Crops
During spring and summer, insecticides can be used by landholders to control locust infestations that could damage crops.
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.
Even slight damage to grain crops could justify the costs of control.
As a general rule, hopper and adult numbers should be closely monitored, and if any damage is seen, then spraying should be commenced immediately.
The Grain Industry Association of Western Australia (GIWA) and Grain Trade Australia (GTA) have receival standards for field insects which include grasshoppers/locusts. The CBH Harvest Guide is available from the CHB website.
Comply with withholding periods for any insecticides sprayed on crops.
Management options
- Assess how much of the cropping program and individual crops are at risk.
- Canola after leaf drop – low risk
- Lupins pod bronzing – low risk
- Pulses pod yellowing – low risk
- Cereal completely dried off – low risk
- Conduct a cost/benefit analysis of locust control.
- Take into consideration the cost of running over the crop (crop damage) with a boomsprayer versus application by a mister or aircraft.
- Consider how long it will take to spray using a boomsprayer versus application by a mister or aircraft.
- Limit swath width of misters to 50m.
- Consider crop desiccation in mid-October in an effort to make crops unattractive to swarming adults.
- If you consider it necessary to spray for locusts refer to registered insecticides web page for chemical options and rates.