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Open 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 %).
Open Access
Studies on Fungal Foliar and Fruit Diseases of Pomegranate (Punica granatum L.)
(University of Agricultural Science, Dharwad, 2016-08) Pavithra S.; Benagi, V.I.
The leaf/fruit spot of pomegranate caused by various organisms such as Colletotrichum gloeosporioides, Alternaria alternata, Sphaceloma punicae, Cercospora punicae, Drechslera sp. and Phomopsis sp., take a heavy toll on the crop. Major pomegranate growing districts of Karnataka were surveyed for the prevalence of fungal diseases. Survey revealed that anthracnose and Cercospora disease severity was highest in Gadag and Belagavi districts respectively in mrig bahar. Scab disease severity was highest in Koppal district during ambia bahar. By standard tissue isolation, microscopic observation and by Koch postulates, the pathogens viz., C. gloeosporioides, C. punicae and Pestalotiopsis algarionsis were proved. Morphological and cultural characters of 30 isolates of C. gloeosporioides were studied. Majority of the isolates produced white mycelia, regular margin, coarse texture with fluffy growth and white to grey pigmentation. The isolates were identified as Colletotrichum sp. by sequencing the amplified ITS rDNA region, and analyzed in NCBI BLAST program. An attempt was made to study the effect of weather parameters on progress of anthracnose. During ambia bahar of 2015 and hasta bahar of 2015-16 RH was significantly positively correlated with disease. Variety Ganesh showed resistant to C. gloeosporioides as accumulation of defence enzymes like PPO (0.074 absorbance/min/g), PAL (0.028) and Peroxidase (0.029) were high in it. In vivo experiment over two locations revealed that captan 2 g/lit followed by vitavax power 1g/lit followed by Iprobenphos 1 g/lit followed by cabriotop 2 g/l followed by captan 2 g/l followed by vitavax power 1 g/l followed by Iprobenphos 1 g/lit followed by cabriotop 2 g/lit of water at 15 days interval gave per cent anthracnose disease reduction of 6.80 and also increase in fruit yield (11.87 kg/tree).
Open Access
Molecular Characterization, Epidemiology and Management of Bhendi Yellow Vein Mosaic Virus
(University of Agricultural Science, Dharwad, 2016-08) Rathod, Suresh; Byadgi, A.S.
Okra (Abelmoschous esculentus L.) Moench is one of the important vegetable crops. It suffers from number of diseases with substantial yield loss. Of all the diseases, bhendi yellow vein mosaic disease is one of the most severe disease leading to heavy crop loss. The results of the roving survey revealed that disease was more severe during summer. Maximum mean PDI was recorded in Vijayapur district followed by Bagalkot, whereas lowest PDI was observed in Dharwad during both summer and kharif season. BYVMV infection produced the symptoms like vein clearing, veinal chlorosis, malformed leaves and reduction of leaf size. BYVMV coat protein gene was amplified using BYVMV coat protein specific primers. In nucleotide sequence comparisons, isolate under study shared highest nucleotide sequence identity with BYVMV Madhurai Variant 3, Aurangabad isolate, Barrackpore isolate and Dharwad isolate. The cross inoculation study using BYVMV specific primers indicated that out of six test plants, Alternanthera sessile and bhendi showed positive reaction in PCR when inoculated from bhendi source plant and vice versa. The BYVMV successfully amplified from both bhendi and Alternanthera sessile test sample indicated that the virus infecting bhendi and Alternanthera sessile was the same. Weather parameters with PDI revealed a highly significant positive correlation with minimum temperature and significant positive correlation with both morning and evening RH. Whitefly population had highly significant positive correlation with maximum temperature and significant negative correlation with rainfall. Management of BYVMV disease by spraying different insecticides, imidacloprid 17.80 % SL (0.05 %) followed by diafenthiuron 50 WP (0.75 g/lit) were best in minimising the incidence of the disease. Significantly lowest mean vector population on three top leaves/plant was recorded in treatment imidacloprid 17.80 % SL (0.05 %). Among the 262 genotypes/lines screened only two lines (Bhendi No. 64 and DBh-102) were highly resistant to BYVMV infection. Four were resistant and six lines were moderately susceptible. Remained were highly susceptible and susceptible reaction. None of the genotypes/lines moderately resistant to the disease.
