Cool it down now to avoid pests

With memories of the summer heatwave fading fast, the HGCA is urging growers to watch out for its legacy in stored grain.

With combines often working in scorching temperatures, a lot of grain entered stores hotter than usual.

That raised the risk of infestation from insect pests such as the saw-toothed grain beetle.

The warm weather also made cooling to keep such quality-wreckers under control harder than usual, says assistant research director Roger Williams.

On many farms conditions meant drying was unnecessary and removed the threat of moulds and mycotoxins developing in store.

“However, storekeepers should not forget the risk of insects,” says Dr Williams.

Even small grain temperature cuts can slow insect development, so it is worth trying to capture any cooling opportunities as they arise, he advises.

The HGCA’s Grain Storage Guide* says the first target is to cool to below 15C within a fortnight to stop saw-toothed grain beetles developing. Thereafter, the grain should be taken below 12C as quickly as possible to prevent all insects breeding.

This could take 150-200 hours aeration.

Farmers lose many potential cooling slots because they fear blowing damp air will increase grain moisture.

But that is a myth, provided the air is about 5C cooler than the grain, says the Central Science Laboratory’s Dean Cook.

“Don’t delay cooling until the autumn.

Even if the ambient temperature is above 15C, providing it is 5C cooler than the grain bulk, fans should still be run, ideally controlled by a differential thermostat, according to the HGCA guide.”

Concern that the trend to hotter harvests may require a rapid cooling rethink lies behind a new HGCA/CSL project sponsored by DEFRA through the Sustainable Arable LINK programme.

“With climate change bringing warmer harvests, we will be modelling the effects to ensure that these strategies are not compromised, developing new strategies if necessary,” says co-ordinator Mr Cook.

In the meantime growers should continue to monitor grain for insects using PC traps, and if in doubt check the guide, he says.