Indian Phytopath. 63 (2) : 212-215 (2010) Evaluation of scented rice genotypes and fungicides against blast and compatibility of pesticides used against neck blast, stem borer and leaf folder RAM SINGH*, S. SUNDER, D.S. DODAN, L. RAM and RATTAN SINGH CCS Haryana Agricultural University Rice Research Station, Kaul 136 021 ABSTRACT: Out of 119 scented rice genotypes, twenty-seven were found consistently resistant to leaf blast while ten genotypes were consistently resistant to neck blast during Kharif 2007 and 2008, indicating that resistance to leaf blast in scented rice cultures is more common than neck blast. Seven genotypes namely, HKR 04-487, HKR 05-436, HKR 05-476, Haryana Mahak-11, PAU 3237-1-B-B-19, PAU 3237-1-B-B-20 and PAU 3237-1-B-B-22 were found consistently resistant to both leaf and neck blast phases during both the years. On the basis of mean data of Kharif 2000 and 2001, carpropamid and tricyclazole were found to be the most promising fungicides in reducing the neck blast incidence followed by kasugamycin and epoxiconazole + carbendazim. However, carbendazim 12% + mancozeb 63% had no significant effect on disease incidence. In addition, kresoxim methyl at 1.5 ml/l and azoxystrobin at 1.0 ml/l were also found highly effective against neck blast and statistically on par with standard fungicide tricyclazole during Kharif 2002 to 2005. The combination treatments of both the fungicides (tricyclazole and iprobenphos) and insecticides (indoxacarb and cartap hydrochloride) were biologically as effective as their individual treatments against neck blast, leaf folder and stem borer of rice, respectively during Kharif 2006 and 2007 along with corresponding increase in grain yield of Taraori Basmati. Tricyclazole alone and in combination with insecticides proved better than iprobenphos alone and in combination with insecticides. Key words: Rice, resistance, chemical control, blast, leaf folder, stem borer, pesticidal compatibility Blast caused by Pyricularia grisea Sacc. [teleomorph Magnaporthe grisea (Hebert) Barr.] continues to be a serious constraint in all the rice ecosystems of the country (Muralidharan, 2006). In Haryana, the disease is particularly devastating in scented rice cultivars grown for export purpose (Ram Singh et al., 2004). All the commercially grown scented rice cultivars are susceptible to the disease (Anonymous, 2006). Moreover, the pathogen is extremely variable and several races have been identified from different regions of the country (Muralidharan, 2006). Constant efforts are required to identify new sources of resistance and effective and economical chemicals for its management. Besides blast, stem borer and leaf folder are the other biotic constraints in realizing the yield potential of scented rice cultivars grown in the state (Kushwaha and Bharti, 1994). As these pests co-exist in the ecosystem and attack the crop almost simultaneously, fungicides and insecticides are commonly used as a single tank mix application for their management. The information on compatibility of effective fungicides and insecticides in rice is limited (Lakshmanan, 1992; Dodan et al., 1997). The present study was, therefore, undertaken to identify the sources of resistance in scented rice genotypes, to find effective fungicides against blast and to evaluate the efficacy of combined application of fungicides and insecticides against blast, stem borer and leaf folder in Basmati rice. MATERIALS AND METHODS One hundred nineteen scented rice genotypes included in various station and coordinated trials were evaluated for resistance to leaf blast in uniform blast nursery (UBN) by alternating each test genotype with a susceptible variety ‘Taraori Basmati’ on all sides (Jennings et al., 1979) during Kharif 2007 at Research Farm, CCS HAU Rice Research Station, Kaul, Haryana. For neck blast screening, one- month-old seedlings of these genotypes were transplanted in two rows of five-meter length at 20 x 15 cm spacing during the same crop season. Delayed sowing and transplanting of the genotypes (July end) and application of slightly higher dosage of nitrogenous fertilizer (75 kg N/ha) was done to ensure maximum disease development. The observations on leaf blast were recorded during last week of September when disease development was maximum on susceptible cultivar Taraori Basmati following Anonymous (1996). The neck blast incidence was recorded by observing all the tillers of 10 randomly selected hills of each genotype. The genotypes showing a disease rating of 0-3, 3.1-5, 5.1-9 were designated as resistant, intermediate and susceptible, respectively. Forty genotypes showing resistance to either leaf or neck blast during Kharif 2007 were retested during Kharif 2008 to confirm their reaction. To compare the efficacy of fungicides, separate field trials were conducted during Kharif 2000 to 2005 in randomized block design with three replications in 5 x 3 m plots using a susceptible variety ‘Taraori Basmati’. The fungicides viz. kasugamycin (Kasu B 3 SL), epoxiconazole + carbendazim (Swing 250 EC), carbendazim 12% + mancozeb 63% (Saaf 75 WP) and carpropamid (Win 300 *Corresponding author: singhdrram@yahoo.co.in