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M. Sc. Dissertations

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Subject: Plant Pathology × End date: 2007 × Start date: 2007 ×
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    ThesisItemOpen Access
    Management of mungbean yellow mosaic virus in mothbean [Vigna aconitifolia (Jacq) marechal]
    (CCSHAU, 2007) Sunil Kumar; Gupta, P.P.
    Mothbean is a major commercial crop of hot arid regions of our country. It is affected by several fungal, bacterial and viral diseases. Among these mungbean yellow mosaic virus (MYMV) disease is the most important. Out of 62 genotypes screened against MYMV disease under field conditions and seventeen among them screened under green house conditions only 12 genotypes including one promising resistant check viz., RMM-47-2, RMM-44, GMO-4, RMO-257, RMB-54, CZM-90, HM-61, CZM-12, RMO-435, GMO-13, GMO-9915, CAZRI Moth-1 were found moderately resistant. Second week of June for sowing and spacing 45 cm were optimum in reducing the incidence of MYMV disease and whitefly population. The yield was also maximum (10.33 q/ha) at this conditions. There was positive correlation between disease incidence and whitefly population and yield was negatively correlated with disease incidence and whitefly population. The correlation of disease incidence with weather parameters were found non-significant. Application of phosphorus and potassium (40 kg/ha each) alone reduces the disease incidence from 47.8% (in control, no application of NPK) to 17.8% and 18.3% respectively. Highest reduction in MYMV disease incidence (70.61%), minimum whitefly population and maximum grain yield with respect to 20 kg/ha nitrogen application alone was recorded when N20P40K40 kg/ha were used. The botanical Azadirachtin (Fortune Aza, 5%) was most effective than other botanicals in reducing the MYMV disease incidence (69.43%) and increasing the grain yield (84.56%). This treatment was statistically at par with the application of Endosulfan (0.07% a.i.). Neem oil (5%) was found better next to the Azadiractin in reducing the disease incidence.
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    ThesisItemOpen Access
    Studies on loose smut of barley caused by ustilago nuda (Jens) rostr.
    (CCSHAU, 2007) Manender Singh; Karwasra, S.S.
    Investigations were carried out on the management of loose smut disease of barley through chemicals, biological means, plant extracts, sowing dates, and host resistance. The effect of loose smut on barley crop revealed that there was maximum reduction in ear head length up to 60 per cent followed by flag leaf area 45.47 per cent. Among 45 barley varieties/entries screened under artificially inoculated conditions, none was found resistant, while 18 entries were moderately resistant, 6 moderately susceptible, 5 susceptible and 16 highly susceptible against loose smut disease. Out of six fungitoxicants tested as seed treatment Raxil and Vitavax @0.2% were found very effective and provided 100 per cent disease control and superior than Bavistin, Pulsor and Thiram. Four antagonistic micro-organisms namely T. viride, T. harzianum, A. chroococcum and B. subtilis were also tested for biocontrol of this disease. Seed treatment with B. subtilis and T. viride provided maximum disease control i.e. 42.48, 41.29 and 40.69, 38.06 per cent on plant as well as tiller basis, respectively. Among six plant leaf extracts tried against the disease, seed treatment with neem leaf extract was found to be most effective and gave maximum control i.e. 60.69 and 83.51 per cent on both plant and tiller basis. There was minimum disease i.e. 29.16 and 16.33 per cent on plant as well as tiller basis in late sowing as compared to early sown crop i.e. 42.40 and 28.13 per cent.
