Temperate pulse viruses: bean yellow mosaic virus

Close-up photo of faba bean leavesBean yellow mosaic virus (BYMV) was first reported on French beans from the USA and the Netherlands in 1925, and is now distributed worldwide.

It has a wide host range which includes the temperate pulses and pasture legumes, tropical legumes and ornamental hosts.

The virus is spread by a number of aphid species non-persistently as well as being seed and mechanically transmitted.

What to look forPhoto of healthy faba bean seeds next to smaller infected beans covered in black spots

Symptoms of BYMV in the major temperate pulses and pasture legumes are:

  • faba beans develop vein yellowing, followed by obvious green or yellow mosaic vein banding with yellowish line patterns (Figure 1). Symptoms are more prominent on young leaves. Seed symptoms include irregular brownish to blackish staining (Figure 2).
  • Symptoms on field peas are variable. The virus may be symptomless or may induce bright mosaic, mottling of leaves and clearance of veins. Necrosis may occur on tips, in stems and veins (Figure 3).
  • Desi chickpeas develop apical necrosis, reddening, plant stunting and premature senescence.
  • Kabuli chickpeas develop apical necrosis, yellowing, plant stunting and premature senescence.
    Lentils develop mild mosaic, light green or yellow leaves. A reduction in leaf size and stunting may occur. Infected plants produce very little seed.
  • Narrow-leaf lupins, infected with the necrotic strain of BYMV, initially develop yellow leaves followed by necrosis of growth tips and plant death (Figure 4). Non-necrotic strains of BYMV cause yellowing and dwarfing, but do not cause death of the plant.
  • Subterranean clover plants develop leaf mottling, leaf deformation and distinct yellowing between the veins. Plants become dwarfed and symptoms usually occur in patches, and along the edges of paddocks.

Disease cycle

Close-up photo of field pea plant leavesTransmission

BYMV is transmitted by more than 50 aphid species in a non-persistent manner.

The main species worldwide are:

  • pea aphid (Acyrthosiphon pisum)
  • black bean aphid (Aphis fabae) (not found in Australia)
  • cotton aphid (Aphis gossypii)
  • foxglove aphid (Aulacorthum solani)
  • cabbage aphid (Brevicoryne brassicae)
  • green peach aphid (Myzus persicae)
  • corn aphid (Rhopalosiphum maidis).

Photo of a lupin crop with many yellowing plantsDuring surveys in Victoria the following BYMV vectors in pulse crops were detected:

  • blue green aphid (Acyrthosiphon kondoi)
  • cowpea aphid (Aphis craccivora)
  • foxglove aphid (Aulacorthum solani)
  • cabbage aphid (Brevicoryne brassicae)
  • green peach aphid (Myzus persicae).

In Western Australia, the following MYMV vectors have been reported (Berlandier et al., 1997):

  • blue green aphid (Acyrthosiphon kondoi)
  • cowpea aphid (Aphis craccivora)
  • green peach aphid (Myzus persicae)
  • dock aphid (Brachycaudus rumexicolens)
  • turnip aphid (Lipaphis pseudobrassicae)
  • corn aphid (Rhopalosiphum maidis)
  • oat aphid (Rhopalosiphum padi)
  • grain aphid (Sitobion miscanthi)
  • spotted alfalfa aphid (Therioaphis trifolii forma maculata).

The virus is also transmitted through seed of most temperate pulses including:

  • faba beans
  • field peas
  • lentils
  • lupins
  • through seed of a number of forage legumes and clovers.

In Victoria, the department found 18% of lentil seed lots tested had BYMV infections of 0.1-0.9%.

In Western Australia, the following BYMV seed transmission was reported (McKirdy et al., 2000):

  • yellow and white lupins 3-6%
  • field peas 0.3-0.8%
  • faba beans 0.4%
  • lathyrus 0.1-0.2%
  • vetch 0.5%.

Seed transmission of BYMV in medics, clovers and weeds has also been reported in Western Australia (McKirdy and Jones 1995):

  • hexham scent (Melilotus indica) (0.5%)
  • burr medic (Medicago polymorpha) (0.9%)
  • barrel medic (Medicago truncatula) (0.3%)
  • hare's foot clover (Trifolium arvense) (0.1%)
  • hop clover (Trifolium campestre) (0.2%)
  • cluster clover (Trifolium glomeratum) (0.05%).

Host range

The host range of BYMV is wide and not limited to Fabaceae. The virus is reported to infect nearly 200 species in 14 families.

Temperate pulse hosts include:

  • chickpeas
  • faba beans
  • field peas
  • lentils
  • lupins.

Temperate legume pasture hosts include:

  • lathyrus
  • lucerne
  • vetch
  • medic and clover species.

BYMV has a number of subtropical and tropical pulse hosts including:

  • soybeans
  • peanuts
  • French beans
  • legume pasture hosts.

