Lucerne flea

As suggested in the last edition of PestFacts, there has been a large amount of lucerne flea (Sminthurus viridis) activity in the last week. John McCredden (North West Ag Services) reports lucerne flea have been the main pest problem thus far in the northern Wimmera and southern Mallee. Most damage has occurred in dry sown vetch and to a lesser extent medic pasture and volunteer cereals, particularly on heavier soil types. John is recommending an organophosphate with knockdown prior to sowing to minimize potential issues during establishment where this pest is a concern.

Brooke Thompson (Crop Facts) has also reported high numbers of lucerne flea in paddocks in the northern and central Wimmera that are about to be sown. Brooke says lucerne flea have already caused damage to weed and volunteer crop plants. Activity has not been restricted to crop borders or defined patches.

Lucerne flea has been a major pest problem in the Wimmera for the last few seasons, affecting pulses and cereals. A consultant from Donald reports lucerne flea on emerging canola seedlings and stubble paddocks in many parts of the Wimmera. Farmer Chris Brain has also observed lucerne flea attacking canola in the Western district around Willaura.

John Sykes (John Sykes Rural Consulting) has seen lucerne flea around the South West Slopes of NSW. Lucerne flea have been found in various pastures and emerging canola. In pasture, lucerne fleas are causing significant damage to approximately 1 in 5 paddocks.

Keep a good look out in paddocks, particularly with seedling canola, lupins and clover. Lucerne fleas are up to 3mm long as adults and ‘spring’ off vegetation when disturbed. The pests work up the plants from ground level, eating tissue from the underside of the foliage. Theyleave distinctive feeding damage of "windows" of transparent leaf membrane. Crops are most likely to have problems where they follow a weed infested crop or a pasture in which lucerne flea has not been controlled. Consider implementing control in the season prior to sowing to minimise numbers.

Snout mites (which have orange bodies and legs) are effective predators of lucerne fleas, particularly in pastures, where they can prevent outbreaks. The complex of beneficial species (including snout mites) should be assessed before deciding on control options for lucerne flea. If spraying is required, do not use synthetic pyrethroids.