Grains Research and Development

Date: 02.09.2013

Grain fumigation alert

Photo of man in front of silos

Peter Botta: Gas-tight means just that.

In the lead-up to the next winter season harvest, concern is building among grain storage specialists about confusion among growers over what defines a sealable silo for fumigation.

Grain storage specialist Peter Botta says some growers, and also some silo manufacturers, have been running into storage quality issues because silos purported to be sealable are still not gas-tight.

“If you intend to fumigate then the silo must be gas-tight, and that means a silo conforming to the Australian Standard (AS2628) for gas-tight sealable silos,” he says.

“A silo cannot perform as a fumigation chamber unless it is gas-tight, and has been tested and passed as such.”

With the increasing importance of on-farm storage for many growers, Mr Botta says that understanding and applying silo standards has become crucial. Fumigation is based on a carefully calculated science.

“Without a gas-tight silo there is not a high enough concentration of gas held in the silo for long enough to fumigate pests effectively. And this means killing all eggs, larvae, pupae and adults,” Mr Botta says.

“Fumigants are quickly lost if the silo is not gas-tight, and because of the duration factor, the issued is not resolved by simply increasing the dosage. At best, adult insects may be killed, but the pupae or eggs will most likely survive. These will develop into adults, quickly reinfesting the grain.”

He says that when buying a silo with fumigation in mind, the first step is to ensure the silo has the AS2628 accreditation.

In addition to fumigation, he also points out that a gas-tight storage system allows grain to be securely stored for long periods without any quality issues, but the fumigation option is there if needed. Because of the importance of this issue and the high cost of a silo failing, Mr Botta urges growers to still pressure test a new silo even when it has the AS2628 accreditation.

Complying with the new standard for gas-tight sealed silos involves conducting a five-minute half-life pressure test, ensuring the oil levels in the pressure relief valve take at least five minutes to fall from 25 to 12.5 millimetres.

He points out that the AS2628 standard, and pressure testing, also must be applied to silos that are retro-sealed for fumigation.

“Many growers are sealing existing silos to improve their grain insect management, with the intended purpose to fumigate the grain if and when insects are detected. If growers are considering this option, then ensuring the silo meets the Australian Standard is essential to be confident the investment pays off.”

More information:

Peter Botta (southern region)
0417 501 890

Phil Burrill (northern region) 
0427 696 500

Ben White (western region)
0407 941 923

The GRDC Grain Storage Extension Project has several fact sheets outlining the selection and management of sealed gas-tight silos and fumigant application. 

A fact sheet on Pressure Testing Sealable Silos is available at: www.grdc.com.au/GRDC-FS-PressureTestingSilos

A fact sheet on Grain Fumigation is available at: www.grdc.com.au/GRDC-FS-GrainFumigation

The Fumigating with Phosphine, Other Fumigants and Controlled Atmospheres booklet is available at: www.grdc.com.au/GRDC-Booklet-Fumigating-with-phosphine

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GRDC Project Code PAD00001

Region National, North, South, West