Agriculture, Food and Rural Affairs

Tomato Brown Rugose Fruit Virus

Cara McCreary

Greenhouse Vegetable IPM Specialist, OMAFRA

AGENDA

• What is a virus?

• What is ToBRFV?

• Background

• Symptoms

• Transmission

• Diagnostics

• Crop protection

What is a Virus?Smaller than a single cell

Signs:NONE

Symptoms:Quite variableStunting or distorted growthLeaf and fruit spots often in rings

Virus Characteristics

• Too small to be seen with a light microscope

• Only visible using electron microscope

• Multiply only in living cells

• All are obligate parasites • cannot replicate without exploiting a suitable

host • without host, will fail to replicate but can

survive away from main host in tissue and some survive on other surfaces such as wood, plastic or metal

• Enter the plant through wounds, broken hairs, or vectors (insect, fungus or nematode)

Transmission of Plant Viruses

Mechanical: sap on tools, hands, clothes, animals

• e.g. tobacco and tomato mosaic virus (TMV/ToMV), Pepper mild mottle mosaic virus (PMMoV), Pepino mosaic virus (PepMV), Cucumber green mottle mosaic virus (CGMMV)

Seed: borne inside seed or transmissible through seed coat

• e.g. ToMV, pepper mild mottle mosaic virus, CGMMV

Fungus: in greenhouse, often soil-borne fungus

• e.g. MNSV or CNSV by Olpidium, in cucumbers

Transmission of Plant Viruses

Insects: many common pests of greenhouse vegetables• Aphids – cucumber mosaic virus (CMV), zucchini yellow

mosaic virus (ZYMV)

• Cucumber beetles & aphids – cucumber mosaic virus (CMV)

• Thrips – tomato spotted wilt virus (TSWV) & impatiens necrotic spot virus (INSV)

• Whitefly – beet pseudo yellow virus (BPYV), tomato chlorosis virus (TOC)

Nematodes: usually soil-dwelling plant pathogenic nematodes• e.g. tobacco ringspot virus

What is Tomato Brown Rugose Fruit Virus?(ToBRFV)

Family: Virgaviridae

Genus: Tobamovirus

• Like TMV (Tobacco Mosaic Virus), ToMV (Tomato Mosaic Virus)

Characteristics of Tobamovirusgenus:

• Very persistent in the environment

• Highly transmissible and easily spread mechanically

• Virulent strains can be very damaging to host crops

DeRuiter

What sets ToBRFV apart?

Tomato Resistance

• Able to overcome all known genetic resistances including the Tm-2² gene

• May result in severe fruit symptoms on cultivars resistant to TMV and/or ToMV

Pepper Resistance

• Does not seem to overcome the L genes (for resistance to TMV and PMMoV) DeRuiter

DeRuiter

American Seed Trade Association (ASTA) QA

Objectives:

1. How to detect the virus

2. Its detrimental impact

3. Prevention and mitigation

https://www.betterseed.org/wp-content/uploads/ToBRFV-QA.pdf

Tomato Brown Rugose Fruit Virus (ToBRFV)

DeRuiter

What crops are affected?

• Tomato and pepper are main hosts

• Several Nicotiana spp. (including tobacco) develop symptoms

• Some weeds, Petunias and other ornamentals may act as reservoirs

• Eggplant and potato did not show symptoms after inoculation in one study; however, recent reports from Mexico of infected eggplant

Note: weed and ornamental hosts may be source of inoculation

Tomato Brown Rugose Fruit Virus (ToBRFV)

Photos: DeRuiter

Symptoms - TomatoesFoliar:

• Chlorosis, fern leaf, mosaic and mottling, leaf narrowing

Calyx:

• Browning of the veins or necrosis at the tips

Fruit:

• Blotchy, pale, yellow or brown necrotic spots

• May be undersized, deformed, irregular maturation, fewer fruit, or complete abortion

Damage estimates:

10-15% symptomatic fruit – 100%

Photo: DeRuiter

Symptoms of ToBRFV

“Note that it has been reported that some tomato

varieties can develop a high virus level without

physically expressing symptoms.

