Farmers face locust invasion
By COLIN BETTLES
FARMERS are bracing their operations for a locust invasion that could reportedly eclipse the damage of the state's 2000 plague.
With the dry spell showing no sign of abating, local farmers will have plenty to do while waiting for rain with most growers already engaged in measures to battle the dry start to the season.
The Agriculture Department has warned the South-West Land Division could be exposed to its biggest Australian Plague Locust (APL) infestation since 2000.
The department has issued advice warning farmers that widespread crop, pasture and native vegetation damage and public nuisance from locusts is possible.
The department is taking action to prevent the locust spread before it escalates but it may be a case of too little too late with locust eggs already laid in some parts of the state.
Experts predicted earlier this month that the plague could cause similar damage to the tune of the $20 million bill that WA growers were forced to pay in 2000.
After spending $9.5m on 180t of pesticide sprayed on more than 600 properties across two-thirds of the South-West agricultural region, the final containment cost was well below the estimated $200m forecast by the Agriculture Department.
This season's plague has been attributed to locust hatchings in 36 shires around Moora, Wongan Hills, York, Beverley and in the east of the state at Bruce Rock and the Kent Shire.
Hatchings this season are due in early September and are expected to be closer to Perth, posing a risk for horticulturalists in the Bindoon and Swan Valley areas.
Department senior entomologist Kevin Walden said green feed in the agricultural regions could help locusts survive for weeks.
Mr Walden said the dry weather wasn't having a major impact on the spread of the pests but the timing of the rain was important to restrict its progress.
"What would suit the locusts is if we have a wetter than normal finish to the season," he said.
"Once the locusts come out of the eggs, if they find suitable food then they will not only survive but they will prosper and reach maximum potential."
Some rain has fallen but rain levels remain at an historic low with Morawa recording a dismal 1.4mm so far for June, while 6.4mm in Cunderdin and 5.4mm in Pingelly have barely wet the gauge.
Esperance is bucking the trend with 30.8mm but the total is still well below the coastal town's overall June average of 84.2mm, while this time last year its measure of 193.4 mm produced the wettest June on record.
Bureau of Meteorology Climate and Consultancy Section regional manager John Cramb said rainfall figures to date had indicated most parts of the South-West Land Division had not yet received as much rainfall this June as in their record driest June.
"A comparison with past totals to June 26 would be too complex a task at this stage but, regardless, the bottom line is that we have a very serious situation," Mr Cramb said.
While the locust outlook is not too rosy, the general pest outlook was much better for growers in other parts of the state.
Agriculture Department principal plant pathologist Robert Loughman said WA farmers had an excellent track record for dealing with crop diseases.Ê
The crop disease expert said the dry start to the season had decreased the likelihood ofÊdisease in general terms.
"When the need arises, growers focus on implementation of management strategies to reduce disease risks and losses," Mr Loughman said.
"The industry is well-informed and supported by research and development."
Mr Loughman said the late season break had forced growers to implement contingency plans for cropping so disease risks associated with a break in green bridge conditions and later sowing opportunities could be reduced.
"One of the principal risks was potential for survival of summer and autumn cereals carrying rust diseases, following wet summer and autumn conditions," he said.
"In many areas volunteer cereals have now died prior to the opportunity to start this season's crops, meaning that the green bridge of cereals that can carry rust risk into the new crop has been broken in many areas.
"Crops at higher risk are cereals already sown in the Esperance region and parts of the eastern Wheatbelt where some sowing opportunities existed when rust carry-over was still likely from green bridge cereals."
Mr Loughman said the diseases to watch out for were wheat stripe rust in eastern areas and stripe and stem rusts of wheat and leaf rust of barley in the Esperance region.
He urged farmers not to panic, saying there was plenty of time to work towards solving the problems.
"Crop monitoring and awareness programs, for example through the department's Pestfax service, will help identify any developing risks early so that growers have time to respond to any problems," Mr Loughman said.
There was some good news for pastures from the current dry spell with biserrula and serradella paddocks standing out.
Department research officer Angelo Loi said biserrula that germinated on summer rain was still providing green feed.
Dr Loi said while other pastures have dried off, another 10mm or more of rain should give the crop an ideal pick-up going into winter.
"Biserrula had been identified as a promising pasture," he said.
"That promise is being emphasised with the current climate situation and there is no doubt it is proving a big advantage where it has been sown."
Productive paddocks have been seen across a wide range of the Wheatbelt including Kondinin, Tincurrin, Badgingarra and Katanning.
Two varieties of biserrula are now commercialised with Casbah, a mid-season cultivar, suited to areas with 325 to 500mm annual rainfall, and Mauro a mid to late-maturing cultivar, suited to regions with 450 to 700mm rainfall.
Dr Loi said biserrula was a prolific seed producer, with seed yields ranging from 300 to 1500kg per hectare. It was high-quality forage in terms of dry matter digestibility, metabolisable energy and crude protein.
Because it was hard-seeded, it had some protection against false breaks, and could survive in the seed bank for a number of years, allowing the use of multiple crop sequences up to five years.
"Biserrula at the moment is the cheapest option among the pasture legumes offered by the market," Dr Loi said.
"It is the best tool to control herbicide resistant weeds, a great nitrogen producer and a very persistent pasture that can survive through long crop rotations.
"Photosensitivity and aphid control are the only real limitations to consider"