Thumbnail Image

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...

News

https://angrau.ac.in/ANGRU/Library_Resources.aspx

Browse

2014 - 201970
Reset filters
Subject: Plant Pathology × End date: 2019 × Start date: 2000 ×
Reset filters

Search Results

Now showing 1 - 9 of 70
  • Thumbnail Image
    ThesisItemOpen Access
    EPIDEMIOLOGY AND MANAGEMENT OF FIELD BEAN ANTHRACNOSE INCITED BY COLLETOTRICHUM SPP.
    (Acharya N G Ranga Agricultural University, Guntur, 2019) NARASIMHA RAO, S; SREE LAKSHMI, B
    Field bean (Lablab purpureus var. lignosus) is a grain legume species and is known by several common names across the world. It is one of the most ancient crops among cultivated plants and is presently grown throughout the tropics, especially in South Asia and African countries. The crop is attacked by a wide range of diseases that infect leaf, stem, root, pod and seed. Among the fungal diseases, anthracnose caused by Colletotrichum lindemuthianum is an important disease occurring throughout the world and infects all above ground plant parts including pods and seeds thereby adversely affecting the yield. Studies were conducted on collection of anthracnose pathogen in major field bean growing areas of Andhra Pradesh and cross infectivity was tested on different beans; variability among the collected isolates with respect to cultural, morphological and molecular characters; assessment of yield losses and influence of weather parameters on the progress of anthracnose and management of disease through botanicals, bioagents and fungicides both in vitro for pathogen and in vivo were assessed. Anthracnose was observed in all the major field bean growing areas of Andhra Pradesh. The causal organism infecting the field bean was isolated, purified and tentatively identified as Colletotrichum lindemuthianum based on cultural and morphological characters and further the pathogenicity was proved by spraying spore suspension (5 x 106) on to ten days old seedlings and confirmed that field bean anthracnose was incited by C. lindemuthianum. The pure culture of representative sample was characterized by slow to medium growth, olive brown to pinkish red colonies on Potato Dextrose Agar Petri plates. Conidia were hyaline, cylindrical and unicellular with obtuse ends, measuring about xxiii 12.00 x 4.35μm. Orange coloured acervuli were produced on 20 days old culture measuring about 120-330μm. Setae were light brown to dark brown in colour measuring about 74-118 x 2.3- 4.2μm with two oil globules. A total of thirty six anthracnose infected samples selected consisting of 24 from stem and four samples from each leaves and pods representing the agro-ecologically distinct bean growing areas of Andhra Pradesh in two types field bean viz., nineteen samples from pole types, ten samples from bush types and seven from semi bush types. Characteristic symptoms were observed on leaves, petioles, stems, pods and seeds. The lesions with small reddish-brown, slightly-sunken spots filled with many spores were present on the stem and pods. Large numbers of acervuli were found scattered all over the necrotic area and clearly evident by naked eye. Cultural traits of different Colletotrichum isolates were studied on PDA and mycelium of Colletotrichum isolates was branched, septate hyphae. The initial growth on PDA was slow and abundance sporulation occurred after 12 DAI. Among the 36 isolates, CI 33 and 32 had superior cultural characters, while morphological characters varied widely among the isolates with conidial length of 9.85 to 14.85 μm and width of 3.50 to 4.65 µm. Of the 36 isolates, 22 isolates (61.11%) recorded maximum mycelial growth (61.00 to 80.00 mm) and 27 isolates (75.00%) were classified as good (>4.0 to 9x 104 per 5mm disc in terms of sporulation. Conidial mass was whitish to brick red in colour. Conidia were hyaline, single celled, straight, cylindrical, dumb-bell shaped, oblong with rounded ends. The conidia contained zero to three oil globules, most of the isolates contained two oil globules per conidia. Molecular variability of twenty isolates of Colletotrichum by amplification of rDNA region by using ITS1 and ITS4 primers produced amplicons of 660bp. PCRRFLP with four restriction enzymes produced the different size bands. High degree of genetic diversity among the Colletotrichum isolates was noticed with Hinf1, while high similarity (polymorphism) was noticed with Taq1. Four solid media were tested for cultural and morphological variability among the isolates. PDA supported cultural characters, while host leaf extract agar supported the morphological characters. Cross pathogenicity of Colletotrichum isolates on different beans revealed that isolates C 8 from horsegram and C 4 from cowpea were most virulent, produced characteristic anthracnose symptoms in all the test hosts, except pole type beans like yard longbean, wingedbean, swordbean and clusterbean. Among the test plants, cowpea expressed the highest susceptibility to all Colletotrichum isolates, while clusterbean expressed the host specificity. Three times spraying of thiophanate methyl (0.1%) at 10 days interval resulted in lowest per cent disease index and area under disease progress curve, and thus highest green pod yield and cost benefit ratio. Highest avoidable losses of green pod yield due to the anthracnose infection were noticed in two sprays of thiophanate methyl (0.1%), which