Farmers can loose up to 25 per cent yield in their field pea crop if they don’t control spread of pea seed-borne mosaic virus. Pictured is a crop where 6.5% infected seed was sown.

Farmers are losing up to 25 per cent of yield in field pea crops due to the spread of pea seed-borne mosaic virus.

Research by the Department of Agriculture and Food in 2005 and 2006 indicated that sowing seed with more than one per cent virus infection resulted in the spread of virus throughout the crop and led to substantial yield loss

Department research officer Brenda Coutts said the trial results showed sowing plots with as little as eight per cent infected seed resulted in the virus spreading to 35 per cent of the crop and overall yield losses of 13 per cent.

Ms Coutts said pea seed-borne mosaic virus caused a seed-borne and aphid-borne disease.

“Symptoms in field peas are often confused by growers with those of nutrient deficiency or herbicide damage, and as a result are under-estimating its economic impact,” Ms Coutts said.

“In past surveys in WA, most commercial field pea seed stocks were found to be infected at varying levels with the virus. 

“The infected seedlings act as a virus source within crops and allow it to easily spread by aphids to healthy plants, therefore, it is very important for growers to be aware of their seed condition prior to sowing.”

Mr Coutts said the extent of yield losses depended on a number of factors including the growing conditions which affect aphid arrival and virus spread, as well as the initial infection level in seed. 

“Crops with high virus levels were found to have subsequently high virus levels in the harvested seed,” she said.

“The virus is difficult to manage in field pea crops, with the most effective strategy being to have seed tested prior to sowing and to plant seed with the lowest amount of virus.

“However, for seed production blocks, the application of insecticides throughout the growing season to control aphids and final crop virus levels can be useful."

“This is why it is recommended that growers have their seed tested before sowing each year.”

A virus testing service for field pea seed samples is 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 and Food in South Perth (telephone 9368 3333).

Further information will be available at Agribusiness Crop Updates being held at Burswood on February 14 and 15.

Crop Updates is supported by the Grains Research and Development Corporation.