INSECTICIDE TREATMENT of on-farm grain stores should be based on risk assessment rather than routine use, since there is no guarantee it eliminates pests anyway.

Provided grain can be dried and cooled quickly enough, routine spraying of grain buildings and equipment to deter insects and mites may not be justified, independent storage specialist Ken Wildey told an HGCA/ACCS meeting.

 Nearly all feed mills and 38% of commercial grain stores surveyed had insect problems, but only 6% of on-farm stores contained pests, he noted.

“Let”s think of risk assessment and be prepared to consider not treating empty stores.”

 To determine whether treatment is necessary growers should ask themselves:

Has the grain been infested in the past three years?

 Is the store near a feed store?

Have I found insects in traps?

Is infestation critical for the intended market?

Do I have an effective drying and cooling system?

If the answer is “No” to the first four questions and “Yes” to the last, then a move to non-treatment may be possible, Dr Wildey suggested.

CSL work showed that clearing pests from stores was not easy. In 13 of 14 trials, using enough spray “to nearly drown them”, live insects were still emerging after 28 weeks.

 But after a season of exceptional pest infestations growers should be cautious about abandoning approved treatments, warns Mark Braithwaite of Igrox.

“We have done more fumigation than for a long time. The CSL idea of cooling is fine in theory, but farmers find it hard to put into practice.”

Saw-toothed beetles can lay 300-400 eggs, each of which can lead to 50 damaged grains within 20 days, adds Alison Bosher of Syngenta which makes Actellic (pirimiphos-methyl).

 “We have always pushed for good store hygiene. Treatment gives reassurance and takes the pressure off.”