show that some cultivars produce much higher yields when protected from foliar diseases. At present, only a few cultivars are partially resistant to foliar diseases. Fungicides are used currently in some regions of Africa (11,18), but several applications are applied to prevent disease. This approach is expensive and therefore not accessible to most farmers. However, a limited number of fungicide applications could substantially increase pod yield. To reduce the number of fungicide applications, approaches such as disease prediction models for alerting farmers to spray have been developed (2). Our objectives were to identify the best combination of timing and number of fungicide applications in relation to cultivars to achieve best pod yield. This article describes results obtained from Bengou (Niger) and Ina (Benin) in the 1991 and 1992 rainy seasons.