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ThesisItem Open Access STUDIES ON UDBATTA DISEASE IN RICE (Oryza sativa L.) CAUSED BY Ephelis oryzae Syd.(Keladi Shivappa Nayaka University Agricultural and Horticultural Science (COA,Shivamogga), 2023-12-02) SUPRITHA, R.; Dr. G. N. HOSAGOUDAR; Dr. SURESHA D EKABOTERice (Oryza sativa L.) is one of the important cereal crop belonging to the family Poaceae. Among the significant diseases affecting rice, the Udbatta disease of paddy caused by Ephelis oryzae is on the rise. The present study was carried out with an aim to survey, isolation, identification and proving the pathogenicity; cultural, morphological and physiological characterization; the in-vitro evaluation of fungicides; in vitro evaluation of seed treatment with fungicides in roll towel method against E. oryzae. A roving survey was carried out in Shivamogga, Kodagu and Chikkamagaluru districts of Karnataka revealed the highest PDI was recorded in Kodagu (11.76 %), followed by Shivamogga (10.98 %). Cultural studies showed that the Potato dextrose agar (35.20 mm) and Sabouraud’s agar (32.85 mm) supported maximum growth of mycelia of the pathogen, whereas the colony was found to be flat and raised to fluffy with waxy and leathery texture. The conidia are needle-shaped, hyaline and aseptate, measuring about 18.0 - 25 µm x 1.0 - 1.9 µm. Physiological studies revealed that the highest dry mycelial weight of the pathogen was recorded at a temperature of 25 °C (41.55 mg) and pH 7.0 (49.78 mg). In vitro studies indicated that, among the contact fungicides evaluated, Copper oxychloride 50 % WP was found to be effective with mean mycelial inhibition of 62.59 per cent. Among systemic and combi product fungicides evaluated, Tebuconazole 45% SC and Carbendazim 12 % + Mancozeb 63 % WP showed a cent per cent mean mycelial inhibition respectively. Among the fungicides tested in the roll towel method, the least mean per cent seed infection (1.00 %), high mean per cent germination (99.00 %) and seedling vigour index of 1967.46 was recorded when seeds treated with Carbendazim 12 % + Mancozeb 63 % WP.ThesisItem Open Access STUDIES ON BLIGHT OF FOXTAIL PALM (Wodyetia bifurcata L.(Keladi Shivappa Nayaka University Agricultural and Horticultural Science (COA,Shivamogga), 2023-11-21) SOUNDARYA, K. Y.; Dr. SURESHA D EKABOTE; Dr. R. GANESH NAIKFoxtail palm is a graceful palm species that has popularity in ornamental and landscaping sectors, attributed to its extraordinary beauty, visual appeal and regal look. Regrettably, this palm is susceptible to number of fungal diseases, out of which blight has become potentially destructive disease under field conditions, significantly diminishing its ornamental value. In this context, the present investigation was carried out to identify the causal organism of blight disease. Leaves showing typical symptoms of blight were collected and the pathogen was isolated and maintained on potato dextrose agar (PDA) media. Cultural and morphological characterization was carried out on different media and the results revealed that PDA (87.33 mm) and host leaf extract agar (79.67 mm) supported the growth of pathogen whereas maximum sporulation was found on PDA and oatmeal agar. Pathogen colonies were dull white having salmon buff spore mass. Conidia were slightly dumb-bell, hyaline, single-celled with two oil globules measuring 35.30 - 35.00 µm × 12.70 - 11.00 µm. Molecular characterization revealed 98 per cent nucleotide similarity with Colletotrichum gloeosporioides and the obtained sequences were submitted to NCBI Genbank and accession number (OR029273) was obtained. Physiological studies revealed that ideal temperature and pH range for the C. gloeosporioides were 25 to 30 ℃ and 6.0 to 7.0 respectively. Among different botanicals evaluated against C. gloeosporioides, Curcuma longa (turmeric) at 15 per cent was found effective by inhibiting 72.96 per cent mycelial growth and among different bioagents highest mycelial inhibition of 55.93 per cent was observed with