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    ThesisItemOpen Access
    Integrated management of sclerotinia rot (Sclerotinia sclerotiorum (Lib.) de bary) of Indian mustard (Brassica juncea L. czern & coss)
    (CCSHAU, 2007) Hieu, Nguyen Thanh; Mehta, Naresh
    Sclerotinia sclerotiorum (Lib.) de Bary is one of the most devastating and cosmopolitan plant pathogen. The pathogen causing stem rot of Indian mustard has been identified as Sclerotinia sclerotiorum. The extracts of Bougainvillea spectabilis (Bougainvillea), Azadirachta indica (Neem) and Allium sativum (Garlic) were significantly effective in checking mycelial growth and sclerotia formation at 50 per cent concentration. Bougainvillea and Garlic extracts were also quite effective in reducing the mycelial growth and sclerotia formation even at 37.5 and 25.0 per cent concentration as compared to control. Optimum irrigation on every 7th day and flooding once in week were significantly better as these treatment produce 4.17 and 4.33 per cent pre and post-emergence damping-off as compared to controls (no irrigation and covered/ no irrigation and un-covered). Optimum irrigation on every 3rd day was best in reducing post-emergence damping-off (15 per cent). Flooding for two consecutive days in a week and optimum irrigation on every 7th day were most effective produce apothecia 18.50 and 19.67/pot, respectively. Minimum lesion length (2.27 cm), disease intensity (41.39 per cent), and disease incidence (48.03 per cent) have been recorded in the treatment where flooding once in a week was provided. Out of three soil types, sandy soil recorded least pre-emergence, post-emergence damping-off, number of apothecia/pot, disease intensity and disease incidence as compared to clay and sandy loam soil. Soil amendment with Bougainvillea and Mehndi leaf were able to reduce the number of apothecia appearance, lesion length and disease intensity. Bougainvillea, Eucalyptus and Jamun leaf amendments were better treatments and contracted disease incidence 36.67, 36.67, and 40.0 per cent, respectively, as compared to control. All cakes/organic manures were significantly reduced number of apothecia production in pots. Poultry manure was most effective and significantly better in reducing lesion length and disease intensity. Isolates of Trichoderma harzianum-3, T. harzianum-4 and Bacillus subtillis were most potent in decreasing the linear growth and number of apothecia production in in vitro conditions. T. harzianum was quite effective in reducing lesion length and disease intensity when applied simultaneously and seven days prior to the pathogen. Antagonist @ 15 g wheat bran/kg soil was better in reducing damping-off, lesion length and disease intensity as compared to 5 g and 10 g. The interaction i.e. attachment, coiling, penetrated and degradation of host wall of the pathogen between antagonists and pathogen was observed under microscope. INA, SA seed treatment or spray @ 100 ppm could reduce seedling mortality, lesion length, disease intensity and disease incidence.
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    ThesisItemOpen Access
    Bioefficacy of Trichoderma spp. in controlling root rot of cotton caused by rhizoctonia solani kühn
    (CCSHAU, 2007) Mahalaxmi Kumari; Hooda, Indra
    Root rot of cotton (Gossypium spp.) caused by Rhizoctonia solani Kühn is one of the most serious disease in irrigated areas of Punjab and Haryana. In the present investigations an effort was made to screen local isolates of Trichoderma spp. against R. solani and their integration with fungicides Bavistin and Emisan and herbicides Trifluralin and Stomp in controlling root rot of cotton under screen house conditions. Seven isolates of Trichoderma spp. were evaluated against R. solani in vitro. In dual culture, T. harzianum-I was most effective as it caused maximum growth inhibition (75.37%) of the pathogen. In culture, T.viride-IV produced maximum amount of volatile metabolites whereas T.viride-III produced maximum amount of non- volatile metabolites. Mycelial growth rate of Trichoderma spp. was not correlated with the amount of metabolite produced. During interaction studies the intensecoiling of T. harzianum and sparse coiling of T. viride around R. solani hyphae were observed. Dissolution of protoplasmic content of R. solani hyphae by all the Trichoderma spp. was also observed. Complete lysis and distortion of R. solani hyphae was shown by T. virens. All the seven isolates and pathogen were screened for their compatibility with three fungicides Bavistin, Emisan and Copper oxychloride and two herbicides Trifluralin and Stomp under in vitro conditions. Among the three fungicides Bavistin had more toxic effect on Trichoderma spp. than pathogen R.solani. While Emisan and Copper oxychloride caused more inhibition to pathogen than antagonists. At higher concentration (500 g a.i/ml) all the three fungicides completely inhibited the growth of pathogen as well as antagonists. The herbicides Trifluralin and Stomp had greater impact on growth of R.solani than Trichoderma spp. Seven isolates of Trichoderma spp. were evaluated as seed and soil treatment in controlling root rot of cotton caused by R. solani under green house conditions during summer and rainy season. Soil treatment with antagonists was better than seed treatment. T.viride-II was most effective among all the isolates in controlling the disease. Therefore, it was used in integrated disease management studies. Three different talc based formulations of T.viride-II were prepared, tested and compared with their respective fresh cultures in controlling the disease. Pellets formulation gave maximum disease control than others. However, fresh cultures were more effective than formulated products. Integration of T.viride-II with half the recommended dose of Bavistin and Emisan gave maximum disease control i.e 78.59 and 71.53 per cent respectively. In integration, Trifluralin reduced the disease controlling efficacy of Trichoderma and also reduced the seedling length of cotton. Stomp had no adverse effect on Trichoderma and cotton plants.
