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ThesisItem Open Access Studies on management of spot blotch [Bipolaris sorokiniana (SACC.) SHOEM.] disease of wheat(Department of Plant Pathology, BAU, Sabour, 2020) Kumari, Puja; Azad, C.S.Wheat (Triticum aestivum L.) is one of the most important crops of India. It is mainly affected by spot blotch, leaf blight, loose smut, powdery mildew and rust in north eastern plain zone of India. Spot blotch of wheat is caused by Bipolaris sorokiniana and it is considered as one of the emerging diseases. The disease affects the crop at any stage right from beginning to maturity of crop and cause 25 to 35 per cent loss in yield. In present study, efforts were made to find out suitable management measures through various chemicals, elicitor and nanoparticles. A fungus was isolated from infected plant parts and based on cultural-morphological characteristics, identified as Bipolaris sorokiniana and pathogenicity test was proved by detached leaf technique. Under in vitro condition, Azoxystrobin 12.5 SC+ Tebuconazole 12.5 SC was highly effective and checked growth of B. sorokiniana even at 25 ppm. Tebuconazole 50 WG + Trifloxystrobin 25 WG, Propiconazole 250 EC and Tebuconazole 250 EC were also found effective as compared to control. Under field condition all the genotypes performed significantly when they were sown timely, however with delay in sowing germination per cent was in decreasing trend. Timely sown crop on 11th Nov. 2018 showed minimum disease severity in double digit scale as compared to late sown (16th Dec. 2018) and Very late sown (7th Jan. 2019). Timely sown crop on 11th Nov. 2018 showed minimum disease severity in double digit scale as compared to late sown (16th Dec. 2018) and Very late sown (7th Jan. 2019). At flowering stage of timely sown treatment there were no disease appearance. Disease incidence and per cent disease index was lowest for timely sown treatment (11th Nov. 2018) as compared to late (16th Dec. 2018) and very late (7th Jan. 2019). Delay in date of sowing of wheat crop even highly resistance variety can become susceptible for the spot blotch pathogen with the enhancement of growth stage of plant. Among elicitors highest increase in enzymatic activities, lowest No. of spot/leaves as well as severity was recorded in Chitosan at 2 mM concentration. Among nanoparticles, it was highest in Silver nanoparticles at 100 ppm concentration. Both elicitors and nanoparticles significantly increased the enzymatic activities over control. On biochemical analysis, significant increase in enzymatic activity was recorded in plants treated with elicitor 24 hour after challenge inoculation of Bipolaris sorokiniana. Highest concentration of PPO, PO and total phenol was observed at 72 hours in all the treatments of elicitors. However, after 72 hrs, there has been gradual decrease in enzymatic activity whereas among nanoparticles maximum enzymatic activity was recorded at 96 hours however, after 96 hours there has been gradual decrease.ThesisItem Open Access Studies on variability of Exserohilum turcicum causing Northern corn leaf blight(Department of Plant Pathology, BAU, Sabour, 2022) Niwas, Ram; Anwer, ArshadMaize is considered as one of the most important staple food crops in the world. This crop has been taken into cultivation after the difficulty and interrelated relationship development; hence these crops have the most established record of cultivation by humanity. In current scenario maize cultivation is facing many challenges by several biotic and abiotic factors. Among all diseases, Northern corn leaf blight (NCLB) caused by Exserohilum turcicum (Passerini) (Leonard and Suggs.) accounts for significant damage to this crop and ultimately responsible for maximum loss in terms of quality and quantity. Disease symptoms first appear on the leaves at any stage of plant growth, but usually at or after anthesis. NCLB is an endemic disease in cooler (18-27 oC) maize growing regions, and potential to bring loss in grain yield ranges from 24 to 91%. In India, NCLB is found to be prevalent in Rabi growing season and one of the major factors in reduction of maize production. The state, Bihar also faces a major problem through NCLB because the area of Rabi maize is highest in all over India. Although being a virulent