Western Australian field pea growers have been advised to get samples of their seed tested for Pea seed-borne mosaic virus infection to avoid substantial yield losses in virus-infected crops.

Latest research by the Department of Agriculture has revealed for the first time that infection with Pea seed-borne mosaic virus causes substantial yield losses in field pea crops.  It also impairs the quality and value of harvested seed.

Department principal plant virologist Roger Jones said this year’s research suggested growers should source field pea seed with less than one per cent virus infection for sowing.

Dr Jones said commercial field pea seed stocks were often contaminated to different extents with the virus.

“Field experiments at Avondale and Badgingarra in 2005 demonstrated 23-25 per cent yield losses when field pea seed with 6.5 per cent infection was sown,” Dr Jones said.

“The experiments also included a range of other simulated infection levels in the sown seed, and the extent of virus spread and yield losses varied depending on the initial seed infection level.  

“Sowing seed infected at 1.1-1.8 per cent caused significant yield losses of 15-18 per cent, but sowing seed infected at 0.3-0.9 per cent caused no significant loss.”

Dr Jones said the virus was transmitted by seed and aphids in field peas. Sowing infected seed resulted in dispersion of infected seedlings throughout the crop and further infection of surrounding plants due to virus spread to healthy plants by aphids.

“Infected areas can be seen as depressions in the crop that contain stunted, pale green plants. When widespread infection occurs early in the life of the crop substantial yield losses result,” he said.

“The virus also damages the quality of the seed harvested by causing brown rings in the seed surface, seed malformation, smaller seed size and seed splitting.”

A virus testing service for field pea seed samples was available to determine whether commercial seed stocks were suitable for sowing. The samples should be sent to AGWEST Plant Laboratories at the Department of Agriculture in South Perth (telephone 9368 3333).