Grasserie Disease Incidence on Silkworm and Development of Botanical Based Management Strategy

The survey on incidence of grasserie revealed that all technical service centres (TSC) in western zone of Tamil Nadu were found to be affected due to grasserie disease. The mean disease incidence ranged from 31.58 to 4.04 per cent with maximum (mean) cocoon yield loss at Dharapuram TSC (30.05 kg/100 dfls). Dusting with TNAU seri dust followed by Psoralea extract per os application drastically reduced the larval mortality from 3.28 to 1.35 per cent. Maximum larval weight, cocoon weight, shell weight, shell ratio and cocoon yield of 3.68 g, 1.74 g, 0.323 g, 18.56 per cent and 78.20 kg/100 dfls respectively were registered in TNAU seri dust + Psoralea extract treated batch. Subsequent On-Farm Trials confirmed the reduction in larval mortality and enhancement in economic as well as yield parameters of silkworm, Bombyx mori L. Higher incremental cost benefit (ICB) of 2.37 was recorded in the batch treated with TNAU seri dust and Psoralea.