EPIDEMIOLOGY AND MANAGEMENT OF SUNFLOWER NECROSIS DISEASE
KrishiKosh
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Title |
EPIDEMIOLOGY AND MANAGEMENT OF SUNFLOWER NECROSIS DISEASE
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Creator |
BHARATI NARAYANA BHAT
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Contributor |
RAJA RAM REDDY, D
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Subject |
diseases, sowing, biological phenomena, planting, crops, necrosis, seed treatment, land resources, application methods, yields
NECROSIS, DISEASE, SUNFLOWER |
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Description |
Survey conducted in sunflower growing areas of Anantapur, Kurnool, Mahabubnagar districts during 2009-10 and 2010-11 kharif seasons and Nizamabad district during 2009-10 and 2010-11 rabi seasons revealed natural occurrence of Sunflower Necrosis Disease (SND) in different mandals with overall average incidence of 4.66 per cent of SND during two consecutive seasons. Symptoms of the disease varied with different cultivars grown under field conditions. Higher incidence of SND was observed in Mahabubnagar (5.34 per cent) followed by Anantapur (4.66 per cent), Kurnool (4.64 per cent) and Nizamabad (3.97 per cent) districts over two years. None of the cultivars (Sunbred- 275, GK-2002, SH-177, SH- 3322, Jwalamukhi, Kaveri- 618, Leader, Advanta- 8699, 64-S-99 and P- Gold) grown in these areas were free from the disease. Irrespective of locations surveyed in the four districts, 10-13 per cent incidence of SND was observed in sunflower cvs. Sunbred- 275, GK- 2002 and P- Gold, while, 4-9 per cent incidence of the disease was recorded in cvs. SH- 177, SH- 3322, 64-S-99, Jwalamukhi, Advanta- 8699 and Leader during two consecutive seasons. However, the severity of the disease varied with the cultivars. Occurrence of thrips fauna was recorded in all sunflower growing areas of four districts surveyed. Population of thrips was comparatively higher in Mahabubnagar (4.48 thrips /plant) followed by Anantapur (3.85 thrips/plant), Nizamabad (3.65 thrips /plant) and Kurnool (3.46 thrips/plant). Four species, viz., Frankliniella schultzei (Trybom), Scirtothrips dorsalis (Hood), Thrips palmi (Karny) and Megalurothrips usitatus (Bagnall) were identified in the present study. Of these, T. palmi was found to be more prevalent in all the areas surveyed. Infestation of M. usitatus was observed during flower head formation stage, while infestation of other three species during vegetative growth stage. Of the ten common weed species found in and around the surveyed sunflower fields, Parthenium hysterophorus was more predominant and found in all the fields followed by Euphorbia geniculata, Achyranthus aspera, Commelina bengalensis, Abutilon indicum, Acanthospermum hispidum, Ageratum conyzoides, Malvestrum coromandelianum, Digeria arvensis and Trianthema portulacastrum in four districts of A.P. during two consecutive years. Symptoms of the disease varied depending on the cultivars. The characteristic symptoms of SND include chlorotic spots, mosaic, necrosis of leaves, stem and bracts, twisting of flower head leading to partial or complete sterility of the head with chaffy seeds in susceptible sunflower cultivars. Similar type of symptoms were also observed in sap inoculated sunflower plants. Severity of the disease also varied with the cultivars. The virus causing SND had a wide host range infecting members of six families. Four (Asteraceae), three (Chenopodiaceae), four (Cucurbitaceae), two (Malvaceae), thirteen (Leguminosae) and seven (Solanaceae) plant species produced visible symptoms of the disease on sap inoculation. However, sunflower necrosis virus failed to infect Raphanus sativus cv. Pusa Himani of Cruciferae and Sesamum indicum cv. local of Pedaliaceae family. No seed transmission was recorded with the seeds of sunflower cultivars (Morden, DRSF-108, KBSH-1, KBSH- 41, KBSH- 44, KBSH- 53, Sunbred- 275, DRSH-1, ASF-107 and RSF-101) collected from SND infected plants in grow-out tests. However, reduction in germination percentage from seeds of diseased plants was noticed as compared to healthy seeds. The method used for purification yielded concentrated preparation of the virus. Electron microscopy of negatively stained, purified and leaf dip preparations revealed the presence of typical isometric virus particles measuring 27-35 nm in diameter. Based on symptomatology, transmission, host range, serology and electron microscopy, the virus causing SND in major sunflower growing areas has been identified as an isolate of Tobacco Streak Virus (TSV) of Ilar virus group. Of the 35 common weed species collected from in and around the sunflower fields, tested for their susceptibility, natural infection of SND