Acharya N G Ranga Agricultural University, Guntur

The Andhra Pradesh Agricultural University (APAU) was established on 12th June 1964 at Hyderabad. The University was formally inaugurated on 20th March 1965 by Late Shri. Lal Bahadur Shastri, the then Hon`ble Prime Minister of India. Another significant milestone was the inauguration of the building programme of the university by Late Smt. Indira Gandhi,the then Hon`ble Prime Minister of India on 23rd June 1966. The University was renamed as Acharya N. G. Ranga Agricultural University on 7th November 1996 in honour and memory of an outstanding parliamentarian Acharya Nayukulu Gogineni Ranga, who rendered remarkable selfless service for the cause of farmers and is regarded as an outstanding educationist, kisan leader and freedom fighter. HISTORICAL MILESTONE Acharya N. G. Ranga Agricultural University (ANGRAU) was established under the name of Andhra Pradesh Agricultural University (APAU) on the 12th of June 1964 through the APAU Act 1963. Later, it was renamed as Acharya N. G. Ranga Agricultural University on the 7th of November, 1996 in honour and memory of the noted Parliamentarian and Kisan Leader, Acharya N. G. Ranga. At the verge of completion of Golden Jubilee Year of the ANGRAU, it has given birth to a new State Agricultural University namely Prof. Jayashankar Telangana State Agricultural University with the bifurcation of the state of Andhra Pradesh as per the Andhra Pradesh Reorganization Act 2014. The ANGRAU at LAM, Guntur is serving the students and the farmers of 13 districts of new State of Andhra Pradesh with renewed interest and dedication. Genesis of ANGRAU in service of the farmers 1926: The Royal Commission emphasized the need for a strong research base for agricultural development in the country... 1949: The Radhakrishnan Commission (1949) on University Education led to the establishment of Rural Universities for the overall development of agriculture and rural life in the country... 1955: First Joint Indo-American Team studied the status and future needs of agricultural education in the country... 1960: Second Joint Indo-American Team (1960) headed by Dr. M. S. Randhawa, the then Vice-President of Indian Council of Agricultural Research recommended specifically the establishment of Farm Universities and spelt out the basic objectives of these Universities as Institutional Autonomy, inclusion of Agriculture, Veterinary / Animal Husbandry and Home Science, Integration of Teaching, Research and Extension... 1963: The Andhra Pradesh Agricultural University (APAU) Act enacted... June 12th 1964: Andhra Pradesh Agricultural University (APAU) was established at Hyderabad with Shri. O. Pulla Reddi, I.C.S. (Retired) was the first founder Vice-Chancellor of the University... June 1964: Re-affilitation of Colleges of Agriculture and Veterinary Science, Hyderabad (estt. in 1961, affiliated to Osmania University), Agricultural College, Bapatla (estt. in 1945, affiliated to Andhra University), Sri Venkateswara Agricultural College, Tirupati and Andhra Veterinary College, Tirupati (estt. in 1961, affiliated to Sri Venkateswara University)... 20th March 1965: Formal inauguration of APAU by Late Shri. Lal Bahadur Shastri, the then Hon`ble Prime Minister of India... 1964-66: The report of the Second National Education Commission headed by Dr. D.S. Kothari, Chairman of the University Grants Commission stressed the need for establishing at least one Agricultural University in each Indian State... 23, June 1966: Inauguration of the Administrative building of the university by Late Smt. Indira Gandhi, the then Hon`ble Prime Minister of India... July, 1966: Transfer of 41 Agricultural Research Stations, functioning under the Department of Agriculture... May, 1967: Transfer of Four Research Stations of the Animal Husbandry Department... 7th November 1996: Renaming of University as Acharya N. G. Ranga Agricultural University in honour and memory of an outstanding parliamentarian Acharya Nayukulu Gogineni Ranga... 15th July 2005: Establishment of Sri Venkateswara Veterinary University (SVVU) bifurcating ANGRAU by Act 18 of 2005... 26th June 2007: Establishment of Andhra Pradesh Horticultural University (APHU) bifurcating ANGRAU by the Act 30 of 2007... 2nd June 2014 As per the Andhra Pradesh Reorganization Act 2014, ANGRAU is now... serving the students and the farmers of 13 districts of new State of Andhra Pradesh with renewed interest and dedication...

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Open Access
STUDIES ON THE INTEGRATION OF CHEMICAL AND BIOLOGICAL METHODS FOR THE MANAGEMENT OF RICE STEM ROT DISEASE CAUSED BY Sclerotium oryzae Catt.
(Acharya N.G. Ranga Agricultural University, 2018) RANGA RANI, ATLA; RAJAN, C.P.D.
