Virus Diseases in Vegetables in Nepal

Progress Report – March 2016

Naidu RayapatiAssociate Professor (Virology)

Department of Plant Pathology

Irrigated Agriculture Research and Extension Center

Washington State University

Prosser, WA 99350, USA

naidu.rayapati@wsu.edu

Acknowledgements

• USAID Mission, Nepal

• IPM IL, VT (Dr. Amer Fayad)

• NARC scientists, Nepal

• iDE team, Nepal

• Rayapati’s team, WSU

Objectives

• USAID Mission priority regions in Nepal

- Primary focus: Banke and Surkhet Districts

- Secondary focus: Salyan, Pokara Districts

• Visit farmers’ fields, collect samples and test for viruses

• Make a preliminary assessment and report findings

• Make recommendations and develop future plans

Activities conducted

(2013, 2014, 2015)

• Visited Banke, Surkhet, Salyan, Pokara regions

• Coordinated by iDE staff and NARC

• Met with members of iDE, DADO, NARC

• Visited farmers’ fields, collected & processed samples

• Met with KISAN Project, CEAPRED, others

• Tested for viruses at Washington State University

• Briefed USAID Mission, iDE and others

Focus on high value vegetable crops

• Solanaceae – tomato, pepper, potato

• Cucurbitaceae – gourds, melons, squash

• Brassicaceae – broadleaf mustard

• Malvaceae – okra

• Fabaceae – various types of beans

Focus on high value vegetable crops

• Visited select farmers’ fields, monitored for symptoms

• Collected samples from plants showing virus-like

symptoms

• Tested by serological and molecular diagnostic assays

- in the field using immunostrips

- printed samples on FTA Classic Cards

- shipped leaf samples to Rayapati’s lab

IPM IL

Virus team

Tissue blot immunoassay (TBIA)

PBNV

TSV

Enzyme-linked

immunoassay (ELISA)

Field-collected tomato samples

ImmunostripsA suite of diagnostic assays

Detection by RT-PCR/PCR

Detection of viruses from

FTA® Classic Cards

Next-generation sequencing

(Deep-sequencing)

Nepal

Bitter gourd

India

Snake gourd

B’desh

Snake gourd

2013, 2014 & 2015 Survey results

A brief summary

Cucurbitaceous crops:

Location Crop Sequence related to:

Surkhet Pumpkin Zucchini yellow mosaic virus

Surkhet Squash Zucchini yellow mosaic virus

Banke Bottle gourd Zucchini yellow mosaic virus

Banke Pumpkin Zucchini yellow mosaic virus

Banke Snake gourd Zucchini yellow mosaic virus

Banke Bitter gourd Zucchini yellow mosaic virus

Pokhara Sponge gourd Zucchini yellow mosaic virus

Characterization of other viruses in progress

Solanaceous crops

Location Crop Sequence related to:

Surkhet Pepper Chilli veinal mottle virus

Surkhet Tomato Tomato leafcurl New Delhi virus

Hemja, Kaski Tomato Tomato leafcurl Karnataka virus

Pokhara Tomato Peanut bud necrosis virus

Pokhara Tomato Cucumber mosaic virus

Kathmandu, & Tomato Potato virus Y, X, ?

other locations

Kathmandu Tomato Tobacco mosaic virus

Nepalgunj Eggplant Cucumber mosaic virus

Various Potato Potato virus Y, X, S, & M

locations

2013, 2014 & 2015 Survey results

A brief summary

Characterization of other viruses in progress

Leguminous crops:

Area Crop Sequence related to:

Surkhet Cowpea Bean common mosaic virus

Surkhet Yardlong beans Bean common mosaic virus

Surkhet French bean Mung bean yellow mosaic virus

Nepalgunj Mung beans Mung bean yellow mosaic virus

Lalitpur Beans Bean yellow mosaic virus

Salyan Rajma beans Bean common mosaic virus

Yardlong beans

Nepalgunj Country beans Dolichos yellow mosaic virus

Characterization of other viruses in progress

2013, 2014 & 2015 Survey results

A brief summary

Other cropsLocation Crop Sequence related to:

Nepalgunj Okra Bhendi yellow vein

mosaic virus

Nepal Broadleaf mustard Turnip mosaic

virus

(many locations)

2013, 2014 & 2015 Survey results

A brief summary

A few examples of virus disease symptoms

in vegetables and legumes

Chilli peppers - Surkhet

Chilli veinal mottle virus

Zucchini - Nepalgunj

Zucchini yellow mosaic virus

Pumpkin-Nepalgunj

Zucchini yellow mosaic virus

Squash - NARC-ARS, Dasharathpur, Surkhet

Zucchini yellow mosaic virus

Cucurbits -Nepalgunj

A cucurbit field devastated by virus

Bitter gourdMomordica charantia

Snake gourd(Trichosanthes cucumerina)

Zucchini yellow mosaic virus

& a related virus

Tomato:

Distinct symptoms in

different regions

Potato - Surkhet

Potato virus Y, X, ??

Okra - Nepalgunj

Bhendi yellow vein mosaic virus

Broadleaf mustard - Surkhet

Turnip mosaic virus

Lablab beans - Nepalgunj

Dolichos yellow mosaic virus

Wrong diagnosis - chilli peppers

‘Symptoms’ due to thrips feeding damage

• 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 diagnosis of a virus is critical

Issues for consideration

Workshop on Seed-borne Viruses of Vegetable Crops

(March 7-11, 2014)

Disease Diagnosis and Basic Plant Pathological

Techniques for Early Career Scientists

NARC station in Khajura, Nepalgunj, April 6-12, 2015

• Many viruses present in high value crops

• Identification of viruses based on symptoms is not

always reliable – need to use diagnostic methods.

• Continue surveys and identification of viruses

towards building a comprehensive data base of

viruses present in vegetable, legume and other

crops of importance to Nepal.

• Impacts of virus diseases on food & nutritional

security (yield, nutritional quality and income

assessment ).

The Way Forward

• Outreach/education through various dissemination

pathways for increased awareness of plant virus

diseases spreading via seeds and insect vectors.

• Strengthen capacity building programs at NARCs

and NGOs for empowering farmers to deal with virus

diseases in in vegetable, legume and other crops of

importance to Nepal.

• Research towards developing strategies for

management of seed-borne and insect-transmitted

virus diseases benefiting subsistence farmers.

• Collaborations among stakeholders is the key.

The Way Forward

• viruses introduced into

new areas

• virus vectors introduced

into new areas

Viruses & vectors

have no passports

via seed, vegetative cuttings, movement of

vectors, shipment of seedlings, international

trade or accidentally

Globalization of agriculture

&

virus diseases

Thanks to:

USAID-Nepal Mission

IPM IL

iDE-Nepal

NARC