pathogen, no efficient and reliable measures for race identification as well as differential lines are available for NCLB in India. A study was conducted to assess the disease incidence and per cent disease index of NCLB in major maize growing districts (Bhagalpur, Begusarai, Khagaria, Katihar and Samastipur) of Bihar in 2020-21 and 2021-22. At the same time geographical distribution of the NCLB disease was also observed. From each representative district, 3 blocks were surveyed based on the production of maize crop and yield losses due to NCLB disease. Out of 3 blocks, 3 villages were selected at the interval of 3-10 km along road side. Such fields were randomly selected on both sides of the road. Each sampling point was marked with the global positioning system (GPS) using GPS receiver for altitude and longitude. Twenty plants in middle of each field were randomly selected and leaf samples were collected from infected maize fields and assessed for DI and PDI. The study was also done to evaluate initially 120 maize genotypes in field condition for NCLB resistance. These genotypes were also screened resistance to NCLB at molecular level by using specific primers of Ht1, Ht2, Ht3 and HtN1 genes. In this way differential lines of maize for E. turcicum were identified, and used in race identification of this pathogen. Virulence and distribution of races were also observed against Ht resistance genes and also identified the E. turcicum race population distribution in Bihar. These isolates were screened on maize differential lines containing Ht1, Ht2, Ht3 and or HtN1 resistance genes. Survey results revealed the DI and PDI of NCLB across all the districts even though at different blocks level. Mean of DI ranged from 35.0% (2020-21) to 51.6% (2021-22) in Bhagalpur to 86.6% (2020-21) to 90.0% (2021-22) in Samastipur and mean PDI varied between 19.0% (2020-21) to 37.0% (2021-22) in Bhagalpur and 63.6% (2020-21) to 70.0% (2021-22) in Samastipur district. Tmax ranged 23.2-35.4 °C, Tmin ranged 9.3-20.1 °C, RH ranged 52.0-78.0 % and rainfall ranged 6.6 mm-17.4 mm were found suitable for the disease development. The results indicate the severity of the disease in the surveyed area of Bihar. To get a clear picture of the disease significance across geographic regions to identify sources of resistant genotypes and the pathotypes/available in Bihar, and to link weather factors with the development of NCLB, it is necessary to conduct successive surveys for NCLB in all the maize growing regions. Among the 45 fungal isolates, cultural, morphological and molecular characterization were done and identified as E. turcicum. These isolates were grouped into four groups based on colony colour i.e. olivaceous brown, blackish brown, whitish black and greyish and into 2 groups based on regular and irregular margin. The conidial shapes were observed to be elongated and spindle with protruding hilum with conidial septa ranged from 2-12. Similarly, conidial length varied from 52.94 μm to 144.12 μm. β-tubulin gene sequences analysis made it possible to verify the identity of fungal strains and phylogenetic relationship of all isolates, were clustered in the same clade. β-tubulin gene sequences of all the isolates showed high level of similarity (100%) with reference isolate from GenBank accession number KU670342.1, KU670344.1, KU670343.1, KU670341.1, KU670340.1. In the study of genotypes for resistance, results showed that genotype ‘98’ had maximum yield 11.93 t/ha followed by genotype ‘118’ with 11.86 t/ha among 120 selected genotypes. The maximum DI 100%, PDI 89% and AUDPC 1844.5%-dsu (percent development stage unit) were recorded in the genotype ‘67’ having no resistant gene and minimum DI 25%, PDI 8% and AUDPC 42%-dsu were recorded in the genotype ‘115’ having all resistant genes. In addition, those genotypes showed the presence of all resistant genes Ht1, Ht2, Ht3 and HtN1 that could be involved in resistance to NCLB. Among the genotypes, three were moderately susceptible, six were moderately resistant, thirty were resistance, sixty nine were highly resistant and twelve were susceptible out of 120 to NCLB, found on the basis of presence/absence of resistant genes and disease parameter under field condition. The molecular based screening used in this study would utilize in other plants that