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Potential impact of fall armyworm on wheat

Fall armyworm populations are unable to persist in regions where temperatures drop below 10°C. However, southerly migrations of fall armyworm from early autumn into winter cereal-growing regions may occur. In the event of such migrations, early-sown winter cereals may be at risk of fall armyworm infestation in some seasons.

Overseas, fall armyworm has rapidly developed pesticide resistance where subjected to repeated and prolonged use of insecticides.

What to look for

Look for small larvae 'windowing' in the leaves of establishing plants. Small larvae will be difficult to detect and may shelter on the ground around the base of the seedlings during the day. Regular crop checking is essential because larger larvae will quickly defoliate seedlings within a few days.

Larvae will continue to actively feed and defoliate plants until they complete their development, or cool conditions slow their activity. A severe frost can kill larvae.

Flea beetles and Spodoptera exigua can cause similar leaf damage. In southern regions, a suite of establishment pests can also cause similar leaf damage (e.g. common armyworm, pasture looper, slugs, lucerne flea). Correct identification of the cause of damage is critical.

How to manage an outbreak

Early detection is essential to prevent seedling loss. Regularly check your crops for insect activity and damage.

An integrated pest management approach is the key to the control of any pest. We are working with industry to identify strategies and tactics for the medium to long-term response.

Some insecticides used for the control of Helicoverpa armigera, other armyworms and caterpillar pests may provide some level of control of fall armyworm. Biocontrol agents released for Helicoverpa are also expected to have an impact on fall armyworm.

For any pesticide use for fall armyworm control, you must consider the implications for chemical resistance development in other pests that may be exposed (e.g. earthmites) and the potential impact on natural enemies.

The APVMA is currently assessing, as a priority, permit applications for the use of chemicals against fall armyworm in other crops. To check for the latest chemical permits applying to fall armyworm, use the APVMAs permit portal—search for 'fall armyworm' and tick the 'pest/purpose' option.

You should already have strong on-farm biosecurity measures to protect your crops from pests and diseases and should implement good farm hygiene for weed control to remove hosts that could build populations.

Be on the lookout and if you suspect fall armyworm, report it immediately by phoning 13 25 23.

Further information

Read the wheat fall armyworm fact sheet.