Demand-Driven Technologies for Sustainable Maize ... - IITA

245expansion of the area under cultivation. The annual production wouldbe higher if the constraints were eliminated or minimized. Some ofthe constraints militating against full expression of the yield potentialof the improved varieties released so far are low soil fertility, poor cropmanagement practices, high cost of production inputs, abiotic stresses,pests and diseases. Cardwell et al. (1997) showed that losses due topests and diseases ranged from 20 to 50% and in the specifi c caseof the grey leaf spot disease, grain yield losses of 90% or more havebeen reported in several parts of the country (MINAGRI 1996).In 1995, countrywide baseline fi eld surveys were conducted withmore emphasis on the humid forest (HF) and western highlands (WHL)to provide basic data on the time, locations and fi eld conditions underwhich maize losses caused by pests and diseases occurred.In 2004, another survey was undertaken in the western highlandsof Cameroon (West and North-West). The primary objectives ofthe study were to (i) obtain a more detailed assessment of the relativeimportance of the most prevalent diseases in ecological zones withhigh disease pressures (ear rots) identifi ed during the previoussurveys, and (ii) identify the locations with reliably high disease pressureto be used in developing and testing Integrated Pest Management(IPM) technologies.Materials and MethodsThe agroecological zonesIn the HF, which is dominated by primary and secondary forests,maize does not constitute the staple food of the population. Shiftingcultivation is the predominant farming system and maize is producedin small areas (