are sensitive to NCLB, particularly using Ht1, Ht2, Ht3 and HtN1 genes. Studies on variability of E. turcicum, five different physiological races were observed based on the symptoms response of the differential maize lines. These races are race 0, race 1, race 3, race 23N and race 123N. E. turcicum race 3 was the most prevalent race having 26.6% frequency followed by race 0 having 24.4% and race 1 having 22.2% and least prevalent races were race 23N and 123N having 13.3% each. Varied resistance response of different isolates was observed on differential lines having different resistant genes. Despite the fact that virulence was seen against all Ht resistance genes, NCLB control might be increased by combining qualitative Ht resistance genes with quantitative resistance.ThesisItem Open Access Host-shift study of Begomovirus from possible host to watermelon(Department of Plant Pathology, BAU, Sabour, 2021-06) Suman, Swastika; Suman, Swastika; Ansar, Mohammad; Ansar, MohammadWhitefly transmitted geminiviruses (Genus – Begomovirus) are the emerging threat in cucurbits including watermelon. The cultivation is broadly hampered by the virus and affecting quality production. The present study documents Begomovirus associated with various hosts including watermelon. Broadly, Tomato leaf curl New Delhi virus (ToLCNDV) was found to infect the majority of solanaceous and cucurbitaceous hosts. Watermelon grown in river banks of Ganges showed typical Begomovirus symptom with incidence ranges from 7.6 to 17.8 %. The suspected watermelon leaves showed infection by ToLCNDV and Tomato leaf curl Joydebpur virus (ToLCJV) confirmed in PCR assay. In sequence analysis, ToLCNDV CP gene showed maximum nucleotide identity with cucurbit infecting isolates. The highest (99 %) identity noticed in sponge gourd isolate. However, the MP gene exhibited an identity between 92-96 % with cucurbit isolates. The sequence obtained from ToLCJV CP gene amplified samples had maximum similarity with Ageratum enation virus (AEV). It showed the highest identity (92 %) being with papaya isolates. Association of betasatellite also confirmed which showed maximum similarity with Tomato leaf curl Joydebpur betasatellite isolate (chilli). Association of both viruses were also confirmed in two weeds e.g., goat weed and nightshade. The year-round presence of both viruses was studied in various crops including weed hosts. In observation majority of rabi season crops infected with ToLCNDV and ToLCJV were overlapped on summer season crops predominantly in cucurbits including watermelon. ToLCNDV was found infecting most of the cucurbits with incidence ranges from 10 to15 %. Moreover, both weeds crucially played a role in harboring the virus between the two major seasons and an active role in disease development. Both mono and bipartite Begomovirus infection in watermelon may be the results of consecutive overlapping or crop diversification. This adaptation of virus or shifting behavior may become a forthcoming threat for melon cultivation in near future. Thus, a sustainable control approach must be framed with integrated tactics.ThesisItem Open Access Determination of Morphological and Biochemical Changes upon Application of Nanoparticle in Plant Pathosystem(Department of Plant Pathology, BAU, Sabour, 2018-06) Kriti, Aakanksha; Ghatak, AbhijeetA large number of fungicides for foliar disease management are developed with sulphur and copper compounds as the basic ingredient. These ingredients are known for environmental pollution with its degradation issue. With a very limited research results it is accepted that plant diseases can be managed by application of nanoparticle (NP) that could replace the mentioned ingredients from the agricultural system. The present investigation was undergone in order to explore the morphological and biochemical variation on nanoparticle application in two plant-pathosystems i.e. Bipolaris-sorokiniana-barley and Alternaria brassicicola-mustard. The laboratory synthesised NPs [25-32 nm for silver (Ag) and 29-37 nm for zinc (Zn)] at 100 ppm revealed almost 75-100% spore germination of B. sorokiniana and A. brassicicola was inhibited. Similarly, the same concentration found best to restrict mycelial growth of the two pathogens. NP-applied leaves produced smaller lesion size in comparison to