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201621
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Subject: Plant Pathology × End date: 2016 × Start date: 2016 × Type: Thesis × Thesis Type: M.Sc ×
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    ThesisItemOpen Access
    Studies on Collar Rot of Brinjal Caused by Sclerotium rolfsii Sacc.
    (University of Agricultural Science, Dharwad, 2016-12) Wahid, S A.; Kamanna, B.C.
    Brinjal (Solanum melongena L.) is one of the important vegetable crop. Collar rot of brinjal caused by Sclerotium rolfsii Sacc. is serious soil borne disease. A study on this was undertaken at the University of Agricultural Sciences, Dharwad during kharif 2015-16. Survey revealed that disease incidence ranged from 2.33 to 24.25 per cent. Highest mean disease incidence (9.75 %) was recorded in black soil. Dhruva hybrid showed high mean disease incidence of 11.52 per cent. . Significantly highest per cent disease incidence of 59.75 was recorded in plants of 15 days old in pot culture studies to know susceptible stage of brinjal. None of the genotypes were found resistant to collar rot pathogen. Among the six systemic fungicides tested under in vitro difenconazole, tebuconazole, hexaconazole and propiconazole at 0.1 per cent and 0.15 per cent concentrations inhibited cent per cent growth of S. rolfsii. Among the five contact fungicides mancozeb at 0.3 % concentration recorded maximum inhibition (60.25 %) of S. rolfsii followed by captan at 0.3 per cent concentration (55.19 %). Combi-products fungicides viz., thiram 37.5 % + carboxin 37.5 % WP and hexaconazole 4 % + zineb 68 % WP at 0.1, 0.2 and 0.3 per cent concentrations inhibited cent per cent o growth of S. rolfsii. Among six bioagents Trichoderma harzianum recorded maximum inhibition. Among thirteen botanicals, parthenium leaf extract recorded maximum inhibition (64.57 %). Among the different treatment combinations tested under pot conditions the combination of seedling dip with thiram 37.5 % + carboxin 37.5 % WP @ 2 g/l + application of FYM @ 200 g/pot + soil application of Trichoderma harzianum @ 4 g/kg followed by soil drenching with thiram 37.5 % + carboxin 37.5 % WP @ 2 g/l on 0, 15, 30, and 45 days after transplanting recorded the least per cent disease incidence (12.04 %).
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    ThesisItemOpen Access
    Studies on Variability in Ramularia areola Atk. Causing Grey Mildew of Cotton and its Management
    (University of Agricultural Sciences, Dharwad, 2016-06) Ganiger, Manjunath; Ashtaputre, S.A.
    Grey mildew of cotton caused by Ramularia areola Atk. is an important foliar disease which results in significant yield loss. Laboratory and field experiments were carried out to study the variability and management aspects of the disease. An intensive roving survey was carried out to know the severity of the disease. Maximum disease severity was recorded in Dharwad district (28.77 PDI) followed by Haveri district (23.46 PDI). The mean least severity was recorded in Bagalkot district (2.25 PDI) and no disease was observed in Raichur and Vijayapur districts. Among the ten R. areola isolates assessed, the isolates viz., Ra-6 Devihosur, Ra-7 Itagi, Ra-4 Navalgund, Ra-3 Naragund and Ra-10 Hiremuttur showed variability with respect to morphological and molecular characters. Based on sequence comparison, the isolates were confirmed as R. areola. There was high level of similarity present among the isolates indicating less diversity. Among the 60 entries screened under field conditions, the 20 entries of Gossypium barbadense and Gossypium hirsutum were showed resistance and among 20 entries of Gossypium arboreum 5 were moderately resistant, 10 were moderately susceptible and 5 were highly susceptible to the grey mildew disease. Among the chemicals under study trifloxystrobin + tebuconazole gave the maximum per cent disease control (PDC) with lesser per cent disease index (PDI) and higher yield, followed by pyraclostrobin + metiram, difenconazole and carbendazim whereas, the maximum increased yield over the control was noticed in the treatment of trifloxystrobin + tebuconazole followed by pyraclostrobin + metiram and difenconazole. With respect to economics of cost benefit ratio, hexaconazole showed higher returns over the rest of the chemicals under study. Hexaconazole can be considered as economically effective in management of grey mildew disease in cotton.
