Screening of Herbicides for Weed Control in Soybeans (Glycine max) in Derived Savanna Agroecology of Nigeria

O. A. Aluko; J. O. Amosun; O. P. Ayodele; I. O. Udemba; J. O. Olasoji

Authors

Aluko O. A. Institute of Agricultural Research and Training, Obafemi Awolowo University, Moor Plantation, Ibadan
Amosun J. O. Institute of Agricultural Research and Training, Obafemi Awolowo University, Moor Plantation, Ibadan
Ayodele O.P. Institute of Agricultural Research and Training, Obafemi Awolowo University, Moor Plantation, Ibadan
Udemba I. O. Institute of Agricultural Research and Training, Obafemi Awolowo University, Moor Plantation, Ibadan
Olasoji J. O. Institute of Agricultural Research and Training, Obafemi Awolowo University, Moor Plantation, Ibadan

Keywords:

Glycine max, Pre-emergence, Post-emergence, Weed control efficiency

Abstract

Weed stress significantly hampers soybean (Glycine max L.) production in sub-

Saharan Africa, a vital source of protein and plant oil. Two studies evaluated

herbicide formulations for pre and post-emergence weed control in soybeans

within the Derived savanna. at Ibadan and Ilora sites in a Randomized Complete

Block Design (RCBD), replicated three times. The experiments involved

random sampling of initial weed flora composition before land preparation. Pre-

emergence treatments featured trifluralin (580, 700, 820 g a.i ha-1) and

metolachlor (1440 g a.i ha-1). Post-emergence treatments included clethodim

(48, 72, 96 g a.i ha-1), quizalofop-P-ethyl (10, 15, 20 g a.i ha-1), and oxyfluorfen

(960, 1200, 1440 g a.i ha-1) applied 5 weeks after sowing. Agronomic data were

collected on soybeans, weed growth, and weed flora composition. The frequent

weeds identified were Mitracarpus villosus in metolachlor-treated plots and -1

Commelina bengalensis in trifluralin-treated plots at 820 g a.i ha . Tithonia diversifolia and Commelina banghalensis were the common post-herbicide application weeds. Trifluralin (580-820 g a.i ha-1) and post-emergence herbicides (clethodim and quizalofop–P-ethyl) increased soybean canopy, seed pods, and yield by 50-90%, with 70-90% weed growth reduction, ensuring significant weed control (76-96%). Trifluralin effectively suppressed weed growth at 7 weeks after sowing, resulting in a noteworthy grain yield. Clethodim and quizalofop–P-ethyl demonstrated superior and comparable weed control to fluazifop-p-butyl (225 g a.i ha-1) and weed-free treatment, respectively, at harvest. Early trifluralin-based pre-emergence weed control led to a 53% increase in grain yield (2.58 t ha-1) compared to post-emergence herbicides (1.38 t ha-1). This study underscores effective herbicide strategies for soybean cultivation in the Derived savanna, contributing to enhanced productivity and weed management.