Etiella moth update

Etiella moth emergence is predicted to have peaked in warmer regions, while other lentil growing regions aren’t far off.

 

Forecasting moth emergence and activity

The Etiella degree-day model (SARDI) predicts peak Etiella (Etiella behrii, Lucerne seed web moth) flight periods based on local temperatures and cumulative degree-days (dd*). This can be used as a guide for when to commence monitoring.

Using both actual temperatures for 2017 up until the 9th October 2017, and then average temperature data (based on 20 year averages), we can estimate the approximate dates for peak Etiella emergence and flight activity in lentil cropping areas:

Horsham (Wimmera, VIC) –  October 16^th

Bendigo (Northern Country, VIC) – October 21^st

With recent warmer temperature in the Victorian Mallee, the threshold for peak moth emergence was exceeded in late September at Swan Hill and October 9^th in the NSW Riverina.

The date when the cumulative total of dd first reaches 351 is the approximate date for expected moth emergence and initial egg-laying. However, the dates are only guides and will depend on temperatures over the next few weeks. Moth activity may occur either side of these dates. Consequently, crop monitoring should begin about two weeks earlier.

Refer to PestFacts Issue No. 8 ­­or further details of the Etiella model and how to use it.

Our advice

Risk periods for Etiella within crops are when pods are green; dry pods are not at risk. Sweep netting is a common method used for estimating Etiella moth numbers in crops. For areas further removed from those listed above, use the SARDI degree-day model to predict flight activity in your region and monitor lentil crops at least once a week for evidence of Etiella activity. A minimum of 3 lots of 20 sweeps should be randomly undertaken within each crop. The recommended action threshold is 1-2 Etiella moths in 20 sweeps.

Click here for comprehensive information on Etiella, including their life cycle, behaviour and management.

* Degree-days are a way of measuring insect development in response to daily temperatures.

 

Field reports

Simon Craig (Farm360, Mallee, VIC)

Brad Bennett (AGRIvision, Mallee, VIC)

Rick Rundell-Gordon (Grounded Agronomy, Mallee, VIC)

Gus Skinner – Landmark (Mallee, VIC)