Effect of organic amendments on the proliferation stability of Trichoderma harzianum and suppression of Phytophthora meadii in cardamom soils in relation to soil microflora

Abstract

An even economical and more frequently used method of attaining biological control of soil borne plant pathogens is incorporating plant residues and organic amendments to the soil, which support high level of microbial activity. In the present study farm yard manure (FYM), poultry manure (PM), coffee husk (CH) and neem cake (NC) were used as soil amendments with or without Trichoderma harzianum to evaluate their efficacy in suppressing Phytophthoora meadii under varying moisture conditions. The survival of Phytophthora was found higher at 50% moisture level. Neem cake with Trichoderma appeared as a suitable amendment at all moisture level and has shown 69% reduction in Phytophthora infection over control. At 75% and 100% (field capaci!)'), no detectable Ievel of Phylophlhonl was observed in treatments where T. harzianum was fortified withCH, PM aud NC. At field capacity, PM and FYM with Trichoderma also reduced the build up of Phytophthora. Native population of Trichoderma was found negligible in non-amended treatments. All the four amendments maintained the population and supported the growth of Trichoderma at all moisture levels. In general, organic manures with T. harzianum reduced the population Ievel of other fungi , while crop residues supported the growth of fungi likc Penicillium,Rhizopus, Aspergillus, Mucor, etc. besides T. harzianum.