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Etiella moth update

Etiella moth emergence is predicted to have peaked in the northern region of the Victorian Mallee, 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) moth flight periods based on local temperatures and cumulative degree-days (dd*). This can be used as a guide for when to commence monitoring.

With recent warmer temperature in the Victorian Mallee, the threshold for peak moth emergence was exceeded around October 9th in Swan Hill.

Using both actual temperatures for 2016 up until the 10th October 2016, and then average temperature data (based on 20 year averages), we can estimate the approximate threshold date for Etiella emergence and flight activity in other lentil cropping areas:

Horsham (Wimmera Vic) – 269 dd (~ October 23rd)

Bendigo (Northern Country Vic) – 234 dd (~ October 27th)

Wagga Wagga (Riverina NSW) – 284 dd (~ October 18th).

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. 9 for 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, behavior and management.

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

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