Infected plants of these varieties can then

unwittingly become a source for spread of ToBRFV

infection to healthy tomato or susceptible pepper

plants.” (ASTA)

Tomatoes

DeRuiter

Symptoms - Peppers

Foliar:

• deformation, yellowing and mosaic

Fruit:

• deformed, yellowing or brown necrotic areas or green stripes

Damage estimates:

• None available

May 8, 201913

Photos: DeRuiter

How is ToBRFV transmitted?

1. Mechanically.

• Through contact: people, hands, tools, clothing, chewing insects, birds, bees, grafting, roots, seeds, etc.

• May be spread by bumble bees or other insects,(as are many other viruses)

2. Seed transmitted.

• Primarily on seed surface, and to lesser extent internally

• Can maintain infectivity for weeks to years

• Transmission from seed to seedling may be low; however, contact with infected material can spread the virus rapidly between plants, ranges, fields, etc.

How can you protect your crops?

• Use certified seed - GSPP

• Practice strict sanitation at all stages of crop production

• All workers and visitors should practice strict hygiene

• Thorough handwashing

• Freshly laundered uniforms or clothes

• Footwear that remains on farm

• Be mindful of people moving from farm to farm

• Use disposable lab coats, gloves (followed by disinfectants) if handling plants

• Do not visit more than 1 operation of the same crop in the same day

• Go home and shower!

Prevention is key

How can you protect your crops?

• Conduct a thorough cleanout between crops

• Manage imports

• Practice clean breaks rather than cutting where possible

• Disinfect:• Use footbaths, tire baths, hand sanitizer (refresh

disinfectants regularly)• Equipment, vehicles, carts, tools, etc. regularly• Irrigation water

• Ensure ALL workers and visitors follow biosecurity protocol

May 8, 201916

May 8, 201917

How can you protect your crops?

CFIA’s Plant Health Biosecurity Guide

http://www.inspection.gc.ca/plants/plant-pests-invasive-species/biosecurity/guide/eng/1323477130171/1323477259986

OGVG’s Visitor Biosecurity Handout

https://www.hortcouncil.ca/wp-content/uploads/2019/04/Visitor-Biosecurity-Handout-EN.pdf

CFIA’s Greenhouse Vegetable Sector Biosecurity Guide

http://www.inspection.gc.ca/plants/plant-pests-invasive-species/biosecurity/greenhouse-vegetable-sector-biosecurity-guide/eng/1484722296145/1484722331070

Biosecurity is your friend

What if you suspect you have it?

Properly identify by sending to Canadian diagnostics lab

The 3 R’s of virus management:

• Restrict access, block off rows

• Promptly remove infected plants – place in sturdy garbage bags and send to landfill

• Rotate crops if possible (the longer the rotation, the better)

May 8, 201919

Photos: DeRuiter

Steps to managing a virus

Step 1: Practice strict biosecurity

Step 2: Quarantine known or suspected plants

Step 3: Properly diagnose

Step 4: Remove infected plants

Step 5: Clean and disinfect regularly

Step 6: Monitor diligently

Step 7: Conduct a thorough clean out between crops

Step 1: PRACTICE STRICT BIOSECURITY

Step 1: PRACTICE STRICT BIOSECURITY

Step 1: PRACTICE STRICT BIOSECURITY

Step 1: PRACTICE STRICT BIOSECURITY

Perhaps MOSTimportantly…

Don’t have fancy boot disinfection equipment?

Here’s what you’ll need:

• Water

• Soap

• Scrub brush

• Disinfectant

• Buckets (optional)

• Spray bottle (optional)

No problem. You can easily clean and disinfect work boots with some basic equipment.

Scrub to remove debris and dirt, rinse before proceeding.

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Dissolve disinfectant and submerge boots and/or spray boots directly with disinfectant.

Step 2: QUARANTINE KNOWN OR SUSPECTED PLANTS

• Assume it is

• Flag the plant

• Restrict access IMMEDIATELY

• Designate equipment and workers to that area

• Manage workflow in infected area:

• Work in one direction• Work in infected area

last

Step 3: PROPERLY DIAGNOSE

HOW?

• Immunostrips

• Send to diagnostics lab in Canada

• Conventional, end point reverse transcription PCR (developed by Ling et al., USDA)

• Followed by sequencing

WHY?

• What disease is it?

