by
Blaine Timlick, Canadian Grain Commission, Canada
The fumigation of bulk commodities, such as grains, has been performed for a century and the requirements for such treatments are increasing. Changing demographics of insect pests into new host ranges, increased commodity production, climate change, increased demand for reduced pesticide use and evolution of insects that are tolerant or resistant to specific pest control products has resulted in the investigation and use of alternate gases.
Of the naturally occurring gases abundant in the environment, CO2 has been the most investigated and is now registered in a number of countries as an alternate fumigant for pest control.
CO2 was discovered to impact insect pests at low levels in grain as early as 1972, where it was discovered that a CO2 concentration increase of as little as one percent could induce a spiracle (breathing tubes) opening response and most insect species responded at concentration changes of between two-to-five percent. At concentrations of CO2 where spiracles remain open for elongated periods, insects perish from lack of oxygen and/or desiccation due to water loss.
Through the 1970’s and 80’s, investigations studied application methods, as there were requirements to determine appropriate methods for generating the gas, the appropriate concentrations to cause effective mortality and techniques for effective application.
Methods such as application of dry ice, purging with gas and blending with air or nitrogen all proved effective. Of these methods, purging the bin from the bottom that forces atmospheric gases out of the bin has proven to be one of the most efficient methods and is what is employed currently in many situations where CO2 is used in pest control.
In using this method, bin preparation and sealing is crucial. Appropriate sealing is an obvious requirement, as the structure enclosing the grain needs to be able to retain the gas with minimal leakage. This can be partially accomplished by using sealant products (foams, membrane and sealing paints, tapes, etc) and applying them to areas where potential leakage can occur (vents, cracks, seams).
Performing this with diligence can assist in improving the maintenance of the gas concentration. However, gas concentrations require constant monitoring, as the effects of wind on larger structures will deplete the concentration. Once sealing is completed, performing a pressure test of the bin will provide information of how well the bin was sealed and, therefore, how effective the fumigation might be.
Read more HERE.
The fumigation of bulk commodities, such as grains, has been performed for a century and the requirements for such treatments are increasing. Changing demographics of insect pests into new host ranges, increased commodity production, climate change, increased demand for reduced pesticide use and evolution of insects that are tolerant or resistant to specific pest control products has resulted in the investigation and use of alternate gases.
Of the naturally occurring gases abundant in the environment, CO2 has been the most investigated and is now registered in a number of countries as an alternate fumigant for pest control.
CO2 was discovered to impact insect pests at low levels in grain as early as 1972, where it was discovered that a CO2 concentration increase of as little as one percent could induce a spiracle (breathing tubes) opening response and most insect species responded at concentration changes of between two-to-five percent. At concentrations of CO2 where spiracles remain open for elongated periods, insects perish from lack of oxygen and/or desiccation due to water loss.
Through the 1970’s and 80’s, investigations studied application methods, as there were requirements to determine appropriate methods for generating the gas, the appropriate concentrations to cause effective mortality and techniques for effective application.
Methods such as application of dry ice, purging with gas and blending with air or nitrogen all proved effective. Of these methods, purging the bin from the bottom that forces atmospheric gases out of the bin has proven to be one of the most efficient methods and is what is employed currently in many situations where CO2 is used in pest control.
In using this method, bin preparation and sealing is crucial. Appropriate sealing is an obvious requirement, as the structure enclosing the grain needs to be able to retain the gas with minimal leakage. This can be partially accomplished by using sealant products (foams, membrane and sealing paints, tapes, etc) and applying them to areas where potential leakage can occur (vents, cracks, seams).
Performing this with diligence can assist in improving the maintenance of the gas concentration. However, gas concentrations require constant monitoring, as the effects of wind on larger structures will deplete the concentration. Once sealing is completed, performing a pressure test of the bin will provide information of how well the bin was sealed and, therefore, how effective the fumigation might be.
Read more HERE.
The Global Miller
This blog is maintained by The Global Miller staff and is supported by the magazine Milling and Grain
which is published by Perendale Publishers Limited.
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