VICTORIAN agronomists and growers have been urged to be vigilant in crop surveillance for fall armyworm (FAW), following the impacts the pest is having on crops in Queensland.
Fall armyworm has rapidly spread across Australia since being found in Queensland in January 2020 and is now established in New South Wales, Northern Territory, Western Australia and parts of Victoria.
Agriculture Victoria plant pests and diseases manager Chris Pittock says a collaborative effort between government, industry and the community is crucial to effectively manage pests such as Fall armyworm.
“If agronomists and farmers find fall armyworm on their property, they should seek professional advice for treatment and management,” Dr Pittock said.
“Given this pest is established in some parts of the state, we have adapted our practices to manage it.
“We have been able to watch what has happened in the northern states and learn from their experiences.
“Detections of concern to us would be if the pest is found outside central Victoria near the Murray River, and some parts of Gippsland.”
Agriculture Victoria has been leading the state response for the national fall armyworm project, which is co-ordinated by Queensland Department of Agriculture and Fisheries.
The project aims to support Australian growers with the latest information and tools to manage FAW.
Early detection of FAW is important to ensure producers are making decisions in observance with best practice methods of control, and to reduce the likelihood of resistance occurring in the pest.
FAW are being detected at unprecedented levels in sorghum crops across Central Queensland, the Western and Darling Downs and northern NSW, causing what experts predict could be the most significant impact on sorghum since the pest’s arrival in Australia.
Queensland Department of Agriculture and Fisheries principal entomologist Melina Miles urged growers to be alert, but not alarmed and take a considered approach to making decisions about the need for control.
“We know FAW can be devastating and we’re seeing significant crop damage in southern and Central Queensland in sorghum,” Dr Miles said.
“We understand the level of damage in crops this year is causing concern amongst growers, but I encourage them to work with their advisers to accurately assess FAW infestations before taking action.”
Dr Miles’ work is part of a Grains Research and Development Corporation and DAF research project aimed at developing FAW economic thresholds and management guidelines for sorghum and maize.
She attributes the high activity this season to an early start to the FAW activity in spring, resulting in higher summer populations.
“In many regions, rain in December has meant later crops, resulting in the coincidence of high FAW activity and susceptible crops. It is also possible that the weather systems associated with the recent cyclones has facilitated the movement of large FAW populations into central Queensland,” Dr Miles said.
“We’re in the early stages of developing robust management recommendations for this pest and research is ongoing, but what we do know is that FAW populations build up between October and March. Where they can, growers are adopting an early-sowing strategy to largely avoid severe damage, and this has been effective in 2021-23.
“This season, we have late crops planted on the December rain. Because of that, more growers are seeing high FAW populations and damage in crops from emergence throughout the vegetative stages.
“Current information indicates that peak FAW numbers typically occur from mid-summer through autumn.” However, we saw high FAW activity as early as October this season and consequently, there has been more time for the population to build up to higher levels.
Dr Miles says in order to decide whether an infestation warrants control, growers should assess the number and size of FAW larvae per plant. The only effective way to do this is to pull plants apart and unroll the whorl.
“Just looking at damage is risky as it doesn’t tell you what the damage potential is of the infestation over the next week or so.
“As with other caterpillar pests, like helicoverpa, the natural mortality of eggs and small larvae is high – possibly as high as 80 per cent, however, the mortality of larger larvae (4th -6th instar) tends to be much lower, so you can assume most of the larger larvae you find will survive and cause damage.”
