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2010 - 2018136
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Subject: Plant Pathology × End date: 2018 × Start date: 2010 × Thesis Type: M.Sc ×
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    ThesisItemOpen Access
    Isolation and Characterization of Pgprs from Rhizosphere of Banana Against Tip Over Disease Caused by Erwinia carotovora subsp. carotovora
    (University of Agricultural Sciences, Dharwad, 2018-08) Rotti, Soumya D.; M.R. Ravikumar
    Survey conducted during 2016-17 revealed that the incidence of tip over disease of banana was ranged from 1.00 to 48.00 per cent with highest per cent mean disease incidence in the Belagavi district (14.41 %) and lowest in Dharwad district (6.06 %). Mean maximum disease incidence 12.55 per cent and 13.88 per cent was observed in black soil and Grand-naine variety respectively and total of 134 isolates of plant growth promoting rhizobacterias (PGPRs) were isolated from the rhizospheric soil of banana collected. Highest numbers of isolates were from Bagalkote district (41) and least from Dharwad district (8). Among them 64 isolates were found to be as Bacillus spp. And remaining 70 isolates were found to be as Pseudomonas spp. The ability of isolated PGPRs to suppress the growth of Erwinia carotovora subsp. carotovora was studied in vitro. Among 12 effective isolates of Bacillus spp., Belagavi isolate 13 has recorded maximum inhibition of 16.67 mm and least inhibition (12.00 mm) was observed by Haveri isolate 5. Among 7 effective isolates of Pseudomonas spp., maximum inhibition (18.00 mm) was observed by Belagavi isolate 8 and minimum inhibition (12.00 mm) was observed by Dharwad isolate 2. Molecular characterization of pathogen was identified as Erwinia carotovora subsp. carotovora. Biochemical and molecular characterization of effective isolates of PGPRs were identified as Bacillus cereus (Belagavi isolates 12, 13 and Vijayapur isolate 2), Bacillus subtilis (Vijayapur isolates 4, 7, Bagalkote isolate 15 and Haveri isolate 5), Bacillus pumilis (Vijayapur isolate 8), Pseudomonas aeruginosa (Belagavi isolates 4, 8, 9, Haveri isolate 3, and Vijayapur isolate 3) and Pseudomonas putida (Bagalkote isolate 5). Under in vitro maximum inhibition (39.00 mm) and (25.00 mm) was observed by Silvax® and K- cycline at 500 ppm and 750 ppm respectively.
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    ThesisItemOpen Access
    Studies on Boll Rot Complex of Cotton
    (University of Agricultural Sciences, Dharwad, 2018-08) Nanda M.; Kulkarni, Venkatesh R.
    The present investigation on cotton boll rot complex was carried out during kharif 2017-18 at Agricultural Research Station, Dharwad and Department of Plant Pathology, College of Agriculture, Dharwad. This included, survey for the disease, isolation and identification of pathogens involved in the disease complex and management of the disease through integrated approach. Roving survey was conducted in five districts of northern parts of Karnataka viz., Belagavi, Dharwad, Gadag, Haveri and Uttara Kannada. Maximum disease severity was noticed in Uttara Kannada district at both boll initiation and maturity stages. Maximum disease incidence was observed on bolls at lower part of the plant compared to those of mid and upper parts. Isolation of pathogens and their identification through morphological and molecular characters indicated the presence of fungal pathogens like Alternaria macrospora, Fusarium oxysporum f. sp. vasinfectum, Exserohilum rostratum, Colletotrichum gossypii, Phoma sp., Trichothecium roseum, Aspergillus niger, Nigrospora oryzae and Rhizopus stolonifer and a bacterial pathogen viz., Xanthomonas citri subsp. malvacearum in the infected boll samples collected during survey. Standardization of artificial inoculation methods indicated that injection infiltration method as the best. Out of 118 genotypes (20 varieties of UAS, Dharwad which are under pipeline, 81 germplasm lines of AICRP and 13 private Bt hybrids and 4 UAS, Dharwad released non Bt varieties/ hybrids) tested, 3 genotypes viz., FDK 281, ANGH-1607 and GShv 894/13 showed highly resistant reaction and 31 genotypes showed moderately resistant reaction against the disease under natural epiphytotic conditions. Among 11 treatments evaluated, trifloxystrobin 25 % + tebuconazole 50 % WG at the rate of 1.0 g/ lit was found effective against the disease complex. However, tebuconazole 25.9 % EC at the rate of 1.0 ml/ lit was found economical with the highest B: C ratio.
