The in vitro studies showed fun gal inhibition bysome cortex extracts of cassava cultivars that were later confirmed to be resistant to CAD both in greenhouse experiments and under field conditions. Germplasm stocks of improved cassava cultivars have also been evaluated for CAD resistance using stem puncture inoculation of the fungus and by field evaluation, under disease pressure conditions (Ikotun and Hahn , 1992; Fokunang et al., 2000c) . These tech- niques are time consuming and laborious. An in vitro screening technique for CAD resistance could serve as a useful preliminary selection strategy for CAD resistance and provide avenues for further studies of the host-parasite relationship. This screening technique for CAD resistance is rapid and applicable in breeding programmes for the preliminary yield trial evaluation of cassava germplasm selections. Rapid in vitro screening for resistance to CAD of cassava cultivars is important because the process of planting of cassava followed by fungal inoculation, before evaluation , can be partly eliminated, thus reducing the period for broad-spectrum evaluation of cultivars for CAD resistance under different agro-eco logical conditions. Screening and selection of cultivars that are resistant to pests and diseases is an important approach within the framework of the integrated pest management strategy, at the International Institute of Tropical Agriculture, towards enhancing sustainable food-crop production in Africa. Farmers depend on the supply of resistant planting materials from breeding programmes for disease control due to the high cost of pesticides.