Root borer (Polyocha depressella Swin.) infestation in different genotypes of sugarcane under field conditions

The experiments were carried out with total number of 92 genotypes screened during 1995–96 and 1996–97 where as the incidence of root borer ranged from 15.7 to 86.2 and 10.2 to 91.6 per cent, respectively. The lowest and highest incidence of root borer was recorded in genotypes Co 86036 and CoH 98 (1995–96) rated as moderately tolerant and CoS 89 and 5-91-76 (1996–97) as highly susceptible. Several genotypes like Co 98003, CoJ 64, CoH 108, CoS 93230, CoP 84211 and CoH 76 were repeated for the second year and their incidence ranged from 79.3 and 90.9, 42.4 and 27.7, 33.3 and 34.3,39.7 and 57.1,78.3 and 58.3 and 41.9 and 36.6 per cent, respectively. However, none was found tolerant, 8 genotypes were graded as moderately tolerant while 17 as susceptible and 67 as highly susceptible, which were 7.71, 18.15 and 74.14 per cent of the total 92 genotypes tested, respectively.