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    ThesisItemOpen Access
    Studies on Powdery Mildew of Capsicum Caused by Leveillula taurica (Lev.) Arn. Under Protected Cultivation
    (University of Agricultural Sciences, Dharwad, 2016-06) Marthand; Virupaksha Prabhu H.
    Experiment was conducted in laboratory and protected structure during 2015-16 in Department of Plant Pathology and Hi-tech Horticulture Unit, Saidapur Farm, University of Agricultural Sciences, Dharwad respectively and results revealed that, Dharwad district had shown maximum disease severity and disease incidence (54.94 PDI and 55.55 %) respectively followed by Belagavi district (49.37 PDI and 48.14 %) and least severity was noticed in Haveri district (38.37 PDI and 38.51 %). Higher amount of total chlorophyll (2.36 mg/g), chlorophyll-a (1.63 mg/g) chlorophyll-b (0.72 mg/g), total phenols (2.47 g %) and reducing sugar (22.89 g %) was recorded in healthy leaves but higher amount of total sugar (33.46 g %) and non-reducing sugar (16.20 g %) was recorded in diseased leaves Azoxystrobin (0.15 %), Tebuconazole + Trifloxystrobin (0.3 %), Sulphur (0.3 %), Pseudomonas fluorescens and Nimbicidin at one per cent was found effective with higher per cent inhibition of conidial germination among systemic, combi product and contact fungicides, bio-agents and botanicals respectively evaluated under in vitro condition. Among different treatments evaluated under protected cultivation Azoxystrobin (0.05 %) found to be most effective in reducing the disease and recorded maximum yield followed by Tebuconazole at 0.05 per cent and developed an regression equation, Y=92.791-0.227x indicating that for every increased in one per cent disease index (X) decreased the yield (Y) of capsicum by 0.227 t ha-1. The observation on yield loss estimation revealed that, three sprays of Azoxystrobin (0.05 %) were optimum for reducing the disease intensity, increase in yield and B:C ratio. In the absence of fungicide treatment, powdery mildew reduced the yield of capsicum by 15.13 per cent. Out of 14 genotypes screened, none of them were found to be immune, highly resistant and resistant. Three genotypes were found to be moderately resistant viz., Bachata, Inspiration and Capsicum Purple.
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    ThesisItemOpen Access
    Biochemical and Nutrient Status in Chickpea Due to Powdery Mildw (Leveillula taurica (Lev.) Arnaud)
    (University of Agricultural Sciences, Dharwad, 2016-06) Angadi, Sunil; Basavarajappa, M.P.
    Powdery mildew of chickpea caused by Leveillula taurica (Lev.) Arn. is a major menace for chickpea cultivation in recent years. The present investigation was conducted at Regional Agricultural Research Station, Vijayapur during Rabi 2015-16, As the days advanced from 63 to 91 DAS, the mean total chlorophyll content in healthy leaves (0.626 mg g-1) as compared to diseased leaves (0.462 mg g-1) the chlorophyll-a, chlorophyll-b and total chlorophyll contents were remarkably reduced. Similarly total mean phenol content in healthy (3.52 mg g-1) as compared to diseased (2.06 mg g-1) and found gradual increase in phenol content in both healthy and diseased leaves. Total mean of sugar content in healthy leaves (2.57 mg g-1) as compared to diseased leaves (2.20 mg g-1). Total mean protein content in healthy leaves (6.33 mg g-1) as compared to diseased leaves (5.04 mg g-1). Total mean of free amino acids in healthy leaves (1.12 mg g-1) as compared to diseased leaves (0.74 mg g-1) and these found gradual decrease in both healthy and diseased leaves. With respect to nutrient analysis it is found a highly negative correlation between N, P, K, Mg, Zn, Mn, Cu and disease intensity, whereas a highly positive correlation was observed between Fe, B, and disease intensity. The healthy leaves had higher concentration of N, P, K, Mg, Zn, Mn and Cu and fewer amounts of Fe and B. For the management of powdery mildew of chickpea new fungicide molecules were evaluated under natural epiphytotic conditions at ARS, Annigeri. Among nine chemicals tested myclobutanil @ 0.02 % and azoxystrobin @ 0.05 % found effective in managing the disease cent per cent and also recorded comparatively more yield. Myclobutanil showed maximum BCR than azoxystrobin and also found to be effective in managing powdery mildew of chickpea.