the leaves devoid of NP application. Overall, lesion size was reduced by ~70% in barley and ~45% in mustard leaves when they received NP application 30 minutes before pathogen inoculation. However, in some genotypes this trend was not constantly evident. Similar result was observed for phenol estimation; the greater phenol was quantified in infected leaves where NP was applied before pathogen inoculation. In comparison to only pathogen inoculated leaves, higher level of phenol expression was seen in leaves treated with NP+P by ~19% and ~13% in barley and mustard, respectively. Higher amount of chlorophyll was harvested in leaves with NP application with or without pathogen infection in comparison to the infected leaves (no NP applied). This indicates the applied NP might catalyze a pathway for chlorophyll production. At the end, the effect of NP at field scale was determined. AgNP showed significantly lower disease severity of B. sorokiniana infection compared to ZnNP across genotypes. However, no definite trend was established for the two NPs in A. brassicicola infected mustard genotypes. The information generated in this work needs the further in-depth study in order to identify the mechanism of respective NP for reducing infection in the two plant pathosystems.ThesisItem Open Access Variability of leaf blight pathogen of Linum usitatissimum L.”(Department of Plant Pathology, BAU, Sabour, 2017-09) Kumari, Sujata; Srinivasaraghavan, A.To study the variability of the Alternaria blight pathogen, a total of 19 isolates including four of ALTERNARIA LINICOLA and 15 of ALTERNARIA LINI were collected from different agro-ecological zones of Bihar. All the isolates were subjected morpho-physiological, cultural and pathogenic variability studies. A good amount of morphological variability was found among the different isolates. In A. LINICOLA, colony colour was found to be greyish black to grey with white and smooth margin. The maximum spore size was found in ALC-2 (40.2-44.6 X 9.5-10µ m) with a septation 9-12 horizontal and 3-4 vertical septa. The days taken to sporulation was found maximum in ALC-1 (14 days) and minimum in ALC-4 (10days). Similarly in A. LINI a colony colour of white or whitish grey to greyish black with whitish grey to white with smooth margin was recorded . Maximum spore size was found in ALN-14 (21.4-23.6 X 12.3-12.9µm) with a septation of (5-7 X 2-3). The days taken to sporulation was found maximum in ALN-1, 6 & 15 (16 days) and minimum in ALN-3 & 12 (11days). Maximum growth on potato dextrose agar (PDA) was achieved after two weeks of incubation. The mean mycelial dry weight of six isolates were measured at different temperature conditions revealed that, 250 C was the most favourable condition for production mycelium (57.2mg). Among the different isolates, ALN 15 (44.2mg) was found to be performing better at all the temperatures. Interestingly, the A. LINICOLA isolates were found better at lower temperatures (150C). Similarly the Relative Humidity (RH) of 90 per cent was found better for all the isolates tested. The maximum radial growth was found in ALN-4 (37.3) at 80 per cent RH. The detached leaf and pod techniques followed to test the pathogenic variability were successfully able to differentiate the isolates. The per cent maximum incidence of on leaf was found in ALN-3 (97.2) and ALN-4 at par with ALN-7 (91.7). The least was recorded on ALC-12 (47.2). The lesion diameter was found maximum in ALN-3 and 4 (7.4mm) followed by ALN-13 (6.80) and the least was found to be in ALN-6 (4.57mm). On pods, highest disease at end of 72 hpi was found in ALC-3 (66.7 %) being at par with other A. LINICOLA isolates which indicated that, A. LINICOLA isolates were more aggressive compared to A. LINI and vice-versa on leaves.ThesisItem Open Access Morpho-physiological variability and antagonistic potential of native fluorescent Pseudomonads from Zone 3A of Bihar(Department of Plant Pathology, BAU, Sabour, 2017-07) Gupta, Annu Kumari; ErayyaBiocontrol agents have great demand now-a-days as they are replacing chemical pesticides to a large extent as they are cost effective and eco-friendly. The use of biological control agents as an alternative to fungicides is increasing rapidly in the present day agriculture due to the deleterious effects of chemical pesticides. Fluorescent