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    ThesisItemOpen Access
    Studies on Powdery Mildew of Cluster Bean Caused by Leveillula taurica (Lev.) Arn.
    (University of Agricultural Sciences, Dharwad, 2018-07) Vijaykumar, K.N.; Kulkarni, Shripad
    Cluster bean is a versatile and multipurpose legume crop cultivated for vegetable, fodder and manure. Cluster bean powdery mildew caused by Leveillula taurica is the major limiting factor for its cultivation in India. The present investigation involving roving survey in five districts, molecular characterization of pathogen, epidemiological studies, in vitro evaluation of botanicals, bioagents and fungicides, field screening of 41 genotypes and management studies were carried out at University of Agricultural Sciences, Dharwad during the year 2017-18. During survey maximum disease severity was observed in Dharwad (39.70 PDI) and least in Haveri district (22.92 PDI). The rDNA sequencing of L. taurica indicated that Dharwad isolate is having 94 per cent homology with Iran and Turkey isolates. Highest conidial germination was observed at 25 °C (63.16 %) and 85 per cent relative humidity. Sowing during first fortnight of November recorded maximum disease severity. Maximum temperature was positively correlated with disease development whereas, minimum temperature, minimum and maximum relative humidity, rainfall and number of rainy days showed negative correlation. Among different botanicals and bioagents tested, maximum conidial germination inhibition was observed with nimbecidine (80.13 %) and Bacillus subtilis (56.72 %). Among different fungicides tested, maximum inhibition was observed with hexaconazole @ 0.1 (100.00 %), wettable sulphur (95.78 %) and tebuconazole 50 % + trifloxystrobin 25 % (94.72 %). None of the genotypes were immune or resistant whereas, two, 37 and two genotypes were found to be moderately susceptible, susceptible and highly susceptible respectively. Field evaluation of fungicides revealed that two sprays of hexaconazole @ 0.1 % resulted in least PDI of 11.75 % with an yield of 6.20 t/ha and C: B ratio of 1:3.23 which was significantly superior over other treatments followed by two sprays of tebuconazole 50 % + trifloxystrobin 25 % (14.27 PDI) with an yield of 5.98 t/ha.
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    ThesisItemOpen Access
    Studies on Anthracnose of Greengram Caused by Colletotrichum truncatum (Schw.) Andrus and Moore
    (University of Agricultural Sciences, Dharwad, 2018-07) Pavithra, L.; Kamanna, B.C.