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    ThesisItemOpen Access
    Studies on Post Harvest Diseases of Mango With Special Reference to Stem End Rot
    (University of Agricultural Sciences, Dharwad, 2016-06) Chakrasali, Savita; Benagi, V.I.
    Mango (Mangifera indica L.) is the one of the most important fruit crop of India. It is being affected by several post harvest diseases. Among them stem end rot caused by Botryodiplodia theobromae (Pat.) Griffon and Maubl. cause drastic reduction in yield as well as market value. A study on post harvest diseases of mango was conducted. It included isolation, identification and proving pathogenicity test. Anthracnose (Colletotrichum gloeosporioides (Penz.) Penz. & Sacc)., stem end rot (Botryodiplodia theobromae ) and Alternaria rot ( Alternaria alternate) were the major diseases which causes for the post harvest losses. Three districts were surveyed. Maximum per cent diseases index was recorded in Dharwad market. Among the varieties, Alphanso showed maximum per cent diseases index. The conidia of Botryodiplodia theobromae was initially unicellular, hyaline and thick-walled. Mature conidia were uniseptate, cinnamon to fawn colored and often longitudinally striate. Cultural studies revealed that among solid media, potato dextrose agar proved to be the best for good growth of the fungus. Among the seven liquid media, potato dextrose broth supported the maximum mycelial dry weight of the pathogen. Physiological studies revealed that optimum pH of 8.0 was favourable for growth and sporulation of the pathogen. Maximum colony diameter and dry mycelial weight of the fungus was recorded at the temperature 30 0C. Under in vitro evaluation of bio-rationals, clove oil (1 %) was found to be effective against B. theobromae. Among the salts tested, potassium bicarbonate was found to be effective at all three concentration (5, 7.5 and 10 %). Under in vivo evaluation of bio-rationals and salt, minimum per cent disease index was observed in neem oil at 1 per cent and potassium bicarbonate at 5, 7.5 and 10 per cent.
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    ThesisItemOpen Access
    Role of Endophytes in Suppression of Plant Nematode Infecting Vegetables
    (University of Agricultural Sciences, Dharwad, 2016-06) Shetty, Akshatha; S. Lingaraju
    Endophytes can be defined as plant associated microorganisms that live inside plant tissues without causing any harm to plants. Endophytes were isolated from five to six week old healthy tomato plants grown in the fields of College of Agriculture, University of Agricultural Sciences, Dharwad. Both fungal and bacterial endophytes were isolated from the plant parts like roots, leaves and stems using standard protocols. Cell-free culture filtrates of fifteen endophytes were tested against root knot nematode juvenile mortality in vitro. Out of eight bacterial endophytes, four endophytic bacteria showed promising results with highest nematode mortality of 92.47 per cent while out of seven fungal endophytes, two were found efficacious with the highest mortality of 81.80 per cent. Based on the in vitro test results, best four endophytic bacteria and best two endophytic fungi were advanced for an in vivo experiment. The effect of endophytic fungi and bacteria against tomato root knot nematode disease and plant growth parameters in tomato were tested employing soil inoculation and seedling dip method of application (using endophytes’ suspension). Plants inoculated with endophytes significantly enhanced plant growth parameters and reduced number of nematode galls compared to control. Between two methods of endophyte inoculation, soil inoculation method showed better results. The efficacious four bacterial and two fungal endophytes were characterized by employing morphological and molecular methods. The bacterial endophytes were identified as Luteimonas aestuarii, Pseudomonas lini, Bacillus pumilus and Bacillus sp. and fungal endophytes were identified as Nigrospora sphaerica and Nigrospora oryzae.
