Widespread lucerne plantings in Western Australia can provide a ‘green bridge’ for legume diseases and pests to survive over summer.

This can cause not only losses in production of lucerne itself, but also nearby pulse and lupin crops and annual pastures, according to Professor Roger Jones of the Department of Agriculture.

In a GRDC-funded survey of three year old lucerne pastures, 30 of the 31 pastures sampled were infected with alfalfa mosaic virus and 11 with luteoviruses.

“Sowing untested lucerne seed risks introducing seed-borne diseases, with initial tests revealing seed-borne virus contamination is high in lucerne seed stocks.

“Testing of lucerne seed to be sown on-farm is therefore recommended to ensure that healthy seed with less than 0.1 per cent infection is sown,” Professor Jones said.