Browsing by Author "Joshi, K. R."
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ThesisItem Open Access Investigation on Sclerotium Rot (Sclerotium rolfsii sacc.) of Soybean (Glycine max (L.) Merrill) Under South GFujarat Condition(Plant Pathology Department, N. M. College of Agriculture Gujarat Agricultural University, 2001-06) Joshi, K. R.; Patel, I. G.soybean (Glycine max (L.) Merrill) is an important oilseed and grain legume crop. The crop suffers from a number of economically important diseases . Among them Sclerotium rot caused by Sclerotium rolfsii Sacco is one disease which brings down the production and productivity. Looking to the importance of the disease in Gujarat, the prescnt investigation was carried out to generate more information for suitable control measures. The isolation form infccted plant parts revealed the association of Sclerotium rolfsii. The identity of the pathogen has been confirmed with the help of cultural and morphological characters (lTCC No. 3973-99) and the pathogenicity tests on different hosts. On inoculation, the symptoms viz., seed rotting; withering droop ing and girdling of seedlings ; yellowing and wilting of mature plants and the production of typical white mycelial mat with abundant light brown to dark brown mustard like sclerotia ori germinated seeds collar region and roots of the plants were observed. Profuse mycelial growth and abundant sclerotia were observed on PDA, potato dextrose medium and Richards' medium. The investigation identified the soW'ces of resistance to the genotypes viz., Gujarat Soybean-I, Gujarat Soybean-2, AMS-II and AMS-27 were moderately resistant. In vitro evaluation of plant extracts, twmeric proved excellent in inhibiting the pathogen. Among the different organic amendments tested, castor cake was the best in reducing disease intensity. In vitro, strong antagonism of the fungus was achieved by Bacillus sublillis, Trichoderma viridi, T. longibrachyalum and T. harzianum, while in pots. T. viridi. T. longibrachyatum and T. harzianum were superior in reducing seedling mortality. In vitro fungicidal test showed that PCNB (Brassicol), mancozeb (Dithan·M·45), MEMC (Emisan). chlorothalonil (Kavach), hexaconazole (Contat), propiconazole (Tilt). penconazolc (Topaz), carbOxin (Vitavax) and thiophanate methyl (Topsin-M) were highly effectivc. while in pots, hexaconazole was Significantly superior in reducing seedling mortality. Of six herbicidcs tested in vitro, alachlor (Lasso) was most fungitoxic.ThesisItem Open Access Studies on Die-Back (Botryodiplodia theobromae) disease of Rose (Rosa hybrida) Under South Gujarat Condition(DEPARTMENT OF PLANT PATHOLOGY N. M. COLLEGE OF AGRICULTURE GUJARAT AGRICULTURAL UNIVERSITY, 2001-01) Dambhla, D. S.; Joshi, K. R.Rose (Rosa spp.) is one of the important flower crops and grown more or less in South Gujarat. Among different diseases, die-back of rose caused by Botryodiplodia theobromae is one of the most dreaded • disease throughout the South Gujarat. Considering the seriousness of the problem, the present investigations were carried out to generate more information for developing suitable control measures. The isolation from infected rose twigs revealed the association of Botryodiplodia sp. with die-back, which was further purified by single <0 spre technique. Cultural and morphological studies were carried out and identified the pathogen as Botryodiplodia theobromae, which was also confumed by Indian Type Culture Collection (LT.C.C.), New Delhi-l 10 012 (LT.C.C. No. 3975-99). The pathogenicity of B. theobromae was proved on detached twigs and in field by artificial inoculation methods viz., cut end injury, pin prick, tooth brush and without injury on detached twigs while cut end injury in field with positive results except in without injury, Out of eight non-synthetic (natural) and synthetic solid media, non-synthetic media viz" carrot root agar, chilli twig agar and mango twig agar were proved best for vegetative growth while Richard's agar, potato dextrose agar, Czapek' s agar were proved best for growth and sporulation of B, theobromae, Oat meal agar was best for sporulation, Among liquid media Richard's medium was proved best for growth and sporulation of fungus, Studies on pH revealed that the fungus produces maximum growth and sporulation at pH 6,5 and 6,0 in both solid and liquid media, whereas maximum dry mycelial weight was obtained at pH 6,0, Host range studies comprising of eight fruits, one spice, nine weeds, two agroforest and two forest plant species belonging to different families indicated that B, theobromae readily infected