Trichoderma harzianum. In vitro studies of contact, systemic and combi fungicides revealed that copper oxychloride (250, 500 and 1000 ppm), tebuconazole (100, 150 and 250 ppm) and propiconazole + difenoconazole (150, 250 and 500 ppm) recorded cent per cent mycelial inhibition and were found to be superior in managing C. gloeosporioides.ThesisItem Open Access BIOASSAY AND MOLECULAR CHARACTERIZATION OF TRICHODERMA ISOLATES FROM WESTERN GHATS ECOSYSTEM OF KARNATAKA(Keladi Shivappa Nayaka University Agricultural and Horticultural Science (COA,Shivamogga), 2023-11-07) SINCHANA, K. G; Dr. B. GANGADHARA NAIK; Dr. R. GANESH NAIKTrichoderma species are successfully used as biocontrol agents against various phytopathogens. The current study was aimed to understand the efficacy of indigenous isolates against fungal phytopathogens. Rhizosphere soil samples collected from 20 different locations in Shivamogga and Chikkamagaluru districts revealed the presence of six different Trichoderma spp., viz., T. asperelloides, T. asperellum T. afroharzianum, T. harzianum, T. pleuroticola and T. erinaceum upon molecular characterization of Trichoderma isolates using tef1 primers. These Trichoderma spp., produced light green to dark green colony color, while reverse colony color of most species varied from white to light green. While the conidial shape varied from globose to ovoid and their color varied from olive green to dark green. In vitro bioassay of all the Trichoderma isolates showed excellent signs of antagonism against fungal pathogens viz., Sclerotium rolfsii, Alternaria porri, Phyllosticta zingiberi, Colletotrichum gloeosporioides, Fusarium oxysporum, Sarocladium oryzae, Ganoderma ryvardenii, Phytophthora meadii and Pythium sp. In vivo evaluation of biocontrol agents viz., T. asperelloides and T. afroharzianum with the commercially available talc formulation based T. harzianum as check along with two fungicides viz., Metalaxyl 35% WS and Captan 50% WP under pot culture studies revealed that, maximum seed germination (93.33 %) was observed in those treatments treated with Metalaxyl, Seed+Soil treatment with native T. harzianum talc formulation (Check) and Seed+Soil treatment with isolate Tr16 (T. asperelloides) talc formulation. Minimum per cent of damping-off was observed in treatments viz., Metalaxyl 35% WS (10.71 %) followed by Seed+Soil treatment with isolate Tr16 (T. asperelloides) talc formulation (14.29 %) and Seed+Soil treatment with native T. harzianum talc formulation (Check) (14.29 %) compared to control (52.00 %). Seed+Soil treatment with T. asperelloides and T. harzianum were found significantly superior in disease biocontrol efficacy and in enhancing overall plant growth parameters viz., shoot length, root length, fresh and dry weight of shoot and root also fruit yield of tomato plants compared to control.ThesisItem Open Access STUDIES ON SHEATH BLIGHT OF PADDY (Oryza sativa L.) INCITED BY Rhizoctonia solani KUHN, IN HILLY AND COASTAL ZONES OF KARNATAKA(Keladi Shivappa Nayaka University Agricultural and Horticultural Science (COA,Shivamogga), 2023-12-08) RAKESH; Dr. G. N. HOSAGOUDAR; Dr. R. GANESH NAIKPaddy (Oryza sativa L.) crop prone to various fungal, bacterial, viral and nematode diseases. Among fungal diseases sheath blight incited by Rhizoctonia solani Kuhn is more prominent and causes huge yield loss in hilly and coastal zones of Karnataka. Survey conducted in five districts during Kharif 2022-23 revealed the highest disease incidence in the fields of AHRS, Ponnampet (42.02 %) in Kodagu district, whereas least per cent incidence of the disease (5.30 %) was recorded at Bilaki village in Shivamogga district. Among the districts surveyed, Kodagu (23.43 %) recorded maximum mean per cent disease incidence. Cultural and morphological studies revealed that among eight different media tested Potato dextrose agar (89.89 mm) recorded highest mean radial growth followed by Oat meal agar (85.96 mm). All the isolates showed wide cultural and morphological variations in terms of colony colour, colony