EFFECT OF WEEDING ON POPULATION OF FALL ARMYWORM (SPODOPTERA FRUGIPERDA) AND YIELD OF MAIZE (ZEA MAYS L.) IN UMUDIKE, ABIA STATE, NIGERIA

Field experiments were conducted in 2017 and 2018 second planting seasons, at the Research and Teaching Farm of the Faculty of Agriculture, Abia State University, Uturu Umuahia Campus to investigate the effect of weeding on the population of Spodoptera frugiperda and yield of maize. Two Maize varieties, OBA SUPER 2 (yellow seeded) and OBA SUPER 98 (white seeded) were planted as the main plot treatment while four weeding schedules (no weeding, 1, 2, or 3 weedings) were included as the sub plot treatments. Seeds were sown on ridges 1.0 m apart and 50.0 cm between stands in 5.0 m(2) plots on 5th day of August each year. Data were collected on the number of larvae of fall Armyworm S. frugiperda larvae, damaged plants and grain yield of maize. All data were subjected to analysis of variance (ANOVA) and separation of means done using Least Significant Difference (LSD). During both years, it was found that the weeded plots had significantly (P<0.05) lower S. frugiperda population than the non-weeded plots. S. frugiperda population decreased significantly with increase in the number of times sub plots were weeded. Thus, S.frugiperda population of 7.6 were recorded in the plots weeded thrice in 2017 and 8.3 in the year 2018; with twice weeding it was 10.3 and 10.5 in 2017 and 2018; and for once weeding it was 12.5 and 13.3 in the two years respectively. The non-weeded plot had 13.0 and 16.5 S. frugiperda in the two years respectively. The frequency of weeding was inversely correlated with S. frugiperda population. Grain yields were significantly higher when weeding was done three times compared with weeding twice, once and no weeding respectively. In the two years, the percentage leaf damaged were decreased as the number of weeding increased. There was no significant correlation between S. frugiperda and the grain yields in the two years suggesting that any of the weeding regimes, especially 2-weeding and 3-weeding can be adopted to reduce S. frugiperda infestation in maize with no significant effect on grain yield. In addition , any of the two varieties can be cultivated in the area to achieve good grain yield.