Pseudomonads, a major constituent of rhizobacteria, encourages the plant growth through their diverse mechanisms. Its name implies, it secretes greenish fluorescent pigment called fluorescein, particularly under condition of low iron availability fluorescent Pseudomonads are one among them which not only enhance the plant growth but also control the fungal pathogens by production of antifungal metabolites. Present investigation was focused towards isolation of fluorescent Pseudomonads from different crop rhizospheres, morpho-physiological characterization and evaluation of antagonistic potential of these isolated fluorescent Pseudomonads against three fungal pathogens viz., Rhizoctonia solani, Sclerotium rolfsii and Fusarium spp. Twenty six fluorescent Pseudomonads were isolated from different crop rhizospheric soils collected from different villages of Bhagalpur and Kishanganj. The isolates were purified on King’s-B medium and confirmed by observing under UV light. Out of twenty six, sixteen isolates were confirmed as fluorescent Pseudomonads. Among sixteen isolates twelve were found producing round to oval shaped colonies and four isolates produced irregular colonies on King’s-B agar medium. Colony colour varied from isolate to isolate viz., slightly yellowish white, green, dull white and whitish green to yellowish. Isolate WHSB produced maximum number of colonies (51.33X10-8/ml) followed by MSSB (28.33 X10-8/ml) on King’s-B medium. Colony size was found maximum (13.33mm) in MRKH followed by TMGH (12.00 mm). Fluorescent Pseudomonads produced different colour pigmentation (light green, dark green, bluish white and bluish green) at lower surface of King’s-B medium. Both the selected isolates, high fluorescent isolate (MSSB) and low fluorescent isolate (WHSB) preferred pH 7.5 for their optimum growth followed by pH 7.0 and 8.0, respectively. The same isolates also preferred the glucose as a carbon source followed by dextrose for their rapid growth. In vitro evaluation studies indicated that isolate BMGH shown maximum antagonism against Rhizoctonia solani with 55.66 per cent inhibition of pathogen over control followed by isolate WHKH (47.16 per cent) and MSKSN (46.22 per cent). Isolate CHGH was found least effective (15.09 per cent) followed by BRKH (16.03 per cent). Against Sclerotium rolfsii, isolate LNSB had maximum antagonism (88.81 per cent) followed by WHKH (79.72 per cent) and isolate BRKH was found least effective (23.78 per cent) followed by CKSB (32.87 per cent). Isolate MZKSN and BRGH were found to have maximum antagonism against Fusarium spp. (58.74 per cent) followed by WHSB (56.65 per cent) and MRKH was found least effective (15.39 per cent) followed by MSKSN (20.29 per cent). The effective isolates screened under in vitro may further tested under field conditions and may used for management of soil-borne fungal plant diseases.ThesisItem Open Access Studies on Rhizoctonia solani inciting rice sheath blight and its eco- friendly management(Department of Plant Pathology, BAU, Sabour, 2017-07) Kumari, Puja; Kumar, SantoshRice (Oryza sativa L.) is grown as an important cereal crop all over the world, but extensively grown in South East Asian countries and is the richest source of energy and is an providing substantial amounts of the recommended nutrient intake of zinc and niacin. Among the various diseases sheath blight of rice caused by R. solani Kuhn is an economically important disease in India. Yield loss varies from 20 to 50%, depending on the weather conditions during the crop growth-period. The present investigation was undertaken to study the cultural and morphological characters of the pathogen, physiological studies and sustainable management of the disease. Fungicides and botanicals were screened for their antifungal activities against the pathogen under in vitro and soil amendments, botanical assess their effect on disease severity under pot culture condition. The pathogen was isolated and maintained on PDA medium. It produced cottony white mycelium which later turned to brownish yellow to dark brown colonies on PDA. The late stage produced sclerotia of nearly uniform texture, irregular in shape with hard structure and brown to black in colour. Maximum radial growth and sclerotial formation was observed on PDA and Radish dextrose agar (RDA), respectively. The pathogen also showed differences in their sensitivity when exposed to different pH and temperatures. Sclerotia inoculation technique was best as compared to others. Among fungicides tested in vitro, hexaconazole proved best followed by carbendazim. Among the botanicals, datura extract was found best antifungal compound followed by ashok. In the pot experiments, soil amendments, neem cake amended with Trichoderma viride had shown the relative lesion height of 11.12% and maximum per cent disease reduction over control (82.75%), followed by farm yard manure amended with Trichoderma viride which had shown (17.95%) RLH and (72.16%) reduction over control. Among the botanicals, datura extract was found best antifungal compound followed by ashok.ThesisItem Open Access Studies on Epidemiology of False Smut (Ustilaginoidea virens) of Rice and Its Sustainable Management(Department of Plant Pathology, BAU, Sabour, 2017-07) Bhargava, Priya; Kumar, SanjeevFalse smut of rice caused Ustilaginoidea virens is considered as one of the emerging disease. The reasons for emergence of this disease are mainly attributed to climate change and intensive rice cultivation. There is little information available with respect to biology and epidemiology if the disease in Bihar. Present study was conducted to understand the biology and epidemiology of false smut of the pathogen. The fungus was isolated by ‘standard ball isolation technique’ of Ustilaginoidea virens and incubated at 27±1°C. Fungus was initially isolated based on the characters described viz., fluffy white growth on PDA and moniliform mycelium with oval or round in shaped conidia. Further, the identity of the fungi was confirmed by the taxonomist’s examination at ‘Indian type culture collection’, New Delhi. Maximum mycelial growth of was U. virens observed on potato sucrose agar medium (32.64 mm) and at pH 6.0 (68.82 mm). Under in vitro evaluation of fungicides against the false smut fungus, all the treatments were found inhibiting the fungal growth at all the concentrations (10, 25, 50, 100 ppm). Among six fungicides, propiconazole was found to be best at all the concentration with cent per cent inhibition at 50 and 100 ppm followed by Azoxystrobin and hexaconazole having cent per cent inhibition at 100 ppm concentration and the least inhibition was observed at in Copper oxy chloride at all concentrations. Among four nano particles, Silver nanoparticles (67.11% inhibition) were highly effective in controlling the fungus at 100 ppm followed by silicon carbide (60.17%) and minimum achieved by aluminium nanoparticles (55.92%) at 100 ppm concentration. Disease severity and disease incidence were observed highest in Sabour ardhajal (19.54% and 52.83% severity and incidence respectively) followed by Sushak samrat (16.66% and 35.56%) and lowest in Sahbhagi (14.72% and 17.41%). Disease severity and disease incidence were maximum in crop sown during 25th June (17.23% and 43.37%) and minimum disease severity and disease incidence was observed in 15th July (15.62% and 23.77%). There was no significant interaction observed between varieties and date of sowing. Epidemiology of pathogen revealed that the maximum disease severity (52.83%) and disease incidence (19.54%) occurred at temperature range between 23.14-31.36ºC, relative humidity (73.50-88.85%), rainfall (6.66 mm) and sunshine hrs (6.20 hrs) in Sabour ardhajal which were flowered during 25th Sept to 20th Oct than other varieties whereas, minimum disease incidence (14.72%) and disease severity (17.41%) occurred in Sahbhagi when flowered during 10th Sept to 5th Oct at same range of temperature and relative humidity but at low sunshine hrs (4.81 hrs) and high rainfall (7.27 mm). Among different date of sowing disease incidence and severity were highest in 25th June sown crop which flowered during 15th Sept to 5th Oct, when temperature, relative humidity, rainfall and sunshine hours occurred between 23.17-31.44ºC, 74.00-87.48%, 6.67 mm and 6.29 hrs. Lowest disease incidence (15.62%) and disease severity (23.77%) were found during 15th July sowing which flowered during 5th Oct to 25th Oct, when rainfall was lower than 0.2 mm besides temperature, relative humidity and sunshine hrs which was relatively similar as 25th June sown crop. In Crop flowered during 7th Sep to 30th Sep and 25th Sept to 15th Oct the disease incidence and severity was lower than crop flowered during during15th Sept to 5th Oct. Among the growth character of different varieties on different date of sowing revealed that germination percentage, days to 50 per cent flowering and days to maturity was highest in Sabour Ardhajal and least in IR-64. 