Warning to check crops for ‘delayed’ locust hatchings as locust plague continues

Broadacre farmers have been urged to keep an eye out for plagues of locusts with reports of hatchings and movements coming in thick and fast across the Wheatbelt.

The Department of Primary Industries and Regional Development issued a warning to grain growers this morning, saying protracted rainfall and mild spring conditions had combined to “delay hatchings” in some parts of the grainbelt.

Australian plague locust activity as been reported at on the border of the Mid West and the Wheatbelt at Perenjori, Coorow and Eneabba, at south of there at Wialki and Coomberdale, and in the eastern Wheatbelt east to Beacon, Southern Cross and Burracoppin.

DPIRD research scientist Svetlana Micic said while many crops were haying off and would not be at risk to locusts, later sown crops and green pastures could still be vulnerable — especially if there is further rainfall.

“Crops that are beginning to dry off when locusts begin to fly are especially susceptible to damage,” she said.

“Recent rainfall, combined with mild weather is expected to increase the availability of green feed, particularly along roadside verges and paddock edges, which could provide sufficient food reserves for locusts to reach the next growth stage.”

There have been limited reports of locust activity from other areas of the grainbelt, although Ms Micic said if wet and mild conditions persisted, locusts could be an issue for landholders further south.

Ms Micic said it was important for landholders to monitor hopper and adult locust numbers and to undertake control measures, if necessary.

“Locusts hatch at variable times so it is important for growers to monitor crops and pastures that are still green to determine if and when to spray,” she said.

“Most activity would be expected in pastures so look for early hatchings and hatching egg beds in bare patches, such as around dam banks, road catchments and along fence lines.”

Ms Micic said the department recommended treating pastures, if the cost of controlling locusts exceeded the cost of replacing feed.

Ms Micic said once locusts were on the wing, they could be difficult to control.

“The threshold for treating pastures is 20 hoppers per square metre or 10 adult locus per square metre” she said.

“To achieve effective control, the best time to apply an insecticide is when locusts are at the hopper stage, ideally at the third to fourth instar growth stage, when they are one to one and a half centimetres long.

“Landholders who observed locusts on their properties in autumn need to be particularly vigilant, as there are likely to be egg beds that have hatched.”

Landholders are reminded to comply with label regulations when treating pastures and crops, particularly the withholding periods.

While it is up to landholders to control locusts on their properties, DPIRD plans to continue to monitor APL over spring and summer and provide advice on treatment measures.

Landholders are encouraged to report observations to DPIRD’s free weekly PestFax newsletter, which includes a PestFax Map of locust activity, to aid regional intelligence using the PestFax Reporter app.

To find out more, visit agric.wa.gov.au/season2021.