Pest incidence of maize crop in regions of Ranchi and Khunti

Abstract

The occurrence and per cent infestation of several insect pests on maize (Zea mays L.) was examined with survey of different eight locations of farmer’s fields during kharif in 2010-11. The survey is done at research farm BAU and in different villages - Thakurgaon, Pithoriya, Mandar, Manatu, Ormanjhi & Chandewe of Ranchi district and village Khunti of Khunti district in Jharkhand state. The five pests were observed under surveyed area stem borer (Chilo partellus Swinhoe), leaf folder (Marasmia trapezalis Guenee), grasshopper (Hieroglyphus nigrorepletus Bolivar), termite (Odontotermes obesus Rambur) and cob borer (Helicoverpa armigera Hubner). The observations are taken by visually according to the leaf injury rating scale (1-9) in the case of stem borer. For grasshopper observations are taken by ten sweep net methods and counted for record. Observations of leaf hoppers recorded by examining the leaves terminal, central and basal parts of the plants (crop sampling). The termite occurrence recorded by presence of termite mounds. Incidence of cob borer was recorded by randomly selected 5 spots of crop field and count total plants & 5 plants randomly selected having cob damage at that spots. The cob damage was converted into per cent cob damage. The occurrence of stem borer, leaf folder, grasshopper, termite and cob borer was recorded in these locations. The maximum per cent infestation was recorded by stem borer (19.6), leaf folder (8.6) and termite (4.6) at research farm BAU and grasshopper (5.3) at Khunti and cob borer (3.2) at Manatu.