The effect of nitrogen and potassium doses on the injuries caused by <i>Spodoptera frugiperda</i> (J.E. Smith) (Lepidoptera: Noctuidae) in a maize crop

Abstract

In order to evaluate the different levels of nitrogen and potassium in the damage index caused by infection of the fall armyworm Spodoptera frugiperda (J. E. Smith, 1797) (Lepidóptera: Noctuidae), in corn plants of the hybrid A4454, a field experiment was carried out in Escola Agrotécnica Federal de Crato-CE, in a soil classified as Eutrophic Red Yellow Argisol . The experiment was set up in a 5 x 5 factorial design, with five levels of nitrogen and five of potassium and five repetitions. The treatments were distributed in random blocks, in plots of 10 m² of experimental area. The index of damage was evaluated at 14, 28, 42 and 56 days the planting (DAE), using scale proposed by Reis & Miranda Filho (2003). The effect of the application of the N and K₂O doses on the index of injury of the plants was evaluated by simple linear regression, using the SISVAR statistic program. The fall armyworm increased the index of damage, in the absence of nitrogen and potassium, as well as in the high doses of nitrogen.