Stage three to five instar nymphs in wheat in a previous plague.
PHOTO: Australian Plague Locust Commission
Western Australian locusts are getting ahead of themselves – failing to remember plagues are traditionally thought to occur once every decade. Locust hatchings this September are just five years after the previous plague in WA in 2007.
Simon Merewether, Department of Agriculture and Food, WA (DAFWA) plague locust operations manager, says there could be a number of reasons for the increased frequency of locust hatchings – changing weather patterns, low summer rainfall and widespread uptake of minimum-till cropping, resulting in less disturbance of beds.
Whatever the cause, he has urged growers to be vigilant this spring-summer period in monitoring and controlling locusts. Hatchings reported in the Yilgarn and Lake Grace shires in September and predictions for a spring emergence of locusts in the southern and south-eastern parts of WA indicate they could be a problem over the harvest period.
Autumn monitoring indicated high-density hatchings may occur in parts of the Ravensthorpe, Jerramungup, Gnowangerup, Esperance (Cascades), Kent, Broomehill-Tambellup, Lake Grace and Katanning shires. Growers are also advised to monitor locusts through summer to identify potential breeding patterns for 2013.
“Control of locusts on-farm is a landholder responsibility and it is in their economic interest to do so,” Mr Merewether says.
“There are registered insecticides available commercially and DAFWA can provide advice on control options.” In recognised high-density areas, DAFWA can help with a locally coordinated approach to controlling locusts.
Crops such as wheat, barley and particularly oats are susceptible to damage from locusts. The susceptibility of lupins, canola, chickpeas, field peas and faba beans is uncertain, but all could potentially be attacked while they remain green.
Established green crops tend to be avoided by hoppers, although the edges of crops can be damaged. Crops that are beginning to dry off when locusts begin to fly are susceptible to damage. Locusts cause little if any damage to crops that have dried off.
As a general rule, hopper and adult numbers should be closely monitored, and if any damage is seen spraying should start immediately.
The CBH Group has receival standards for locust body parts and grain damaged by locust feeding. Growers are reminded to comply with withholding periods for any insecticides sprayed on crops.
The 2012 Locust Assistance Scheme has been established to provide eligible landholders with a $3-per-hectare subsidy to control locusts in commercial pastures. However, there is no subsidy for crop spraying.
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