Eco-Friendly weed management with giant milk-weed (Calotropis procera) leaf extract

Weed infestation remains a major constraint to maize production in the Sudan Savanna of Nigeria, necessitating sustainable and effective weed management strategies. This study evaluated the efficacy of Calotropis procera leaf extract as a bioherbicide, applied alone and in combination with hoe weeding and synthetic herbicides, on weed suppression, growth, and yield of maize at Bayero University Kano (BUK) and ICRISAT Research Farm, Minjibir during the 2024 rainy season. The experiment was laid out in a randomized complete block design with eleven weed control treatments which were replicated three times. Data were collected on weed characters, maize growth parameters, yield components, and grain yield. Weed control methods significantly influenced weed pressure, maize growth, and yield at both locations. Hoe weeding at 3 and 6 weeks after sowing and pendimethalin followed by nicosulfuron recorded the lowest weed density (66.7-73.0 plants m-2 at BUK) and dry weed biomass (1,400-1,950 kg ha-1), resulting in the highest weed control efficiency (up to 98.5% at Minjibir). These treatments also produced taller plants (up to 232–241 cm at 12 WAS), higher grain yield (2.04-2.23 t ha-1 at BUK and 0.92-0.95 t ha-1 at Minjibir), and superior yield components compared with other treatments. Integrated application of C. procera leaf extract (60–80%) with hoe weeding or early post-emergence spraying significantly reduced weed infestation and improved maize growth and yield relative to the weedy check, which consistently recorded the highest weed density (420-560 plants m-2) and the lowest grain yield (0.12-0.50 t ha-1). The soils at both sites were sandy loam with low inherent fertility, emphasizing the importance of effective weed suppression to reduce competition for limited nutrients. Overall, the study demonstrates that C. procera leaf extract, particularly when integrated with conventional weed control practices, offers a viable and eco-friendly option for improving maize productivity in the Sudan Savanna agro-ecological zone of Nigeria.