TIME-LINKED DOSAGE APPRAISAL OF TRICHOGRAMMATIDS AGAINST CNAPHALOCROCIS MEDINALIS (GUENEE) AND SCIRPOPHAGA INCERTULAS (WALKER) IN ORGANIC AROMATIC RICESudhendu Sharma and Naveen Aggarwal
To facilitate ecologically acceptable management of rice pests and to have pesticide free produce, timelinked dosages of Trichogramma chilonis Ishii and Trichogramma japonicum Ashmead were evaluated against Cnaphalocrocis medinalis (Guenee) and Scirpophaga incertulas (Walker) at farmers field. The studies was conducted during 2012 and 2013 in aromatic rice under organic farming conditions. Five doses (50000, 75000, 100000, 125000 & 150000 eggs/ha) and two release intervals (7 and 14 days) were studied for the incidence of damaged leaves (DL), dead hearts (DH) and white earheads (WE). The results of research revealed that higher doses, i.e. 150000 (4.04% DL, 1.83% DH & 2.12% WE), 125000 (4.47% DL, 1.77% DH & 2.09% WE) and 100000 (5.57% DL, 2.00% DH & 2.02% WE) with 7 day release interval significantly reduced the incidence. Doses of 125000 (5.83% DL, 2.42% DH & 2.32% WE) and 150000 (5.45% DL, 2.31% DH & 2.34% WE) also proved effective even at 14 day release interval. The highest grain yield was recorded with dose of 125000/ha (26.21 q/ha) followed by doses of 150000 (26.05 q/ha) and 100000 (24.79 q/ha) when applied at 7 day interval. When the interval between releases increased to 14 days, the yields remained relatively stable in these higher doses (23.30-24.48 q/ha).
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