Viruses Found in California Garbanzo Beans

Carol Frate, Farm AdvisorUCCE –Tulare County

May 1, 2013

Why this topic?

At the Garbanzo Council meeting at Santa Nella in March, 2013, questions on viruses came up:

What do we know about viruses in CA garbanzos?How do they infect plants?Symptoms?What damage do they do

Are there potential virus threats that the industry should be preparing for?

What should be the priority of viruses (known & unknown) for your research dollars?

within the breeding program?in addition to the breeding program?

Most Recent Thorough CA Study

Studies on Epidemiology of Virus Disease of Chickpea in CaliforniaN.A. Bosque-Perez & I. Buddenhagen

Work done in mid-80’s; Published in 1990

1958 Irwin & Snyder “Yellowing of Garbanzo Beans1989 Bosque-Perez & Buddenhagen “First report of lettuce mosaic virus on chickpea”

`

Compendium of Garbanzo Diseases

Published in 2011 By APS

Published 1990Plant Disease Vol 74

Disease symptom photos usedin this presentation are from the Chickpea and Lentil APS publication and cannot be reproduced

Informational…….no reason to panic

There have been garbanzo viruses known in CA for a long time:

1956 – Legume Yellows Virus1990 – Alfalfa Mosaic Virus

Cucumber Mosaic VirusSubterranean clover red leaf virusLegume Yellows VirusBeet Western Yellows VirusLettuce Mosaic Virus

Cannot tell one from the other just by symptoms. Even with the same virus, symptoms may vary due to strains of the virus or different genotypes of the garbanzos.

Bromoviridae Viruses

Alfalfa Mosaic Virus (AMV)Cucumber Mosaic Virus (CMV)

- Scattered distribution of individual symptomatic plants, characteristic of viruses transmitted by aphids in chickpea crops. Primary infection and secondary spread are by winged aphids that fly between distant plants. There are few colonizing unwinged that walk between adjacent plants. (Courtesy M. W. Schwinghamer)

Shoot tip necrosisearly AMV

Late AMV Healthy

Alfalfa Mosaic Virus Symptoms

Internode reduction at shoot tips and kinking of chickpea stems caused by Cucumber mosaic virus. (Courtesy M. W. Schwinghamer)

Bushy stunting caused by Cucumber mosaic virus in Desi chickpea (two plants at right). (Courtesy M. W. Schwinghamer)

CMVCucumber Mosaic Virus Symptoms

Internode reductionat shoot tips;

Kinking of stems

Bushy stunting

Healthy

Symptoms of early infection with Cucumber mosaic virus including stunting, necrosis of primary shoot top, and reduction and narrowing of leaves on earliest growth. Healthy plant is at left. (Courtesy R. C. Larsen)

CMV

Healthy

Earlyinfection

Phloem browning in chickpea caused by Soybean dwarf virus. A shallow cut was made at the collar to reveal the discoloration. (Courtesy M. W. Schwinghamer)

Luteoviruses:

Subterranean clover red leaf virus (SCRLV), (syn. Soybean Dwarf Virus)

Legume Yellows Virus (LYV)(syn. Bean Leafroll Virus)

Beet Western Yellows Virus (BWYV)

“Yellowing viruses”Phloem limitedInfection usually lethal

As a group, probably cause greater losses in garbs than any other group of viruses.

Discolored phloem

Vectors of Luteoviruses: Pea aphid

Cowpea aphid

Green peach aphid

Once aphid is infected, it can transmit for a long time.

Luteoviruses:

Subterranean clover red leaf virusLegume Yellows VirusBeet Western Yellows Virus

Symptoms of Bean leafroll virus (BLRV). Top, stunting and yellowing in a chickpea breeding line inoculated with an isolate of BLRV (left) and an uninfected plant (right). Bottom, stunting and yellowing of leaf margins in chickpea. (Courtesy M. W. Schwinghamer[top] and R. C. Larsen [bottom])

SymptomsStuntingChlorosisYellowing of leaf marginsDeath

Yellowing and reddening of leaf margins, epinasty, leaf folding, and stunting in the Desi chickpea cultivar Amethyst inoculated with an isolate of Bean leafroll virus. Two infected plants are surrounded by noninfected plants. (Courtesy M. W. Schwinghamer)

Infected plantis stunted.

If infection is early,healthy plants overgrow it.

% of Plants with Virus Symptoms - 1988Bosque-Perez & Buddenhagen

0

10

20

30

40

50

60

70

80

90

BWYV LYV SCRLV BWYV LYV SCRLV

Davis WSFS

Feb

Mar

April

May

•Migrant aphids

•Virus Reservoirs (no grasses)

•LYV: main vector is pea aphid; reservoirs are alfalfa, white clover, other legumes

•SCRLV pea aphid, white and red clover, (no evidence that alfalfa is a reservoir)

•BWYV – green peach aphid, many hosts including legumes & weedscowpea aphid, mainly legumes, some Brassicae, alfalfa has not been show to be important.

Factors of Luteoviruses that relate to disease spread

Why aren’t the viruses worse?*

Aphids don’t do well in garbanzos- they fly in but don’t reproduce- little within field spread

With the non-persistent viruses – aphids lose ability to transmit quickly

*They may be very serious in a particular field

Summary of “Current” CA Virus Situation in Garbs

• Aphids are the main virus vectors

– Aphids bring the virus into the garb fields“viruliferous invaders”

– Little within the field spread

• Secondary spread is not important because aphids don’t usually colonize garb fields.

• Due to timing of aphid movement, infection often occurs after flowering when impact on yield is less.

To have severe virus impact, need a lot of viruliferousaphids entering a field, the earlier the more severe.

Small fields near virus hosts are most at risk for impact.

What can growers do?

•Don’t plant late•Get a good stand•Control adjacent weeds•If possible, don’t plant next to alfalfa•Larger fields will be less at risk•Don’t spray for aphids

Poorly established crops are most vulnerable to virus infection. (Courtesy R. C. Larsen)

- Scattered distribution of individual symptomatic plants, characteristic of viruses transmitted by aphids in chickpea crops. Primary infection and secondary spread are by alatae that fly between distant plants. There are few colonizing apterae that walk between adjacent plants. (Courtesy M. W. Schwinghamer)

Potential Virus Threats?

Tomato Spotted Wilt Virus (TSWV)currently a problem in CA tomatoes; has not shown up

in garbs here to our knowledgehas been reported in garbs – tip necrosis, plant death

Brazil 1990’sAustralia early 2000’sHard to say how widespread & if it continues in

those countries

Adult Nymph

Western flower thrips

Potential Virus Threats?

Tomato Spotted Wilt Virus (TSWV)currently a problem in CA tomatoes; has not shown up

in garbs here to our knowledgehas been reported in garbs – tip necrosis, plant death

Brazil 1990’sAustralia early 2000’sHard to say how widespread & if it continues in

those countries

Pea Streak Virus (PeSV)In the Palouse region of eastern WA in 1979Severe epidemics in 1983, 1990, 1996, 2005Pea aphid is the vectorSymptomless in alfalfa, the main sourceCan be severe

Where should virus issues rank in garbanzo research priorities?

Are they a problem?What is the status now? (Work by Boque-Perez & Buddenhagen > 20 yrs ago)

Survey for symptoms? How widespread? Yield loss?Survey what viruses are out there?Provide the breeding program funds to get plant path support?

- minimum of virus id from plants in breeding plots?- are there genetic markers?

Call for proposals will come late summer. It will be helpful to know what growers and industry feel about the need to conduct research on viruses.

Thank you for your attention.

Any Questions?