Effects Of Different Control Strategies On Maize Plant Recovery And Yield After Fall Armyworm Infestation

ABSTRACT

The larvae of Fall Armyworm (FAW), Spodoptera frugiperda (J. E. Smith), (Lepidoptera:Noctuidae), can cause significant damage to crops such as maize if not well managed. The purpose of this study was to determine the levels of natural infestation of FAW along the phenology of maize under field conditions, investigate the critical stages for FAW control along maize phenology, and to ascertain the effect of different treatments on maize recovery and yield after FAW infestation. This was a descriptive cohort study in which 270 plants (150 for screen house and 120 for natural field) were infested with FAW at the various growth stages and followed to assess the level of damage using a scale developed by Davis and colleagues. The field plants were also treated with three different pesticides (Neem extract, Bacillus. thuringiensis, and Emamectin benzoate) to assess their effects on FAW and maize recovery and yield. Findings from this study reveal that, the most critical stages for controlling the FAW along the maize phenology are the seedling and vegetative growth stages. These stages are most susceptible to damage by FAW. Yield of maize was significantly higher on the plot with B. thuringiensis insecticide treatment (133.33 ± 4.76)kg/h followed by Emamectin benzoate (125.43 ± 1.383) kg/h and Neem extract (10.96 ± 1.64) kg/h , P < 0.01 . Concerning recovery, in the screen house experiments, all the plants infested at the seedling and vegetative stages died before they could reach the tasseling stage. Meawhile, no death occurred when plants were infested at  the tasseling  and fruiting stages. On the natural field, no plant death was recorded (100.0% survival) on the treatment plots (Neem, Bt.and Emamectin benzoate) along the growth stages, while 4/30 (13.3%) of the plants died at the vegetative growth stage on the control plots. The insecticides used in the study had varied effects on FAW damage at different growth stages of the maize plant.Ths implies that each growth stage of the maize plant may require different insecticide treatment for effective control of FAW population especially at the seedling and vegetative stages where maize plants are most susceptible to FAW infestation. Interventions and policies aimed at controlling FAW on maize plants should therefore concentrate on the  seedling and vegetative stages.