Field Screening of Rice Genotypes against Leaf Folder, Cnaphalocrocis medinalis (Guenee)

Abstract

Rice leaf folder, Cnaphalocrocis medinalis (Guenee), damages foliage and can reduce the performance of rice crops. Identifying rice genotypes with comparatively stable field resistance may support breeding programmes aimed at pest management. The present study evaluated rice genotypes against the leaf folder at the Rice Research Centre, ARI, Rajendranagar, during the kharif seasons of 2024 and 2025. The field screening included the susceptible check TN1 and the resistant check W 1263. The genotypes were evaluated in three replications, and leaf-folder infestation was encouraged through adult releases under netting. Damage was assessed as the percentage of leaves showing injury, and reactions were classified using the International Rice Research Institute's Standard Evaluation System. In 2024, the recorded leaf damage ranged from 11.7% to 62.2%, whereas in 2025 it ranged from 3.4% to 51.0%. The genotype RP 5490-PTB-1-1-2 maintained a moderately resistant reaction in both seasons, with 16.9% and 16.6% damaged leaves, respectively. The resistant check W 1263 recorded 11.7% and 5.4% damaged leaves, respectively. NPK 8 showed moderate resistance in 2024 but was moderately susceptible in 2025. Although reactions varied across seasons, RP 5490-PTB-1-1-2 exhibited the most consistent moderate resistance among the evaluated test cultures. Its field response indicates potential for further assessment as a resistance source, subject to validation across locations and infestation levels.