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Lucerne flea

Lucerne flea (Sminthurus viridis) continues to be problematic this season. Agronomist, Phil Stoddart (Landmark), has reported lucerne flea causing damage to many crops around Mudgee, in the Central Tablelands district of New South Wales. Phil says canola and emerging pastures have experienced the biggest problems with lucerne flea. Many paddocks have been sprayed with insecticides to manage lucerne flea numbers, which Phil says, are the highest he can recall seeing around Mudgee.

We have also received reports of lucerne flea causing damage to emerging crops in the Western district of Victoria and the South West Slopes district of New South Wales. In several cases, foliar sprays have been necessary even though insecticide seed treatments have been used. Lucerne fleas are also known to be present across many other regions of Victoria and New South Wales, and are still causing issues for many growers.

Growers should continue to monitor crops for signs of lucerne flea damage. Lucerne fleas are generally a problem in regions with loam/clay soils. Paddocks are most likely to have problems where they follow a weed-infested crop or pasture in which lucerne flea has not been controlled. Adult lucerne fleas are approximately 3 mm in length and appear yellow-green to the naked eye, although their globular abdomens are often a mottled pattern of darker pigments. Lucerne fleas ‘spring-off’ vegetation when disturbed. They have a wide host range and will attack most broad-acre crops, including canola, lucerne, pastures, cereals and some pulses.

If chemical control is required, do not use synthetic pyrethroids. In paddocks where damage is likely, a border spray may be sufficient to prevent movement of lucerne fleas into the crop from neighbouring paddocks. As lucerne fleas are often distributed patchily within crops, spot spraying (rather than spraying the entire paddock) is often all that is required.

Click here for images of lucerne fleas.

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