A moderate flight of moths occurred in the Victorian Mallee last week, while other regions have had minimal activity. Predicted dates for larval activity are provided.
Where have they been reported?
Pheromone trap catches for native budworm (Helicoverpa punctigera) in the past two weeks have been relatively low in comparison to those observed in early spring in past years.
The highest weekly catches (80-155) recorded so far across the Victorian and NSW network were observed between the 14th -17th September at Ouyen, Kerang and Swan Hill in the Victorian Mallee.
In the Victorian Wimmera and the NSW Riverina and Central West Slopes and Plains, moth catches have been very low.
In contrast, some extreme weekly catches (eg 1600 moths) have been recorded in the lower Eyre Peninsula of South Australia. These populations have the potential to be source populations for Victoria’s Central and South West districts.
In the Mallee, very low numbers of budworm eggs and larvae have been found in lupins and lentils.
Moths arriving in flowering crops will generally start laying eggs immediately. Based on this assumption, we use a predictive modelling tool to generate forecasts of budworm larval development rates at different locations based on average daily temperatures for each location.
Starting with a surge of moths from 14th September in the Victorian Mallee, the model predicts that third instar larvae from this flight will be first seen in sweep nets in mid October (third instar larvae are typically more readily seen in sweep nets than the earlier stages).
These will add to the pool of eggs and young larvae generated by earlier but smaller flights.
Similarly, fifth instar larvae are predicted to occur from around 22nd – 26th October. This is the larval stage that starts to have a more serious impact on pods and grain; fifth and sixth instar larvae consume about 90% of all food intake throughout the caterpillar’s life.
These predictions are only guides; development rates will vary if temperatures are above or below average.
Second and third instar budworm are reasonably easily seen in sweep nets, and relatively easily controlled, particularly with biologically active insecticides.
We thank the following for providing various forms of support to this forecast service:
Dr’s Peter Gregg and Alice del Socorro – School of Environmental & Rural Science, University of New England, Armidale
Bill Kimber – SARDI
Alex Mills – Adama Australia
Brad Bennett – Consultant, AgriVision (Victorian Mallee)
Jim Cronin – Agronomist, Landmark (NSW Central West Slopes and Plains)
Allan Edis – Agronomist, Landmark (NSW Riverina)
Bill Gardner – Agronomist and Grower, (Victorian Wimmera)
Shayn Healy – Agronomist, Crop Rite Pty Ltd (Victorian Mallee)
George Hepburn – Agronomist, Tylers Hardware & Rural Supplies (Victorian Wimmera)
Damian Jones – Irrigated Cropping Council (Victorian Mallee)
Jake Leith – Tech Services Agronomist, AgriVision (Victorian Wimmera)
Rob Sonogan – Consultant, AgriVision (Victorian Mallee)
Greg Toomey – Agronomist, Landmark (Victorian Northern Country)
David & Lachlan Trewick – Growers (Victorian Northern Country)
David White – Agronomist, Delta Agribusiness (NSW Riverina)
Sources of field reports of native budworm
Anna Fry – Trainee Agronomist, SHC (Victorian Mallee)