Open Access
Epidemiology, Molecular Characterization for Resistance to Turcicum Leaf Blight and Integrated Management of Major Foliar Diseases in Maize
(University of Agricultural Science, Dharwad, 2016-08) Hulagappa; Nargund, V.B.
Survey was conducted during two kharif and rabi seasons (2014-15 and 2015-16) in northern Karnataka for recording foliar diseases severity. Among the foliar fungal diseases of maize turcicum leaf blight (TLB) caused by Exserohilum turcicum is major yield limiting factor. Survey study revealed that maximum disease severity (96.00 PDI) of TLB was noticed in Gurlapur village of Belagavi district. Kalburgi district remained free from all foliar diseases even at the cob formation stage. The maximum severity of TLB was recorded in 2014 kharif compared to 2015. Thirty isolates collected during survey showed morphological variation on PDA. The full length ITS rDNA region of E. turcicum was amplified with ITS-1 and ITS-4 primers. Genetic variation among isolates of E. turcicum was studied by analysis of the ITS-RFLP profile after the digestion with restriction enzymes (Taq I, and Hind II) which showed specific polymorphism. Field experiments were undertaken during two kharif seasons at MARS, Dharwad (2014 and 2015). Among 23 inbred lines screened under artificial epiphytotic condition, three lines (PDM-74-1, 4641 and 260) exhibited moderate resistant reaction.The application of different SSR markers successfully provided the information on similarity and/or diversity as well as the heterozygosity of the allelic loci for all the 23 inbred lines. Epidemiological study revealed a positive correlation with cumulative rainfall and temperature. The multiple linear regression equation was developed and the coefficient of determinative value (R2) was more than 0.90 in two consecutive kharif seasons. In the fungicidal management of TLB, spraying of propiconazole @ 0.1 per cent at 35, 50 and 65 days after sowing recorded least PDI (12.44) with maximum grain and fodder yield (73.01 q/ha and 10.33 t/ha). In the four integrated disease management modules, highest grain and fodder yield were recorded in chemical module (72.40 q/ha and 9.01 t/ha) with 2.58 B:C ratio.
Open Access
Studies on Viral Diseases of Cucumber
(University of Agricultural Science, Dharwad, 2016-07) Revadi, Muttanna; Patil, M.S.
Cucumber mosaic disease (CMD) infected plants produced dark green mottling, mosaic, dwarfing of vines. Chlorotic spots, yellowing, dark green islands and vein banding were typical symptoms of zucchini yellow mosaic disease (ZYMD). Tomato leaf curl disease (ToLCD) infected leaf samples exhibited bilstering, upward curling and crumpling. During kharif 2014 and summer 2015, highest mean CMD incidence was recorded in Dharwad (23.94 %) and least in Bagalkot (21.31 %). Haveri (6.79 %) and Bagalkot (5.80 %) were recorded highest and lowest mean ZYMD incidence. Highest mean incidence of ToLCD was noticed in Dharwad (3.14 %) and Belagavi recorded lowest incidence of 2.70 per cent. The coat protein genes of CMV (657 bp), ZYMV (242 bp) and ToLCV (492 bp) were amplified by specific and degenerate primers and further confirmed by sequencing. The nucleotide sequences of CMV, ZYMV and ToLCV Dharwad isolates revealed 97-99, 97-98 and 96-98 per cent homology respectively with the available sequences in NCBI. Coat protein gene of CMV-DWD isolate was cloned into PTZ57R/T (pCMRP13) and further sub-cloned pQE30 and moved in to E. coli M15. A SDS-PAGE indicated protein band of 26 KDa. Expressed CMV-CP was purified and used as an antigen. The M13K07 helper phages were amplified. Two scFv monoclonal antibody clones viz., pCMRPAB3 and pCMRPAB13 showed strong binding affinity to the CMV-CP. The pCMRPAB13 was validated using CMV infected field samples. CMV was mechanically transmitted to seven host crops, which produced mosaic, mottling, chlorotic spots and leaf distortion symptoms and showed 17-65 per cent transmission. ZYMV produced mosaic, vein banding and vein clearing symptoms on cucurbitaceous hosts. Adoptive module (M2) showed least incidence of CMD (6.56 %), ZYMD (3.78 %) and aphid (1.00 aphids/3 terminal leaves) and highest yield of 15.80 t/ha with 2.52 cost benefit ratio which was also on par with chemical intensive module (M3) in yield (14.25 t/ha) and cost benefit ratio (2.14).
Open 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.
Open 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.
Open 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.
Open 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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