Investigation Of Vectors And Alternate Hosts Of Tomato Spotted Wilt Virus Tswv In Lettuce Crops Final Report

Author : Brenda Coutts
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (1 download)

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Download or read book Studies on Virus Diseases of Cultivated and Wild Plants of Western Australia written by Brenda Coutts and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The first plant virus disease report for Western Australia (WA) was in 1901 on passionfruit. Since that time, more than 72 plant viruses have been identified infecting cultivated and wild plants in WA, and detailed research activities undertaken with some of them. This PhD thesis covers research studies I have taken a leading role with over a 15 year period on viruses causing diseases to cultivated (vegetable, broadacre and pasture) and wild (naturalised weeds, and native flora) plant species growing in the unique and diverse environments of WA. These studies were undertaken across three distinct climatic regions, the tropical north, the sub-tropical central west and the south-west with its Mediterranean-type climate. The areas within each climatic region growing cultivated plants are isolated from each other by vast expanses of arid, unpopulated tracts of land. Also, plant cultivation in these three cropping areas is a relatively recent activity (south-west 185 years, central west 85 years and north 50 years). Through field surveys and field, glasshouse and laboratory experimentation, valuable information and understanding about diverse virus-plant species pathosystems has been gathered. This has included information on virus occurrence, distribution, epidemiology, biological and molecular characterisation, and vectors. In addition, the yield and quality losses that virus infection causes on various plant species were determined and effective virus control measures devised. Within this thesis, examples of virus pathosystems of vegetable and broadacre crops, perennial pastures and wild plants are discussed.The main viruses and vegetable crops investigated were Zucchini yellow mosaic virus (ZYMV) in cucurbit crops, Potato virus Y (PVY) in potato, Tomato spotted wilt virus (TSWV) in tomato, pepper and lettuce, and Lettuce necrotic yellows virus (LNYV) and lettuce big-vein disease (LBVD) in lettuce. All these viruses were studied in the south-west, except for ZYMV which was also examined in the tropical and sub-tropical regions of WA. Findings from surveys and experimentation provided new understanding of the epidemiology of these viruses and identified effective control measures (including manipulation of planting date, using non-host plant barriers, planting upwind of infection sources, using cultivars with virus resistance, improved hygiene practices). Highlights include demonstrating the contact transmissibility, stability and inactivation of ZYMV and PVY in infective sap; and determining spatial patterns of spread of ZYMV, TSWV, LNYV and LBVD in relation to internal and external virus sources. These findings enabled additional control recommendations to be added to the existing integrated disease management (IDM) strategies for ZYMV in cucurbits, PVY in potato and TSWV in lettuce, tomato and pepper.The main viruses and broadacre crops investigated were Beet western yellows virus (BWYV) (= Turnip yellows virus) and Turnip mosaic virus (TuMV) in canola, Wheat streak mosaic virus (WSMV) in wheat, and Pea seed-borne mosaic virus (PSbMV) in field pea and other legumes. These studies were done in the south-west of WA. From surveys and experimentation, alternative hosts of BWYV, TuMV and WSMV were identified, vectors of BWYV and WSMV were studied, canola genotypes were found with resistance to BWYV and TuMV, and insecticide seed dressings suppressed BWYV infection. For WSMV in wheat, the environmental conditions that drive its spread and the importance of seed-borne infection in initiating WSMV epidemics in a Mediterranean-type climate were identified. For PSbMV, cool-season crop legume genotypes varied in their resistance/susceptibility to infection, and with field pea use of virus resistant cultivars, cultural control practices (including seeding rate and stubble groundcover) and a threshold value of.