Australian plague locusts

Australian plague locusts caused significant damage to crops across many regions during autumn and spring last year and although populations are markedly lower this year, there is still potential for damage to emerging crops. Summer rainfall has created a green bridge and provided locusts with ample food to persist in high numbers between cropping seasons. Victorian state locust commissioner, Gordon Berg, says growers in areas that have been affected over the past 12 months should be aware of current locust activity in their region when sowing.

Growers should assess the risk status of their properties, and where necessary take steps to manage the risk of locust damage. Locust activity will continue to decrease as we approach winter, so delaying sowing time may help to ensure crops emerge after locusts die off. However this should be weighed up against the impact of missing the optimal sowing window.

Protecting crops from adult locusts is difficult, as they are highly mobile and tend to move away from ground-based machinery as it approaches. Should you decide to spray to protect emerging crops, the best time to treat locusts is when they are settled. Avoid chemical applications during the warmer parts of the day, and remember to check surrounding paddocks, particularly pastures. Insecticide seed treatments should only be used as part of other management strategies and not specifically to target locusts. For more information, refer to the publication: Australian Plague Locusts - autumn sowing 2011 or the APLC website.

Adult locusts that are currently flying or swarming are expected to remain active until late May, and low numbers may persist through winter. There is unlikely to be any significant immigration of locusts from northern regions in autumn. No further egg hatching is expected and the majority of eggs laid by the current generation will not hatch until October. In spring, there is a moderate probability of localised high-density nymphal bands forming in areas of Victoria where swarms were active after mid-March this year including, Bendigo, Boort-Charlton, St. Arnaud-Horsham and Ararat-Lake Bolac. In New South Wales, there is generally a low risk across most areas for significant hatchings in spring, apart from the Corowa-Oaklands area in the Riverina district where the risk is moderate.