Stem rot of rice, caused by Sclerotia oryzae Catt. is a serious threat to rice production in India. Fungicides provide control of this pathogen but also have ill effects on the environment. In an attempt to develop better integrated strategies using fungicides and bacterial bio agents for management of stem rot disease, a total of eight isolates from different localities of Nellore district were isolated. The isolates of S. oryzae were designated as SO 1, SO 2, SO 3, SO 4, SO 5, SO 6 SO 7 and SO 8. Variability among these isolates of S. oryzae based on growth rate on PDA and also in utilizing various carbon sources was assessed using four different growth media. Depending on the growth rate on PDA medium, these isolates of S. oryzae could be categorised into four groups. Group 1 had the very fast growing isolate SO 3. Group 2 comprised of four isolates SO 1, SO 4, SO 6 and SO 7 which were fast growing. Group 3 consisted of the medium growing isolates i.e. SO 2, SO 8. Group 4 consisted of isolate SO 5 is very slow growing. Among the growth media tested, PDA was best supported for growth of all isolates and there was no growth of all the isolates of S. oryzae grown on CDA. Among the eight isolates, isolate SO 3 which was fast growing with abundant sclerotial production was selected for further studies. A total of thirteen antagonistic bacteria were isolated from rhizosphere soil of rice. Highest inhibition was recorded in case of RRB-2 (74.07%) followed by xiii RRB-4 with 70.73% inhibition, RRB-1 with 65.92% inhibition and RRB-3 with 62.22% inhibition. Least inhibition was observed with RRB-12 (31.84%) and with RRB-13 (33.31%). Four of these effective bacterial antagonists were used for further studies. Thirteen plant extracts, five plant essential oils and five natural preparation were tested for their bio efficacy against S. oryzae at different concentrations. The extract (powdered seeds) of Brassica juncea was found to be the most effective in inhibiting the growth of S. oryzae (100%) at 20 and 25% concentrations followed by rhizome extract of Curcuma longa (84.81) at 20% concentration, bulb extract of Allium sativum (84.44) at 2.0% concentration, leaf extract of Eucalyptus glubulus (76.29%). The bulb extract of Allium cepa recorded the least mean inhibition (4.40%) of S. oryzae at 5%. Out of the five essential oils, lemon grass oil showed 100 % inhibition of the test fungus at all tested concentrations. Spearmint oil at 1%, 1.5% and 2% concentrations and eucalyptus oil at 2% and 3% concentrations recorded 100% inhibition in the growth of S. oryzae. The mustard oil at 0.5% concentration recorded least inhibition (7.77%) followed by neem oil at 0.5% concentration with 19.25% inhibition in the growth of S. oryzae. Among the natural preparations, neemasthra was found to be the most effective in inhibiting the growth of S. oryzae (55.56%) followed by brahmasthra (49.66%), agniasthra (36.66%) and jeevamrutham (35.56). The neem seed kernel recorded the least mean inhibition (2.23%) of S. oryzae at 5000 ppm. Among the fifteen fungicides tested, Carbendazim, Propiconazole, Hexaconazole, Difenoconazole, Tebuconazole, Trifloxystrobin + Tebuconazole, Azoxystrobin, Isoprothiolane, Mancozeb + Carbendazim, Benomyl and Thiophanate-methyl completely (100%) inhibited the growth of S. oryzae at all concentrations in vitro. Thifluzamide (0.04%) recorded least per cent inhibition. Twelve fungicides were tested in vitro for the compatibility with potential biocontrol agents viz., RRB-1, RRB-2, RRB-3 and RRB-4. Isolate RRB-4 was found to be most compatible antagonistic bacteria as it has shown highest compatibility when compared to other isolates. Hexaconazole showed highest compatibility with all the four isolates followed by propiconazole. Effective fungicides and antagonistic bacterial isolates in in vitro studies were evaluated under field conditions. Results of pooled analysis of Rabi 2016-17 and early Kharif 2017-18 revealed that, among the fungicides, treatment Hexaconazole recorded lowest PDI. While among the bacterial antagonists, treatment Root dipping with RRB-4 + foliar spray showed less PDI after second spray. Hence, these two treatments were selected for further field trial during Rabi 2017-18 to evaluate the strategies involving the integration of effective fungicide and bacterial antagonist for the management of rice stem rot disease. Pooled analysis of the yield data revealed that the highest grain yield was recorded in Hexaconazole treatment (7.43 t/ha) followed by Difenoconazole (7.29 t/ha), Tebuconazole (7.19 t/ha), Root dipping with RRB-4+ foliar spray (6.97 t/ha), Carbendazim (6.91 t/ha) and Mancozeb + Carbendazim (6.89 t/ha). Least grain yield was xiv observed in untreated control (5.22t/ha) followed by Root dipping with RRB-3+ foliar spray (5.74 t/ha) which were statistically at par with each other. In case of straw yield, Hexaconazole treatment (7.22 t/ha) recorded highest straw yield followed by Difenoconazole; 6.88t/ha and Propiconazole; 6.84 t/ha which were statistically at par with each other. Least straw yield was observed in untreated control (5.47 t/ha). During Rabi 2017-18, the evaluation of the strategies of integration of effective fungicide Hexaconazole (0.2%) and the antagonistic isolate RRB-4, results revealed that, among the seven treatments consisting of different strategies, the following strategies were found superior. 1. Alternate sprays with hexaconazole and RRB-4 (40.00 PDI; 7.56 t/ha grain yield and 10.26t/ha straw yield). 2. Seedling dip with RRB-4 and two sprays followed by two sprays with hexaconazole (44.40 PDI, 6.95 t/ha grain yield and 8.53 t/ha straw yield). 3. Two sprays with hexaconazole followed by two sprays with RRB-4 (48.35 PDI, 7.37 t/ha grain yield and 7.73 t/ha straw yield).