resulted in minimum disease severity and maximum profit. A strong negative correlation was detected between disease scores and green pod yield where, r = (-) xxiv 0.986 and (-) 0.989, and for test weight r = (-) 0.993 and (-) 0.994 during 2016-17 and 2017-18, respectively. Weather variables on field bean anthracnose indicated that disease severity was significantly influenced by dates of sowing. The PDI increased gradually and progressed up to the harvesting stage. The progress of PDI (weekly increase or decrease of PDI, logit and Gompertz transformation) in relation to the weather variables exhibited sigmoidal pattern of the curve in both the years irrespective of sowing dates. The comparative account of disease progress curves on two growth models (Logistic and Gompertz) revealed that Logistic model provided better fit and linearization of progress curves on the basis of high correlation co-efficients and least standard error of estimation. Correlation studies revealed that, the PDI had significant and positive correlation with maximum temperature and significant negative correlation with evening relative humidity; minimum temperature, sunshine hours and evaporation showed non significant positive, while rainfall expressed non significant negative correlated with PDI. Multiple correlation co-efficients indicated strong relationship between PDI and weather variables, contributing more than 95.10 per cent variation in PDI during 201617 and 93.90 per cent during 2017-18. Among five fungicides, propiconazole at 0.15 per cent inhibited mycelial growth as well as spore germination followed the thiophanate methyl. In case of botanicals, Lantana camara leaf extract at 10.0 % concentration was significantly superior to the rest of the concentrations and inhibited mycelial growth and also spore germination. Trichoderma viride was superior and found most effective with highest mycelial growth inhibition and inhibition of spore germination followed by Bacillus subtilis. Propiconazole was significantly superior in reducing the disease severity and rate of infection thereby increasing the yield followed by thiophanate methyl in management of anthracnose under field condition. Considering incremental cost: benefit ratio (ICBR), the most economical treatment, which recorded highest cost: benefit ratio was the fungicide carbendazim +mancozeb followed by thiophanate methyl and propiconazole. Fungicides were more effective followed by bioagents and botanicals in reducing the terminal PDI and increasing the per cent disease control of Field bean anthracnose.
  • Thumbnail Image
    ThesisItemOpen Access
    STUDIES ON URDBEAN LEAF CRINKLE DISEASE ONURDBEAN [Vigna mungo (L.) HEPPER]
    (ACHARYA N G RANGA AGRICULTURAL UNIVERSITY, GUNTUR, 2019) USHA RANI, L; MANOJ KUMAR, V
    The present investigation on “Studies on urdbean leaf crinkle disease on urdbean [Vigna mungo (L.) Hepper]” was carried out at Agricultural College, Bapatla, Guntur district, Andhra Pradesh during 2018-19. Blackgram cv LBG 752 belonging to Leguminosae tested for their reaction to Urdbean leaf crinkle disease(ULCD) by sap incoulation method, the disease symptoms with crinkling and curling of infected leaves . Seed treatment with hot water (500C for ten min) significantly lowered the incidence (10%) of ULCD followed by seed treatment with 16% trisodium orthophosphate (20.00%) when compared to untreated control (28.33%). Aphid (Aphis craccivora) transmitted ULCD with an acquisition access period of ten minutes (10.00%) and inoculation access period of 24 h (20.00%). Maximum ULCD incidence was noticed with 20 aphids per plant (13.33%). Beetle (Henosepilachna dodecastigma) transmitted ULCD with an acquisition access period of six hours (3.33%) and inoculation access period of 12 hours (6.67%). ULCD infected sample showed the highest protein content when compared to healthy samples. Phenol content was also the highest in ULCD infected plants when compared to healthy plants. When the healthy leaf tissues were assessed, the highest protein content was observed at 40, 55 and 70 DAS in MgSO4 @ 0.2% + ZnSO4 @ 0.2% with 1.43, 1.71 and 2.35 mg/100mg of leaf tissue respectively and the lowest was in check 1.34, 1.41and 1.63 mg/100 mg of leaf tissue at the respective interval 15 days from 40 DAS and in infected maximum was observed in ZnSO4 @ 0.2% (1.97, 2.18 and 2.34 mg/100 mg at 40, 55 and 70 DAS) of leaf tissue and minimum was observed in check (1.44, 1.69 and 1.85 at 40, 55 and 70 DAS). 13 The maximum phenol content in healthy leaf tissue at 40, 55 and 70 DAS in MgSO4 @ 0.2% + ZnSO4 @ 0.2% with 0.60, 0.66 and 0.72 mg/100mg of leaf tissue sprayed plots while minimum was in check (0.34, 0.40 and 0.45 mg/100mg respectively). In infected tissues the highest phenol was observed at 40, 55 and 70 DAS inMgSO4 @ 0.2% + ZnSO4 @ 0.2% with 0.89, 0.92 and 0.97 mg/100mg and the lowest was observed in check (0.51, 0.55 and 0.59 mg/100mg). Presence of auxins was tested using TLC plates and the Rf values are recorded as 0.92, 0.896 and 0.901 in stranded, infected and healthy leaf samples respectively. Among the micronutrients tested, spraying of MgSO4 @ 0.2% + ZnSO4 @ 0.2% recorded significantly lowest AUDPC value (466.97) of ULCD followed by ZnSO4 @ 0.2% (567.84) as against unsprayed control (955.92). The highest B:C ratio was found in MgSO4 @ 0.2% + ZnSO4 @ 0.2%(2.11) and lowest in control (1.42).