mango, citrus, chilli, guava, mulberry, nafatia, sharu, nilgiri, typha and lantana, Among the thirty four evaluated rose varieties against the die-back, only one variety 'Love' was moderately resistant, while fifteen varieties viz" Mercedes, Avon, Summer holyday, Golden times, Samurai, Blue moon, Cremean night, Jalaranda, Mabella, Snow white, Maria callus, Ena harkness, Thambhabarni, Arizona, Ashaiar were found moderately susceptible and remaining 18 varieties were found susceptible, The phytoextracts of fifteen plant species belonging to different families screened in vitro by poisoned food technique against B, theobromae, turmeric powder and black tulsi leaves were proved strongly inhibitory followed by garlic bulb, onion bulb and tulllleric rhizomes, Nilgiri was proved as growth stimulant In vitro antagonistic study revealed that Trichoderma longibrachyatum, Aspergil/usjlavus, T. har:ianum and A. niger were proved more inhibitory against B. theobromae in both antagonist at centre and pathogen at centre mt!thods. III vitro screening of fungicides was carried out by the poisoned 100d technique, which indicated that in systemic group Carbendazim. Thiophanate methyl, Benomyl, Propiconazole and in nonsystemic group MEMC, Chlorothalonil were highly fungi toxic to the B. theobromae upto thirteenth days of incubation. In integrated management of die-back, eight promising fungicides and non-fungicidal measures were evaluated in field. Among them Cello tap was proved best followed by turmeric powder (without inoculation), Benomyl, Parafin Wax (W. I.) and Bordeaux mixture.ThesisItem Open Access Studies on Leaf Blight of Onion Caused by alternarla alternata (Fr.) Keissler(Plant Pathology Department, N. M. College of Agriculture Gujarat Agricultural University, 1991-10) Patel, Mukeshchandra Jivarajbhai; Joshi, K. R.ThesisItem Open Access Studies on Leaf Spot (Colletotrichum gloeosporioides Penz. and Sacc.) of Turmeric (Curcuma longa L.) Under South Gujarat Conditions(Plant Pathology Department, N. M. College of Agriculture Gujarat Agricultural University, 2000-11) Patel, R. V.; Joshi, K. R.Turmeric (Curcuma fonga L.) is one of the important spice crops, which is grown in Val sad and Sabarkantha districts of Gujarat. During the survey, occurrence of leaf spot disease in turmeric (cv. Sugandhum) was observed in serious proportion inflicting heavy losses in South Gujarat. Considering the seriousness of the problem, the present investigations were carried out to pinpoint exact cause, symptomatology, physiological studies and to develop suitable management strategy. The repeated isolations from infected leaves revealed the association of Col/efofrichum sp., which was identified as Col/efofrichum g/oeosporioides Pen z. and Sacco (I.T.C'.C. No.3705-99). The pathogenicity was proved hy artificial inoculation method with • positive results. Test of C. g/oeosporioides produced symptoms identical to mango anthracnose. Out of seven synthetic and semi-synthetic solid media tested, Richards' agar and potato dextrose agar were proved best followed by mango leaf extract agar. Amongst liquid media, Richards' medium was proved to be the best for the growth and sporulation of the fungus. Studies on pH revealed that the fungus produced maximum growth at pH 5.0 and 5.5 in solid media, whereas, in liquid media, maximum dry mycelial weight and sporulation was produced at 5.0 pH. Twelve different varieties of tUi meric were screened for resistance to C. gloeosporioides under natural incidence in field. Of these, cultivars Voltamita and S-3 reacted as resistant while Kesar and Sugandhum reacted as susceptible to leaf spot disease. Studies on interaction of known antagonists by three methods viz. dual culture, test organism at centre and pathogen at centre revealed strong antagonism of Trichoderma sp. against C. gloeosporioides in vitro, whereas, Aspergillus niger and Gliocladium virens also appeared as potential antagonists against C. gloeosporioides in vitro. The phytoextracts of 19 plant species evaluated in vitro by poisoned food technique against C. gloeosporioides revealed that extracts of gando baval, bhoy ringni and ginger were strongly inhibitory followed by eucalyptus, datura and guvar, while the extract of cactus, tulsi, bodio kalar, sankal chain and mehendi were proved as growth stimulant. In vitro screening of fifteen fungicides by poisoned food technique at three different concentrations showed that in systemic group Carbendazim, Thiophanate methyl, Propiconazole, Hexaconazole and Tricyclazole were highly fungi-toxic to C. gloeosporioides, while in non-systemic group M. E. M. C. was most effective followed by Thiram.