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Temperate Pulse Viruses: Bean Yellow Mosaic Virus (BYMV) | AG1266 |
Mohammad Aftab and Angela Freeman, Horsham
November 2006
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Bean 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.
Host Range
The host range of BYMV is wide and not limited to Fabaceae. The virus is reported to infect neally 200 species in 14 families. Temperate pulse hosts include chickpeas, faba beans, field peas, lentils and lupins. Temperate legume pasture hosts include lathyrus, lucerne, vetch and medic and clover species. BYMV has a number of sub-tropical and tropical pulse hosts, including soybeans, peanuts and French beans as well as legume pasture hosts. It also infects ornamental hosts, the most common being gladiolus species.
Symptoms
Symptoms of BYMV in the major temperate pulses and pasture legumes are as follows:
- Desi chickpeas develop apical necrosis, reddening, plant stunting and premature senescence.
- Kabuli chickpeas develop apical necrosis, yellowing, plant stunting and premature senescence.
- Fababeans develop veinal 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 and 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).
- Lentils develop mild mosaic, light green or yellow leaves, 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.
Economic Importance
During our pulse surveys in south eastern Australia from 2000-2005, BYMV infections were uncommon and found in less than 1% of surveyed crops. However, BYMV was sometimes found in faba bean crops and occasionally in peas with within crop virus incidences of 1-15% and up to 7% respectively. In NSW, 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 WA in 1998-1999 showed that some faba bean and field pea crops were infected with BYMV and the within crop virus incidences were 1-31% and 1-11% respectively. Plot trials in WA showed that lupins infected with the necrotic strain of BYMV can have grain yields reduced by 95%.
Transmission
BYMV is transmitted by more than 50 aphid species in a non-persistent manner: the main species are Acyrthosiphon pisum, Aphis fabae, A. gossypii, Aulacorthum solani Brevicoryne brassicae, Myzus persicae and Rhopalosiphum maidis. During our surveys in Victoria we have found the following BYMV vectors in pulse crops: Acyrthosiphon kondoi, Aphis craccivora, Aulacorthum solani, Brevicoryne brassicae and Myzus persicae. In WA Acyrthosiphon kondoi, Aphis craccivora, Myzus persicae, Brachycaudus rumexicolens, Lipaphis erysimi, Rhopalosiphum maidis, R. padi, Sitodion miscanthi and Therioaphis trifolii have been reported as BYMV vectors.
The virus is also transmitted through seed of most temperate pulses, including faba beans, field peas, lentils, and lupins and through seed of a number of forage legumes and clovers. In Victoria, we found 18% of lentil seed lots tested had BYMV infections of 0.1-0.9%. In WA, the following BYMV seed transmission is reported: yellow and white lupins 3-6%, field peas 0.3-0.8%, faba beans 0.4%, lathyrus 0.1-0.2% and vetch 0.5%.
Seed transmission of BYMV in medics and clovers has also been reported in WA as follows: Melilotus indica (0.5%), Medicago polymorpha (0.9%), M. truncatula (0.3%), M. indica (1%), Trifolium arvense (0.1%), T. campestre (0.2%) and T. glomeratum (0.05%).
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 (see AG1250: Seed Health Testing in Pulse Crops). 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 WA. 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 from in and around paddocks.
More Information |
Figure 1. Faba beans develop vein yellowing, green or yellow mosaic
Figure 2. Irregular staining of faba bean seeds infected with BYMV (right) healthy seeds (left) (Photograph courtesy of Safaa Kumari ICARDA)
Figure 3. Field peas develop systemic mosaic and, interveinal yellowings on the basal leaves (Photograph courtesy of Joop vaLeur DPI NSW)
Figure 4. Narrow leaf lupins develop yellowing, followed by necrosis of growth tips and death of plant (right). Healthy plant (left)
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Jones RAC (1992). Australian Journal of Agricultural Research 43, 1229-1241.
Latham LJ, Jones RAC (2001). Australian Journal of Agricultural Research 52, 397-413.
McKirdy et al. (2000). Australian Journal of Agricultural Research 51, 325-345.
McKirdy SJ, Jones RAC (1995) Australian Journal of Agricultural Research 46, 135-152.
Van Leur J, Makkouk K, Freeman A, Schilg M (2002).
Proceedings of the 8th International Congress of Plant Pathology, 2-7 February, Christchurch, New Zealand, p 265.
Acknowledgement
Thanks to Wendy Bedggood for assisting in preparing this Note.
The advice provided in this publication is intended as a source of information only. Always read the label before using any of the products mentioned. The State of Victoria and its employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication.
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