  • Thumbnail Image
    ThesisItemOpen Access
    BIOEFFICACY OF FUNGICIDES AND THEIR COMPATIBILITY WITH INSECTICIDES IN MANAGING BLACKGRAM DISEASES
    (ACHARYA N G RANGA AGRICULTURAL UNIVERSITY, GUNTUR, 2019) EDEN GEORGIA, K; ANIL KUMAR, P
    In toto, nine combinations, viz., azoxystrobin + triazophos, azoxystrobin + acetamiprid, azoxystrobin + chlorantraniliprole, propiconazole + triazophos, propiconazole + acetamiprid, propiconazole + chlorantraniliprole, mancozeb + triazophos, mancozeb + acetamiprid and mancozeb + chlorantraniliprole were assessed for their physical and chemical compatibility at three doses, i.e., recommended dose, half the recommended dose and double the recommended dose using three types of water, i.e., distilled water, tap water and standard hard water. All the combinations were found physically (sedimentation test and specific gravity) and chemically compatible (pH and E.C). Pot culture experiments indicated no phytotoxic effect on 21 day old blackgram plants indicating test combinations were not detrimental to plants. Against blackgram powdery mildew, pooled analysis of kharif and rabi 2018-19 data revealed that propiconazole (3.65 PDI and 91.94% disease reduction) and its combination with triazophos (5.67 PDI and 87.49% disease reduction) gave significantly superior control of powdery mildew. Against Alternaria leaf spot, pooled analysis of kharif and rabi 2018-19 data revealed that i.e., azoxystrobin (25.61 PDI and 63.97% disease reduction) and its combination with triazophos (27.49 PDI and 61.33% disease reduction) gave significantly superior control of Alternaria leaf spot. Against flea beetle and Spodoptera litura, the incidence of which was noticed only during kharif 2018-19, and spotted pod borer, Maruca vitrata, the incidence of which was noticed both in kharif and rabi 2018-19, chlorantraniliprole alone was found xvii best among all the treatments. Against whitefly, Bemisia tabaci, the incidence of which was noticed only during rabi 2018-19, acetamiprid alone (54% reduction in whitefly population) was found best. Pooled data of kharif and rabi 2018-19 indicated superiority of azoxystrobin + chlorantraniliprole sprayed plots (11.36 q ha-1) followed by azoxystrobin + triazophos (10.94 q ha-1). When insecticides were combined with mancozeb, yield levels were reduced compared to other combinations i.e., either with azoxystrobin or propiconazole. When yield attributing characters were analysed based on pooled data of kharif and rabi 2018-19, number of primary branches per plant, number of pods per plant, number of seeds per pod and test weight were significantly higher in azoxystrobin + chlorantraniliprole sprayed plots followed by azoxystrobin + triazophos sprayed plots. The present investigation revealed that though yield levels can be increased with compatible pesticide combinations, care need to be taken to assess synergistic and antagonistic effects of pesticides on one another.
  • Thumbnail Image
    ThesisItemOpen Access
    EPIDEMIOLOGY AND MANAGEMENT OF FUNGAL FOLIAR DISEASES IN COTTON UNDER HIGH DENSITY PLANTING SYSTEM
    (ACHARYA N G RANGA AGRICULTURAL UNIVERSITY, GUNTUR, 2019) YAMUNA, CHUKKA; SREE LAKSHMI, B
    Present investigation was taken up to study the epidemiology and management of fungal foliar diseases in cotton under high density planting system. Symptoms were found to be distinct in each of the fungal foliar diseases. Circular brown spots with or without zonations were observed in Alternaria leaf spot whereas, target board symptom with yellow halo was characteristically observed in Corynespora leaf spot. Helminthosporium leaf spots were with purple margins, Circular brown spots with sporodochia in spherical rings occurred in Myrothecium leaf spot while, irregularly angular, pale translucent spots with a definite margin on the under surfaces in grey mildew infection. In case of rust infection, light orange uredo sori appeared on the under surface of affected leaves. Observations were taken during different stages of crop viz., seedling, squaring, flowering, boll formation and boll development, boll maturity and bursting and boll bursting and picking stages to assess the incidence of fungal foliar diseases of cotton in compact genotypes under High Density Planting System (HDPS) and Normal Planting System (NPS) at RARS, Lam, Guntur. Incidence of Alternaria leaf spot was persistent in all the fields from seedling stage to harvesting stage, Corynespora leaf spot was observed during boll maturity and bursting stage while grey mildew and rust developed during boll bursting and picking stage, Myrothecium and Helminthosporium leaf spots did not appear at any stage of the crop. The Per cent disease index (PDI) of Alternaria leaf spot was high under HDPS at all the stages when compared to NPS. Peak PDI of Alternaria leaf spot ranged from 11 to 22% in HDPS and 10 to 20% under NPS during boll formation and boll development stage. Among the coordinated compact genotypes, the average PDI was xviii 16.6 and 15.7% under HDPS and NPS respectively. Corynespora leaf spot was observed only during boll maturity and bursting stage to an extent of 3 to 4% under HDPS and 1 to 4% under NPS. Grey mildew and rust diseases were observed during boll bursting and picking stage only to an extent of 3.5 to 6.5% and 4.5 to 8.0%, respectively under HDPS and 4.25 to 10.0% and 5 to 12%, respectively under NPS. Multiple regression analysis of Alternaria PDI data from kharif 2018-19 under HDPS with weather parameters indicated significantly positive correlation between PDI and minimum temperature, morning relative humidity, sunshine hours, rainy days and evaporation. While under NPS minimum temperature, rainfall and wind speed showed significant negative correlation with PDI. In Corynespora leaf spot under HDPS there was a significant positive correlation between PDI and maximum temperature, while under NPS morning relative humidity showed significant positive correlation. Incase of grey mildew, under HDPS, it was observed that morning relative humidity, rainfall and evaporation showed significant positive correlation, while under NPS morning relative humidity showed