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Update on Australian plague locusts

Australian plague locusts (Chortoicetes terminifera) are continuing to cause extensive damage to autumn sown cereal, canola and fodder crops across north-western Victoria, south-western New South Wales and parts of South Australia. The current level of swarming activity remains very high, and is somewhat unusual for this time of year. According the most recent update from the Australian Plague Locust Commission (APLC), swarm densities were predicted to decline during May. However, continued dry and mild weather conditions over recent weeks appear to have facilitated ongoing locust activity.

In addition to the mature locust swarming activity, there have been sightings of young locust nymphs this week in parts of New South Wales and north-western Victoria. Senior Technical Officer, Ken Henry (SARDI), says these isolated hatchings are unusual and may not survive over the winter months. The majority of eggs laid in recent weeks are diapause eggs and will remain in the soil over winter, hatching out in spring. Ken says locust numbers are slowly declining with the cold weather and the occurrence of frosts in many regions. It is now highly unlikely that there will be any further large migration of locust swarms from northern areas.

As a result of locust activity and egg-laying to date, there is expected to be a serious widespread nymph infestation in spring. Areas affected include much of New South Wales, northern Victoria and eastern South Australia. A plague situation consisting of high locust densities across several states may continue throughout spring and into summer if nymph survival in spring is high. The Australian Plague Locust Commission (APLC) has published predicted locust hatching dates in spring for various towns in New South Wales, Victoria and South Australia, based on the observed egg-laying dates from recent weeks. Hatching dates are available on the APLC website and some examples are: Mildura-Ouyen (VIC) - 7th October, Narrandera-Griffith (NSW) - 10th October, Swan Hill-Boort (VIC) - 16th October, Parkes-Cowra (NSW) - 18th October, and Wagga Wagga–Cootamundra (NSW) - 25th October.

In light of the ongoing locust issues this season, Rural Solutions SA have produced a sowing advice sheet for growers. For additional information refer to PestFacts Issue No. 1 or the APLC website.

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