15th July sowing had highest days to 50% flowering and 25th June had least days to 50% flowering. The days to maturity were vice versa to days to 50 per cent flowering for date of sowing. Grain yield and chaffy grain/panicle were found to be highest in Sushak samrat. Lowest grain yield was observed in Sahbhagi and chaffy grains/panicle was in Sabour ardhajal. During 25th June sowing highest yield (41.20 q/ha) and chaffy grains/panicle (22.40 grains/ panicle) were found whereas lowest was found during 15th July (36.93 q/ha) in case of yield and during 5th July (18.40 grains/panicle) in case of chaffy grains/panicle.ThesisItem Open Access Deciphering the role of Nightshade (Solanum nigrum) in epidemiology of Tomato leaf curl virus infecting Tomato (Solanum lycopersicum)(Department of Plant Pathology, BAU, Sabour, 2017-07) Karn, Monika; Ansar, MohammadTomato (Solanum lycopersicum L.) is the world’s fourth important vegetable crop with an annual production of 162 million metric tons. At present India ranks second in overall production worldwide. The crop is severely hampered by various biotic constraints, among them viruses play an important role. In whitefly (Bemisia tabaci) transmitted geminiviruses, Tomato leaf curl virus (ToLCV) affect tomato cultivation to a huge extent. The disease may cause up to 90 per cent or more reduction in fruit yield due to its devastating nature. Weed plants are well known reservoir of begomoviruses which act as major factor in epidemiology of the disease in different crops. Considering the economic importance of crop and potentiality of associated virus the present investigation was undertaken to study the prevalence of ToLCV disease in Bhagalpur locality along with associated Solanum nigrum (nightshade) weed. The study covered molecular detection and characterization of virus in tomato and nightshade weed, reciprocal transmission experiments and temporal dynamics of viral incidence. The survey for viral infection in tomato and nightshade in rabi season (2016-17) revealed ToLCV was present in almost locations of Bhagalpur district. Disease incidence ranged from 25 to 38 per cent in tomato and 11 to 22 per cent in nightshade. Population dynamics of whitefly during survey revealed 1 to 3 individuals/plant on tomato and 0.3 to 3 on nightshade plant. In molecular detection of virus carried out through PCR assay, with specific primer pairs (Deng-F/R, ToLCNDV-F/R, and ToLCNDV-AF/AR). PCR amplified product expected size of 957 bp band in gel electrophoresis. The product having CP gene was clonned and sequenced through outsourcing. After procurement of sequence, full CP gene sequence were checked through ORF finder which revealed a single open reading frame with 771 nucleotide encoding 256 amino acid. The full sequence was submitted to GenBank under the accession number KY112754. Sequence data was subjected to multiple sequence alignments and phylogram was constructed using CLUSTAL W software. Based on the CP gene homology of the virus isolates infecting nightshade regarded as an isolates of ToLCNDV and is designated as ToLCNDV:SN (94-96 % homology with isolates of ToLCNDV). In artificial transmission experiment of ToLCV, average rate of 16.6 per cent recorded from infected tomato to nightshade plant (seedling, 6-leaf and flowering stage). Back transmissibility of ToLCV from infected nightshade to healthy tomato plant was found to be 12.21 per cent. In temporal dynamic studies of leaf curl in tomato and nightshade incidence progressively increases upto middle February. A similar trend was observed in case of nightshade plant but the appearance was noticed after symptom expression in tomato. A positive correlation was found in tomato and nightshade leaf curl incidence under the study. The study covers a detail exploration of associated nightshade weed in epidemiology of tomato leaf curl virus. The result seems to helpful in growers community in order to manage the disease by destroying weeds.
