With spring just around the corner, growers should be starting to keep an eye out for winged pest insects in grain crops.
SAGIT-funded research at the South Australian Research & Development Institute (SARDI*) is studying the behaviour and management of Etiella, a common pest of lentils, and Russian wheat aphid, a major cereal pest.
SARDI Entomology leader Greg Baker says the SAGIT Etiella project is working to improve the existing ‘degree-day’ model which provides growers with advice on when to monitor their crops. This includes the development of an app using the project findings coupled with meteorology data to warn growers of impending Etiella flight.
“We have eight trial sites across the Lower-North, Mid-North and northern Yorke Peninsula where we are combining data logging of temperatures with intensive monitoring of Etiella activity,” he says.
Researchers are monitoring Etiella using pheromone traps and sweep nets over two years to provide a better understanding of the timing of Etiella moths arriving in lentil crops in spring.
“Not a lot is currently known about the ecology and behaviour of Etiella,” Mr Baker says.
The incidence of the pest was very low in 2016, though Mr Baker says the limited research on the moth in the past means he can’t say exactly why the pressure was low, or what that indicates about the Etiella risk for the 2018 season.
“We know that 2017 was an outlier for low populations, but we don’t know if that means this year will present a lower risk than usual or not,” he says.
While there is no universally agreed economic threshold, many agronomists recommend an economic threshold for Etiella of 1-2 adults in 20 sweeps to avoid quality downgrades.
Mr Baker says that reports of activity are welcome to assist with understanding Etiella, particularly reports of early or significant sightings.
Separately, Russian wheat aphid (RWA) specialist Maarten Van Helden is working on a different SAGIT-funded project studying the risk RWA poses to SA cereal crops.
Dr Van Helden says the two-year study has so far seen low impacts on crops, with very few measurements above economic thresholds and only one trial site with statistically significant yield losses.
“In 2017 only one of our trials saw yield loss from RWA, and this was in a late-sown crop at Loxton where the crop was suffering from drought stress, and RWA were attracted to the struggling crop in spring,” he said.
Dr Van Helden says most growers are using best-practice management for RWA, including green bridge control and monitoring and treating as necessary.
To date this season, the SAGIT trial sites have witnessed low aphid populations, even at control sites where seed treatments are not applied. Dr Van Helden says the dry 2017/18 summer is likely to have reduced the starting population, but even if there is low RWA activity this season growers should remain cautious and ensure there is no green bridge over summer.
- Etiella reports: Kym Perry, (08) 8429 0738 or [email protected] or twitter @PestFactsSARDI
- Etiella day-degree model available from PestFacts on the SARDI website.
*SARDI is a division of Primary Industries and Regions SA