Open Access
CHARACTERIZATION AND MANAGEMENT OF Alternaria porri (Ellis) Cif. CAUSING PURPLE LEAF BLOTCH OF ONION (Allium cepa L.)
(Acharya N.G. Ranga Agricultural University, 2018) NAGA LAKSHMI, T; SARADA JAYALAKSHMI DEVI, R
Purple leaf blotch caused by Alternaria porri is one of the most destructive diseases of onion causing significant bulb yield losses. Keeping in view the importance of disease, studies were conducted on cultural, morphological, pathological and molecular diversity, in vitro efficacy of fungicides and integrated management of disease at field by using fungicides and bioagents at Horticultural Research Station (HRS), Anantharajupeta. Survey was carried out to understand the disease severity in major onion growing areas i.e YSR Kadapa and Kurnool districts of Andhra Pradesh. Cultural and morphological characters of the native isolate were studied on six different media viz. Carrot agar, Corn meal agar, Czapek’s Dox agar, Host leaf extract agar Potato dextrose agar and Yeast extract agar medium. Out of all the media tested, growth was fast in Czapek Dox medium and slow in corn meal agar medium. Sporulation was best in Host leaf extract agar and potato dextrose agar and less in corn meal agar and Yeast extract agar medium. The pathogen produced septate mycelium. Conidiophores were produced either singly or in small groups. The conidiophores were straight or flexuous some times geniculate, septate, pale or mild brown in colour and measured upto 135μ long and 7-10 μ thick, with one to several conidial scars. xvii Conidia are straight or curved, rostrate, beak generally equal to the length of the body of the conidium pale brown to mild golden brown in colour. Overall length of the conidia ranged from 70-265 μ, 10-21 μ thick in the broadest part with 7-12 transverse and zero to six longitudinal septa, beak flexuous, pale 2-4 μ thick and tapering. A total of 15 Alternaria porri isolates were collected from different locations of Andhra Pradesh, Karnataka and Telangana. Later the isolates were identified and pathogenicity and virulence studies were conducted and found that leaves and the morphological character of the re-isolated organisms confirmed the pathogenicity. Among the isolates, Anantharajupeta (AP-1), Mydukur (AP-3), Gonegandla (AP-4) and Nandikotdur (AP-5) isolates were found highly virulent and potential with highest 41.67 to 56.58 PDI. Cultural and morphological characters of 15 isolates were studied. Conidial length of the isolates ranged from 23-170μ, with an average length of 96.5μ, width from 15-23μ, beak length ranging from 6-29μ and with beak width of 4-9μ. Colour from pale to mild golden brown, horizontal septa ranging from 3-13, with an average of 6-8 between isolates and vertical septa ranging from 0-5, with an average of 2-3 between isolates. Colony growth rate was fast in 8.14 mm in AP-1 and slow in 3.43 mm in KA-2 with an average growth rate of 5.74 mm per day among the fifteen isolates. Molecular characterization was done using 5.8s rDNA specific ITS1 and ITS4 primers. All the 15 isolates of A. porri yielded single PCR amplified product of 560 bp confirming the pathogen identity. Out of 15 isolates, five samples viz., AP-1, AP-4, AP-5, KA-2 and TS1 were sequenced and phylogenic tree was constructed and isolates were divided into two clades. Two groups AP-1 and AP-4; KA-2 and TS-1 were aligned in Clade I and AP-5 alone was grouped in clade II. Genetic diversity studies were carried out to assess the degree of genetic diversity/relatedness among 15 isolates of A. porri. Out of 10 SSR molecular markers used, only four SSR primers i.e., SSR-5 (115 bp) for KA-4, SSR-7 (215 bp) for KA-3, SSR-8 (250 and 340 bp) for AP-2 and SSR-10 (153, 237, 245 and 450 bp) for AP-6, AP-3, AP-6 and AP-4 respectively, produced unique bands. The PIC (Polymorphic Information Content) value ranged between ranged from 1.0 (SSR-1 and SSR 6) to 0.249 (SSR-1 and SSR-4) with an average of 0.826 for all 10 primers among the 15 isolates. In vitro screening of eight fungicides against native pathogen isolate revealed the efficacy of fungicides at varied levels. Hexaconazole was found effective and inhibited cent per cent growth at 1000 and 1500 ppm. Mancozeb was least effective and the mean inhibition per cent was 53.63 among the treatments. The highest toxicity index was observed in hexaconazole xviii (454.85) followed by propiconazole (431.05) on maximum toxicity index of 500. The least toxicity was 268.16 in the treatment of Mancozeb. In vivo evaluation of fungicides revealed that, hexaconazole at 0.1% with 12.50% of PDI and highest CB ratio (2.11) was found significantly superior over other treatments. Increased bulb yield over control and other treatments was observed in hexaconazole. Area under disease progress curve (AUDPC) calculated and yield (t/ha) data were also recorded. The data reveals that in T2 (Hexaconazole 0.2%), lowest AUDPC (399) was observed with highest yield (29.30 t/ha). While in control, highest AUDPC (1008) and lowest yield (9.67 t/ha). Fourteen fungal bioagents viz., Th-1, Tsp-2, Tsp-3, Th-4, Tsp-5, Tkn-6, Th-7, Tlb-8, Trs-9, Th-10, Tsp-11, Tsp-12, Tsp-13 and Tsp-14 comprising of Trichoderma harzianum, , T. koningii, T. reesii and T. longibrachiatum and six bacterial bioagents viz., P. fluorescens-1- Pf- 6 were evaluated against the pathogen and Th4 significantly superior in both in non volatiles (59.97%) and volatiles (57.325%) production over other Trichoderma isolates tested. Evaluation of 28 onion cultivars/ lines under two different