ABSTRACT
Armyworm is a voracious pest that has successfully established across sub-Saharan Africa where it continues to disrupt agriculture, particularly smallholder cereal production. Historically, synthetic pesticide has been used to manage this pest alongside aqueous organic extract. However, plant residues may have a beneficial effect in managing armyworm. Therefore, a field study was conducted during the early cropping season of 2020 at the experimental site of the Department of Crop Science, Faculty of Agriculture, University of Benin, Benin City, Nigeria, to evaluate different levels of neem leaf residues on maize in managing armyworm under natural infestations. The experiment was laid out in a randomized complete block design (RCBD) replicated four times. The treatment comprised five levels (0, 7.5, 15, 22.5, 30 kg) of neem leaf residues. Hybrid maize seeds (Oba 98) obtained from Premier Seeds Nigeria Ltd, was used in the study. The attributes measured were days to 50% anthesis, days to 50% silking, anthesis-silking interval, plant height, days to 95% cob maturity, grain yield, 1000-seeds weight, and severity of armyworm damage on corn plants. Neem residue influenced days to maturity, 1000-seed weight and grain yield. These variables increased with increased rate of neem leaf residue. Maize plants treated with 15, 22.5 and 30 kg neem residues took more days to maturity (95.5, 96.5 and 97 days respectively) compared to control. Similarly, heavier seeds were obtained where neem residues were applied compared to control. Highest grain yield (5108.3 kg/ha) was obtained when 22.5 kg neem residue was applied. Although the study was done for one year, it may be recommended that smallholder farmers should grow maize using neem leaf residues at a rate of 22.5 kg to manage armyworm. This is because of the high organic matter content together with moisture retention plus the release of azadirachtin fumes on decomposition, which inhibits the insect’s activities through olfactory cue thereby minimizing the damage done and promoting higher yield.
