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Potential impact of fall armyworm on cotton
At this early stage, it is difficult to know if fall armyworm will be a significant pest of cotton in Australia.
While not registered for the control of Spodoptera species, the Bollgard 3 varieties that are widely grown, are expected to provide incidental suppression of this pest.
The incidence of this pest may be similar to the native cluster caterpillar, Spodoptera litura, which can cause limited damage to tropical cotton crops in some seasons.
Similar to the United States of America, fall armyworm is expected to be more prevalent in Australia's tropical regions and could be less frequent in temperate areas further south.
Be vigilant in monitoring crops for excessive leaf damage and fruiting sites feeding. If damage does appear, it is important to obtain a clear identification of the larvae species likely to be causing the damage.
What to look for
Look for the presence of larvae that may be hatching on masses from egg clusters and monitor crops for excessive leaf damage and fruiting sites feeding. If damage does appear, it is important to obtain a clear identification of the larvae species likely to be causing the damage.
Fall armyworm looks similar to other species of Spodoptera already present in Australia. In particular, it has a similar appearance to lawn armyworm (S. mauritia) and day-feeding armyworm (S. exempta), which are not found in cotton.
Cluster caterpillar (S. litura) is native to Australia and can be a minor pest of cotton, but is easily distinguished from fall armyworm.
CottonInfo's Insect ID guide provides a detailed guide to identifying fall armyworm.
How to manage an outbreak
Early detection is essential. Regularly check all your crops for insects and damage. Pheromone traps may provide an indication of local fall armyworm activity.
Key to the control of any pest is an integrated pest management approach. With industry, we are working to identify strategies and tactics for the medium to long-term management.
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.
It is essential with any pesticide use for fall armyworm control that the implications for chemical resistance development in other pests that may be exposed are considered (e.g. Helicoverpa, mites, aphids), and the potential impact on natural enemies.
The Australian Pesticides and Veterinary Medicines Authority (APVMA) is currently assessing, as a priority, applications for permits for the use of chemicals against fall armyworm in cotton. 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' button.
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.
Read the cotton fall armyworm fact sheet.