• How is it transmitted?

• How can you prevent it from spreading?

Step 4: REMOVE INFECTED PLANT(S)

• Remove infected plant(s) IMMEDIATELY.

• Depending on how the virus is transmitted, may need to remove a number of plants surrounding the infected plant(s).

• Properly dispose of ALL plant material.

How to dispose of infected plants

Follow ALL biosecurity protocol to prevent further spread of infection. This includes wearing protective gear and frequent disinfection of footwear.

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Cut the infected plant free from its support and disinfect scissors.

Cut block free from the slab and disinfect knife.

With help, carefully place the infected plant inside a sturdy garbage bag, keeping the garbage bag’s

exterior clean and seal the bag.

What not to do…

Step 5: CLEAN AND DISINFECT REGULARLY

• Regularly clean and disinfect tools, equipment, pathways, especially in or near an infected area.

• Remember: anything that has plant sap/residue on it, could be a source of inoculum. Focus on high risk areas.

• MUST remove organic matter PRIOR to disinfecting

36 Presentation Name

Step 5: CLEAN AND DISINFECT REGULARLY

• Picking crates…• Hard plastic

• Microbreaks are a great place for viruses to hide

Photo credit: https://groups.google.com/forum/#!topic/greenhouse-marketing-forum/jo5j3ztshsQ

Step 5: CLEAN AND DISINFECT REGULARLY

• Think about what hands touch AFTER they touch plants.

• e.g. bathroom door knobs, keyboards, mouse, lunch table, etc.

Is pasteurization an option?

Temperatures for Killing Some Organisms

Pest Temp (0C) Time (min)

Bacteria 60 10

Botrytis 55 5

Pythium 46 40

Insects & mites 60-71 20

Weeds 70-80 15

Temperatures at which certain viruses lose infectivity after exposure for minimum of 10 min

Pepino Mosaic Virus 65-700C

Tomato Spotted Wilt Virus 450C

Cucumber Mosaic Virus 700C

Melon Necrotic Spot Virus 600C

Zucchini Yellow Mosaic 600C

Cucumber Necrosis Virus 75-800C

Tobacco Etch Virus 550C

Tobacco mosaic virus > 900C

Cuc green mottle MV 90-1000C

But this is so overwhelming…

• Tools

• Scissor carts

• Picking crates

• Pallets

• Packing lines

• Door handles

• Fork lifts (especially forks)

• Walkways

• Irrigation equipment (incl. nutrient solutions, drip lines, etc.)

• Vehicles

• Tractors

• Sprayers

• Other hand tools

Regularly CLEAN and disinfect surfaces with heavy traffic and contact with plants or people, including:

Dr. Oualid Ellouz, 2017

Step 6: MONITOR DILIGENTLY

• Continue scouting, focusing on expected patterns based on what’s known about virus transmission.

• For example:

• Mechanically transmitted viruses tend to spread in the same direction as workers, focus on these areas.

• For insect transmitted viruses, monitor and manage insect populations.

• If more infected plants are found, return to step 2

Step 7: CONDUCT A THOROUGH CLEAN OUT BETWEEN CROPS

• Properly dispose of old crop

• Maintain warmer temperatures

• Remove all organic matter

• Clean irrigation system

• Clean, rinse and disinfect equipment

• Clean, rinse and disinfect structure

"None of the actors (seed companies, nursery gardeners, producers, distributors)

can avoid implementing all preventive containment measures: if only one link of

the chain fails, it risks putting the entire Sicilian tomato production at risk.”

Quote from the Mar 11 Hortidaily

It is a “community pest”

Next steps

“Seed companies are diligently working on identifying and introducing resistance to the virus

in new varieties. However, it could take several years until new resistant varieties are introduced”

(ASTA)

Future research

• Attenuated virus

• Disinfectants

Take Home Messages

Biosecurity is your first line of defense

• Focus on riskiest pathways first

• Think: Sanitation, Disinfection, Hygiene

Establish a support network

• Government

• Grower organizations

• IPM specialists, suppliers, consultants

• Supply chain

BE EMPOWERED!

Thank you

Contact:

Cara McCreary, Greenhouse Vegetable IPM Specialist, OMAFRA

cara.mccreary@ontario.ca