agro-climatic conditions i,e., Anantharajupeta and Mahanandi to find the source of resistance, revealed that none of the genotypes was found to be either resistant or immune to the disease . However, the cultivars Bhima Super and Arka Kalyan showed moderately resistant reaction at both the locations. Management studies conducted over two seasons revealed that the integrated strategy with soil application of T.harzianum enriched FYM @ 100 kg/ha + seed treatment with T.harzianum @ 8g/kg of seed + two foliar sprays, one with liquid formulation of T.harzianum @ 5 ml/lt at first appearance of the disease followed by hexaconazole @ 0.2% at fortnightly interval was found significantly effective in reducing the disease intensity by recording a lowest PDI (14.09) with 79.69% disease reduction and yield 29.94 t/ha with 87.81% increased yield over control. This treatment recorded highest (1.99) cost benefit ratio, which was followed by tolerant variety Bhima Super (1.81).
Open Access
CHARACTERIZATION OF Pyricularia oryzae Cavara, INCITANT OF RICE BLAST AND ITS MANAGEMENT
(Acharya N.G. Ranga Agricultural University, 2018) BHASKAR, B; SARADA JAYALAKSHMI DEVI, R
The present investigation was undertaken with an aim to know the variability between leaf blast and neck blast pathogen populations. Studies carried out on the variability of isolates using cultural, morphological, pathological and molecular characteristics. In another study efforts were made to identify the promising lines for both leaf blast and neck blast resistance. Attempts were also made to manage the disease with biocontrol agent P. fluorescens, fungicides and their integration. Survey was conducted in nine major rice growing districts of Andhra Pradesh during 2015-16. The highest mean blast disease incidence 29.05% was recorded in Nellore district. The lowest mean PDI 20.79% was recorded in Srikakulam district. Regarding the mandals, highest mean blast incidence was recorded in Kovvur mandal of Nellore district with 38.99% in a range of 20.45% to 51.14%. The lowest incidence 15.41% with 10.94% to 21.02% range was noticed in Madugula mandal of Visakhapatnam district. The disease incidence was highly varied among the cultivars rather than the locations. The ascending order of the cultivars regarding the mean disease incidence was NDLR-8 (3%) < MTU-3626 (4.46%) < MTU-1121(5.89%) < NLR-34449 (11.09%) < RGL-2537 (12.86%) < MTU-1061 (16.83%) < MTU-1001 (19.74% ) < ADT-37 (23.81%)
Open Access
EDAPHOLOGY, EPIDEMIOLOGY AND MANAGEMENT OF STEM ROT OF GROUNDNUT CAUSED BY Sclerotium rolfsii Sacc.
(Acharya N.G. Ranga Agricultural University, 2018) DARVIN, GOTTAPU; KRISHNA PRASADJI, J
Stem rot disease incidence was found to range from 2.1 to 15.3% and severity from 2.1 to 15.1%, with the highest mean stem rot incidence (12.0%) and severity (11.7%) in Ananthapuram district and the lowest incidence (4.6%) and severity (4.4%) in Chittoor district. In Ananathapuram, Chittoor and Guntur districts variation in stem rot incidence between mandals was narrower than in Srikakulam and Vizianagarm districts. Stem rot distribution in most groundnut fields of Ananathapuram, Chittoor and Guntur districts was either uniform or highly uniform compared to Srikakulam and Vizianagaram districts. Stem rot incidence was not found to have significant correlation with soil pH in the survey. Mean leaf spot severity (PDI) in the surveyed fields was found to range between 0 and 62% which had a strong positive correlation with stem rot disease incidence. Distinct variation was observed in colony dispersion (cottony, profuse or sparse, flat or raised), colour (shades of white for most isolates but two showed shades of pink) and sclerotial colour (shades of brown mostly with a few isolates producing cream coloured sclerotia). Sclerotium rolfsii isolates differed in radial growth (79 to 90 mm in six days); time for sclerotial initiation (4.5 to 11 days) and number of sclerotia (5.5 to 761.5); time taken for groundnut stem rot initiation (15 to 34.5 days); in causing stem rot incidence (25 and 100%) and severity (25 to 83%). Using Mahalanobis Euclidean (D2) distance statistic and Ward’s minimum variance dendrogram, 30 S. rolfsii isolates were grouped in to six clusters. Twenty five S. rolfsii isolates were grouped in to two major clusters following NTSYS cluster analysis based on the RAPD banding profile with eight markers. Isolates from one geographical region of Ananathapuram and Chittoor districts were found to group together in both methods of diversity assessment. Sandy soil, sandy + red and sandy + black soils were found conducive for groundnut stem rot development. Moisture holding capacity at 40% and 60% was found optimum for stem rot development. Although stem rot incidence was recorded at pH ranging from 5.0 to 8.0, pH between 5.0 and 6.0 was found to be optimum for stem rot infection in ground nut. Groundnut stem rot progress was found to assume polycyclic pattern at least within close spatial proximity which deviated from the expected monocyclic disease pattern because of initial addition of inoculum to the field soil and rapid inoculum, particularly of sclerotia development on infected plant debris, and subsequent spread in irrigated groundnut crop. Disease progress curves though not typically sigmoid were close to those of polycyclic diseases. Age of the crop under applied inoculum conditions was found to have profound influence on stem rot progress through regression analysis. Soil temperature alone was found to have a significant (P=0.05) positive