NEW predictions suggest locusts will hatch in Victoria's wheat belt before grand final day, September 25 - early enough to be a substantial threat to crops.
Federal authorities have brought forward their estimates for when Victorian hatchings will occur by up to 12 days. The calculations are based on weather conditions over the past 10 years.
Earlier hatchings would be a bigger threat to the grain crop, because the earlier dates increase the likelihood that some crops would still be developing and be green enough to be appetising.
AFL grand final day has been nominated as the ''peak hatching date'' for locusts in the first region (covering Mildura and Ouyen), but substantial hatchings will also occur in the seven to 10 days before and after September 25. Up to 40-50 per cent of eggs in the Mildura-Ouyen region could have already hatched before September 25, the Australian Plague Locust Commission estimates.
The Victoria predictions apply to six districts in the north-west where millions of tonnes of grain and other crops are grown each year. The crops can earn the state economy more than $1.4 billion a year. The six regions identified by the commission include Mildura-Ouyen, Swan Hill-Boort, Echuca-Bendigo, Shepparton-Tungamah, Nhill-Warracknabeal and Horsham-Stawell.
Commission director Chris Adriaansen urged farmers to carefully check their paddocks for signs of emerging locusts ''at least a week'' before the ''peak hatching date'' in their area.
''What it means is that landholders are going to have to be prepared to undertake locust control earlier than they might have previously anticipated,'' Mr Adriaansen said.
''It also means that, potentially, some areas will still have significant areas of unharvested green crops in the ground when these locusts have hatched out.
''If the earlier forecasts would have held true, some areas would have actually had their crops off before the locusts had become a problem. What it means now is that the locusts are more likely to have a damaging effect on some of these crops immediately prior to harvest - unless they're effectively controlled.
''It does, to a limited extent increase the risks, particularly to grain crops.''
But he urged farmers to be patient, saying they would get a better result from spraying if they waited until locusts were about 16 days old, instead of immediately after they hatched.
If farmers waited until this point, the immature locusts would be aggregated in their highest density and be unable to fly.
Premier John Brumby said it was ''vital that landholders are equipped and ready to treat locusts after they hatch as there is a relatively short time span of about two weeks when immature hoppers are most vulnerable to chemical spraying".
Mr Brumby said the state government had developed a $43.5 million strategy to fight the locust threat, which could become ''the worst locust plague in 75 years''.