INTRODUCTION Rice is the second most important staple food crop of the world consumed by more than half of the world's population. Asian continent itself accounting for 90% of the world production (IRRI, 2019). China is the leading rice producer followed by India, Indonesia and Bangladesh. The estimated area, yield and production of rice crop in the world is 162.46 million ha, 4.63 metric tonnes per ha and 504.17 million metric tonnes respectively, during 2020-21. Globally, India accounts for 27.08 % and 23.99 % of the total acreage and production. In Telangana, rice is mostly cultivated under wells, tanks and canals in an area of around 129.78 lakh acres during kharif and rabi, 2021-22. The crop is grown in 41.85 lakh acres during kharif, 2021, whereas 52.80 lakh acres during rabi, 2020-21 (Department of agriculture). A remarkable increase in rice area was recorded during 2020-21 in Telangana state is due to increased irrigation facilities, availability of high yielding varieties and farmer pro-government policies. Although, the crop suffers from many diseases caused by fungi, bacteria, virus, nematodes and other parasites. Among the fungal diseases, sheath rot once a minor and geographically limited disease is becoming major threat and gained momentum in many parts of the world (Bigirimana et al., 2015) as well as in India (Saravanakumar et al., 2009). It is a serious menace to rice cultivation and considered as an important emerging rice production threat causing yield losses ranging from 3-85% depending upon disease severity (Chakravarthy and Biswas 1978) and complete suppression of panicle exertion (Raina and Singh 1980). Sheath rot of rice is a complex disease that can be caused by various fungal and bacterial pathogens depending on the area, varieties grown, prevailing environmental conditions, farming systems and involvement of other insect-pests. The major pathogen associated with sheath rot in rice are Sarocladium oryzae, Fusarium fujikuroi complex and Pseudomonas fuscovaginae (Bigirimana et al., 2015)., Recently, Albifimbria terrestris from northern India (Sharma et al., 2021) and Fusarium proliferatum from eastern India (Prabhukarthikeyan et al., 2021) have been reported incausing sheath rot, grain discolouration, sterility and chaffiness of therice panicles. The various described sheath rot pathogens will cause similar disease symptoms in rice (Cottyn et al., 1996). Although, several pathogens have been associated with rice sheath rot, but Sarocladium oryzae (sawada W. Gams and D. Hawksw) is a major important seed borne fungal pathogen reported in India. Sheath rot pathogen infects upper most flag leaf sheath that enclose the emerging young panicles during the boot leaf stage. The major symptoms of sheath rot according to Ou, (1985), the lesions are oblong or irregular oval spot and usually expressed as reddish-brown discoloration of flag leaf sheath. Early infection affects the panicles, so that it partially emerges. The un-emerged portion of the panicle rots, turning florets red-brown to dark brown. Grains from damaged panicles are chaffy and the disease is appropriately known as "empty earhead" and is familiar as "rice abortion" (Kindo, 2012) and it affects seed viability, nutritional and market value (Sakthivel, 2001; Gopalakrishnan et al., 2010). The symptoms of Fusarium proliferatum is more or less similar to the symptoms caused by Sarocladiumoryzae. However, little information is available on the prevalence and distribution of the disease in Telangana state. Hence, the present investigation was undertaken to study the disease distribution during kharif, 2021 by following a survey of major rice growing districts of Telangana state. MATERIALS AND METHODS A. Collection of diseased/infected plant samples A roving survey was conducted to collect sheath rot infected plant samples from major rice growing areas of Northern Telangana Zone (Nirmal, Jagtial, Nizamabad, Peddapalli, Kamareddy and Karimnagar), Southern Telangana Zone (Nalgonda, Suryapet, Nagarkurnool and Mahabubnagar) and Central Telangana Zone (Medak, Sangareddy, Siddipet, Warangal and Khammam) of Telangana state during kharif, 2021. Survey data collected includes crop and field details such as sample number, name of the village, mandal and district, field location, variety grown, crop stage, previous crop, source of irrigation, panicle type and percent disease incidence (PDI) of sheath rot disease. Infected plant samples were collected for isolation of sheath rot pathogen Sarocladium oryzae. The external signs and symptoms such as the presence of reddish-brown oblong lesions or irregular oval spots on flag leaf sheath were used to determine the incidence of the sheath rot disease in the fields surveyed. Five plots measuring 1 m × 1 m were selected such that one plot was in the centre of the field and the rest were randomly placed on the four corners leaving 1 m from the border. The total number of productive tillers were counted in each plant and then counted the number of sheath rot infected panicles and finally computed the sheath rot incidence percentage. Ten plants were randomly selected per one sq. m area and above procedure followed to obtain sheath rot disease incidence percentage. Percent disease incidence was calculated by the following formula: Number of infected