was detected in twelve weed species viz., D. arvensis, A. aspera, Lagasca mollis, P. hysterophorus, A. hispidum, A. conyzoides, C. bengalensis, E. geniculata, Phyllanthus niruri, M. coromandelianum, A. indicum and Physalis minima by back inoculation on assay host, cowpea cv. C-152 and further confirmed by DAC-ELISA using polyclonal antiserum of TSV. Under artificial inoculated conditions, of the twelve weed species tested for their reaction to SND, A. conyzoides, Gomphrena globosa and P. minima produced both local and systemic symptoms. Whereas, three weed species viz., Amaranthus viridis, P. hysterophorus and T. portulacastrum were symptomlessly infected. Studies on the effect of different dates of sowing of sunflower cv. Morden on thrips population and SND incidence revealed that thrips infestation was high in June sown crop followed by July sown crop. The disease incidence was more in July sown crop and less in November and December sown crop. Thrips population was at peak level in the initial stages of crop growth and declined gradually at senescence stage. Various weather parameters affected thrips population and incidence of SND. Maximum temperature had significant positive impact on thrips population, while significant negative correlations were found with relative humidity (I and II) and rainfall. Incidence of SND was positively correlated with relative humidity and rainfall. Disease severity had definite effect on yield and yield attributes of sunflower cv. Morden. With the increase in disease severity, there was corresponding decrease in yield and yield attributes. Maximum reduction in yield and yield attributes was recorded when the disease severity was > 50 per cent followed by 11-50 per cent and < 10 per cent severity level. The sunflower plants became increasingly resistant with the age to the SND infection as maximum (100 per cent) infection was recorded in 10 day old plants as against 35 per cent infection in 30 day old plants under artificial inoculated conditions. Twenty R lines, 12 each of CMS A & B lines, 100 germplasm lines and 12 cultivars of sunflower were evaluated against SND under artificial inoculated conditions using a six point scale (0-5). Highly susceptible reaction was shown by all R lines and CMS lines tested. Of the hundred germplasm lines screened, 8, 23 and 69 lines were moderately susceptible, susceptible and highly susceptible, respectively. Of the 12 sunflower cultivars screened, 5 and 7 cultivars exhibited highly susceptible and susceptible reaction, respectively. An integrated disease management strategy was worked out against SND at field level for two consecutive years during kharif season. Of the 15 treatments evaluated, seed treatment with thiomethoxam (4g/kg seeds), three sprays of thiomethoxam (0.05 per cent) at 15, 30 and 45 days and three rows of border crop (sorghum) followed by seed treatment with imidacloprid (5g/kg seeds), three sprays of imidacloprid (0.05 per cent) at 15, 30 and 45 days with three rows of border crop (sorghum) were found best in not only reducing the disease incidence and thrips population, but also increasing the yield and yield attributes of sunflower cv. Morden. Economics of different treatments revealed that, maximum incremental benefit cost ratio (IBCR) was obtained with the seed treatment alone with imidacloprid (5g/kg seed) followed by seed treatment with thiomethoxam (4 g/kg seed) at the time of sowing compared with other treatments. Based on IBCR, the next best treatments in the management of SND were bordering of sunflower crop with sorghum and seed treatment with imidacloprid or thiomethoxam at the time of sowing. Reverse Transcription- Polymerase Chain Reaction (RT-PCR) of RNA extracts of eight SND infected sunflower samples collected two each from Andhra Pradesh, Maharashtra, Karnataka and Tamil Nadu using primers specific to the coat protein gene of TSV did not show any variation. Infectivity assay of the eight virus isolates of SND collected from various locations on cowpea cv. C-152 and N. tabacum cv. Samsun showed no variation in symptom expression. |
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Date |
2016-06-09T14:27:01Z
2016-06-09T14:27:01Z 2011 |
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Type |
Thesis
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Identifier |
http://krishikosh.egranth.ac.in/handle/1/67134
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Language |
en
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Relation |
D8871;
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Format |
application/pdf
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Publisher |
ACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY
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