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2013 IPM IL virus survey in Nepal . Naidu Rayapati Associate Professor (Virology) Department of Plant Pathology Irrigated Agriculture Research and Extension Center Washington State University Prosser, WA 99350, USA naidu.rayapati@wsu.edu. Background.
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2013 IPM IL virus survey in Nepal Naidu Rayapati Associate Professor (Virology) Department of Plant Pathology Irrigated Agriculture Research and Extension Center Washington State University Prosser, WA 99350, USA naidu.rayapati@wsu.edu
Background • Plant Virus Global Theme (IPVDN) Project objective: • - to identify economically important viruses affecting vegetables in target countries identified by USAID. • Nepal is one of the priority countries for IPVDN activities • USAID-Nepal Mission Associate Award for IPM IL • - One of the activities is “Management of virus diseases impacting vegetable crops” in target regions of Nepal (priority areas - Banke and Surketh Districts).
Objectives of the 2013 survey • Accurate identification of viruses is the first critical step for management of virus diseases • Survey farmers’ fields in Banke and Surketh districts • Collect samples from vegetable crops showing virus-like symptoms and test for known viruses • Make a preliminary assessment based on test results and report findings to USAID Mission in Nepal • Make recommendations and develop future plans
Activities conducted (May 17-23, 2013) • Visited Nepalgunj and Surkhet areas • (Naidu Rayapati & Amer Fayad) • Coordinated by iDEand staff • Met with iDEstaff, DADO, NARC (Lalitpur, Surkhet, Nepalgunj) • Visited farmers’ fields, collected and processed samples • Briefed USAID Mission (Evan Meyer) • Tested for known viruses at Washington State University • Shared results via progress report with USAID Mission
Focus crops & viruses • Mainly vegetables • Tomato, peppers, various types of cucurbits, and • other crops (yardlong beans and cowpeas) • Visited select farmers fields, monitored for symptoms • Collected samples from plants showing virus-like symptoms • Blotted samples on FTA Classic Cards for virus testing • Tested by molecular assays (PCR) for : • - Potyviruses (seed- and aphid-transmitted) • - Begomoviruses (whitely-transmitted) • - Tospoviruses (thrips-transmitted) • - Cucumber mosaic virus (seed- and aphid-transmitted) • Cloning and sequencing for confirmation of virus(es)
Detection of viruses from FTA® Classic Cards Diagnosis by RT-PCR/PCR
Chilli peppers - Surkhet Chilliveinal mottle virus
Chilli peppers - Surkhet ‘Symptoms’ due to thrips feeding damage
Tomato - Surkhet Two viruses - highly similar to: Tomato leaf curl New Delhi virus Bean common mosaic virus
Cowpea - Surkhet Bean common mosaic virus
Squash - NARC-ARS, Dasharathpur, Surkhet Zucchini yellow mosaic virus
Pumpkin-Nepalgunj Zucchini yellow mosaic virus
Cucurbits -Nepalgunj A cucurbit field devastated by virus
Beans - Lalitpur Bean yellow mosaic virus
2013 Survey results – A summary • Distinct viruses are present in vegetable crops surveyed Area Crop Virus Cucurbitaceous crops: Surkhet Pumpkin Zucchini yellow mosaic virus Surkhet Squash Zucchini yellow mosaic virus Nepalgunj Bottle gourd Zucchini yellow mosaic virus Nepalgunj Pumpkin Zucchini yellow mosaic virus Solanaceous crops: SurkhetChilli pepper Chilliveinal mottle virus Surkhet Tomato Tomato leafcurl New Delhi virus Leguminous crops: Surkhet Cowpea Bean common mosaic virus Lalitpur Beans Bean yellow mosaic virus
Issues for further consideration • Symptom-based diagnosis of a virus disease is not always reliable • Symptoms are variable due to: • - crop species & cultivar • - strain of a virus • - age of the crop • - environmental conditions • - mixed virus infections • - symptomless infections • Different viruses can produce similar symptoms • - mosaic symptoms • - necrotic symptoms • Accurate identification of a virus is critical
Suggestions for action plans • Identification of viruses based on symptoms is not always reliable – apply modern diagnostic methods. • - Serological (ELISA, TBIA) and molecular (PCR) • Continue surveys for identification of viruses towards building a comprehensive data base of viruses affecting vegetable crops grown in Nepal. • Impacts of virus diseases on food & nutritional security (yield, nutritional quality and impacts on family income)
Suggestions for action plans • Outreach/education programs for increased awareness of plant virus diseases spreading via seeds and by insect vectors. • Strengthening capacity building programs to empower stakeholders and national research programs in dealing with virus diseases in vegetablecrops. • Research towards developing strategies for management of seed-borne and insect-transmitted virus diseases benefiting subsistence farmers in Nepal. • Training the next generation of scientists/researchers • (short-, medium-, & long-term-training, and curriculum improvement in academic programs) • Collaborations are the key
Thanks to: iDE-Nepal NARC