texture, angle of branching, number of sclerotia/plate, color of sclerotia, nature of sclerotia and days taken for sclerotial body formation. Molecular characterization revealed the pathogen as Rhizoctonia solani by polymerase chain reaction (PCR) assay using ITS rDNA. Studies on vegetative compatibility of Rhizoctonia solani isolates revealed that all the isolates belongs to same anastomosis group and compatibility with tester strain revealed all isolates belongs to anastomosis group one (AG1). In vivo evaluation of fungicides against sheath blight carried out during Kharif season at Agricultural and Horticultural Research Station, Ponnampet, Karnataka, revealed that the lowest per cent disease index was noticed in the treatment with Trifloxystrobin 25 per cent + Tebuconazole 50 % WG @ 0.4 gm/L with 15.60 per cent with a highest yield of 52.10 q/ ha.ThesisItem Open Access STUDIES ON ANTHRACNOSE OF BETELVINE (Piper betle L.) INCITED BY Colletotrichum spp(Keladi Shivappa Nayaka University Agricultural and Horticultural Science (COA,Shivamogga), 2023-11-21) MOUNA, H. N; Dr. SURESHA D EKABOTE; Dr. R. GANESH NAIKAn investigation was carried out on Colletotrichum spp., which causes "Anthracnose" of betelvine, poses a serious threat for the cultivation of betelvine. Present study was carried out with an aim to survey the betelvine gardens for the incidence of disease, characterizing the pathogen through cultural, morphological, physiological and molecular means, in-vitro evaluation of botanicals and fungicides against Colletotrichum spp. Among the districts surveyed Davanagere recorded maximum per cent disease incidence (31.83 %) and Chitradurga recorded least disease incidence (28.28 %). Cultural studies showed PDA (90.00 mm) and Czapek’s dox agar media (84.00 mm) supported maximum growth of mycelia of the pathogen whereas, pathogen colony found to be oblong or cylindrical, dumbel, aseptate with rounded ends. Fungal hyphae were hyaline, 33.10 – 38.90 µm in length and 10.20-13.70 µm in width. Physiological studies showed that the highest dry mycelial weight was attained when the incubation temperature was set at 30 °C (480 mg) and the highest dry mycelial weight of pathogen was obtained at a pH of 5.5 (650 mg). Molecular characterization revealed the pathogen as C. gloeosporioides by polymerase chain reaction (PCR) assay using ITS rDNA. Sequencing and Blast analysis revealed 95-100 per cent nucleotide similarity with Colletotrichum gloeosporioides isolates and the isolates were submitted in NCBI Genbank and accession numbers were obtained. In-vitro evaluation of botanicals revealed highest mycelial inhibition of 70.70 per cent by Curcuma longa followed by Azadirachta indica with 58.34 per cent mycelial inhibition. In-vitro studies of contact, systemic and combi fungicides, revealed that copper hydroxide, Difenoconazole, Propiconazole + Difenoconazole and by Fluopyram + Tebuconazole recorded maximum mycelial inhibition of C. gloeosporioides.ThesisItem Open Access STUDIES ON ANTHRACNOSE OF DRAGON FRUIT (Hylocereus spp.)(Keladi Shivappa Nayaka University Agricultural and Horticultural Science (COA,Shivamogga), 2023-10-03) BHAGYASHREE, G.; Dr. R. GANESH NAIK; Dr. B. GANGADHARA NAIKDragon fruit is an exotic crop cultivated in many parts of India due to its nutritional qualities and health benefits. This crop suffers from various diseases, among them anthracnose is the major disease causing 30-50 per cent yield loss annually. Present study was carried out with objectives of isolation, identification and characterization of pathogen by cultural, morphological and molecular means along with in vitro evaluation of various botanicals, bioagents and fungicides against pathogen. Pathogen was isolated from diseased stem samples of dragon fruit plant and was confirmed based on its mycelial and conidial characters. Upon confirmation, the pathogen was maintained on Potato Dextrose Agar medium for further studies. Koch’s postulates were proved by detached leaf technique as well as pot experiment in