significant positive correlation. With respect to rust under HDPS, there was a significantly positive correlation between PDI and minimum temperature, morning relative humidity. In NPS minimum temperature and rainy days showed significant negative correlation with PDI. Among the eight fungicides tested in vitro, hexaconazole @ 0.2%, propiconazole @ 0.1%, hexaconazole + captan @ 0.1% and mancozeb @ 0.3% showed highest inhibition of the mycelia growth of A. macrospora, C. cassiicola, M. roridum and H. gossypii followed by trifloxystrobin + tebuconazole @ 0.05% over check. All the four selected fungicides were significantly reduced the cotton fungal foliar diseases under natural conditions. Maximum reduction of diseases was recorded with three sprays of hexaconazole @ 0.2% i.e., Alternaria leaf spot (4.41%) equivalent to 81.2% disease reduction over control, Corynespora leaf spot (2.50%) with 64.2% disease reduction over control, grey mildew (4.17%) with 59.6% reduction over control and rust (4.66%) with 62.7% reduction over control, followed by three sprays of hexaconazole + captan @ 0.1% i.e., Alternaria leaf spot (5.00%) equivalent to 78.7% disease reduction over control, Corynespora leaf spot (3.06%) with 56.2% disease reduction over control, grey mildew (4.73%) with 54.2% reduction over control and rust (5.00%) with 60.0% reduction over control. Hexaconazole @ 0.2%, hexaconazole + captan @ 0.1%, propiconazole @ 0.1% and mancozeb @ 0.3% were effective in reducing these foliar diseases and improving growth in terms of number of sympodial branches per plant and boll number per plant which ultimately led to significantly higher yields in kharif 2018-19. The highest yield (3613.3 kg ha-1) and B: C ratio (3.06) were obtained with hexaconazole @ 0.2% over unsprayed check.
  • Thumbnail Image
    ThesisItemOpen Access
    STUDIES ON SEED BORNE NATURE AND MANAGEMENT OF ALTERNARIA LEAF SPOT IN BLACKGRAM
    (ACHARYA N G RANGA AGRICULTURAL UNIVERSITY, GUNTUR, 2019) PRATHYUSHA, DIGUMARTHI; ADINARAYANA, M
    Black gram (Vigna mungo L. Hepper) is a premium pulse crop amongst all pulses and is also rich in phosphoric acid. It is affected by fungi, bacteria, viruses, nematodes and also abiotic stresses. Among the fungal diseases, Alternaria leaf spot disease caused by the Alternaria alternata (Fr.) Keissler is becoming a major problem in blackgram growing areas of Andhra Pradesh. The survey on occurence of blackgram Alternaria leaf spot in Guntur and Krishna district of A.P, revealed that the disease kept on increasing with increase in the age of the crop. There was no disease observed upto 30-35 days old crop. In Guntur district during kharif, the disease progressed upto 54.30% in Mangalagiri mandal and 52.64% in Tadikonda mandal at 60 DAS and during rabi the disease progression was up to 49.49% in Mangalagiri and 48.66% in Ponnur mandal at 60 DAS. In Krishna district during kharif the disease progressed up to 63.04% in Kanchikacherla and 52.20% in Veerullapadu mandal at 60 DAS. Among the 83 blackgram genotypes screened during kharif and rabi 201819, none of the genotypes were found resistant. 14 genotypes were moderately susceptible, 15 genotypes were susceptible and rest of the genotypes were highly susceptible. xv Total phenols, total proteins, total sugars (0.82-0.84, 7.84-7.99 and 1.731.74 mg/100 mg of leaf tissue respectively) were higher in moderately susceptible genotypes than that of highly susceptible genotypes (0.51-0.57, 7.077.14, 1.46-1.47 mg/100 mg leaf tissue respectively). The test pathogen A. alternata was found to be both externally and internally seed borne. Among the externally seed borne mycoflora detected, A. alternata and Aspergillus spp. were higher in association with blackgram seeds ranged from 13 to 26% (mean 19.62%) and 17-29% (mean 23.62%) respectively. In case of internally seed borne association, A. alternata was ranged from 5-16% (mean 10.12%) and showed higher association than the other fungi. The seed mycoflora of blackgram exhibited different distribution pattern as externally and internally seed borne and among which A. alternata and Aspergillus had higher colonizing frequency (CF) and isolation recovery (IR) in case of externally seed borne, and in case of internally seed borne A. alternata exhibited higher CF and IR than the rest of the seed fungi, irrespective of location. For externally seed borne mycoflora, the highest Simpson‟s diversity index (DI = 0.785) and Shannon-Wiener diversity index (H‟ = 1.642) were in the seed samples from Mangalagiri mandal. The highest species richness (0.347) and evenness (0.916) were also recorded from seed samples of Mangalagiri mandal. The highest diversity of internally seed borne fungi was in seeds from Tadikonda mandal with the highest DI (0.783) and H‟ (1.635) while the greatest species richness (0.550) and evenness (0.912) were also recorded from the seed samples of Tadikonda mandal. Among the seven chemicals tested in vitro mancozeb @ 0.25% and hexaconazole @ 0.20% showed highest inhibition (100%) of the mycelial growth of A. alternata followed by trifloxystrobin + tebuconazole @ 0.05% (78.93%) over check. All the chemicals evaluated were significantly effective in reducing the Alternaria leaf spot on blackgram in vivo. Maximum reduction of disease was recorded with combination treatment i.e., seed treatment (ST) with mancozeb @ 0.25% followed by two sprays (FS) of trifloxystrobin + tebuconazole @ 0.05% (25.51) which with 61.65% disease reduction over unsprayed check followed by two sprays of trifloxystrobin + tebuconazole @ 0.05% (27.62%) alone, with 58.47% disease reduction and azoxystrobin (FS) @ 0.05% (28.95%) alone with 56.47% disease reduction over unsprayed check. Apart from reducing the disease they were also effective in improving growth in terms of pod number per plant and seeds per pod which ultimately led to significantly higher yields in both kharif and rabi 2018-19. The highest yield (12.06 q ha-1 in kharif and 12.75 q ha-1 in rabi) and B:C ratio of (2.73 in kharif and 2.77 in rabi) were obtained with combination treatment i.e., mancozeb (ST) @ 0.25% and trifloxystrobin + tebuconazole (FS) @ 0.05%.
