Peak Etiella moth emergence draws near for warmer localities

Based on local temperatures, Etiella moth activity may peak soon and is expected to reach warmer districts first.

Etiella moth adult (left) and larvae on damaged pods (right) (Source: SARDI)

 

Lentil crops are susceptible to Etiella (Etiella behrii) or lucerne seed webmoth damage as soon as the first pods appear, from late flowering onwards. Female moths lay eggs directly onto pods or their petiole. A key feature of the biology of Etiella is that the newly hatched larvae bore into immature pods within 24 hours of hatching to begin feeding on developing grain. Once inside lentil pods, larvae are protected from insecticide applications so when chemical control is needed, sprays must target adult moths before egg lay commences.

Forecasting moth activity

The SARDI Etiella degree-day model predicts peak Etiella moth emergence and flight periods based on local temperatures - this can be used as a guide for when to commence monitoring.

Using 2017 temperatures and 20 years of average temperature data, peak moth activity is expected in Swan Hill, Victoria around September 29^th.

We have also estimated dates for other lentil growing regions of Victoria and NSW:

Wagga Wagga – predicted October 14^th

Horsham – predicted October 17^th

Bendigo – predicted October 21^st

 

The dates provided are only guides and will depend on temperatures over the next few weeks. Moth activity may occur either side of these dates.

We encourage growers and advisers to run the model for their localities of interest by downloading the Etiella degree-day model. Temperature data for your local region can be obtained from the Bureau of Meteorology website. Daily minimum and maximum temperatures for a specific location need to be entered from June 21^st onwards. The date when the cumulative total of degree-days (dd) first reaches 351 is the date to commence crop monitoring. No further temperatures need to be recorded after a value of 351dd has been reached.