Infection can cause general stunting of plants and severe yield loss. The only economic control measure is by rotation with non-host plants such as grasses. Bacterial wilt Bacterial wilt can cause serious losses in the eastern States but has not yet appeared in Western Australia. Symptoms include yellow-green foliage and stunted plants. Leaf margins are often 'cupped' or curled upwards.
Symptoms can appear on single plants scattered throughout the stand or on patches of plants.
Contact Agriculture Western Australia if bacterial wilt is suspected. Virus diseases infecting lucerne in Australia include alfalfa mosaic, white clover mosaic, lucerne Australian latent, lucerne Australian symptomless, lucerne transient streak, bean yellow mosaic, cucumber mosaic, beet western yellows, red clover necrotic mosaic and subterranean clover red leaf viruses. So far only alfalfa mosaic and white clover mosaic viruses have been reported infecting lucerne in Western Australia through bean yellow mosaic, beet western yellows, cucumber mosaic and subterranean clover red leaf viruses have been found here on annual pasture legumes. Alfalfa mosaic virus is widespread in lucerne in this State and causes significant herbage production losses. The distribution and importance of the other viruses in lucerne in Western Australia has yet to be determined.