7 June 2002

Interest rises for gas fumigation use

GRAIN fumigation is attracting rising interest from grain growers, following the Pesticides Safety Directorate decision to withdraw approval for pirimiphos methyl-based Actellic dust insecticide from 2003.

Although not due to be implemented until next August, the ban has already led to a shortage of the farmer-applied insecticide and boosted demand for contractor-applied phosphine gas fumigation.

From the end of August 2003 only non-dust formulations of Actellic and chlorpyrifos methyl-based Reldan will be approved for farmer-application. Both contain organo-phosphorus compounds.

"But with the application of liquids to grain, every tonne has to be put over a conveyor so it can be treated," points out Ian Clayton-Bailey, of Igrox, which claims to be the UKs largest grain fumigation specialist.

"This is not only costly but very labour intensive and time consuming."

Chemical cost for remaining farmer-applied insecticides may only be 50-60p/t, but associated costs, such as handling, push the total to £5-10/t, he suggests.

Altogether contractor-applied phosphine works out cheaper than farmer-applied insecticides at £1-4/t and does not involve farm staff.

"Phosphine has been available for years and been used widely around the world, but until now it has always been a second-choice treatment for UK cereal growers. Actellic dust has been preferred as it is easy to apply without the need for a contractor, and could be used as a spot treatment for `fire-brigade` control of localised infestations," Mr Clayton-Bailey comments.

The gas is highly toxic so can only be applied by British Pest Control Association approved contractors, and operators holding a diploma in fumigation. Virtually all stores can be treated, apart from where walling is unable to hold the gas, or where livestock buildings adjoin.

Phosphine controls all stored product insects, hitting all life stages, not just adults, so has a wider field of activity than liquid Actellic or Reldan, which only control insects in the moving stages of their life cycle, adds Mr Clayton-Bailey. &#42

&#8226 Actellic dust approval ends Aug 31, 2003.

&#8226 Supplies drying up.

&#8226 Other Actellic formulations still approved.

&#8226 Phosphine contractor-applied only.

&#8226 No need to move grain.

&#8226 Cost £1-4/t treated.

&#8226 Suits cereals + OSR.

If clean grain is combined and immediately cooled and dried before going into a thoroughly cleaned out and well monitored store there may be no need for pest control chemicals, says grain merchant Richard Whitlock of Banks Cargill. "But if treatment is necessary phosphine must be the way forward. If applied by a top notch contractor there should be no residue on the grain, a big attraction for the food industry."

Phosphine fumigation is gaining popularity for controlling in-store pests as supplies of alternatives dry up.