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    ThesisItemOpen Access
    Studies on Postharvest Diseases of Banana
    (University of Agricultural Sciences, Dharwad, 2016-06) Divya Jagana; Hegde, Yashoda R.
    Market survey conducted in Hubballi and Dharwad for postharvest diseases of banana indicated that anthracnose (Colletotrichum musae) and crown rot (Fusarium semitectum) were predominant in both markets. Finger rot (Lasiodiplodia theobromae) and cigar end rot (Verticillium theobromae) were observed in traces. The mean disease incidence and severity of banana anthracnose was highest during rainy season in all the varieties and very less during summer. Crown rot was observed only during rainy season. Conidia of C. musae were hyaline, aseptate, broadly elliptical or cylindrical with rounded ends. Macroconidia of F. semitectum were mostly straight or slightly curved, 3 - 5 septate. Peak growth of both C.musae (82.67 mg) and F. semitectum (76.00 mg) was recorded on 10th day after inoculation. C. musae grew well on oat meal agar (89.83 mm) with excellent sporulation. F. semitectum grew well on potato dextrose agar (89 mm) and Richards’s agar (88. 38 mm) with excellent sporulation. Among ten liquid media tested, Richards’s broth was best for both the pathogens C. musae (340 mg) and F. semitectum (434 mg). Both the pathogens have shown maximum radial growth at 25°C (89.83 mm & 89.81mm) and pH range was 6.0 pH (398 mg & 425 mg) to 7.0 pH (383 mg & 419.67 mg). Consortium of three bioagents (Bacillus subtilis + Pseudomonas fluorescens + Trichoderma harzianum) effectively arrested the mycelial growth of both the pathogens; C.musae (89.26 %) and F. semitectum (93.41%). Among the botanicals, neemgold at 2.0 per cent effectively arrested the mycelial growth of C. musae (80.38%) and F.semitectum (75.82%). Out of five oils evaluated in vitro, complete inhibition of mycelial growth of C. musae was recorded in clove oil at 0.5 per cent and eucalyptus oil at 2.0 per cent concentration. Among the four salts evaluated in vitro against C. musae, complete inhibition of mycelial growth was recorded with boric acid and sodium bicarbonate at both 5.0 and 10.0 per cent concentration. Most effective nanoparticles (NPs) against C. musae were Ajwain-Mg NPs (0.2%), Ajwain-Ni NPs (0.2 %) and Neem-Ag NPs (0.1 & 0.2 %) where complete inhibition of spore germination was noticed. Among the bioagents tested in vivo, highest per cent disease reduction (82.86%) was noticed in consortium of three bioagents; neemgold and discheck at 2.0 per cent (92.11%) among the botanicals; lemongrass oil at 2.0 and 1.0 per cent and neem oil at 2.0 per cent (91.89%) among oils; boric acid at 5.0 and 10.0 per cent and sodium bicarbonate at 10.0 per cent (91.18 %) among salts. Minimum PDI (6.67%) was recorded at 0.05 per cent concentration of Neem-Ag NPs. Among all the biorationales evaluated, postharvest dipping of banana fruits with boric acid at 5.0 per cent (11.11PDI) and lemongrass oil at 1.0 per cent (14.44PDI) were most effective in managing postharvest anthracnose of banana
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    ThesisItemOpen Access
    Diversity of Pigeon Pea Wilt Pathogen [(Fusarium udum (Butler.)] and Rhizobacterial Interactions
    (University of Agricultural Sciences, Dharwad, 2016-06) Rashmi U.S.; Chattannavar, S.N.