  • Thumbnail Image
    ThesisItemOpen Access
    STUDIES ON ANTAGONISTIC POTENTIAL OF METHYLOTROPHIC BACTERIA AGAINST Sclerotium rolfsii IN GROUNDNUT (Arachis hypogaea L.)
    (ACHARYA N G RANGA AGRICULTURAL UNIVERSITY, GUNTUR, 2019) SUSHITHA; MANOJ KUMAR, V
    Groundnut (Arachis hypogaea L.) is one of the important economic oilseed crops of the world. Fungal, virus and bacterial pathogens attack the crop at various stages of growth and cause severe yield losses. Among the soil-borne fungal diseases of groundnut, stem rot caused by Sclerotium rolfsii Sacc. is a disease of economic significance throughout the world, which causes yield losses of 10-25%, but under severe disease conditions, yield loss up to 80% was observed. The present investigation on “Studies on antagonistic potential of methylotrophic bacteria against Sclerotium rolfsii in groundnut (Arachis hypogaea L.)” was aimed at isolating native methylotrophic bacterial isolates from the phyllosphere and rhizosphere of groundnut plants collected from different places of Guntur district and to study the efficacy of the isolates in controlling the stem rot pathogen S. rolfsii and in enhancing growth of groundnut plants. As many as 35 isolates of methylotrophs (20 from phyllosphere and 15 from rhizosphere) were isolated from groundnut plants and morphological and biochemical characterization was done. All the isolates were screened rapidly for their antagonistic potential against S. rolfsii using dual culture technique. Eight isolates out of 35 isolates was found better in inhibiting the mycelial growth of the pathogen with and inhibition per cent ranging from 8.78 to 18.54 per cent. When antagonistic potential of methylotrophic bacteria against S. rolfsii was evaluated under pot culture, PPFM 6 and PPFM 3 was found better in inhibiting the disease and PPFM 3 was found better in enhancing shoot length and root length. Highest vigour index was obtained when PPFM 6 was applied. Among all methods of isolates combined application of methylotrophic bacteria through seed treatment and soil application was found better in controlling stem rot and enhancing the plant growth. xiv The plant growth promotional ability of methylotrophs was evaluated under pot culture without pathogen inoculation. The methylotrophic bacterial isolate PPFM 3 significantly enhanced germination, shoot length, root length and vigour index of plants compared to remaining isolates tested. Combined inoculation of bacteria through seed treatment and soil application was found as the most effective method in enhancing growth compared to seed treatment and soil application. The isolate PPFM 3 was selected for field management of stem rot, because it was found better in inhibiting stem rot and enhancing growth of the plant at the same time. Among different treatments employed for management of stem rot under field conditions, seed treatment with bacteria+ tebuconazole seed treatment+ soil application of bacteria was found better in inhibiting stem rot with 86.12 per cent reduction of stem rot over control and in enhancing the growth of the plant measured in terms of germination, shoot length, root length and yield. The treatments applied for management of stem rot also controlled late leaf spot severity in the field. Foliar application of methylotrophs was found most effective among all the treatments with 51.32 per cent disease reduction over control, followed by the treatment seed treatment with bacteria+ tebuconazole seed treatment+ soil application of bacteria with 44.30 per cent reduction over control.
