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Birsa Agricultural University, Ranchi

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Subject: Mycology and Plant Pathology × End date: 1996 × Start date: 1996 ×
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    ThesisItemOpen Access
    Studies On Collar Rot Of Okra Caused By Macrophomina Phaseolina( Tassi) goid
    (Birsa Agricultural University, Ranchi, 1996) Ajit Kumar Jha; S.C.Dubey
    Okra (Abelmoschus esculentus (L.) Moench) suffers from collar rot a very destructive disease caused by Macrophonina phaseolina (Tassi) Gold (Rhizoctonia bataticola (Taub.) Briton-Jones). Disease incidence varied from 12.7 to 58.3% in different localities of Ranchi. The characteristic symptom of the disease was observed on both root and collar region of seedlings as well as adult plants. The pathogen was isolated, Purified and identified by standard method. The pathogen satisfied koch's postulate tests. Potato dextrose agar (solid) and Richards' (liquid) media supported maximum mycelial growth and sclerotial production. 6.5 pH was found to be optimum for mycelial growth and sclerotial production in Richards liquid medium. All 13 plant species belonging to 6 families were infected during host range studies. 21 days old plant were highly susceptible to infection and older plants showed resistance to infection. High temperature, low rainfall and low humidity were favourable for disease development. Significantly negative correlations were established in between disease incidence and age of plants, average temperature, average relative humidity and rainfall. However, the disease incidence was positively correlated with average relative humidity and rainfall during 1995 only. Late sowing minimized the disease development and gave good yield. In general, low disease incidence and higher yield were recorded during rainy season sown crop than summer season sown crop. Okra varieties, Supriya (F), and Arka Anamika showed moderately resistant and tolerant reaction, respectively against disease. The local isolate of Trichoderma viride showed maximum inhibition of mycelial growth of pathogen followed by T. harzianus (local isolate) and T. viride (Pantnager isolate) in vitro. All six isolates of three fungal antagonists inhibited cent per cent sclerotial production. Nature of mycoparasition was established. Among different plant extracts, Bhangria leaf extract showed maximum inhibition of mycelial growth (32.6%) followed by Marigold (29.1%) and Karanj (26.1%) leaf extracts at 5 per cent concentration. Whereas at 10 percant concentration, Bharbhand leaf extract showed maximum inhibition of mycelial growth (45.0%) followed by Bhangria" (39.0%) and Marigold (34.4%) leaf extracts.
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    ThesisItemOpen Access
    Investigation on Leaf Spot of Soybean (Glycine mas (L) Merril) Caused By cercospora sojina In Chotanagpur (Bihar)
    (Birsa Agricultural University, Ranchi, 1996) Basanti Oraon; B.Mishra
    Soybean (Glycine max (L.) Morril) suffers from leaf spot disease caused by Cercospora sojina. The characteristic symptom was observed on leaf, atom, petioles and pads as also in seeds. The pathogen has been described in detail which appears to be a now host record in the plateau region of Bihar. It causes on appreciable damage (incidence 4.96-9.67 per cent) and severity (12.0 to 38.50 per cent) in and around Ranchi. In cultural studies, the radial growth and sporulation was best in Potato dextrose agar as well in Potato dextrose broth. However, the later gave excellent sporulation. The growth and sporulation were maximum at 28.1°C and pit 6.0 and thus were optimum temperature and pit, respectively. Glucose and Calcium nitrate were best sources of carbon and Nitrogen, respectively for maximum growth and sporulation. The diseased plant debris and diseased seed cause 16-65 per cent infection in the crop. The diseases was more severe with the environmental variables viz; reinfell (18.6 mm), relative humidity (71.7 %) and temperature (23.7°c) in Kanke conditions. In management trials, Drago variety of soybean proved to be moderately resistant against the pathogen. The pathogen could be effectively controlled with savistin (0.05 per cent) and Captor (0.2 per cent). In bio control, leaf extract of Argemon maxicana (20 per cent) inhibited maximum growth and sporulation of the pathogen.