2013 IPM IL virus survey in Nepal
Naidu RayapatiAssociate Professor (Virology)Department of Plant Pathology
Irrigated Agriculture Research and Extension Center Washington State University
Prosser, WA 99350, [email protected]
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 surveyAccurate 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 iDE and staff
• Met with iDE staff, 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)
Diagnosis by RT-PCR/PCR
Detection of viruses fromFTA® Classic Cards
Visit with farmers in Surkhet
Chilli peppers - Surkhet
Chilli veinal 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
Source of seed ??
Beans - Lalitpur
Bean yellow mosaic virus
2013 Survey results – A summary
Area Crop Virus Cucurbitaceous crops:Surkhet Pumpkin Zucchini yellow mosaic virusSurkhet Squash Zucchini yellow mosaic virusNepalgunj Bottle gourd Zucchini yellow mosaic virusNepalgunj Pumpkin Zucchini yellow mosaic virusSolanaceous crops:Surkhet Chilli pepper Chilli veinal mottle virusSurkhet Tomato Tomato leafcurl New Delhi virusLeguminous crops:Surkhet Cowpea Bean common mosaic virusLalitpur Beans Bean yellow mosaic virus
Distinct viruses are present in vegetable crops surveyed
• 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
Issues for further consideration
• 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 vegetable crops.
• 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
Suggestions for action plans
Thanks to:
iDE-NepalNARC
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