Sharma, Bipan KumarRana, Nikhil2023-02-212023-02-212022-12-26https://krishikosh.egranth.ac.in/handle/1/5810194195Black point disease of wheat is common in all the wheat growing areas and has become a major constraint in recent years for successful and profitable cultivation of wheat in India. The investigations on different aspects of the disease were carried out at Plant Pathology Laboratory, Department of Plant Pathology, CSK HPKV Palampur and Research Sub Station Akrot (HP). There was considerable variation in the level of black point infection in grain samples collected from seven districts of Himachal Pradesh. The highest disease occurrence (83.33%) was recorded in Kangra district during Rabi 2021-22 cropping season. Out of five pathogens isolated, namely Alternaria alternata , Helminthosporium sativum, Aspergillus niger, Fusarium spp. and Curvularia spp. A. alternata was found to be the predominant pathogen associated with black point infection. The agar plate technique outperformed moist blotter technique for growth and spore formation by the fungus A. alternata. Potato dextrose agar was found most suitable media for A. alternata due to profuse growth of mycelia growth under lab conditions followed by Oat meal, Malt extract and least in Corn meal agar. The mycelium was light greenish to greenish black in most media. A. alternata growth was found to be maximum at 30 ± 2°C. Artificial screening of twenty five wheat cultivars showed varying degrees of susceptibility to black point incidence, ranging from 42.50 (VL-907) to 68.0 per cent (HS-240). The black point index ranged from 5.0 (VL-907) to 9.32 (HPW-360) with an overall range of 0-15.33. When exposed to conidial suspension sprays (20,000 conidia/ml) at various crop stages, susceptible varieties PBW-343 and HS-240 developed varying level of black point infection and ear head half outside boot leaf stage was found to be most susceptible stage for black point infection. Among quality characters tested under laboratory conditions in twenty five cultivars, there was 7.7- 18.96 per cent decrease in seed germination due to black point infection and overall 12.78 per cent increase in seed weight of infected seeds over healthy seeds.EnglishThesis