It also infects ornamental hosts, the most common being gladiolus species.

Economic importance

In New South Wales a small survey showed that faba bean crops had an average within-crop incidence of BYMV of 26% of plants (ranging from 1-63%) (van Leur et al. 2002).

Field surveys in Western Australia in 1998-1999 showed that some faba bean and field pea crops were infected with BYMV and the within crop virus incidences were 31% and 18% respectively (Latham and Jones 2001).

Plot trials in Western Australia showed that lupins infected with the necrotic strain of BYMV can have grain yields reduced by 95% (Cheng and Jones 1999). Seed yield losses recorded on subterranean clover due to infection with BYMV were 58-76% (Jones 1992).

Pulse crop surveys in the last 10 years indicate that BYMV is a minor problem, but in some years the virus levels may be high in lupins, field peas and faba beans in south eastern Australia.

Percentage of pulse crops infected with bean yellow mosaic virus in south eastern Australia and within crop virus incidence

Victoria — Lentil

Year

% of sampled crops infected

Within crop virus incidence range %

2000

2

1

2001

Virus not found

Virus not found

2004

Virus not found

Virus not found

2006

Crop not sampled

Crop not sampled

2007

Virus not found

Virus not found

Victoria — Faba bean

Year

% of sampled crops infected

Within crop virus incidence range %

2000

6

15

2001

Virus not found

Virus not found

2004

9

2

2006

Crop not sampled

Crop not sampled

2007

20

1 to 7

Victoria — Field pea

Year

% of sampled crops infected

Within crop virus incidence range %

2000

Virus not found

Virus not found

2001

Virus not found

Virus not found

2004

Virus not found

Virus not found

2006

10

3

2007

31

1 to 24

Victoria — Lupin

Year

% of sampled crops infected

Within crop virus incidence range %

2000

Virus not found

Virus not found

2001

Virus not found

Virus not found

2004

Crop not sampled

Crop not sampled

2006

Crop not sampled

Crop not sampled

2007

75

5 to 11

South Australia — Lentil

Year

% of sampled crops infected

Within crop virus incidence range %

2001

Virus not found

Virus not found

2003

Virus not found

Virus not found

2004

Virus not found

Virus not found

2005

Virus not found

Virus not found

2006

Virus not found

Virus not found

2007

33

1 to 4

South Australia — Faba bean

Year

% of sampled crops infected

Within crop virus incidence range %

2001

Crop not sampled

Crop not sampled

2003

Virus not found

Virus not found

2004

Virus not found

Virus not found

2005

Virus not found

Virus not found

2006

Virus not found

Virus not found

2007

5

1

South Australia — Field pea

Year

% of sampled crops infected

Within crop virus incidence range %

2001

Crop not sampled

Crop not sampled

2003

Virus not found

Virus not found

2004

Virus not found

Virus not found

2005

Virus not found

Virus not found

2006

Virus not found

Virus not found

2007

18

2

South Australia — Lupin

Year

% of sampled crops infected

Within crop virus incidence range %

2001

Crop not sampled

Crop not sampled

2003

Crop not sampled

Crop not sampled

2004

Crop not sampled

Crop not sampled

2005

Crop not sampled

Crop not sampled

2006

Virus not found

Virus not found

2007

Virus not found

Virus not found

New South Wales — 2006 Southern

Crop

% of sampled crops infected

Within crop virus incidence range %

Lentil

Crop not sampled

Crop not sampled

Faba bean

Virus not found

Virus not found

Field pea81
Lupin

Crop not sampled

Crop not sampled

In 2009, chickpea surveys were conducted in Victoria, South Australia, Southern and Northern NSW. BYMV was not found in any chickpea crop sampled.

Management

Seed is considered to be one of the main sources of BYMV, therefore sowing virus tested seed is recommended and commercial seed tests are available.

BYMV causes heavy losses in narrow leafed lupins, so only virus tested seed is recommended for sowing. Virus resistant lupin varieties are now available in Western Australia.

BYMV infected pastures are another major source of the virus, which is then spread to crops by aphids. Chemical control of aphids is not an effective method for controlling non-persistently transmitted viruses such as BYMV.

Pulse crops should be sown away from legume pastures to minimise the spread of BYMV. The spread of virus can also be reduced by controlling weed hosts in and around paddocks.

Further references

Contact

Dr Piotr Trebicki
Virologist — Horsham
(03) 4344 3111

Field Crops Pathology
Grains Innovation Park
110 Natimuk Rd
Horsham 3400
(03) 4344 3111

Or call the Customer Service Centre, 136 186

Image credits

Figure 2 photograph courtesy of Safaa Kumari ICARDA

Figure 3 photograph courtesy of Joop vaLeur, DPI NSW

Acknowledgments

Mohammad Aftab, Angela Freeman, Frank Henry. Support by the Grains Research and Development Corporation is gratefully acknowledged.

Page last updated: 21 Jun 2021