    Laboratory and field experiment were conducted at Department of Plant Pathology, College of Agriculture and Agricultural Research Station, Mugad, UAS, Dharwad to study the host range and survivability of pathogen, epidemiology, molecular variability and integrated management during kharif, 2017. A roving survey was carried out for the severity of anthracnose of greengram in four major greengram growing districts of northern Karnataka revealed that, the disease severity was found highest in Gadag (37.83%) and least in Haveri (29.86%) districts. Among eight pulses tested for host range studies, Vigna mungo, Glycine max and Macrotyloma uniflorum proved to be hosts for C. truncatum. Viability of conidia of C. truncatum in different storage conditions showed conidia were viable for maximum period of 360 days in freeze condition and the viability was reduced to 105 days under field condition. The first onset of anthracnose was noticed at 30 days after sowing with per cent index (PDI) of 7.86 and increased gradually with the PDI of 43.24. The correlation studies between PDI and weather parameters indicated the anthracnose development was positive correlation with rainfall, morning relative humidity, evening relative humidity and sunshine, whereas, negative correlation was noticed with maximum temperature, minimum temperature, evaporation and wind speed. Genetic variability among eight isolates of C. truncatum showed that maximum genetic variation exists in DwdCt1 followed by GadCt3 and TNAUCt7 isolates and less genetic variation in HsnCt5 and ShvCt4 isolates which showed 88 per cent similarity. In vitro bioassay revealed that, propiconazole, captan, trifloxystrobin + tebuconazole were found effective. Among bioagents and ITKs, Trichoderma harzianum and panchagavya respectively, were most effective against C. truncatum. Two foliar sprays of propiconazole (0.1%) at 15 days interval was most effective fungicide in managing the anthracnose of greengram.
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    ThesisItemOpen Access
    Investigations on Pomegranate Wilt Complex
    (University of Agricultural Sciences, Dharwad, 2018-07) Ashwathkumar; Vastrad, S.M.
    Pomegranate wilt complex caused by Ceratocystis fimbriata Ell. and Halst. and Meloidogyne incognita is one of the most important diseases, which results in complete wilting in pomegranate crop. The prevalence and severity of pomegranate wilt complex was found to be more in Koppal district (42.84%) followed by Bagalkot (34.13 %), Vijayapur (30.48%) and Gadag (27.73%). During survey, shot hole borer incidence and Root knot nematode symptoms was observed only in two districts i.e. Koppal and Bagalkot. Cultural studies revealed that oat meal agar was found to be best solid and liquid media and source of growth C. fimbriata. The fungus showed maximum growth on PDA broth on 16th day after inoculation. Glucose and sodium nitrate were noticed to be the best carbon and nitrogen source for the mycelial growth of the fungus on liquid media, respectively. The dendogram constructed from the pooled data clearly showed that there were differences among the isolates. However, in the interaction study, greatest reduction in growth parameters like shoot and root length and shoot and root weight was observed in first inoculation with nematode followed by fungus treatment as compared to all other treatments. Among the fungicides, bio agents and botanicals tested in vitro against C. fimbriata, tricyclazole and hexaconazole among systemic fungicides, carboxin (37.5%) WP + thiram (37%) WP (Vitavax Power) among combi products and copper oxychloride among nonsystemic fungicides, T. harzianum in bioagents and ginger rhizome extract among botanicals were found superior in inhibiting the mycelial growth of C. fimbriata.
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    ThesisItemOpen Access
    Studies on Variability of Leveillula taurica (Lev.) Arn. Causing Chilli Powdery Mildew and its Management.
    (University of Agricultural Sciences, Dharwad, 2018-07) Bademiyya, Sabeena; Ashtaputre, S.A.
    Laboratory and field experiment were conducted at Department of Plant Pathology, College of Agriculture and Main Agricultural Research Station, Dharwad to study the variability and management of chilli powdery mildew involving survey, survival study of pathogen and yield loss estimation during kharif, 2017. The maximum disease severity was noticed in Dharwad district (62.03%) and the least severity was noticed in Belagavi district (22.01%). Among the 24 isolates morphological variability observed in terms of shape, size and colour of the conidia, branching and length of conidiophores. Viability of conidia of Leveillula taurica was observed up to 140 days under freeze condition and least under field condition up to 84 days. Higher amount of total sugars and non- reducing sugars was recorded in diseased leaves but higher amount of phenols and reducing sugars was recorded in healthy leaves. The observations on yield loss estimation revealed that, three sprays of Sulphur 80% WP (0.3%) were found to be effective in reducing disease severity (76.44%), increasing yield (9.54 q/ha) and cost benefit ratio (1: 3.03). Yield loss of 50 per cent was noticed due to powdery mildew in unsprayed plots. Maximum germination of conidia was observed in 2 per cent sucrose solution (50.78%) at 24 hr after incubation. Azoxystrobin (0.1%), Bacillus subtilis (1%), nimbicidin (0.5%) were found effective with higher per cent inhibition of conidial germination among different fungicides, bioagents and botanicals respectively evaluated under in vitro condition. The observations on integrated management of powdery mildew revealed that, three sprays of azoxystrobin (0.1%) at 12 days interval was most effective with highest yield (13.25 q/ha) and cost benefit ratio(1:3.33). Azoxystrobin (0.1%) was most effective in managing powdery mildew of chilli.
