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Lucerne flea

There have been several reports of lucerne flea hatchings in parts of Victoria and southern New South Wales. Agronomist, Brendan Reinheimer (Elders), reports that lucerne flea nymphs and adults are present in high numbers across many paddocks around Charlton, St. Arnaud and Whycheproof, in the Wimmera district of Victoria. Most activity has been observed in barley and vetch crops. In many instances, spraying will be required to protect emerging seedlings.  Agronomist, Ben Batters (Elders), has reported lucerne flea attacking emerging barley seedlings around St. Arnaud. Agronomist, Brett McEwan (Elders), reported lucerne flea in a barley crop near Kerang, in the Mallee district of Victoria. There is some evidence of feeding damage, although Brett says the low numbers suggest control is not warranted at the present time. Consultant, Sandy Biddulph (Biddulph Rural Consulting), says lucerne flea have also emerged around Cootamundra, in the South West Slopes of New South Wales.

Lucerne flea hatch following periods of good soaking autumn or winter rains. Adult lucerne fleas are approximately 3 mm long and appear yellow-green to the naked eye although their globular abdomens are often a mottled pattern of darker pigments. They ‘spring off’ vegetation when approached which can make detection difficult. Click here for images of the lucerne flea.

The pests work up the plants from ground level, eating tissue from the underside of the foliage. Feeding results in the appearance of distinctive transparent ‘windows’. Severe damage can kill young seedlings. Crops, particularly canola and pulses, should be inspected frequently at and immediately following emergence, when they are most susceptible to damage. 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. In crops, spot spraying is generally all that is required; do not blanket spray unless the infestation warrants it. If spraying is required, do not use synthetic pyrethroids.

Snout mites (which have orange bodies and legs) are effective predators of lucerne fleas, particularly in pastures, where they can prevent pest outbreaks. The complex of beneficial species (including snout mites) should be assessed before deciding on control options. Click here for images of snout mites.

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