  • Thumbnail Image
    ThesisItemOpen Access
    CHARACTERIZATION OF SORGHUM TURCICUM LEAF BLIGHT PATHOGEN AND ITS MANAGEMENT
    (ACHARYA N G RANGA AGRICULTURAL UNIVERSITY, GUNTUR, 2019) SUMANTH KUMAR, M; PRASANNA KUMARI, V
    In the present research on “Characterization of sorghum turcicum leaf blight pathogen and its management”, survey was undertaken to assess the turcicum leaf blight (TLB) severity in major sorghum growing mandals of Guntur and Prakasam districts. PDI of 30.12% in Prakasam and 27.22% in Guntur district was recorded. The cultural variability of E. turcicum isolates on PDA was assessed at 8 DAI. Initally mycelium was white and later turned to greenish black (2.5/10Y). The soluble pigment production varied from dark bluish to bluish black. Among all the isolates, Prakasam isolates KTP (8.96 cm) and ELC (8.94 cm) were significantly rapid in their radial growth with growth rate varying between 0.47 mm h-1 to 0.21 mm h-1. Sporulation varied from 0.02 x104 spores/ mm2 (SMG) to 0.35 x 104 spores/ mm2 (IRP). The mean conidial size of E. turcicum isolates ranged from 56.13-72.39 x 15.0015.83 μm and septa varied from 5.67 to 6.71. Conidiophore size ranged from 140.38 to 183.38 x 6.32 to 7.02 μm. The incubation period of the isolates varied between 24 h (SMG) to 37.33 h (IRP) with least lesion size in DVT (1.68 cm) at 20 DAI. Maximum PDI of 28.64% was recorded with the SMG isolate Molecular variability was analysed using a total of 25 RAPD arbitrary primers for 12 fungal isolates. A total of 84 bands were obtained that showed 100% polymorphism. The PIC (Polymorphic Information Content) values varied from 0.10 to 0.46. The highest PIC value was recorded with OPA-03 primer, followed by OPH-18 (0.41). The similarity coefficient varied between 0.45 and 1.00. The lowest similarity 0.45 was noticed between KMR and BPT while the highest similarity was noticed xv between the isolates of RJP and EDM of 0.93. The dendrogram obtained had two clusters or groups irrespective of the isolates obtained from the geographical distribution. Among the Guntur district isolates, from Bapatla mandal BPT and DVT isolates had 54 per cent dissimilarity and Muppalla isolates IRP and BVM had 68% similarity indicating the existence of different isolates. However, Rajupalem isolates were noticed with 92% similarity (RJP and RDG) and limited variation indicates absence of variation among the isolates. Similarity of 87% existed between isolates especially EDM (Prakasam district, Komarolu isolate) and RDG (Guntur district, Rajupalem isolate) though geographically far apart. Under in vitro conditions henna @15% concentration was found to inhibit the radial growth of pathogen significantly (2.64 cm) and could significantly inhibit sporulation to maximum extent (0.007 x104 spores/ mm2). Panchagavya @ 10% was found significantly effective among the cow based natural products with complete inhibition of mycelial growth and sporulation. Combined treatment of Trichoderma (ST+ FS) + Panchagavya @15% (ST+FS) treatment was found most effective in controlling the disease even two weeks after second spray (64DAS) with the lowest PDI (18.89%) and with minimum area under disease progress curve of 474.26 as against unsprayed check (760.49). Treatment 5 - Trichoderma (ST+ FS) + Panchagavya @15% (ST+FS) was found with highest number of grains per panicle 502.40 with highest test weight of 3.44 g, yield of 2388 kg ha-1. However, the benefit cost ratio (BCR) of the different treatments varied from 0.70 to 1.56 with the highest BC ratio being recorded with fungicidal spray of 0.25% mancozeb (1.56). However, among non chemical treatments best B: C ratio was obtained in T4 (Trichoderma (ST+ FS) + Henna @ 15% FS) with 1.48 followed by T 5 with a BC ratio of 1.40 treatments which represents a potential alternative to fungicide treatments.
  • Thumbnail Image
    ThesisItemOpen Access
    STUDIES ON FRUIT ROT OF CHILLI CAUSED BY Colletotrichum capsici (SYD.) BUTLER AND BISBY AND ITS MANAGEMENT
    (Acharya N G Ranga Agricultural University, Guntur, 2019) VENKATA RAMESH, KOTA; SARADA JAYALAKSHMI DEVI, R
    The present investigation was undertaken with an aim to know the variability among Colletotrichum capsici isolates causing chilli anthracnose and fruit rot in Andhra Pradesh and Telangana and its integrated management. Among the districts surveyed during 2014-15 in AP, highest (50.84 %) incidence was observed in Guntur and lowest (33.01 %) incidence was observed in Chittoor district. Mean per cent incidence was 43.61 % in AP and 40.84 % in Telangana. Highest and lowest incidences of of 54.63 % and 33.54 % were recorded in Warangal and Ranga Reddy districts. Studies on the seed mycoflora of fruit rot infected fruits revealed that Colletotrichum capsici was the predominant fungus observed in 64.53 % and 58.83 % of samples of Andhra Pradesh and Telangana states, respectively. Other mycoflora associated with infected seeds were C. gloeosporioides, Cercospora spp. Aspergillus spp., Alternaria spp., Fusarium spp. and Penicillium spp. Forty isolates (Cc 1 to Cc40) of C. capsici were isolated and their pathogenicity was proved on detatched fruits by pin prick method. Isolates were also identified by molecular means through species specific primers. Morphological and cultural variability existed among the isolates. Colony colour of greyish white to black, fluffy or suppressed growth, margins regular or irregular, colour of the conidial mass is grey or orange. Based on the pathogenic variability, isolates were divided the isolates into five groups. Isolate Cc 20 from Chittoor with lowest pathogenic ability is in Group I where as three isolates Cc 3, Cc 5 and Cc 39 with highest pathogenic ability were in Group V. Molecular