Fall armyworm the “biggest biosecurity concern” for WA’s $6 billion grains industry

Farmers and researchers are battling to suppress outbreaks of fall armyworm in five parts of WA, with no silver bullet in sight as the pest proves difficult to control with insecticides and continues to march towards the State’s $6 million grain crop. Two moths were caught in a trap near Gingin earlier this month, the southernmost detection in WA since the pest was found in the State for the first time — in Kununurra — in March. Fall armyworm has since been detected near Broome, Carnarvon and Geraldton, sparking concerns it could also spread to grain-growing areas after seeding. The Kununurra detection came just one month after fall armyworm arrived on mainland Australia through the Torres Strait islands in February. Interstate, it has since spread throughout Queensland, and to parts of northern NSW, the Northern Territory and WA, with the Gingin detection and a detection at Maitland in NSW’s Hunter Valley have been the southernmost detections in Australia so far. Department of Primary Industries and Regional Development senior scientist Helen Spafford said while no larvae or feeding damage had been detected in the area, she encouraged horticulture, grain and turfgrass growers to be checking “in their crops and monitor for unusual levels of damage”. “Suspected fall armyworm should be reported to DPIRD to assist with surveillance and potential management options,” she said. “This trap and others further south will continue to be monitored as part of DPIRD’s ongoing surveillance program.” Grain growers have been encouraged to report fall armyworm sightings to DPIRD, but 70 pheromone lure traps placed across the grainbelt this year did not detect any signs of the pest. Grains Research Development Corporation last week released an online fall armyworm continuity plan for the Australian grains industry, designed to be a comprehensive guide for identifying and managing the pest in grains crops nationwide. The 79-page document includes management strategies, regional risk, damage thresholds, reporting, signs and symptoms, geographic spread, chemical management costs and the economic impacts of infestation. Cesar research lead Olivia Reynolds said the national plan would be an important resource to aid industry in dealing with the exotic pest at this early stage. WAFarmers grains policy manager and Grains Biosecurity Advisory Committee grower representative Jess Wallace said fall armyworm was the “biggest biosecurity concern” WA’s $6 billion grains industry had seen for a long time, “because of how invasive it is”. “Growers do take biosecurity seriously... especially because of how much damage has been done (by fall armyworm) in Queensland,” she said. “WAFarmers is working with the department to monitor the pest of spread in WA, to stay across the issues in case there is any spread. “We encourage growers to be hyper vigilant. “If they recognise any abnormal or unusual looking pest species, they need to report it.” Insecticide resistance has been heralded a major threat to biological control for fall armyworm, with Queensland Department of Agriculture and Fisheries principal entomologist Melina Miles telling a fall armyworm webinar last week that cheap, broad-spectrum biological chemistry was “unlikely to be effective” because of resistance. She said fall armyworm had so far shown a preference towards corn, while cotton had escaped relatively unscathed. However, she said the pest did prefer tropical and subtropical conditions — meaning it was “not adapted to cool conditions” in southern Australia. “It may be uneconomic to grow some crops in some regions and that is a pretty sobering consideration,” Ms Miles said. “Reducing reliance on conventional chemistry is unlikely to be effective because of resistance.” Ms Miles said the ‘check and spray’ approach wasn’t working as effectively as it has with other insect pests because of the frequency of egg lays and the propensity of larvae to feed hidden behind wrapper leaves and in the whorl of host plants. Dr Miles said the inability to control fall armyworm with conventional chemistries was a major risk to the cropping industry. She said options being considered included an “attract and kill” approach to kill females, strategic natural enemy releases, host plant resistance, mating disruptions, and trap crops. “It is really important to think about how we reduce our reliance on conventional chemistry. That will be key to the long term ability to manage not only fall armyworm but Helicoverpa,” Dr Miles said. “The only way that will be achieved is by employing more of the available tools that are not conventional chemicals and developing new ones to fit the system.” To find out more, including monitoring and management techniques, visit the DPIRD website. The Fall Armyworm Continuity Plan is at planthealthaustralia.com.au/fall-armyworm/.