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20003
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Subject: Plant Pathology × Author: KAU × End date: 2000 × Start date: 2000 × Type: Thesis ×
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    ThesisItemOpen Access
    Etiology and management of bacterial of anthurium
    (Department of Plant Pathology, College of Agriculture, Vellayani, 2000) Dhanya, M K; KAU; Mary, C A
    Bacterial blight incited by Xanthomonas axonopodis pv. dieJJenbachiae (Me Culloch and Pirone) Vauterin et al. (1995) is a serious disease of anthurium (Anthurium andreanum Linden) causing heavy economic loss to growers in Kerala. The diseased plants showed both foliar and systemic infections. The bacterium was a Gram negative, motile rod. Morphological, physiological and biochemical characters of the six isolates were same except for some characters like nature and rate of growth, virulence and hydrolysis of starch. The bacterium inciting this disease was identified as Xanthomonas axonopodis pv. dieffenbachiae based on morphological, physiological and biochemical characters coupled with pathogenicity. Potato Sucrose Agar was found to be the best medium for growth and slime production of the bacterium. Dieffenbachia sp., Philodendron oxycardium, Aglaonema robelinii, Colocasia esculenta and Syngonium podophyllum were carriers of Xanthomonas axonopodis pv. dieJJenbachiae. The pathogen survived In infected plant debris kept in soil under glass house conditions and In refrigerated conditions for about 45 days and in soil for 60 days. Under in vitro evaluation, 100 ppm streptocycline and 0.3 per cent captan were most effective in inhibiting the growth of the pathogen. Under in vivo conditions, the relative efficiency of four ecofriendly management practices namely the application of turmeric powder + sodium bicarbonate, Pseudomonas jluorescens (proprietary product), neem oil and cowdung extract at three different levels were compared with that of spraying with 100 ppm streptocycline and 0.3 per cent captan. It was observed that the use of 0.15 per cent turmeric powder + sodium bicarbonate (10 : 1 proportion) was most effective and the extent of disease control achieved after a schedule of five sprayings at one week interval was same as that of 100 ppm streptocycline.
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    ThesisItemOpen Access
    Bio control of postharvest diseases of solanaceous vegitables
    (Department of Plant Pathology, College of Agriculture, Vellayani, 2000) Rajkumar, T; KAU; Susamma Phillip
    The fungi commonly associated with the spoilage of solanceous vegetables viz., brinjal, chilli and tomato under storage conditions were isolated and identified. Based on the frequency of occurrence Phomopsis vexans was selected in brinjal, Colletotrichum capsici in chilli and Fusarium solani, Rhizoctonia solani and Geotrichum candidum in tomato. These fungi were used for the further study. The studies on epiphytic mycoflora of the fruits yielded maximum epiphytes for brinjal followed by tomato and chilli. These included several fungi, yeast and many other saprophytes. Yeasts like Cryptococcus sp. and Sporobolomyces roseus and fungi like Aspergillus niger, Pencillium wortmanni and Fusarium solani were common to all the three vegetables. All the epiphytes were subjected to in vitro studies and tested against each pathogen. Gliocladium virens and Trichoderma harzianum were found to be effective from the in vitro test The mechanism of G. virens and T. harzianum was studied in detail and was found to be through coiling and penetration, coiling and granulation, coiling and vacuolation, disiegration of mycelia and formation of infection pegs. The role of T. harzianum and G. virens as biocontrol agents was studied in vivo. It was found that T. harzianum was effective in reducing the rots for brinjal in all the pathogens under study. G. virens however was found to infect the tomato fruits. T. harzianum was formulated in talc, coir pith, charcoal and wheat flour. Among these, maximum viability was recorded in talc. The number of spores increased initially only in the case of flour while for the rest it registered a steep decline and a stagnation after fifth week. T. harzianum was thus formulated in talc at 25 per cent concentration. The viable spore count at the end of the seventh week was of the order of 106 c.f.u./g of the formulation. The formulated antagonist was applied on the fruit by dipping as well as dusting. For the chilli anthracnose (C. capsici) neither of the methods were effective. In the case of brinjal rot (P.vexans) dusting was as effective as dipping in controlling the rot, for tomato dusting was slightly better than dipping in controlling sour rot (G. candidum). Both the methods were ineffective in controlling Fusarium rot (F. solani) of tomato while Rhizoctonia rot was controlled better by dusting than dipping in the formulation of the antagonist.
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    ThesisItemOpen Access
    Integrated management of phytophthora rot in black pepper nursery
    (Department of Plant Pathology, College of Horticulture, Vellanikkara, 2000) Binimol, K S; KAU; Vilasini, T N
    Studies on the 'Integrated management of Phytophthora rot in black pepper nursery' was conducted at the College of Horticulture, Vellanikkara during January to August 1998. Potting mixture was inoculated with Phytophthora capsid Leonian, emend. Alizadeh and Tsao before solarization. Transparent, 150 guage polyethylene sheets were used for solarization of the potting mixture. Maximum soil temperatures recorded at 10 cm depth III solarized potting mixture was 51.0°C while, it was 42.0°C in non-solarized one. Soil temperature of solarized potting mixture was more than 45°C for 40 days and above 50°C for four days. Solarization enhanced the sprouting of pepper cuttings. Solarization was effective in reducing the pre-sprouting mortality and mortality of rooted cuttings by the pathogen.F ortyfive days solarized, Trichoderma viride incorporated Fytolan drenched treatment exerted cent per cent control of the mortality of rooted cuttings. Solarization significantly reduced the foliar infection of rooted cuttings. Forty five days solarized, T viride incorporated treatment was highly effective and recorded 97.22 per cent control of the disease. Maximum disease incidence (87.58%) was noticed in the non-solarized control. Reduction in Phytophthora population ranged from 94.41 to 97.35 per cent in solarized potting mixture immediately after the removal of polyethylene sheets. Maximum population of Trichoderma spp. was observed in solarized Trichoderma spp. incorporated treatments. Solarization reduced fungal, bacterial and actinomycetes population of potting mixture. Plants grown in solarized potting mixture exhibited better colonization of Azospirillum. However, root colonization of V AM in pepper cuttings was less in solarized treatments. Availability of nitrogen, phosphorus and potassium was increased by solarization. Solarization effectively reduced the weed population ill the pepper nursery. Solarization resulted in increased growth response of rooted pepper cuttings. All growth parameters like height of plants, number of leaves, length and breadth of leaves and development of root system were influenced by solarization.