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    ThesisItemOpen Access
    Studies on Fruit Diseases of Pomegranate and Their Management
    (University of Agricultural Sciences, Dharwad, 2018-07) Hemantha Naik, N.; Benagi, V.I.
    The experiment on fruit diseases was carried out during 2017-18 in the Department of Plant Pathology, UAS, Dharwad. Field experiment was carried out at Chikkasavanur village (Gadag District) during ambia bahar. Pomegranate is affected by various fruit diseases viz., bacterial blight (Xanthomonas axonopodis pv. punicae), anthracnose (Colletotrichum gloeosporioides), Alternaria spot (Alternaria alternata), Pseudocercospora spot (Pseudocercospora punicae) and scab (Sphaceloma sp.). Survey was conducted in major pomegranate growing districts of Karnataka viz., Bagalkote, Belagavi, Chitradurga, Gadag and Vijayapur for the prevalence of above mentioned fruit diseases which revealed that, bacterial blight and scab severity was maximum in Bagalkote whereas, anthracnose and Pseudocercospora spot severity was highest in Chitradurga. Alternaria spot severity was more in Gadag. Severity of fruit diseases were maximum during mrig bahar. By standard tissue isolation, microscopic observation and by proving Koch postulates pathogens were identified . In vitro evaluation of different fungicides and bactericides against Xanthomonas axonopodis pv. punicae revealed that, the following fungicides and bactericides were effective i.e. captan, hexaconazole, metiram + pyraclostrobin and copper oxy chloride + streptocycline. With respect to fungi, copper oxychloride, iprobenfos, carboxin + thiram and copper oxychloride + copper hydroxide showed maximum per cent mycelial inhibition of Colletotrichum gloeosporioides and Alternaria alternata in different fungicides and bactericides respectively. Studies on the effect of weather parameters on progress of fruit diseases showed that during ambia bahar rainfall, maximum and minimum temperature were significantly positively correlated with diseases. In vivo studies revealed that, captan 2 g/l  hexaconazole 1 ml/l copper oxychloride 2.5 g/l + streptocycline 0.5 g/l vitavax power 2 g/l  Pseudomonas fluorescens 10 g/l  iprobenfos 1 ml/ l Pseudomonas fluorescens 10 g/l at 15 days interval showed less per cent disease index (11.22) of fruit diseases and highest fruit yield (13.27 kg/ tree).
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    ThesisItemOpen Access
    Synthesis, Characterization and Evaluation of Chitosan Based Copper and Silver Nanoparticles Against Diseases Caused by Xanthomonas spp.
    (University of Agricultural Sciences, Dharwad, 2018-07) Chidanandappa; Nargund, V.B.
