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, USAnaidu.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 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