EFFECT OF SOIL FERTILITY ON HOST RESPONSE TO BLACK LEAF STREAK OF PLANTAIN (MUSA SPP, AAB GROUP) UNDER TRADITIONAL FARMING SYSTEMS IN SOUTHEASTERN NIGERIA

Plantain (Musa spp., AAB group) is a staple food crop in the humid for est regions of West and Central Africa. Its cultivation is threatened by black leaf streak (BLS), an air-borne fungal leaf spot disease, cau sed by Mycosphaerella fijiensis Morelet. An on-farm survey for BLS sev erity in relation to soil fertility was conducted in two different geo morphological zones, the main plantain-growing areas of Rivers State w here plantain is mostly cultivated in compound gardens and in outlying fields mixed with other food crops. Plantain in the Meander belts zon e (the Central Niger Delta area) was less infected by BLS than in the Coastal plain sands (the east of the Niger delta). In addition, planta in grown in homestead gardens had a much lower BLS severity than that planted in field-plots. The host plant response is attributable to the difference in soil fertility both between the two geomorphological zo nes and between the two farming systems. Therefore, the success of a s ystem would depend on managing the soil in a way that fertility is mai ntained. Since chemical fertilizers are not readily and economically a vailable to the farmers, the potential of traditional organic fertiliz ers needs to be better exploited.