RESUMEN
Seed treatment protects the seed or young plant against pests and diseases transmitted by seed or soil and stimulates germination and plant growth. Extracts from three Chadian plants, prepared from leaves of Azadirachta indica and bark of Boswellia dalzielii and Cassia sieberiana were evaluated for their efficacy as seed treatment on two varieties of cotton seeds; Stam F and A51 in Petri dishes and plastic trays. Cotton seed were soaked separately for one hour in various concentrations of aqueous and ethanolic extracts and plated on blotters as well as in sterilized soil in plastic trays. The results showed that seed treated with leaf extracts of Azadirachta indica and bark of Boswellia dalzielii reduced significantly (P ≤ 0,05) seed borne infection, improved seed germination and vigour index of cotton seeds when compared to those treated with Cassia sieberiana bark extract and distilled water. It can be suggested that extracts of A. indica and B. dalzielli have antifungal effect and can be used to treat seed against seed borne pathogens of cotton, increase seed germination and vigour index.