At this stage, most management suggestions are still based on overseas information. In partnership with industry, staff at the Department of Agriculture and Fisheries will be conducting research to understand the pest status of this insect within our production systems with the aim of identifying and developing a range of sustainable practices (cultural, biological and chemical) to enable effective control.
Insecticide resistance has been a feature of FAW infestations with almost complete failure of all options in Brazil causing significant management issues. Insecticide resistance management of this pest, and the consideration of how its management will impact on resistance development in Helicoverpa armigera and other species will be a key focus of research.
In the interim, Industry bodies are collaborating to secure emergency permits to provide growers with chemical management options should control be required. See the APVMA permits portal (search for fall armyworm) for permits currently available.
Crops at risk
While FAW has a wide host range, in Australian broadacre systems to date it has shown a marked preference for (both grain and forage crops) of maize, followed by sorghum.
There are currently no locally-derived thresholds to guide management of fall armyworm due to lack of opportunity to assess the impact on crops in Australia. DAF is working with industry to identify appropriate thresholds for Australian conditions. Some examples based on overseas data are listed below. These should be treated with caution, as some may be for Bt crop varieties not currently available in Australia:
Maize whorl stage
|3 or more larvae per plant
*50% of plants with fresh feeding20% of plants with one or more larvae
*>75% of plants with feeding
|Based on US recommendations:
*Purdue University: Need to consider economics of control i.e. $/ha to treat vs potential yield loss ($/ha).
|15% of infested plants||US recommendations:
If necessary, control at tassel emergence is more effective than applications in the vegetative stages.
Sorghum grain fill
|30% defoliation, or
>2 larvae per whorl
Use helicoverpa threshold calculator
|Based on US recommendations.
Damage at grain fill equivalent to Helicoverpa.
|Cotton||–||Monitor crops for leaf damage and fruiting site feeding. Bollgard 3 will incidentally suppress FAW.|
|Based on S. litura (DAF)|
|Pasture (hay production only)||2-3 larvae /sq foot||No permits currently.
Armyworm outbreaks (other species) are not uncommon.
How FAW will manifest as a pest species under Australian conditions longer term is currently unknown. More detailed information will be made available as we learn more about this pest, its behaviour and impacts under local cropping systems.
It is possible that FAW infestations will be severe in the first few years of this incursion. This has been the pattern for other exotic species in recent years (e.g. silverleaf whitefly outbreak in CQ and solenopsis mealybug). As industries become more confident and experienced in managing this pest, and natural enemies start to suppress outbreaks, FAW is likely to become more easily managed in our farming systems.