KRISHNAYYA, P.V.APPALA RAJU, KONNI2018-05-072018-05-072016http://krishikosh.egranth.ac.in/handle/1/5810044758D5266Studies on the response of twenty one rice varieties against rice leaf folder Cnaphalocrocis medinalis (Guenee) on various morphological, biochemical aspects of host plant resistance and efficacy of certain new insecticides were conducted during kharif 2015 at Agricultural college farm, Bapatla, Andhra Pradesh. The cumulative mean per cent of leaf folder damage in twenty one rice varieties indicated that the lowest leaf damage was recorded in BPT-2231 (7.10%) and the highest damage was observed in BPT-5204 (18.20 %) followed by BPT- 2570 (16.90%). According to International Rice Research Institute (IRRI), Standard Evaluation System (SES) the ratings were given to the varieties against leaf folder damage. The varieties were categorized into ten resistant (under a rating of ‘1’) eleven moderately resistant (under a rating of ‘3’). Highly resistant (under a rating of ‘0’) and highly susceptible (under a rating of ‘9’) varieties were not recorded. Among morphological characters, leaf length did not influence the leaf folder incidence whereas positive significant correlation was observed with leaf width. Among biochemical constituents nitrogen, protein and chlorophyll content exhibited positive significant correlation whereas silica was negatively correlated with leaf folder damage. Among different insecticidal treatments, flubendiamide 480 SC @ 0.2 ml l-1 (T1) was found most effective treatment with lowest (4.93%) mean per cent the leaf folder damage ( 63.20 per cent reduction over control) followed by cyantraniliprole 10 OD @ 1.2 ml l-1 (T6) (7.17%), chlorantraniliprole 18.5 SC @ 0.3 ml l-1 (T5) (7.06%), fipronil 5 SC @ 1.2 ml l-1 (T7) (7.76%), cartap hydrochloride 50 SP @ 2 g l-1 (T8) (8.20%) with 51.26, 50.81, 49.67 and 44.95 per cent reduction over control, respectively. The lowest mean per cent reduction of leaf damage was recorded with dinotefuran 20 SG @ 0.4 g l-1 (T3) (17.41%) over control followed by chlorpyrifos 20 EC @ 2.5 ml l-1 (T2) (10.09%) and acephate 95 SC @ 1.5 ml l-1 (T4) (9.28%) with 35.90, 39.83 per cent reduction over control, respectively indicated that their reduced efficacy against rice leaf folder.en-USnullThesis