glasshouse. Cultural characters of pathogen was studied on different growth media and the results revealed maximum mycelial growth of 88.67 mm on Mathur’s agar medium. Morphological studies revealed the production of white cottony mycelia which later turns to grey colour and the conidia were found to be aseptate, hyaline and cylindrical shape with round ends. Molecular characterization of two pathogen isolates was done through amplification of ITS regions of rDNA yielding bands at 550 bp. Sequencing and blast analysis of both isolates showed 98 per cent homology with Colletotrichum fructicola. Obtained sequences were deposited at GenBank and got the accession numbers (OR026465 and OR342386). Among the various botanicals evaluated against C. fructicola, neem seed kernel extract showed highest mean mycelial inhibition of 38.71 per cent, followed by garlic extract (36.57 %). In vitro evaluation of bioagents using dual culture technique revealed better efficacy of Trichoderma harzianum in inhibiting the maximum mycelial growth of 50.74 per cent. In vitro evaluation of fungicides showed that, Mancozeb, Tebuconazole, Difenoconazole and Mancozeb+Carbendazim were effective in inhibiting the mycelial growth of the pathogen.ThesisItem Open Access STUDIES ON ANTHRACNOSE OF CHILLI (Capsicum annum L.) INCITED BY Colletotrichum spp.(Keladi Shivappa Nayaka University Agricultural and Horticultural Science (COA,Shivamogga), 2023-11-18) ANAGHA, G.; Dr. SURESHA D EKABOTE; Dr. R. GANESH NAIKThe Chilli (Capsicum annum L.) belongs to the family Solanaceae and is an important spice cum vegetable crop grown worldwide. It is a rich source of vitamins, oleoresin, and minerals such as calcium, phosphorus, ferrous and copper. Anthracnose of chilli caused by Colletotrichum spp. is a pre and post-harvest disease with 10-54 per cent yield loss in India. Anthracnose infected green chilli samples were collected from farmer's fields. Infected fruits had water soaked lesions and straw colour, which later became concentric rings with black pin head size acervuli. Among the different solid media evaluated, host leaf extract agar (90 mm) was best for growth and Richard’s agar was suitable for maximum sporulation. The conidia of Colletotrichum spp. were cylindrical to fusiform, hyaline and aseptate with narrow curved ends with 10.10 to 13.21 µm × 2.69 to 4.49 µm range of length and breadth, respectively. The maximum dry weight of Colletotrichum spp. was observed from physiological studies at 25°C (248 mg) and pH at 5.5 (464 mg). Molecular characterization revealed a cent per cent similarity with Colletotrichum acutatum for one isolate and another with 98.62 per cent similarity. In vitro studies showed that fungicides like Mancozeb 75 % WP, Copper oxychloride 50 % WP, Tebuconazole 45 % SC, Difenoconazole 25 % EC, Propiconazole 13.9% EC + Difenoconazole 13.9 % EC and Fluropyram 200 g/L + Tebuconazole 200 g/L SC were effective in inhibiting the complete growth of pathogen. Among the eight varieties analyzed for seed borne nature of pathogen using the agar plate method and standard blotter method, Arka Tejasvi and WS-2207 showed no seed infection. Among the different organics tested against Colletotrichum spp. in Byadgi Dabbi seeds infected with anthracnose disease, vermiwash and cow urine recorded maximum germination percentage and seedling vigour.ThesisItem Open Access PROBIOTICS FROM DIFFERENT FRUIT PLANTS AS PLANT GROWTH PROMOTING MICROORGANISMS (PGPM) AND BIOCONTROL AGENTS(COLLEGE OF AGRICULTURE, KELADI SHIVAPPA NAYAKA, UNIVERSITY OF AGRICULTURAL AND HORTICULTURAL SCIENCES, SHIVAMOGGA, 2022-10-06) NAVEESH, Y. B.; Dr. M. K. NAIK; Dr. M. Y. SHREENIVASAThe study on probiotics from different fruit plants as plant growth promoting microorganisms (PGPM) and biocontrol agents was carried out during 2019-2021. A thirty probiotic lactic acid bacteria (LAB) isolates showing gram positive and catalase negative that were further subjected to carbohydrates fermentation, antibiotic sensitivity patterns and acidic, bile salt tolerances, cell