Temperate pulse viruses: bean leafroll virus

Yellow, stunted faba bean plantsBean leafroll virus (BLRV), also known as pea leafroll virus, is distributed worldwide but was not reported in Australia until 1999.

The virus is transmitted by aphids in a persistent manner but not through inoculation of sap or through seed.

Virus infected legume plants show yellowing, leaf rolling and significant reduction in pod setting. Yield losses of 50 to 90 per cent have been reported in Europe.

The natural host range is limited to the Fabaceae family.

The virus infection may be minimised by early spraying for aphids. Other control measures include sowing virus resistant varieties, aphid monitoring and spraying and eradication of virus source plants.

What to look forHealthy lentil plant next to a much smaller, yellower infected plant

The general symptoms of BLRV on pulses are:

  • interveinal chlorosis
  • yellowing
  • stunting
  • leaf rolling.

These symptoms could easily be confused with subterranean clover stunt virus (SCSV) or other luteoviruses such as beet western yellows virus (BWYV) and subterranean clover red leaf virus (SCRLV) or nutrient stress symptoms.Healthy chickpea plant next to a much smaller, yellower infected plant

Symptoms on specific crops are:

  • faba beans develop interveinal yellowing, top yellowing, upward rolling of leaves and stunting of plants
  • lentils develop yellowing, small leaves and stunting of plant
  • chickpeas develop yellowing and stunting of plants
  • vetch develops yellow leaves and tip necrosis
  • lucerne is usually symptomless but bright yellow vein clearing may be associated with infection
  • field peas develop stunting, yellowing of young leaf tips, and sometimes downward leaf rolling
  • sub-clover and crimson clover develop interveinal yellowing followed by reddening at margins of older leaves
  • white clover develops yellowing, reddening and rolling of leaves.

Disease cycleHealthy fetch plant next to an infected plant with brown and yellow leaves

Transmission

BLRV is transmitted by several aphid species in a persistent manner. It is not transmitted mechanically and not through seed.

Pea aphid (Acyrthosiphon pisum) is the principal vector of BLRV. The following species are also reported as vectors of BLRV:

  • foxglove aphid (Aulacorthum. solani)
  • cowpea aphid (Aphis craccivora)
  • black bean aphid (Aphis fabae) (not found in Australia)
  • cotton aphid (Aphis gossypii)
  • potato aphid (Macrosiphum euphorbiae)
  • vetch aphid (Megoura viciae)
  • green peach aphid (Myzus persicae).

In surveys the two most common aphid vectors of BLRV found on faba bean, vetch and lentil are cowpea aphid (Aphis craccivora) and green peach aphid (Myzus persicae).

Host range

The natural host range of BLRV is limited to the Fabaceae family.

It infects temperate pulses (faba bean, field pea, chickpea, lentil, vetch), other legumes (soybean, sweet pea, French bean, cowpea) and pastures (lucerne, white clover, red clover and subterranean clover).

In experiments BLRV is transmitted to 3 of 17 non-legume hosts (Ashby 1984).

Economic importance

In Europe 50 to 90 per cent yield losses have been reported (Heathcote and Gibbs 1962). In NSW up to 37 per cent incidence of BLRV has been reported on faba beans (Van Leur et al. 2002).

Surveys of pulse crops in the last 10 years indicate that BLRV is an important virus of faba bean and field pea crops in south eastern Australia.

