Integrated management of sheath rot of rice (Oryza sativa L.)

Abstract

Sheath rot disease of rice, caused by Sarocladium oryzae Gams and Hawksworth, is one of the most important diseases of rice in Kerala. The present investigation was to work out an efficient ecofriendly integrated control measure utilising biocontrol agents and plant products in combination with the minimum dose of fungicides against this disease. The antagonists found effective against Sarocladium oryzae are Trichoderma sp., Aspergillus sp. and Penicillium sp. Among these, Trichoderma sp. was found to decrease the disease intensity and increase the yield, the most. tried, best. Among the various methods of application of antagonists seed treatment and root dip method were found to be the In the pot culture trial conducted to find out the mode of action of antagonists under various systems of application, none of the treatments proved superior to others. Leaf extract of Ocimum sanctum (10 per cent) had maximum inhibition of the radial growth of the fungus. Minimum dry weight was seen with the bulb extract (10 per cent) of Allium sativum and extract (10 per cent) of Ocimum sanctum. Carbendazim at 0.025 per cent concentration brought about 100 per cent inhibition of radial growth and mycelial weight of S. oryzae. Total inhibition of radial growth of the fun~u9 WBB achieved by the application of 0.25 per cent Ediphenphos and total inhibition of the mycelial growth was achieved by the application of Ediphenphos at 0.075 per cent concentration. For mass multiplication of antagonists, bits of jack seeds proved to be the best substrate for Trichoderma ap. as evidenced by fungal growth. Tapioca rind and wheat grains was the best suited Aspergillus ap. Wheat bran:sand (1:10 w/w) proved to be the best medium for Penicillium sp. For Pestalotiopsis Sp., wheat bran: sand mixture at a proportion of 1:3 and 1:10 were found equally good. The integrated management practices revealed that none of the treatments were superior over others when yield and disease intensity were considered. However, least disease intensity was noticed with the application of Trichoderma sp. as seed treatment, followed by foliar spray of Ediphenphos and leaf extract (10 per cent) of Ocimum sanctum. Highest yield was obtained in the treatment combination of Trichoderma sp, applied as seed treatment followed by the foliar application of Carbendazim and the bulb extract (10 per cent) of Allium sativum.