14 July 1995

risk from hunger

Profits at hordes of

STORED grain is vulnerable to pest infestations. Each year an estimated 5% is lost due to weight loss and contamination leading to rejections. Prices are firm, so much will again be at stake this year.

Risks can be minimised by cleaning and fumigating stores. But this must be done effectively, as pests soon exploit unhygienic conditions.

A ministry survey in 1988 found an average of one in every three-and-a-half stores had pockets of potentially harmful insects.

Many different beetles and weevils threaten stored corn. The main ones are saw-toothed grain beetles, grain weevils, rust red flour beetles and rust red grain beetles.

In warm grain they breed freely – each female can lay 200-400 eggs.

Their life cycles are as short as 21 days and populations can escalate alarmingly. A single pair can be responsible for hundreds of millions of offspring over a long storage season.

"Damage can be extreme and very costly," says Henry Cobbold of Suffolk-based pest control specialist Dealey & Associates of Sapiston Mill, near Bury St Edmunds, which manages 350,000t of stored grain in East Anglia. "Insect activity creates heat, and when hot air rises and meets cold air it condenses," he says.

"Moisture and heat combine to create ideal conditions for the development of moulds and fungi which form hot-spots. Apart from direct feeding damage, insects also cause loss of germination to affect seed and malting barley and loss of Hagbergs in wheat. Loss of premiums in these crops can be economically disastrous."

Moulds and fungi can render grain unfit for sale. The cost of redrying and dressing can, with a "fire-brigade" fumigation treatment included, add up to £15/t to costs. This, plus the loss of premium, can wreck profits.

Infestations can be controlled but seldom eradicated, says Mr Cobbold. "But do-it-yourself efforts can be hazardous because a farmer who sells pest-infested grain is legally liable for all costs and losses suffered by the recipient," he warns.