Susceptibility of rice varieties of different durations to rice leaf folder, Cnaphalocrocis medinalis Guen. evaluated under varied land situations*

Among the 24 rice varieties tested for their reactions to leaf folder, Cnaphalocrocis medinalis Guen., the varieties IET 7564, ES 29-3-3-1, Pusa 2–21 and Type-3 having 3.80, 4.45, 4.97 and 6.02% infestation respectively were feast susceptible. On the other hand, varlaties Rashi 17-4B-13 (35.35%), Rajshree (30.08%), Rashi 16-4B-11 (30.19%) and UPR 238T (28.25%) were highly susceptible. The maximum infestation was observed in mid early (24.73%), medium (18.93%) and late duratfon (16.01%) varieties when compared with extra-early (4.49%) and early (8.97%) varieties. The chemical analysis of these varieties revealed that leaf area and phosphorus content of the leaf failed to pronounce any effect on the infestation. But, correlation coefficient between silica content (r =-0.610) as also potassium (r =-0.702) and percentage infestation due to leaf folder revealed that varieties having higher content of silica and potash produced low infestation and vice-versa.