tillers PDI = Total number of tillers observed Isolation of sheath rot associated pathogen The leaves showing the typical symptoms of sheath rot were selected and washed with sterile distilled water. Small piece of diseased tissue along with some healthy tissue was cut with the help of a sterile scalpel and surface sterilized with 0.1% sodium hypochlorite solution for one min, rinsed thrice in sterile distilled water and dried with sterilized filter paper. The surface sterilized samples were placed on Potato Dextrose Agar (PDA) medium with the help of sterilized forceps and placed in BOD incubator at 28±2 ºC. The pathogens were isolated from the infected tissue and further purified by hyphal tip method (Lilly and Barnett 1951). Sheath rot associated pathogen was identified based on cultural and morphological characters of the isolated fungi. RESULTS AND DISCUSSION A roving survey was conducted to collect the information on occurrence of sheath rot in major rice growing areas of Northern Telangana Zone (Nirmal, Jagtial, Nizamabad, Peddapalli, Kamareddy and Karimnagar), Southern Telangana Zone (Nalgonda, Suryapet, Nagarkurnool and Mahabubnagar) and Central Telangana Zone (Medak, Sangareddy, Siddipet, Warangal and Khammam) of Telangana state during kharif, 2021. The roving survey was carried out in 72 villages of fifteen major rice growing districts of Telangana state. A total of 84 samples were collected during survey. The data was collected on GPS coordinates, varietal pattern, disease incidence along with district, mandal and village. The data regarding the survey was tabulated in the (Table 1). Data collected during the survey indicated that majority of the farmers opted for mono-cropping of rice in total surveyed districts except in the Nagarkurnool district where groundnut crop was grown in one season (during rabi) and rice crop was grown in another season (during kharif). 50% of the farmers in the surveyed villages were cultivating the MTU1010 and BPT5204 rice varieties. Fields were majorly irrigated through canals in Nalgonda and Suryapet and remaining districts through borewells tabulated in Table 1. During the survey, stage of the rice crop was milky to mature stage. The maximum sheath rot incidence was observed in the surveyed fields were seen at mature stage of the rice crop. Percent disease incidence of sheath rot in the surveyed fields ranging from 3.0 to 37.7 per cent. The highest incidence of sheath rot (37.7%) was noticed at Lingala village of Achampetmandal of Nagarkurnool district followed by Jalalpur village of Bhoodan Pochampallimandal of Nalgonda district and Thatipally village, Jagtialmandal of Jagtial district with a disease incidence of (33.33%) while the lowest incidence (3%) was recorded in Pendlipakala village, Kondamallepally mandal of Nalgonda district followed by Navipet village, Ghanpurmandal of Medak district. Out of 84, samples of sheath rot, forty six samples from fine grain varieties and thirty eight samples from coarse grain varieties of rice. The maximum sheath rot incidence was noticed in fine grain varieties range from (10.5 to 37.7%) when compared to coarse grain varieties range from (3.0 to 33.0 %) indicating that most of the fine grain varieties were having compact nature of the panicle favouring the sheath rot disease initiation. Majority of the rice area in Telangana during kharif, 2021 was under fine grain varieties where sheath rot disease affected the farmer fields drastically. If the fine grain varieties cultivation occupies 60-70% of the total cultivated rice area in Telangana, the yield losses estimated to be nearly 60%. Among the 84 samples were collected from farmer fields in different villages 9 data points were showing the severe (25-70%) incidence, 67 data points showed moderate (6-25%) incidence and 8 data points showed less (0-5%) incidence of sheath rot disease (Fig. 1). Bar graph was drawn with varied PDI and total samples which is represented in Fig. 2. Similar findings were reported by Kumar & Priya (2016), Vengadeshkumar et al. (2019). Kumar et al. (2017) reported highest incidence of sheath rot was recorded in Orathur (30.5) village and the least incidence was noticed in Vennankuzhi (12.1) village of Tamil Nadu state. Vengadeshkumar et al. (2019) reported the disease incidence ranged from 12.32 to 30.43 per cent in Nagapattinam district of Tamil Nadu state. Identification of Sarocladium oryzae was done based on the cultural and morphological characterstics such as colony colour varied from white to pale orange. Pigmentation on the bottom of the plate varied from white to brown. Conidiophores were simple or branched. Conidia was cylindrical, aseptate and hyaline, 4-7 x 1-2 µm in size, and arranged in slimy heads (Bigirimana, 2016) (Fig. 3). Identification of Fusarium proliferatum was done based on the cultural and morphological characterstics such as the colonies produced white aerial mycelium with violet to pink pigmentation. Hyphae was hyaline and septate. Abundant single celled, oval shaped microconidia were produced, whereas macroconidia was not produced (Prabhukartikeyan et al., 2021) (Fig. 4). Finally, 38 isolates of Sarocladium oryzae and 2 isolates of Fusarium proliferatum were obtained from infected rice leaf sheaths. The two Fusarium isolates were obtained from sample no SO26 and SO72.