Assessment of farmers' crop management practices influencing Striga hermonthiea infestation and grain yield of sorghum (Sorghum hieolor)

Striga hermonthica (L) Moench, a parasitic weed species, is a major constraint to sorghum production in the savanna zones of north-eastern Nigeria. The aim of this study was to assess the influence of farmer practices on Striga infestation of sorghum fields in the region. Random sampling technique and semi-structured questionnaires were used to sample 54 sorghum fields and assess farmer-practices in nine communities of Borno State in north-eastern Nigeria. About 39% of the farmers had continuously cultivated their fannlands for more than 10 years, 60% planted in June, and 41 % practiced sorghum-legume rotation, 45% practiced sorghum+legumes relay intercropping, 58% applied nitrogen fertilizer and 43% conducted hoe-weeding three times . In northern and southern Guinea savannas, prolonged period of land cultivation, early planting, and inadequate nitrogen fertilization promoted Slriga infestation as these practices were positively associated with Slriga counts. However, late planting, sorghum-cowpea or groundnut rotation, and increased weeding frequency reduced infestation as these were negatively correlated with Strigo counts . Relay intercropping reduced grain yield ha-1 (r = -0.52*) in· northern Guinea savanna, but sorghum-legume rotation, weeding frequency, and increased nitrogen fertilizer rate increased grain yield as these were positively associated with grain yield ha-1 in both zones. In Sudan savanna, Slriga counts were reduced by relay intercropping of sorghum with legumes, as the practice was negatively associated with Striga count, while inadequate weeding promoted infestation (r = 0.44*). However, grain yield ha-I was positively associated with nitrogen fertilizer rate and weeding frequency. Thus prolonged period of land use, continuous cropping of sorghum, inadequate nitrogen fertilization and early planting or less than 3 hoe-weedings promote Striga infestation, while sorghum-legume rotation, sorghum + legume intercropping or 3 hoe-weeding reduced infestation and increased grain yield of sorghum in the three zones.