A New Scoring Technique for Assessing the Infestation of Maize Fall Armyworm, Spodoptera frugiperda (J.E. Smith)

Abstract

Maize fall armyworm, Spodoptera frugiperda (J.E. Martin (Noctuidae: Lepidoptera), first recorded in the Americas spread to Africa during 2016 and later spread to more than 40 countries including India during July, 2018. Infestation by maize fall armyworm results in extensive defoliation besides damage to tassels and cobs at later stages of the crop. The infestation levels are measured through various injury rating scales of which the 1-9 whorl leaf injury rating scale (Davis et al., 1992; Ni et al., 2011) is the mostly used one. It was felt that, the Davis 1-9 scale proposed by Davis et al. (1992) was prone to observer bias in field experiments conducted at Tamil Nadu Agricultural University by a team of researchers and students. Thus, a new TNAU 1-5 scale was evaluated which was more feasible, precise, easy and less time consuming compared to modified Davis et al., (1992) 1-9 scale proposed by Ni et al.