~ 1902 ~ Journal of Pharmacognosy and Phytochemistry 2018; SP1: 1902-1908 E-ISSN: 2278-4136 P-ISSN: 2349-8234 JPP 2018; SP1: 1902-1908 Ashok Kumar Koshariya Department of Plant Pathology, CoA, IGKV Raipur, Chhattisgarh, India Indra Kumar Department of Plant Pathology, CoA, IGKV Raipur, Chhattisgarh, India Anil S Kotasthane Department of Plant Pathology, CoA, IGKV Raipur, Chhattisgarh, India Toshy Agrawal Department of Plant Molecular Biology and Biotechnology CoA, IGKV Raipur, Chhattisgarh, India Priyanka Department of Plant Pathology, CoA, IGKV Raipur, Chhattisgarh, India Correspondence Ashok Kumar Koshariya Department of Plant Pathology, CoA, IGKV Raipur, Chhattisgarh, India Evaluation of new fungicide against sheath blight (R. solani) of Rice Ashok Kumar Koshariya, Indra Kumar, Anil S Kotasthane, Toshy Agrawal and Priyanka Abstract Rice sheath blight, caused by the fungal pathogen Rhizoctonia solani Kuhn [Sexual stage: Thanetophorus cucumeris (Frank) Donk] is one of the major production constraints in rice-growing countries of the world. Under conditions favoring disease, up to 50% of grain yield may be lost (Marchetti and Bollich 1991). Control may be achieved with fungicides (Groth 2008), but cost and the potential for development of pathogen resistance make plant genetic resistance preferable. Plants can be induced locally and systemically to become more resistant to diseases through various biotic or abiotic stresses. The best characterized signal pathway for systemically induced resistance is SAR (systemic acquired resistance) that is activated by localized infections with necrotizing pathogens. It is characterized by protection against a broad range of pathogens, by a set of induced proteins and by its dependence on salicylic acid (SA) Various chemicals have been discovered that seem to act at various points in these defense activating networks and mimic all or parts of the biological activation of resistance. Resistance inducing chemicals that are able to induce broad disease resistance offer an additional option for the farmer to complement genetic disease resistance and the use of fungicides. If integrated properly in plant health management programs, they can prolong the useful life of both the resistance genes and the fungicides presently used Thifluzamide is a member of the carboxamide class of fungicides which is single-site inhibitors of the succinate ubiquinone reductase or succinate dehydrigenase (Sdh) complex in the respiratory chain (FRAC 2007) interfere with fungal respiration via their inhibitory effect on succinate dehydrogenase within the tricarboxylic acid cycle. (O’Reilly1995). We have observed Thifluzamide to be effective in controlling rice sheath blight and therefore the fungicide can fit into resistance management system by integrating in spray schedules in potential rice growing tracts. Keywords: Sheath blight, disease incidence, Fungicide 1. Introduction Sheath blight caused by RhizoctoniasolaniKühn (teleomorph: Thanatephoruscucumeris (A.B. Frank) Donk) is a major constraint (second only to rice blast) to rice production (Teng, Torres, Nuque, & Calvero, 1990), causing 5-10% yield losses in low land tropical Asia (Willocquet et al., 2004). The pathogen has a wide host range and can infect more than 32 plant families and 188 genera (Srinivasachary, Willocquet, & Savary, 2011), often infecting legume crops grown in rotation with rice (Zou et al., 2000). The emergence of R. solani as economically important rice pathogen has been attributed to the intensification of rice cropping systems with the development of new short-stature, high-tillering, high-yielding varieties, high plant densities and increased level of fertilizers and other inputs (Chahal et al. 2003, Siddiq 1999) and these factors promote disease spread by providing favourable micro climatic condition due to dense leaf canopy with an increase leaf-to-leaf and leaf to- sheath contact (Savary et al. 1995). Both seedlings and adult plants are equally affected but loss is much more when the disease appears in seedlings. The older plants are attacked in flooded conditions and swampy rice fields (Dodman and Flentje 1970, Kannaiyan 1987, Shimamoto 1995). The infection and spread of disease before the flag leaf stage revealed 20% grain loss. Further, a strong relationship between the severity of symptom and yield reduction was reported among cultivars (Marchetti and Bollchi 1991). Sheath blight can be effectively controlled with the application of systemic fungicides. However, bio-fungicides and resistant varieties are the other options of control management but, are not at par with chemical control. These fungicides are very popular and are at the peak of its usage which may lead to reduced residual period and efficacy due to increased virulence of R. solani. 2. Materials and methods The present investigation entitled “Evaluation of new fungicide against R. solaniin rice.” was conducted at the Molecular Plant Pathology, laboratory of Biotechnology,