variability studies using RAPD divided the isolates into three clusters (I-III) in the phylogenetic tree dendrogram at 0.49 co efficient of similarity. The topology of the dendrogram suggested that most isolates were more than 20% different xiv from each other, and indicated the existence of both local and geographical polymorphism among the isolates. Cross inoculation studies of three isolates of C. capsici from betelvine, chilli and turmeric, revealed the presence of pathogenic variability and host preference among the isolates from different hosts. Isolates were more pathogenic when they were inoculated on their original hosts. Results of the In vitro evaluation of fungicide revealed that mancozeb and difenoconazole inhibited 77.78 % and 75.93 % of mycelial growth at 100 ppm concentration. Among the fungal and bacterial bioagents tested, T. longibrachiatum Tl 1 (78.15 %) and P. fluorescens Pf 1 (64.81 %) were effective in inhibiting the mycelial growth. In IDM experiment involving the effective fungicides and bioagents in different modules, in nursery, highest germination (85.40 %) and low seedling mortality (3.00 %) was recorded in chemical module whereas highest seed vigour index was recorded in integrated module (731.40). From the data of the main field for two years and their pooled analysis, pertaining to the effectiveness of different modules (T1, T2, T3, T4) the three modules (T1, T2, T3) significantly reduced the disease and increased the yield compared to control (T4). Among the three effective modules, integrated module (T3) recorded highest yield where as the biological module T1 recorded the lowest dry chilli yield. Residues of fungicides were detected through LC MS/MS and GC MS/MS studies in dry chilli samples collected from different fields during harvesting season. Among the fungicides, tebuconazole and carbendazim were most commonly detected. All the fungicide residues detected in the present study were lesser than the prescribed MRL’s. From the above results it can be concluded that the risk of residues of fungicides in dry chillies is very limited (none of the fungicides detected were above MRL’s). From the present study, it can be concluded that fruit rot of chilli is an important limiting factor for chilli production with highest incidence up to 54.63 per cent recorded in Warangal district. Isolates differed in their morphology, cultural studies, pathogenic levels and also in molecular studies. However, there is no correlation between the three different types of studies and the geographical distribution of the isolates. The aerial spread of the pathogen along with seed infection and movement of the seed to different areas might be the reason for such distribution. C. capsici isolates can cross infect between the crop and are more aggressive on their original host. Mancozeb, difenoconazole in fungicides and T. longibrachiatum and P. fluorescens were effective in in vitro studies and integrated module, involving the bioagents, fungicides and SAR inducing chemicals successfully reduced the disease compared to control and recorded the highest yield. Fungicide residue studies revealed that the fungicides, tebuconazole and carbendazim were most commonly detected but were found to be lesser than the MRL levels.
  • Thumbnail Image
    ThesisItemOpen Access
    STUDIES ON FUSARIUM WILT OF CHICKPEA AND ITS MANAGEMENT
    (ACHARYA N G RANGA AGRICULTURAL UNIVERSITY, GUNTUR, 2019) VENKATARAMANAMMA, K; BHASKARA REDDY, B.V
    The present investigation was undertaken with an aim to study cultural, morphological and genetic variability of Fusarium oxysporum f.sp. ciceris isolates, races identification, evaluation of bioagents (Trichoderma, fluorescent Pseudomonas and Bacillus isolates) against pathogen, molecular characterization of potential antagonists and screening for plant growth promotion characters. In another study, screening of germplasm/genotypes were undertaken to identify resistant lines. Attempts were also made to manage the disease with potential bioagents, fungicides and their integration. A roving survey was conducted during rabi, 2014-15 in six districts of Andhra Pradesh and recorded per cent wilt incidence in the range of 0.2 to 15.5%. Lowest mean wilt incidence of 5.9% was observed in Nellore district and the highest mean wilt incidence of 8.32% was observed in Kadapa district. Other districts such as Anantapuramu, Kurnool, Prakasam and Guntur recorded the mean wilt incidence of 7.28%, 7.77%, 6.6% and 6.74% respectively. A total of 32 Foc isolates were collected from Andhra Pradesh and Telangana. A total of 21 Trichoderma, 12 fluorescent Pseudomonas and 10 Bacillus isolates were collected from soil samples of chickpea rhizosphere. xviii Cultural characters like mycelial colour, margin, texture and pigmentation were studied for all Foc isolates. Morphological characters like size of micro conidia, macro conidia and chlamydospores were measured under microscope. Mean length of macro conidia was in the range of 15.02 µm (Foc-19) to 28.72 µm (Foc-9), and mean width was in the range of 2.72 µm (Foc-3) to 5.10 µm (Foc-28). The mean micro conidia length varies from 7.1 µm (Foc-11) to 11.78 µm (Foc-28) and width varies from 2.51 (Foc-9) µm to 4.3 µm (Foc-17). Chlamydospore diameter was observed in the range of 2.87 µm to 6.15 µm. Maximum sporulation was observed in Foc14 (2.2 × 106/ml) and minimum was observed in Foc-26 (0.2 × 106/ml). Maximum radial growth of 79 mm was observed in Foc-15, Foc-30 at 6 days and minimum radial growth of 39 mm was observed in Foc-12. There was no distinct correlation for cultural and morphological characters of Foc isolates, except for three isolates (Foc-6, Foc-12 and Foc-17). These isolates have white