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This leaves methyl bromide ( MeBr ) fumigation . However , MeBr is not without its own issues . The biggest is “ fumo burn ”. Symptoms do not always appear immediately after treatment , but can develop during storage and transport – doubly bad news when fruit has already travelled several thousand kilometres .
Most current schedules for treating with MeBr use concentrations of 32g . m3 or more . For example , the current interstate schedule requires application of up to 40g . m3 MeBr for 2 hours at 15 to 21 ° C . Indonesia requires fruit to have been treated with 64g . m3 MeBr for 2 hours at 21 ° C .
Nectarines were infested by placing them into cages of mature Queensland fruit flies , and allowing the flies to oviposit naturally into the fruit . Photo : P . Wyatt
Low dose fumigation is a new concept . This treatment uses less than half the usual amount of methyl bromide , but with more than double the time to be effective .
Chief investigator Dr Pauline Wyatt , QDAF .
Longer but lower
It seemed possible that if treatment time was longer , the dose could be reduced . Less MeBr for longer is likely to be just as effective at killing insects , but less likely to also kill the fruit .
Pauline Wyatt and her team at DAF Qld are experts in fumigation . While normal fumigation has been studied on many crops , their recently completed HIA project on “ Low dose methyl bromide against fruit flies to improve market access for summerfruit ” is the first time a complete data set has been gathered on this method .
According to Pauline , “ Methyl bromide is a very old method of disinfestation , and already used all around the world for disinfesting fresh products . However , low dose fumigation is a new concept . This treatment uses less than half the usual amount of methyl bromide , but with more than double the time to be effective ”.
“ Low dose methyl bromide can avoid damaging products , but still be effective against pests . In fact , we believe this is a world-first , having produced a summerfruit . com . au December 2016 | Australian Stonefruit Grower 19