MANAGEMENT OF ROOT MEALYBUGS, Geococcus spp. IN BANANA CV. NENDRAN

Abstract

Soil ameliorants, botanicals, chemical insecticides and fungal bio-agents were screened against banana root mealybug, Geococcus spp.  Among the soil ameliorants, application of sodium silicate and calcium oxide at the time of planting effectively reduced the population of root mealybug. Drenching of neem seed kernel extract (NSKE) @ 3 % at monthly intervals was superior to neem cake, neem oil and pongamia oil. The entomopathogenic fungus, Cephalosporium lecanii Zimmerman was the best among the three fungi screened. At five months after planting, C. lecanii recorded
1.95 colonies per sample followed by Hirsutella sp. (2.25 / sample) and the control recorded
5.70 per sample. Among the synthetic chemicals, drenching chlorpyriphos (0.05%) at monthly intervals @ 2.5 ml l-1 effectively reduced the root mealybug population and was found to be the best treatment.  Field experiment conducted with the best treatment in each of the category and their combinations revealed that, almost all treatment combinations containing chlorpyriphos caused maximum reduction of root mealybug. Among the combinations without synthetic insecticides, sodium silicate (S) alone and its combination with NSKE and C. lecanii (SNV) were effective in reducing the mealybug population at sixth and seventh month of the crop. Application of chlorpyriphos gave the highest benefit cost ratio of 2.46 followed by sodium silicate (2.30).