Singh, S. N.OMPRAKASH, Mr.2023-02-032023-02-032022M/PP/052/2020-21https://krishikosh.egranth.ac.in/handle/1/5810193184Sugarcane (Saccharum officinarum L.) is a major crop cultivated throughout the world's tropical and subtropical climates. It is a perennial, monocotyledonous large grass belonging to the family Poaceae, sub family Ponicoideae, tribe Andropogoneae, sub tribe Saccharastrae and genus Saccharum. The globe produces 181.2 million tons of sugarcane in 2020-21 covering an area of 21.73 million hectares. India produces approximately 25% of the world's sugarcane, making it the secondlargest producer after Brazil. Bihar is a significant sugarcane producing state in the country.It has occupied an area of 0.22 mha with a production of 10.71mt with an average productivity of 48.92 t/ha. Sugarcane is grown throughout approximately every district in Bihar. In this study it is clear that among the four districts under surveyed, East Champaran district was highly affected with red rot disease of sugarcane with mean disease incidence of 27.65% and Samastipur district was least affected by red rot disease with mean disease incidence of 21.02 %. Red rot disease is responsible for quick decline of commercial varieties and it is mainly due to the development of new pathotypes in red rot flora or another reasons. The results clearly indicate that 30 genotypes tested against red rot, 8 genotypes (CoP16437, BO91, CoP17437, CoP17438, CoP9301, CoP16439, CoP17440 and CoSe16451) were found resistant, 12 genotypes (CoSe18452, CoP17441, CoP2061, CoP16438, CoLK16470, CoSe01421, CoSe16454, CoSe16456, CoLK16468, CoLK94184, CoP17444 and CoP17446) were found moderately resistant, 3 genotypes (CoSe16452, CoLK16469 and BO156) were found moderately susceptible and 7 genotypes (CoLK16466, CoSe17451, CoBln17501, CoBln16502, CoSe92423, CoSe17452 and CoSe95422 as check) were found susceptible against red rot of sugarcane. Under in-vitro conditions, four fungicides were tested against Colletotrichum falcatum on oat meal agar medium with the application of the Poison food technique. Fungicides were tested at concentrations of 50, 100 and 200 parts per million(ppm). Among them Azoxystrobin+ Tebuconazole showed highest inhibition percentage of mycelium in all the tested concentrations and Thiophanate methyl showed lowest inhibition percentage of mycelium in all the tested concentrations against the test pathogen Colletotrichum falcatum. Under in vitro conditions, four stains of Trichoderma harzianum were studied against Colletotrichum falcatum on oat meal agar medium with the application of the dual culture technique. Four stains of T. harzianum viz; TPU-1, TSR-1, TSR2, TDH - 1 are tested in-vitro against pathogen C. falcatum. Among four strains of T. harzianum,TPU-1 showed highest inhibition percentage (60.05) and TSR -1 showed lowest inhibition percentage (51.60) against the pathogen Colletotrichum falcatum.EnglishThesis