correlation with stem rot DI (0.374*) and PDI (0.380*). Stepwise regression analysis identified soil temperature and minimum temperature as the independent principal variables that explain groundnut stem rot progress up to 31%. Trichoderma asperellum isolate showed the maximum inhibition of S. rolfsii on PDA. Isolate E among the 11 Bradyrhizobium sp isolates was found to have the maximum inhibitory effect on S. rolfsii and the best compatibility with T. asperellum isolate. Diammonium phosphate, ammonium sulphate, poultry manure, gypsum and neem cake were found to inhibit S. rolfsii growth on PDA. All the treatments in the IDM were able to significantly decrease stem rot incidence than untreated control. In both pot culture and field experiments in 2013-14 and 2014-15, treatment involving integration of seed treatment with T. asperellum + Bradyrhizobium sp, gypsum soil application twice as basal and 30 DAS, poultry manure soil application twice as basal and 45 DAT, neem cake with T. asperellum soil application at 45 DAT and spray application of tebuconazole 0.1% twice at 30 and 60 DAS gave the best control with the lowest incidence and severity. Treatments particularly those involving tebuconazole were effective in reducing leaf spot severity in groundnut. In the most effective treatment, reduction in stem rot disease incidence resulted in increasing pod and haulm yield with the highest pod yield of 2296.3 kg ha-1 in 2013-14 and 1963 kg ha-1 in 2014-15 which was about 50% more than in control. Linear equation constructed by regressing yield with stem rot incidence revealed that for every one per cent increase in stem rot incidence there would be loss of 35.54 kg in groundnut pod yield. The effective treatments for management of stem rot also had a positive effect in increasing shelling percentage of pods, test weight and oil content. The economic analysis yielded the highest B:C ratio of 1.78 in the treatment involving gypsum application as basal and 30 DAT + tebuconazole 1% at 30 and 60 DAS which was closely followed by B:C ratio (1.74) in the best treatment for stem rot management.
Open Access
STUDIES ON VARIABILITY OF Fusarium udum BUTLER, CAUSAL AGENT OF PIGEONPEA WILT [Cajanus cajan (L.) Millsp.] AND ITS MANAGEMENT
(Acharya N.G. Ranga Agricultural University, 2017) ARUNODHAYAM, K; SARADA JAYALAKSHMI DEVI, R
Pigeonpea [Cajanus cajan (L.) Millspaugh] is the prominent drought tolerant pulse crop with multiple benefits viz., source of dietary protein, protects soil from erosion and enriches it, medicinal properties, stover and fuel wood etc. Pigeonpea wilt caused by Fusarium udum is the most important soil borne disease. F. udum isolates from the same site or diverse geographical origins have been shown to exhibit high variability in cultural and pathogenic characteristics. Information on the variability of the pathogen among isolates collected from different agro-ecological zones of Andhra Pradesh is lacking. Hence variability among 25 isolates of F. udum from Andhra Pradesh and Telangana were studied. The laboratory experiments pertaining to the research work were conducted during the year 2013-2016 in the Department of Plant Pathology, S.V. Agricultural College and Institute of Frontier Technology, RARS, Tirupati, Chittoor district, Andhra Pradesh. Field experiments were conducted during kharif 2013 and kharif 2014 at Agricultural Research Station, Tandur, Rangareddy district, Telangana. Glass house experiments were conducted during 2014-15 in the Department of Legumes Pathology at International Crops Research Institute for the Semi Arid Tropics (ICRISAT), Patancheru, Medak district, Telangana. xvi A total of 25 diseased specimens were collected from different pigeonpea growing areas of Andhra Pradesh and Telangana viz., Chittoor, Kadapa, Anantapur, Warangal, Khammam, Kurnool, Guntur, Prakasam, Rangareddy, Medak and Mahaboobnagar during kharif, 2013. The pathogenic isolates were isolated and designated as FU-1 to FU-25. Pathogenicity test was conducted using root dip inoculation method. Cultural and morphological variability was studied and categorized 25 isolates into various groups based on radial growth, growth pattern, mycelial characters, mycelial colour, pigmentation, dry mycelial weight, septation of macro and micro conidia and size of micro and macro conidia. Molecular characterization was done using RAPD and found polymorphism with K1 primer at 450 bp in FU-25, with K2 primer at 620bp in FU-3, with K3 primer at 320 bp in FU-10, with K4 primer at 550 bp in FU-3 and with K5 primer at 750 bp in Fu-11. The polymorphic bands were used in developing SCAR markers for rapid detection of F. udum isolates. Based on wilt incidence and reaction on selected host differentials (ICP 2376, C 11, ICP 8863 and ICP 9174), 25 F. udum isolates were categorized into six races/variants viz., Variant 0, Variant I, Variant II, Variant III, Variant VIII and Variant IX. SCAR was developed successfully for FU-25 isolate with 450 bp band and for FU-3 with 620 bp. Screening of pigeonpea germplasm was done under sick plot conditions at Tandur and found TRG-59 as best genotype with lower wilt incidence of 17.42% and highest yield of 214.1 g per plant. Potential fungal antagonist T1, potential bacterial antagonist B2 and effective fungicide carbendazim were imposed as treatments in Integrated Disease Management program. Among seven treatments imposed in IDM T5 (Asha-red seed coat resistant check) was found best followed by T2 (Seed treatment with bacterial biocontrol agent).
