A panel of fall armyworm (FAW) experts have told growers of the importance of keeping tabs on numbers in crop and whether they are at levels where there would be an economic benefit to control them.
A heavy infestation of FAW, particularly in Queensland, is wreaking havoc with many summer crops, in particular maize and sorghum, with authorities labelling it the worst season for the pest since it arrived in Australia in 2020.
The Grains Research and Development Corporation hosted a webinar last week to discuss management of the invasive species across the northern cropping belt.
Queensland Department of Agriculture and Fisheries (DAF) principal entomologist Melina Miles and Joe Eyre from the Queensland Alliance for Agriculture and Food Innovation (QAAFI) are working on a project to accurate assess FAW-created yield loss and the economic thresholds for control.
Dr Miles said it was critical to act early to manage FAW infestations.
"We understand that the level of damage in crops this year is causing concern amongst growers and I encourage them to work with their advisers to accurately assess FAW infestations before taking action," Dr Miles said.
"We want to help those growers that are impacted by FAW for the first time this season and aren't sure when it is appropriate to act on an infestation, or how to effectively manage infestations," she said.
Dr Eyre warned Australian growers they could not simply observe control methods that have worked overseas and implement similar systems and hope for success, due to Australia's drier, lower yielding cropping systems.
"From our research so far, we think Australian growing environments might require a different approach to overseas FAW management approaches," he said.
"The overseas recommendations are to take action based on damage caused by the caterpillars, which may result in crop loss occurring before action is taken or encourage spraying when the pest is no longer active in the crop."
"Neither of these are economically efficient nor ecologically friendly strategies for Australian grain growers."
He said information was critical for growers.
"Most growers here have not had to worry about defoliation prior to flowering and how much yield damage that can do, so growers are looking for guidance."
Darling Downs agronomist Ross Pomroy said FAW had been observed in higher numbers in his region in recent years.
"We've seen a substantial increase in numbers on the Darling Downs, so there's a lot of questions about what to do and what we have been doing."
GRDC grower relations manager Rebecca Raymond said it was not as simple as going out and treating the pests, and that farmers had to make their own economic assessments.
"The issue for many sorghum growers is the cost of control measures and likely return on investment," she said.
"The complexity is the tricky part, what are the FAW populations, what is the crop stage of growth, what are the chances my crop will 'grow away' from the ongoing damage levels, can I 'over row' spray to reduce costs and many other considerations."