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    ThesisItemOpen Access
    Epidemiology and management of soybean root rot caused by rhizoctonia solani kuhn
    (CCSHAU, 2007) Kakhandaki, Annasab; Hari Chand
    The studies on “Epidemiology and management of soyabean Root rot caused by Rhizoctonia solani Kuhn.” was carried out under in vitro conditions during 2005-06. Inoculum amount @ 3 g/lit. of water induced maximum disease severity (35.23%). Seven days old inoculum was found more virulent (48.23% disease severity) among the others (3, 5, 10 and 12 days old). Plants younger in age (7 days) were found more susceptible to the pathogen (54.38% disease severity). Minimum disease severity was recorded in treatment N15P24. It reduced the disease from 26.43% in control to 17.66%. FYM gave 5.39% reduction in disease severity as compared to control. None of the genotypes screened against the pathogen in screen house and in laboratory by tissue culture method, was found resistant to the disease. Minimum disease severity (20.33%) was observed in the genotype SH40. Among the four bio-agents tested for the control of disease under screen house conditions Trichoderma viride was found to be the most effective which reduced disease severity from 52.56% in control to 17.89%. In dual culture method of testing bioagents also T. viride gave highest reduction in radial growth (79.33 percent inhibition and percent overlapping was 67.22). Among the five organic amendments tested for the control of root rot Neem was found to be most effective. It reduced the disease from 52.48% in control to 25.44%.
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    ThesisItemOpen Access
    Management of sheath rot of rice caused by sarocladium oryzae (sawada) gams and hawksworth
    (CCSHAU, 2007) Chauhan, Ranbir Singh; Sharma, S.K.
    Sheath rot of rice caused by Sarocladium oryzae (Sawada) Gams and Hawksworth considered to be minor disease has become destructive and widely damaging in the recent years. The studies carried out on various aspect of disease revealed S. oryzae was frequently isolated from cultivar Jaya while Fusarium moniliforme was frequently isolated from PR-106 and HKR 126. Carbendazim was highly effective in inhibiting the fungal growth with EC50 value of 2.4 ppm a.i. closely followed by Propiconazole with EC50 value of 5.0 ppm a.i. Neemgold was found highly effective in inhibiting the fungal growth with EC50 value of 6.3 ppm a.i. closely followed by Achook with EC50 value 12.6 ppm a.i. -4- Combination of propiconazole and Achook was found most effective in reducing disease incidence and increasing grain yield. In terms of benefit: cost ratio, fungitoxicant alone followed by Achook in combination of either of the fungitoxicants (propiconazole or carbendazim) was better over all treatments. Among non conventional chemicals, zinc sulphate proved to be the most effective in reducing disease incidence and increasing grain yield. Out of the 123 genotypes/ cultivars screened, only 9, 1 and 6 were found highly resistant, resistant and moderately resistant to sheath rot respectively.