Predicted dates for Etiella flights are approaching

Peak Etiella moth activity can be predicted by the SARDI degree-day model; moths will arrive in warmer localities first.

An Etiella moth landing on some lentil foliage (Image credit: SARDI).

 

Lentil crops are susceptible to Etiella (Etiella behrii) or lucerne seed web moth damage as soon as first pods appear, from late flowering onwards. Female moths lay eggs directly onto pods or their petiole and the newly hatched bore into immature pods within 24 hours of hatching to feed 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.

 

Damaged pea pod caused by an Etiella caterpillar (Image credit: SARDI).

 

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.

Daily minimum and maximum temperatures for a specific location are entered from June 21st onwards. The date when the cumulative total of degree-days (dd) first reaches 351 represents the onset of peak activity for that particular locality.

However, this is a prediction and flights can occur on either side of these dates. Therefore, we recommend a buffer period and beginning to monitor 1-2 weeks prior.

Using 2018 temperatures up until September 13^th/14^th and 20 years of average temperature data from there on, we have estimated dates for lentil growing regions of Victoria and NSW.

 

Swan Hill, VIC – 23^rd-24^th September

Wagga Wagga, NSW – 11-12^th October

Horsham, VIC – 13 - 14^th October

Elmore, VIC – 17-18^th October

 

The dates provided are only guides and will depend on temperatures over the next few weeks.

We courage growers and advisers to run the model for your specific locality - download the Etiella degree-day model (XLS 64.5 KB). Temperature data for your local region can be obtained from the Bureau of Meteorology website. No further temperatures need to be recorded after a value of 351dd has been reached.

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. Sample crops at least once a week during podding 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.