Abstract

A two-year investigation into the effects of weed management practices, sowing dates and maize varieties was made in a Striga endemic field at Minna, Nigeria. The treatment was a factorial combination of variety (SAMMAZ 15, 17, 37, 40 and SUWAN-1-SR-Y), weed management practices (weedy check, two hoe weeding (HW) at 3 + 6 weeks after sowing (WAS), pre-emergence (PE) Atrazine at 2.4 kg a.i ha-1 + 1 HW at 6 WAS and PE Atrazine at 2.4 kg ha-1 + post-emergence (POE) Nicosulfuron at 0.06 kg ha-1 at 6 WAS) and sowing dates: early (28th May), mid-season  (18th June) and late-season (9th July) in 2018 and early-season (26th May), mid-season (16th June) and late-season  (7th July) in 2019 laid in a split plot arranged in a randomized complete block with three replications. Maize variety and weed management practices were combined as the main plot and sowing dates constituted the subplot. Delayed Striga shoot emergence and reduced shoot density were observed in SAMMAZ 15 and 40 and higher grain yield with SAMMAZ 17 in 2018 and 2019. Application of Atrazine plus Nicosulfuron significantly delayed Striga shoot emergence, reduced shoot density and higher maize grain yield in both years. Sowing in May significantly delayed Striga shoot emergence and reduced shoot density in both years. Sowing in June significantly increased maize grain yield in 2018 and 2019. These results suggest that SAMMAZ 15 and 40 in combination with PE Atrazine at 2.4 kg a.i ha-1 and POE Nicosulfuron at 0.06 kg a.i ha-1 and sowing in May effectively reduced Striga infestation. SAMMAZ 17 in combination with PE Atrazine at 2.4 kg a.i ha-1 and POE Nicosulfuron at 0.06 kg a.i ha-1 and sowing in June increased maize grain yield.

Key words: Maize variety, sowing date, Striga, weed management.