    In this study chitosan based copper nanoparticles (Ch-CuNPs) and silver nanoparticles (Ch-AgNPs) were synthesized by utilizing water soluble chitosan (1%) and pomegranate aril extract (1.4%) with copper sulphate and silver nitrate as precursors at the College of Agriculture, University of Agricultural Sciences, Dharwad, during 2017-2018. Synthesized nanoparticles showed absorption spectra peak of 553 nm for Ch-CuNPs and 430 nm for Ch- AgNPs by UV-Visible spectrophotometer. Particle size analyser showed mean diameter of 71.60 nm and 89.39 nm for Ch-AgNPs and Ch-CuNPs respectively. Atomic Force Microscope showed nanoparticles having size ranged from 30 - 140 nm and 20 - 95 nm for Ch-CuNPs and Ch-AgNPs respectively. Scanning Electron Microscope revealed spherical to irregular shape of both nanoparticles. Synthesized Ch-CuNPs and Ch-AgNPs were evaluated against bacterial pathogen of citrus canker [Xanthomonas axonopodis pv. citri (Xac)] and pomegranate bacterial blight [Xanthomonas axonopodis pv. punicae (Xap)] under in vitro condition by paper disc assay. The results revealed that, Ch-CuNPs effectively inhibited growth of Xac (7.67 mm) and Xap (9.67 mm) at 4,000 ppm. Ch-AgNPs showed inhibition zone of 12.67 mm for Xac and 13.66 mm for Xap at 250 ppm. In glasshouse studies, management of citrus canker, Ch-CuNPs at 3000 ppm recorded PDI of 8.67 compared to untreated control (29.33 PDI). In case of Ch-AgNPs, the minimum disease severity was recorded at 250 ppm concentration (5.56 PDI) compared to untreated control (27.11 PDI). Evaluation of nanoparticles against management of bacterial blight of pomegranate revealed that, Ch-CuNPs were effective at 3000 ppm concentration with minimum disease severity (7.82 PDI) compared to untreated control (31.33 PDI). Further, Ch-AgNPs were effective at 250 ppm with the least disease severity (10.00 PDI) compared to untreated control (PDI 45.00 PDI). Ch-CuNPs and Ch-AgNPs against bacterial diseases of citrus and pomegranate, were effective at 3000 and 250 ppm respectively.
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    ThesisItemOpen Access
    Studies on Turcicum Leaf Blight and Common Rust Diseases of Sweet Corn (Zea mays L. saccharata)
    (University of Agricultural Sciences, Dharwad, 2018-07) Pallavi, H.U.; Harlapur, S.I.
    An investigation was undertaken on loss assessment, epidemiology, screening and management of turcicum leaf blight (TLB) (Exserohilum turcicum (Pass.) Leonard and Suggs.) and common rus t (Puccinia sorghi Schw.) diseases of sweet corn at Main Agricultural Research Station, UAS, Dharwad. Roving survey carried out during kharif, 2017 in Bagalkote, Belagavi, Dharwad and Chikkaballapur districts indicated, maximum mean severity of TLB (56.54 %) and minimum severity of common rust (37.81 %) were observed in Chikkaballapur district. Maximum mean severity of common rust (43.73 %) and minimum severity of TLB (49.00 %) were noticed in Belagavi district. Crop loss estimation studies revealed that, avoidable green ear and fodder yield losses in susceptible genotype were to an extent of 33.90 and 40.40 per cent, respectively. Five sprays of tebuconazole 250 % EC @ 0.1 % recorded least severity of TLB (5.35 %) and common rust (3.04 %) diseases. The weather factors, viz., maximum temperature (27.0oC to 29.1oC), minimum temperature (19.8oC to 21.3oC), relative humidity (>90.0 %) and rainfall (103.0 mm to 233.8 mm) were congenial for development of both the diseases. Rainfall and number of rainy days were significantly positively correlated with the severity of both the TLB and common rust. The regression models developed were, Y = 16.101- 0.098 X5+ 4.159 X6 with R2 = 0.97 for TLB and Y = -4.771-0.102 X5+ 3.547 X6 with R2 = 0.95 for common rust. Among 33 genotypes screened, one genotype, SW-3 was found resistant against common rust but none of the genotypes found resistant for TLB. Genotypes, SW-2 and Hibrix-39 registered moderately resistant reaction for both the diseases. Foliar spray with tebuconazole 250 % EC @ 0.1 % at 35 and 50 days after sowing was effective in managing both the diseases and recorded maximum green ear yield (16.35 t/ha) with highest B:C ratio (2.75).