Sheath blight of rice caused by Rhizoctonia solani Kuhn is an important soil-borne disease throughout the rice-producing areas of the world. Twenty-nine bacterial endophytes were isolated from different plant sources and tested for their efficacy against R. solani inciting sheath blight in rice. Bacillus subtilis var. amyloliquefaciens (FZB24) caused a maximum 36% inhibition of R. solani over the control in vitro. Rice plants (cv. ADT 39) treated with FZB24, in combination with seed treatment @ 4 g kg 21 , seedling dip @ 4 g l 21 , soil application @ 500 g ha 21 and foliar application @ 500 g ha 21 , gave the lowest severity of sheath blight (33%) with around 55% reduction over the control under glasshouse conditions. In addition, the B. subtilis (FZB24) treated rice plants showed higher induction of defence-related enzymes, peroxidase, polyphenol oxidase and phenylalanine ammonia lyase, and resulted in higher accumulation of total phenols than in the untreated control plants. The endophytetreated rice plots had a significantly lower intensity of sheath blight than untreated control plots and also recorded a higher grain and straw yield.

During 2012-2014, mosaic disease on chayote in the farmers field of Kodaikanal region (high altitude zone) of Tamil Nadu was observed. The disease was characterized with severe mosaic, cupping and enation on leaves with reduced fruit size. Disease was found to causes an yield loss of more than 60% with the maximum disease incidence of 100% for the past 5 years consecutively. Preliminary serological and molecular screening indicated the association of begomovirus with the disease. Complete nucleotide sequence and phylogenetic analysis of DNA A revealed the identity of the virus as tomato leaf curl New Delhi virus (ToLCNDV). In recombination analysis study, the major parent was identified as ToLCNDV from Pakistan infecting tomato. Thus the present finding confirms expansion of new geographical region and host for ToLCNDV causing mosaic disease on chayote from Tamil Nadu. To our knowledge this is the first confirmed report for the occurrence of ToLCNDV on chayote in southern India.

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In this study, the toxicity of liquid culture media from different isolates of Lasiodiplodia theobromae was characterized and some properties of the toxic metabolites were distinguished. In this work toxin producing ability of L. theobromae was revealed by studying the physical parameters viz., osmotic potential, toxin concentration, pH, temperature and biological parameter like host specificity and wilting index. The obtained results showed that the optimal toxin-production conditions for L. theobromae in potato dextrose broth under pH 6.0, at 25-35°C for 7 days. The liquid culture from all isolates were toxic to mango plants and induced the rapid wilting. The toxin obtained from the liquid culture has thermal, acid base stability and a broad range of toxicity to main host and non-host plants. Moreover, the direct bioassay for two components of the liquid filtrates precipitated by ethanol showed that the active ingredient of the toxin is a kind of non protein substance, which was further endorsed by the papain hydrolysis analysis. Our results confirmed the chemical nature of toxic compound elucidating the favorable environmental conditions for toxin production of L. theobromae and proved potential role of toxic metabolites in the mechanism of disease development.