Standardisation of food bases for selected antagonistic microflora against soil-borne pathogens

Abstract

Techniques for mass multiplication and production of antagonistic microflora isolated from the forest soils of Kerala for the biocontrol of soil-borne pathogens viz., Rhizoctonia, Pythlum and Phytophthora were investigated. The antagonists used were Trichoderma harzianum, T, Ionqibrachiatum, Aspergillus terreus, Panicillium citrinum, P.simplicissimum and Bacillus subtillis. The food bases tried were rice, wheat bran, paddy straw, rice bran, cowpea, forest soil and soil + dried.cowdung. The growth and survive! of antagonists in various food bases were estimated in vitro. A pot culture experiment was laid out during the period from March to September 1989 at the College of Horticulture, Vellanikkara to assess the population dynamics of the Introduced antagonists in rhizosphere of crop plants end to find out the effect of carrier based antagonist in controlling collar rot of cowpea caused by Rhizoctonia solani, soft rot of ginger caused by Pythium myriotylum and quick wilt of black pepper caused by Phvtophthora palmivora. Milled rice was found to be the most promising food base for all the isolates tested. Wheat bran was also found good for all the Isolates except T. longibrachiatum, T. longibrachiatum as well as B. subtilis were found to grow well in rice broil. A. terreus and P. citrlnum exhibited good growth while moderate growth of T. longibrachiatum and P. simpliciasimum was observed with cowpea as a food base. In general paddy straw, forest soil and soil + cowdung was found to be poor substrates compared to other food bases. But in paddy straw, T. harsianum ,A. terreus. P. citrinum and B. subtilis survived better compared to other food bases.