mycelium, cream colour pigmentation, slow radial growth and highly pathogenic (100% wilt incidence). In addition, Foc-6 and Foc-12 have sectors on the reverse side of the colonies on PDA plates. The differences among isolates for all these characters might be due to the genetic differences because all of them were cultured under same laboratory conditions. Twenty primers were used for RAPD analysis of 26 selected Foc isolates and only 16 primers amplified the DNA. Nine primers such as P8, K2, K4, K5, K6, K7, P17, OPX-10 and OPX-13 had given 100% polymorphic bands. PIC values varied from 0.16 (P21 primer) to 0.49 (K4 primer). Maximum number of bands (253) were produced by the P2 primer. UPGMA cluster analysis based on RAPD profiles separated the 26 Foc isolates into three major clusters. The cluster I comprised of eight isolates, cluster II consists of nine Foc isolates and cluster III has seven isolates. Similarity matrix among the 26 isolates indicated that maximum genetic similarity between Foc-27 and Foc-28 with 80.3%. Some of these isolates possess similar cultural characters and virulence pattern and the RAPD technique could differentiated them. Among 20 isolates studied for identification of races, 17 isolates were categorized into race-1 based on resistant reaction on CPS-1, BG-212 and GPF-2. Two isolates such as Foc-3 and Foc-32 exhibited resistant reaction on Chaffa and Annegiri besides CPS-1 and C-104 were categorized as race-6. One isolate (Foc-19) recorded 0% wilt incidence on differential lines except JG-62 (10% incidence) and Chaffa (6.66%) which is a new reaction. The primer pairs SCAR 1F/SCAR 2R and SCAR 2F/SCAR 1R were successfully validated the DNA fragment size of 700 bp in Foc-12. All the 21 Trichoderma isolates were tested for their antagonistic potential against F. oxysporum f.sp. ciceris and recorded inhibition percentage in the range of 10.3 to 48.44%. Maximum percentage of inhibition (48.44) was xix observed in the isolate Tr-20, followed by Tr-6 (45.74%) and Tr-1 (44.02) and Tr-10 (37.52). Ten isolates of Bacillus were evaluated against Foc and recorded inhibition percentage in the range of 5.46 (Bacillus-2) to 74.36 (Bacillus-7). Among 12 Pseudomonas isolates evaluated against the pathogen the isolate CRP-6 was recorded highest inhibition percentage of 58.32, followed by the isolate CRP-8 (56.90%). Clear inhibition zones were observed in dual culture of pathogen with Bacillus (Bacillus-3, 4, 5, 6 and 8) and Pseudomonas (CRP-6 and CRP-8). It might be due to the antifungal substances and/or cell wall degrading enzymes released by the bacteria into the culture medium. From the results of dual culture, four Trichoderma isolates (Tr-1, Tr-6, Tr-10 and Tr-20) two fluorescent Pseudomonas isolates (CRP-6 and CRP-8) and two Bacillus (Bacillus-5 and Bacillus-7) isolates were selected to study plant growth promotion characters. Four potential Trichoderma isolates produced IAA, HCN, chitinases and cellulases and none of them was able to solubilize phosphates. Among the potential bacterial isolates only one isolate (CRP-8) produced IAA, one isolate (Bacillus-5) solubilize phosphates and all of them were produced HCN and chitinases were not detected in bacterial isolates and only two isolates produced cellulases. These potential Trichoderma isolates were identified as T. asperellum based on 18S rDNA sequencing. Two potential Bacillus isolates were identified as Bacillus cereus strains and one potential Pseudomonas isolate was identified as Pseudomonas flourescens based on 16S rDNA sequencing. Eighty five germ plasm lines/advanced genotypes were screened for two rabi seasons i.e., 2014-15 and 2015-16 in wilt sick plot. Pooled data for both the years indicated that 7 entries (ICC-294, ICC-6279, ICC-14669, NBeG-3, NBeG-47, NBeG-119 and NBeG-49) were recorded as resistant and 6 entries were moderately resistant. Among thirteen entries screened (selected in field screening) for three virulent isolates in green house, five entries such as NBeG-3, ICC-14669, NBeG-49, ICC-6279 and ICC-294 recorded 0% incidence. Among the six fungicides evaluated against F. oxysporum f.sp. ciceris the treatments T1 (carbendazim 12% + mancozeb 63%) and T2 (carbendazim 25% + mancozeb 50%) recorded 100% inhibition of pathogen growth, followed by T3 (carbendazim 50%) and T4 (Vitavax power) that inhibited the pathogen growth to the extent of 98.03% and 81.6% respectively. Four potential Trichoderma isolates were tested at 0.2%, 0.15% and 0.1% for compatibility with effective fungicides (carbendazim 12% + mancozeb 63%, carbendazim 25% + mancozeb 50% and carbendazim 50%) and found that none of the fungicides were compatible. Vitavax power (carboxin 35% + thiram 35%) was found moderate compatible with Tr-1, Tr-6 and Tr-20 at 0.1%. xx Vitavax power was tested for compatibility studies with four potential bacterial antagonists i.e., CRP-6, CRP-8, Bacillus-5 and Bacillus7 and found only CRP-6 and CRP-8 antagonists were compatible. Trichoderma isolates Tr-1, Tr-6 and Tr-20 were studied for compatibility with two potential Pseudomonas isolates (CRP-6 and CRP-8) and found that only one isolate Tr-6 was found compatible. The Trichoderma isolate (Tr-6) and Pseudomonas isolate (CRP-8) was selected for field experiments. Seed treatment with reduced dosage (0.1%) was followed for field experiments that have integrated treatments. Among the different treatments imposed, T6 (Seed treatment with Vitavax power @ 1 g/kg, Trichoderma and pseudomonas talc formulation each @ 8 g/kg of seed and soil application of Trichoderma and Pseudomonas multiplied on FYM) recorded higher germination percentage of 91.09, lower wilt incidence of 22.86% and higher yields of 1501 Kg/ha, followed by T4, T9 and T10 treatments.