surface hydrophobicity and resistance to phenol. Among thirty isolates, twenty isolates thrived well at pH 2.0, pH 3.0 and pH 6.0 and exhibited strong resistance up to 0.3 per cent bile salt proving that the isolates were resistance to gastric conditions. Probiotic LAB isolates NRB7, NRB14, NRB15, NRB20, SF3, PE4, PGA1, RC3, BE2 and SF1 showed maximum mycelial inhibition against Fusarium solani, Colletotrichum gloeosporioides and Aspergillus flavus, inciting wilt, anthracnose and aflatoxin contamination in chilli crop respectively. Tested for hydrolytic enzyme activity and plant growth promotion attributes, all isolates showed positive reaction for protease, amylase, cellulase and chitinase activity and siderophore production. Probiotic isolate NRB14 showed highest P solubalization efficiency of (372.4%), maximum IAA production (36.91±1.31μg/ml), highest seed germination (97.78 per cent) and seed vigor index 1081.22. In pot culture experiment, inoculation of NRB14, PGA1 and RC3 increased plant growth parameters and least disease incidence against F.solani, C. gloeosporioides and A. flavus. Based on molecular characterization, effective probiotic isolates namely NRB14, PGA1 and RC3 were identified as Lactiplantibacillus plantarum. Different media used for mass multiplication of Lactiplantibacillus plantarum, MRS media and molasses+ yeast extract media showed maximum cfu count per ml. Among different carrier materials used, maximum cfu count was observed in liquid formulation followed by talc carrier based formulation. In the induced defense enzyme assay, those seeds treated with probiotic isolates namely NRB14, PGA1 and RC3 showed maximum PO (peroxidase), PPO (polyphenol oxidase), PAL (phenyl ammonia layase) defense enzyme activity against all three tested pathogens.ThesisItem Open Access EPIDEMIOLOGY AND MANAGEMENT OF BACTERIAL LEAF STRIPE OF ARECANUT(COLLEGE OF AGRICULTURE, KELADI SHIVAPPA NAYAKA, UNIVERSITY OF AGRICULTURAL AND HORTICULTURAL SCIENCES, SHIVAMOGGA, 2021-11-14) NANDEESHA K. L; Dr. B. GANGADHARA NAIKBacterial leaf stripe is an emerging disease in arecanut caused by Xanthomonas vasicola pv. arecae which infects during the early stage of the crop growth (1-6 years), resulting in the death of the plants. Considering the importance of the crop and magnitude of this disease, investigations were undertaken to study the pathogen and disease thoroughly in bringing out appropriate management practices to mitigate the disease effectively. Survey conducted during 2019-20 and 2020 - 21 revealed, highest disease incidence and severity was noticed in Davanagere district, whereas, disease occurrence was not observed in Tumakur and Uttara Kannada districts. Growth of pathogen isolates on seven different nutrient media showed considerable variation with respect to colony colour, size, shape, appearance and mucoidness. Among the media tested, Nutrient Glucose Agar (NGA) media supported best growth of all the isolates. The biochemical profiling of the pathogen isolates showed positive reaction to catalase test, liquefaction of gelatin, KOH test, methyl red test ammonia production, starch hydrolysis and hydrogen sulphide production. Whereas, the negative reactions were observed in fluorescent test and gram staining. PCR amplification of ≈1490 bp region corresponding to 16S rRNA gene was amplified and ≈ 491 bp corresponding to gyrB loci was targeted from pathogen isolates through polymerase chain reaction (PCR) using 16S rRNA and gyrB specific primers. Weather parameters viz., intermittent rainfall, temperature maximum (35.53 and 35.60 0C) and minimum temperature (21.26 and 21.80 0C), along with relative humidity maximum (83.29 and 77.00 %) and minimum relative humidity of 50.57 and 37.00 per cent were found favourable for the disease development and its severity during 2019-20 and 2020-21. Trichoderma harzianum was found to be effective under in-vitro. Whereas, Kasugamycin + Copper oxychloride (Conica) was found to be an effective chemical both under in-vitro and field conditions.