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Potential impact of fall armyworm on sweetpotato

Fall armyworm has a strong preference for maize, sweet corn, sorghum, rice and grass crops. Under high pest pressure, sweetpotato crops can be infested, and defoliation may occur.

Sweetpotato is not a preferred host of fall armyworm, so the potential for damage to sweetpotato crops is unclear. Some rotation crops used in sweetpotato farming systems may be greatly affected. Sorghum, corn and some tropical and subtropical grasses are known hosts, while sugarcane may suffer damage under high fall armyworm pressure.

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

What to look for

Look for egg masses and small and large larvae. Leaf damage can be windowing, tattered leaf margins, skeletisation, or defoliation of leaves.

Fall armyworm damage may be confused with damage caused by other caterpillars.

There are already species of armyworm that look similar to fall armyworm present in Australia, so correct identification is important in determining the risk and response.

How to manage an outbreak

Early detection is essential. Regularly check your crops for egg masses, larvae and damage. Pay particular attention to sweetpotato nursery beds for pest damage and to ensure you do not transfer the pest to newly planted crops.

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.

Overseas, fall armyworm populations have developed resistance to insecticides when similar groups of chemistries are frequently sprayed in crops. It is essential to consider the potential impact of insecticides on natural enemies and the implications for development of chemical resistance when developing spray programs.

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 sweetpotato fall armyworm fact sheet.