Table 1: Percentage of pulse crops infected with bean leafroll virus in south eastern Australia and within crop virus incidence

Victoria — Lentil

Year

% of sampled crops infected

Within crop virus incidence range %

2004

16

1 to 2

2006

Crop not sampled/tested

Crop not sampled/tested

2007

38

1 to 2

2009

Crop not sampled/tested

Crop not sampled/tested

Victoria — Fababean

Year

% of sampled crops infected

Within crop virus incidence range %

Victoria

  

2004

27

1 to 13

2006

Crop not sampled/tested

Crop not sampled/tested

2007

7

2

2009

Crop not sampled/tested

Crop not sampled/tested

Victoria — Chickpea

Year

% of sampled crops infected

Within crop virus incidence range %

2004

Virus not found

Virus not found

2006

Crop not sampled/tested

Crop not sampled/tested

2007

Virus not found

Virus not found

2009

8

1

Victoria — Field pea

Year

% of sampled crops infected

Within crop virus incidence range %

2004

Virus not found

Virus not found

2006

50

2 to 87

2007

62

1 to 5

2009

Crop not sampled/tested

Crop not sampled/tested

South Australia — Lentil

Year

% of sampled crops infected

Within crop virus incidence range %

2003

Virus not found

Virus not found

2004

29

1 to 2

2005

Virus not found

Virus not found

2006

60

1 to 2

2007

22

4 to 6

2009

Crop not sampled/tested

Crop not sampled/tested

South Australia — Fababean

Year

% of sampled crops infected

Within crop virus incidence range %

2003

4

4

2004

65

1 to 27

2005

Virus not found

Virus not found

2006

100

18 to 53

2007

25

3 to 10

2009

Crop not sampled/tested

Crop not sampled/tested

South Australia — Chickpea

Year

% of sampled crops infected

Within crop virus incidence range %

2003

Virus not found

Virus not found

2004

Crop not sampled/tested

Crop not sampled/tested

2005

Crop not sampled/tested

Crop not sampled/tested

2006

Virus not found

Virus not found

2007

Virus not found

Virus not found

2009

8

2

South Australia — Field pea

Year

% of sampled crops infected

Within crop virus incidence range %

2003

Virus not found

Virus not found

2004

11

1 to 2

2005

Virus not found

Virus not found

2006

Virus not found

Virus not found

2007

27

1 to 3

2009

Crop not sampled/tested

Crop not sampled/tested

New South Wales — Lentil

Year

% of sampled crops infected

Within crop virus incidence range %

2006 Southern

Crop not sampled/tested

Crop not sampled/tested

2009 Southern

Crop not sampled/tested

Crop not sampled/tested

2009 Northern

Crop not sampled/tested

Crop not sampled/tested

New South Wales — Fababean

Year

% of sampled crops infected

Within crop virus incidence range %

2006 Southern

100

28 to 42

2009 Southern

Crop not sampled/tested

Crop not sampled/tested

2009 Northern

Crop not sampled/tested

Crop not sampled/tested

New South Wales — Chickpea

Year

% of sampled crops infected

Within crop virus incidence range %

2006 Southern

Crop not sampled/tested

Crop not sampled/tested

2009 Southern

29

1 to 5

2009 Northern

24

1 to 9

New South Wales — Field pea

Year

% of sampled crops infected

Within crop virus incidence range %

2006 Southern

63

1 to 50

2009 Southern

Crop not sampled/tested

Crop not sampled/tested

2009 Northern

Crop not sampled/tested

Crop not sampled/tested

In 2006 in South Australia 88 per cent of lupin crops were infected having within crop incidence of 3 to 15 per cent. In 2007 in South Australia 20 per cent of lupin crops were infected having within crop incidence of 5 per cent.

Management

  • Crop monitoring, and spraying for aphids is essential if the population of aphids develops early in the season.
  • Disease resistant varieties should be sown in the high incidence areas. Breeding of pulses for BLRV resistance is being undertaken at NSW-DPI, Tamworth. Currently, field trials are being conducted on virus screening nurseries to find BLRV resistant cultivars but no resistant varieties have been released yet.
  • Virus reservoir weeds and volunteer legume hosts should be eradicated.
  • Legume crops should be rotated with cereal crops to reduce the virus and vector sources.

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

Figures 2 and 3 courtesy of Safaa Kumari ICARDA.

Acknowledgments

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

Page last updated: 21 Jun 2021