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19863
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Subject: Plant Pathology × End date: 1986 × Start date: 1984 × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    Study of bacterial leaf spot of betel vine- biochemical changes and control
    (Department of Plant Pathology, College of Agriculture, Vellayani, 1986) Koshi, Abraham; KAU; James, Mathew
    The bacterial leaf spot is one of the most serious diseases of betel vine in Kerala. The bacterium is one of the most serious disease of betal vine. Confidering the seriouness of the disease , studies were undertaken on the different aspects of the disease and to find out a suitable control /management practice.
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    Strain variation in Rhizoctonia solani Kuhn [Thanatephorus cucumeris (Frank) Donk] causing sheath blight of rice
    (Department of Plant Pathology, College of Agriculture, Vellayani, 1986) Vijayan, M; KAU; Chandrasekharan Nair, N
    Symptoms of sheath blight disease usually develop towards the tillering stage of the rice crop. Discolouration initially appearing on the sheath at or above the water level develop into ellipsoidal lesions. The lesions are light greenish gray in colour with dark brown margin. As the disease progress the lesions coalesce and become oblong to irregular in shape. In severe condition the lesions encircle the culm and cause rotting of the sheath. The disease then spreads to the leaves and such plants are killed. Sclerotia and silvery threads of the fungal mycelium appear on the affected regions under high humid conition. The casual organism was Isolated and identified as Rhizoctonia solani Kuhn. The hyphae branched near the distal septus with a costriction at the branch base. Hyphae were multinucleate and in culture showed brown pigmentation. Nature sclerotia were subglobose with rough regular surface.
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    Effect of application of plant protection chemicals on the survival of Rhizoctonia solani Kuhn
    (Department of Plant Pathology, College of Agriculture, Vellayani, 1986) Lulu Das; KAU; Chandrasekharan Nair, M
    In Kerala, the incidence of sheath blight of rice is endemic causing great economic loss. The present investigation was undertaken to make a critical assessment of the efficacy of various palnt protection chemicals, viz., fungicides, insecticides and herbicides on the incidence and intensity of sheath blight of rice and on the survival of the pathogen. The organism was isolated from naturally infected rice fields and its pathogenicity proved. Studies on the viability of sclerotia revealed that they sclerotia remained viable upto 210 days in all the different types of soils namely sandy, clayey and loamy. The organism could survive on straw bits upto 180th ady only.