Open Access
MOLECULAR DIAGNOSIS, BIOLOGICAL AND GENETIC DIVERSITY OF Tobacco streak virus
(Acharya N.G. Ranga Agricultural University, Guntur, 2016) SUNIL KUMAR, M; SARADA JAYALAKSHMI DEVI, R
Tobacco streak virus (TSV) belongs to the genus Ilarvirus of family Bromoviridae and its virions were characterized by quasi-isometric particles measuring about 27 – 35 nm in diameter. TSV was found to be a serious production constraint in several field and horticultural crops. A study was undertaken to characterize and develop suitable management strategies against TSV. Survey conducted during Kharif 2014-15 and 2015-16 in Andhra Pradesh and Karnataka revealed disease incidence of 9-28 per cent in groundnut, 6-18 per cent in sunflower and 5-22 per cent in cucumber. TSV infected samples collected from groundnut (GNAP7), sunflower (SFAP17), cucumber (CUKA13) and parthenium (PHAP15) was maintained on cowpea for biological and molecular characterization. TSV isolates (GNAP7. SFAP17, CUKA13 and PHAP15) maintained on cowpea were cross inoculated on five popularly grown cultivars of groundnut (JL-24, K-6, Prasuna, K-9, Kadiri harithandra), sunflower (KBSH-44, DRSH1, NDSH-1012, Mordent, Sunbred-275) and cucumber (Long green, Swarna poorna, Swarna ageti, Swarna sheetal, Pusa uday). Incubation period required for the initiation of local and systemic symptoms varied among different hosts and cultivars. Local symptoms of veinal necrosis, leaf yellowing and wilting, petiole necrosis, chlorotic spot, tip necrosis and systemic symptoms of mosaic, wilting, necrotic streaks on stem, bud necrosis, axillary shoot proliferation were observed in different hosts and cultivars. Out of 23 plant species tested against TSV by sap inoculation, 14 plant species were susceptible to TSV, which included Beta vulgaris, Abelmoschus esculentus, Cicer arietinum, Solanum melongena, Ricinus communis, Phaseolus vulgaris, Gerbera jamesonii, Macrotyloma uniflorum, Vigna unguiculata ssp. unguiculata, Tagetus erecta, Allium cepa, Phaseolus coccineus, Solanum lycopersicum and Vigna unguiculata ssp. sesquipedalis. Complete genome sequence of TSV isolates, groundnut (GNAP7), sunflower (SFAP17), cucumber (CUKA13) and parthenium (PHAP15) was done and submitted to Genbank, NCBI and showed high level of diversity at nucleotide and amino acid level. Phylogenetic analysis of RNA1, RNA2 and RNA3 genes revealed that TSV isolates under present study (Groundnut, Sunflower, Cucumber and Parthenium) clustered into one group along with other Indian TSV isolates. A total of eleven recombination events in RNA1, eight recombination events in RNA2 and six recombination events in RNA3 were identified. The motif distribution and secondary structures (α helix, β strand and coiled region) in replicase protein, RNA dependent RNA polymerase protein, movement protein and coat protein of groundnut, sunflower, cucumber and parthenium isolates showed high level of variability among TSV isolates. For quick diagnosis of TSV, various molecular diagnostic techniques like IC-RT-PCR, RT-LAMP and IC-RT-LAMP were standardized. Cucumber fruits from sap inoculated plants and from naturally infected plants (fruits collected from cucumber plants with parthenium as border crops) were collected and found positive for TSV in immature seeds. Among different treatments or modules used to study Integrated Disease Management (IDM) of TSV in groundnut during Kharif 2014-15 and 2015-16, Treatment 3 (T3) (improved practice) (Border crop (4 rows of Jowar) + seed rate @ 200 kg ha-1 + seed treatment with Imidacloprid, Gaucho 600 FS @ 2 ml kg-1 seed and Mancozeb @ 3 g kg-1 seed + spraying of Thiocloprid 480 SC @ 150 ml ha-1 at 20 DAS followed by Acetamiprid 20 SP @ 100 g ha-1 at 35 DAS.) was found to be effective with lowest PSND disease incidence and thrips damage at 7 and 14 days after 1st and 2nd spraying and with more yield parameters followed by Treatment 2 (T2) (recommended practice) (Border crop with Jowar, 4 rows around the field + Seed rate @ 200 kg ha-1 + Seed treatment with Imidacloprid 600 FS @ 2 ml kg-1 seed and Mancozeb @ 3 g kg-1 seed + foliar spray of Dimethoate @ 2 ml l-1 of water at 20 days after sowing) which were significantly different from each other.
