THE weekend's wet weather may have further delayed the emergence of locusts in Victoria but it is only a temporary respite.
According to the Australian Plague Locust Commission, the first hatchings could be as early as this weekend in the state's far northwest around Mildura.
The APLC has revised its forecast for locust hatchings, putting back peak hatchings by up to three weeks due to cold weather.
APLC director Chris Adriaansen said heavy rain did not kill locusts but the accompanying cold weather could slow their development in underground nests.
However Victorian plague locust commissioner Gordon Berg said the jury was still out on whether flooding and waterlogging of egg beds could kill young locusts.
Mr Berg said waterlogging could have an effect just prior to hatching, in terms of depriving locusts of oxygen, exposing eggs to predators and making them more susceptible to fungal and other diseases.
But he said farmers could not afford to be complacent, given most egg beds in northwest Victoria were not subject to flooding or waterlogging.
Revised hatching dates depended on soil temperatures and other observations, with sandier country remaining warmer during winter than clay soils.
The APLC has left peak hatching dates for the Mallee areas unchanged, while in central Victoria, locusts are expected to emerge about 10 days later than earlier forecast.
In the Riverina, the estimated peak hatching dates have been put back by 7-9 days.
From Mildura to Ouyen, the peak hatching is September 25.
Mr Adriaansen said some locusts could emerge from their nests 10-14 days before the APLC's peak hatching date while others were expected 10-12 days after the peak.
That meant the first locusts might emerge around Mildura this weekend.
He said landholders should inspect their properties about 14 days prior to peak hatching dates.
Spraying should begin about two weeks after peak hatching.
- Peak hatching dates are: Hay-Balranald Oct 5; Swan Hill-Boort Oct 6: Nhill-Warracknabeal Oct 17; Horsham-Stawell Oct 24; Shepparton-Tungamah Oct 20; Echuca-Bendigo Oct 24; Wagga Wagga Oct 25.
