Quantitative Assessment of Crop Losses from Striga Weed in Sorghum and Maize in North Central Nigeria

This study provides a quantitative assessment of crop losses caused by Striga hermonthica and Striga asiatica infestations in sorghum and maize production in North Central Nigeria, contributing rigorous loss data to support investment decisions in Striga management programmes. Striga is arguably the most destructive agricultural weed in sub-Saharan Africa, causing severe yield losses in cereal crops that disproportionately affect poor farmers on infested soils. Despite widespread acknowledgement of the Striga problem in North Central Nigeria, reliable quantitative crop loss estimates are lacking. This study conducts controlled infestation trials at Nasarawa and Niger State sites using known Striga seed densities, and simultaneously conducts farm-level yield gap surveys on 120 farmer fields with varying natural Striga infestation levels in Kogi, Niger, and Benue States. Yield loss estimation uses the plot-pair method comparing farmer fields with and without Striga management. Relationships between Striga emergence density and percentage yield loss are modelled using non-linear regression. Economic loss valuation uses current crop prices. Findings reveal that Striga infestations at typical farmer field densities cause average yield losses of 43 percent in sorghum and 38 percent in maize. Economic losses attributable to Striga in the three surveyed states are estimated at 12.4 billion naira annually. The relationship between Striga emergence density and yield loss follows a negative hyperbolic response curve. The study contributes original loss quantification data for North Central Nigeria and recommends the modelled loss-density relationships for use in Striga management extension decision tools.

Keywords: Striga, crop losses, sorghum, maize, North Central Nigeria.