Open Access
STUDIES ON BIOLOGICAL CONTROL OF CHICKPEA COLLAR ROT CAUSED BY SCLEROTIUM ROLFSII USING TRICHODERMA
(Acharya N.G. Ranga Agricultural University, 2016) SWATHI, B; ANIL KUMAR, P
When twenty five isolates of Trichoderma spp. were dual cultured individually with S. rolfsii, incitant of chickpea collar rot, Trichoderma antagonized S. rolfsii in 11 interactions (44%). In 12 interactions (48%), S. rolfsii antagonized Trichoderma. Only two (8%) interactions resulted in static growth. Isolate T14, T15, T17, T22, Tps1, Th4, Th5, Tv2 and Tsugarcane were found to be more antagonistic to S. rolfsii in dual culture when lysis and overgrowth were taken in to consideration. In pot culture, isolate Th4 (64.4%), T22 (60.2%), Tckp (60.2%), T14 (56.0%), T15 (56.0%), Th2 (52.3%), Th3 (52.3%) and Trice (51.4%) gave more than 50% control of chickpea collar rot when applied to soil. Isolate T12 (63.4%), Th4 (60.2%), Tv3 (52.3%), T2 (51.4%) and Trice (51.4%) gave more than 50% disease control when applied as seed treatment. The Trichoderma isolate Th4 (renamed as Th4-w) was found superior with better in vitro antagonistic potential and with better disease control potential in pot culture. Among the eight solid formulations of Trichoderma assessed using soil application and seed treatment methods, talc formulation (51.0% and 65.9%, respectively) and pesta granules (47.7% and 66.4% respectively) gave superior disease control. Among the three liquid formulations tested by soil application and seed treatment methods, mineral oil formulation (50.0% and 54.0%, respectively) gave superior disease control. Among the three additives tested, viz., CMC, casein and culture filtrate, addition of CMC @ 1% was found better with superior disease control over others. When shelf life of Trichoderma was monitored in terms of Trichoderma population, a gradual decline in the shelf life of Trichoderma was noticed when the formulations in different packing material were stored at ambient and refrigerated temperatures. Talc powder formulation stored in paper cover (7.7x108cfu/g) and mineral oil formulation stored in pet jar (16.7x109cfu/ml) showed longest shelf life (ten months) with highest Trichoderma population among all the treatments tested over both the storage temperatures. Different formulations stored at different temperatures and in different packing material were found superior to pathogen inoculated check in terms of increased germination per cent and plant stand per cent. Two mutants were obtained – one tolerant to DAP (Th4-MDAP) alone and another to both DAP and tebuconazle (Th4-MTEB+DAP) using UV irradiation. Field experiments conducted during Rabi seasons of 2012-13, 2013-14 and 2014-15 under natural field conditions revealed chickpea plant mortality due to S. rolfsii, Fusarium oxysporum f. sp. ciceri and Macrophomina phaseolina. Up to 30 days of crop growth period, there was attack of S. rolfsii only, at 45 days after sowing, mortality due to both S. rolfsii and F. o. f. sp. ciceri was noticed, at 60 days of crop period plant mortality was found to be due to S. rolfsii, F. o. f. sp. ciceri and M. phaseolina, and at 75 days, incidence due to F. o. f. sp. ciceri and M. phaseolina were observed but not due to S. rolfsii. At the final stage (90 days) of crop period only attack of M. phaseolina incidence was noticed. Pooled analysis of 2012-13, 2013-14 and 2014-15 (treatments with wild type only) revealed that plant mortality was 60.8% in absolute control. The lowest plant mortality (34.7%) and the highest disease reduction (42.7%) were observed in seed treatment + soil application of Th4-w. Pooled analysis of 2013-14 and 2014-15 (treatments with wild and mutant isolates) revealed 75.6% plant mortality in absolute control. The lowest per cent disease incidence was noticed with seed treatment + soil application of Th4-MDAP (43.7%), seed treatment + soil application of Th4-w (45.1%) and integration of tebuconazole seed treatment with seed treatment + soil application of Th4-MTEB+DAP (45.6%).
Open Access
BIOLOGY, EPIDEMIOLOGY AND MANAGEMENT OF Alternaria spp. CAUSING EARLY BLIGHT OF TOMATO (Lycopersicon esculentum Mill.)
