Comparative Study of Herbicides for Pre-Emergence Weed Control in Maize (Zea mays L.) in Derived Savanna of Nigeria

Aims: To evaluate and compare the efficiency of candidate herbicides and increase the latitude of herbicides for pre-emergence weed control in maize.

Study Design: Randomized Complete Block Design, with three replicates was used in the study.

Place and Duration of the Study: Candidate herbicides were obtained Rainbow Nig. Limited for evaluation. The study was carried out between June – September, 2014 and 2015 at Ibadan (0.7.38N; 003.84E) and Ilora (07.81N; 003.82E) research stations of the Institute of Agricultural Research and Training, Obafemi Awolowo University, Ibadan.

Methodology: Weed flora composition was taken with 1sqm quadrat placed randomly before land preparation. Acetochlor 500 g/L, Acetochlor 900 g/L, Metholachlor 720 g and Ametryn 80 WP were applied randomly at three rates of active ingredient (a.i) at maize sowing, while Atrazine (reference), weed-free and weedy check were the control. Agronomic and weed data were taken, analysed and means separated using Duncans Multiple Range Test (DMRT) at p≤ 0.05.

Results: Result showed that weed flora composition before land preparation was dominated by annual weeds {broadleaves (80%) and grass (20%)}. At 6 weeks after sowing (WAS), weed flora composition comprised of 8% spiderwort, 8% sedge, 25% grass weeds and 59% broadleaf weed species. Weed flora dynamics after treatments application might have been influenced by types of herbicides, herbicidal activities and previous cultural practices. Herbicides application resultantly increased plant height (50%) and grain yield (46 - 60%) relative to plant height in weedy check at both locations. These might have accrued from minimal weed interference hence, high weed control efficiency (WCE) recorded in herbicides applied (WCE ≥80%) and significant reduction in cumulative weed dry matter of about 80%.

Conclusion: Herbicides applied significantly reduced weed growth and enhanced maize grain yield. Notwithstanding, investigation of the benefit cost ratio and the environmental impact assessment of herbicides applied are imperative for sustainability of maize production and agro-ecology.