    Pigeon pea (Cajanus cajan (L.) Millsp.) is among the world’s most important pulse crops in India and grown in almost all states. The diseases are the major constraints in realizing the high yield potential of improved pigeon pea genotypes and among the diseases Fusarium wilt plays a major role which can cause 100% yield losses. Maximum disease incidence was recorded in Vijayapur district (36.15%) followed by Yadagiri district (35.02%) and minimum disease incidence was observed in Belagavi district (13.76%). Morphological and cultural diversity were observed among nine isolates for colony diameter (61.91 to 90.00 mm), pigmentation (white to red) and colony colour (creamy white to pink), mycelial growth (flat to raised), sporulation (excellent to no sorulation), formation of chlamydospore, presence or absence of microconidia and macro conidia, Septations in micro conidia (0-1) and macro conidia (3-5) and its size, mycelial width and chlamydospore diameter. Variation was observed in growth pattern and also virulence (Yadagiri-1isolate was found to be more virulent). Among different media tested potato dextrose agar, Richards’ synthetic agar and oat meal agar were found to be better for growth of all the isolates with varied spore production. The ITS rDNA sequence of these isolates separated them in to two clusters. The similarity coefficient was upto 2.4 and Yadagiri-1 isolate was separated within the cluster and was in a separate sub cluster of cluster-A which could be the reason for its virulence nature. Among 43 rhizobacteria screened in vitro three rhizobacterial strains (two actinomycetes AUDT502 and AUDT 626 and one fluorescent pseudomonads strain 218(1)) showed maximum per cent inhibition and further pot culture experiments with these selected isolates of rhizobacteria showed less disease incidence and also increased plant growth parameters which was later confirmed with growth promotional activities of the rhizobacteria by qualitative assay in vitro.
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    ThesisItemOpen Access
    Studies on Black Rot of Cabbage Caused by Xanthomonas campestris pv. campestris (Pammel) Dowson
    (University of Agricultural Sciences, Dharwad, 2016-06) Bathula Jagadeesh; Yadahalli, K.B.
    The major constraint for the cultivation of cabbage which is one of the most popular vegetables grown in Karnataka is the black rot disease. The black rot incidence and severity was noticed in all the surveyed locations of Haveri, Dharwad and Belagavi districts and incidence ranged from 40.78 to 67.50 per cent. The mean maximum per cent disease incidence (53.07) was observed in Haveri district, followed by Belagavi district (50.71). Whereas, the least per cent disease incidence (49.31) was observed in Dharwad district. Black rot severity was noticed in all the locations surveyed with a range 13.56 to 29.03 per cent. The mean maximum per cent disease index (24.00) was observed in Belagavi district, followed by Haveri district (23.53). Whereas the least per cent disease index (18.78) was observed in Dharwad district. The bacterium was identified through morphological, biochemical characteristics and pathogenicity tests. With regard to morphological variations, the isolates varied in their morphology on different solid media used for screening. Biochemical tests such as Gelatin liquification, KOH solubility and utilization of glucose, fructose for acid production were used. Among six different pathogenicity tests carborundum abrasion method proved best and these revealed that the bacterium is related to Xanthomonas campestris pv. campestris. The lowest mean per cent disease index was observed in seed treatment with K-cycline (0.5g) + Copper oxychloride (3.0g), seedling dip with Pseudomonas fluorescens (10g), first foliar spray with K-cycline (0.5g) + Copper oxychloride (3.0g) and second foliar spray with Pseudomonas fluorescens (10g) (24.93) and high (48.50) disease control over check with the mean yield of 309.25 q/ha.