(Acharya N.G. Ranga Agricultural University, Guntur, 2015) RAMA DEVI, P; KRISHNA PRASADJI, J
The present investigation on the biology, epidemiology and management of early blight of tomato caused by Alternaria spp. was carried out in the Horticultural Research Station, Dr. Y. S. R. Horticultural University, Venkataramannagudem, West Godavari district of Andhra Pradesh during 2010-11 to 2013-14. Early blight symptoms on tomato leaves were observed as irregular to regular brown necrotic spots with obscured concentric rings and as brown almost circular necrotic spots with characteristic concentric rings. A. alternata from samples showing first type symptoms and A. solani from samples with second type of symptoms were isolated and pathogenicity of the two Alternaria spp. was proved. The disease incidence was found to range from 31.76 to 70.56% and severity from 20.06 to 54.43%, with highest mean incidence (52.47%) and severity (34.27%) in West Godavari district. Variety of the crop plant, soil type and pH were not found to greatly influence early blight incidence and severity. However, age of the crop was found to have a positively significant correlation with per cent disease incidence and disease severity with r values of 0.79 to 0.87 and 0.62 to 0.85, respectively in the districts surveyed. Colonies of most A. alternata isolates were light grayish to brown while that of A. solani were mostly light grayish brown on potato carrot agar. Differences in radial growth (6.48 to 8.98 cm), time for sporulation (8.00 to 12.23 days), sporulation (9.56 x 104 to 32.44 x 104/ml) and conidial dimensions (27.54 to 59.99 µm length; 9.41 and 18.29 µm breadth and 3.56 to 22.76 µm beak length) among A. alternata isolates were noticed. Such differences were also observed among A. solani isolates (6.89 to 8.08 cm in radial growth; 16.17 to 18 days for sporulation and 0.67 to 2.15 x 104/ml in number of spores). A. solani isolates’ spores were longer (99.89 to 172.35 µm) than A. alternata spores with beak length being the primary determinant of spore length. Incubation period among A. alternata (4.0 to 5.33 days) and A. solani (4.33 to 5.0 days) isolates did not differ significantly. Isolates also exhibited wide and significant differences in the number of spots produced, total spotted area and disease ratings. The twenty isolates i.e., 16 of A. alternata and four of A. solani were grouped into five clusters by Ward’s minimum variance dendrogram using Mahalanobis-Euclidean (D2) distance statistic. The chief characters viz., number of spots produced, per cent spotted area and conidial beak length that contributed the maximum to clustering of isolates were identified by Wilks’ test. Isolates were found to cluster based on the morphological and pathogenicity characters but not on the basis of geographical relationships. The apparent rate of infection (r) varied in both the seasons. The r values ranged between a maximum of 0.440 during 66 and 70 DAT and a minimum 0.006 during 96 and 100 DAT with a mean of 0.075 units/day in 2010-11 crop season. In 2012-13, r values were between a maximum of 0.290 and a minimum of 0.025 with a mean of 0.068 units/day. Regression analysis of PDI with DAT revealed that the age of the plant was an important factor explaining disease development up to 98 to 99%. Maximum temperature ranging between 25.50 C and 32.750 C and morning relative humidity ranging between 68 and 95% were found to be significantly positively correlated (r =0.35 and 0.39, respectively). A regression equation with the data sets of weather and PDI for the two seasons was constructed which revealed that maximum temperature and morning relative humidity would influence early blight development in tomato up to 46%. Y = -239.67 + 5.88 (max temp*) – 3.28 (min temp*) + 1.92 (RH 0800*) N = 46 R2 = 0.46 F value = 12.04 Standard error = 16.30 * significant at 5% Alternaria spp. were isolated from both surface sterilized and unsterilized seeds following blotter paper and agar plate methods indicating both externally and internally seed borne nature of the pathogen. The pathogen was found to exhibit greater survival at deeper depths in soil as isolation frequency of the pathogen from samples stored at different depths (0 to 120 cm) increased from 5.31 to 20.63%. Stemphylium botryosum was found more aggressive in interaction with A. alternata by producing significantly more number of spots. Salicylic acid was not found effective at concentrations between 100 and 500 ppm as a systemic acquired resistance (SAR) elicitor in reducing the severity of early blight. However, significant reduction in number of spots over unsprayed check (35.33/leaf) was recorded in plants treated with Pseudomonas fluorescens (24.50/leaf) and Trichoderma asperellum (27.17/leaf). Tebuconazole, copper oxychloride, chlorothalonil, dimethomorph, mancozeb and azoxystrobin in that order significantly inhibited the radial growth, sporulation and spore germination of A. alternata in vitro. Tebuconazole seed treatment followed by eight foliar sprays of tebuconazole and copper oxychloride alternated with each other recorded the lowest terminal disease severity (PDI=35.39%) that was lesser by 53.17% than that recorded in check (75.57%) and gave the maximum yield (25.71 t/ha) with 86.47% increase over control and with a benefit : cost ratio of 1.60. Significantly higher yield (19.38 t/ha) was also realized with the treatment with P. fluorescens as four foliar sprays preceding four sprays of tebuconazole and copper oxychloride alternated with each other that had significantly decreased disease severity.

Acharya N G Ranga Agricultural University, Guntur

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