Vapormate - She'll be apples

[Photos: Left - Representatives of BOC Ltd have been involved in the development of Vapormate ™ throughout the resesarch project. Watching the trials at Walla Walla were the manager of BOC Ltd at Wagga, Gavin Holt, and BOC Ltd manager market support, Robert Ryan. Right - Andrew Kotzure, of Modern Engineering and Construction at the trials of Vapormate ™ on his farm in Walla Walla. Photos by Kellie Penfold]

A naturally occurring substance found in green apples and cabbages is the new weapon in the fight against insects which attack stored grain.

With questions raised regarding the safety and efficacy of traditional chemicalbased grain treatments and emerging resistance problems, the pressure has been on the grain industry to come up with a new solution to an age-old problem.

Five years ago CSIRO Entomology, based at the Stored Grain Research Laboratory in Canberra, started focusing on the technology for using ethyl formate as a replacement for methyl bromide or phosphine, and for the past three years the GRDC-funded project has worked in collaboration with private enterprise to develop a commercial product.

Known as Vapormate™, the new treatment is a cylinderised mixture of ethyl formate and carbon dioxide (CO2) produced by BOC Ltd, which received registration for commercial sale in March. Vapormate™ will suit small and large-scale grain storage facilities, such as silos, mills, exporters and warehouses, and can only be applied by a licensed fumigator.

BOC Ltd has plans to develop the product over the next decade, and foresees a time where it will be available as a routine treatment to be used on farms or by transport companies delivering grain.

Greg Dojchinov, an experimental scientist from CSIRO Entomology, has spent the past three years trialling and assessing the ethyl formate/carbon dioxide treatment combination on the three main grain pests - rice weevil, grain borer and flour beetle. He says the results illustrate the success that comes from grower organisations, researchers and private enterprise working together.

"Ethyl formate is a natural substance, present in lots of fruits," he says. "It is also a registered natural food additive, used to enhance the flavour in products such as icecream. Ethyl formate is already used as a fumigant in the dried fruit industry, particularly with sultanas, because it is a safe, benign chemical."

Mr Dojchinov says the research has concentrated on devising an aimed application system for Vapormate™ which will maximise the concentration of ethyl formate in the bin, but minimise the loss to grain sorption. "We are also investigating the optimal exposure periods to achieve high mortality of a range of stored product pests."

At a demonstration of the trial work at Modern Engineering and Construction at Walla Walla in southern NSW, Mr Dojchinov explained the ethyl formate and CO2 was delivered in cylinders and released into a sealed silo using vaporisation.

The insect larvae, pupae and adults take up more ethyl formate in the presence of CO2 - which enters their systems and quickly breaks down into natural products, including ethanol and formic acid, causing the insect to die.

After trials in WA, Queensland, the ACT and Walla Walla, researchers have developed a standard concentration for a 50-tonne silo of grain which takes 12 minutes to apply, three hours to fumigate and two hours to air out with no withholding period.

"Basically the fumigation can be carried out in one shift by one worker," Mr Dojchinov says. The traditionally-used phosphine has a minimum five-day fumigation period and methyl bromide requires at least 24 hours. "With no withholding period, it means there are minimal delays. If you are selling grain, you can have it applied quickly and maintain quality or if it is going into milling, it can be ready the next day free of live insects.

"As there is a chance of resistance occurring in insects treated with fumigants including ethyl formate, we are already testing and monitoring for this the laboratory."

BOC Ltd"s market support manager, Robert Ryan, says that initially the treatment will only be able to be applied by licensed fumigators: "But we hope to develop the product so farmers can use it in sealed storage on-farm, and fumigation requirements will be met by their occupational health and safety responsibilities.

"Another idea, down the track, is applying it to grain in the back of a truck when it is on its way to the point of delivery. There are lots of potential time and cost savings for the grain industry as the product is developed."

While the Vapormate™ label will list the product as poison, Mr Ryan says only high doses could affect humans.

The full findings of the research project will be presented to the National Working Party on Grain Protection Conference in Western Australia in June.

GRDC Research Code CSE0009. For more information: Victoria Haritos, 02 6246 4245, victoria.haritos@csiro.au

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