Heating grain can kill pests

HEATING GRAIN with a hot air dryer could help kill insect pests and minimise the risk of rejection, according to research findings.

The Home-Grown Cereals Authority funded project is in response to calls from the industry to find alternatives to chemical pest control in stored cereals, said assistant research director, Roger Williams.

“Passing grain through a hot air dryer had been shown to have potential in Australia but ensuring pest kill without damaging grain quality has proven to be a careful balancing act.”

Exposure of 15, 30, 45 and 60 minutes would be required to kill 99.9 percent of the most heat resistant stages of the grain weevil at grain temperatures of 52, 50, 48 and 46°C, respectively, results using malting barley showed.

A ‘window of opportunity‘ had to be established when disinfection could be achieved without damage to the grain.

This window is widest at low grain moisture and with barley of high initial germination. But, if grain is allowed to heat above the recommended level, some loss of germination can be expected, he said.

But, while tests had found using a hot air dryer could produce effective grain weevil control without grain damage, keeping temperatures and grain flow constant and uniform can be difficult, Dr Williams acknowledged.

The temperature ‘window‘ is widest at low grain moisture and with barley of high initial germination.

The impact on barley germination was used, as this is the most sensitive crop to heat and the findings can therefore be applied to other cereals, he said.