7 June 2002

Grain store preparation – now is the right time

This weeks Baseline

Advice article provides a quick-fire guide to

preparing grain stores

in readiness for the frenetic

harvest rush

NOW is the time to get grain stores in order, ensuring they are weatherproof, free from rodents and birds, and clear of insects, advises a leading storage consultant.

A key issue is to check for leaks or structural defects that could allow water in, says Mike Kelly of Acheta, an independent training and consultancy company specialising in pest control.

"Where grain is allowed to get wet, it encourages mites and fungus-feeding beetles." Grain should be dried to 14% moisture. At 16% mites breed quickly, removing the germ from grain to leave it unfit for malting, causing taint and acting as powerful allergens.

Insects

There is no tolerance of insects by the trade so it is important to control them all, continues Mr Kelly.

Primary storage pests develop independently of moisture, but need warmth to complete their life cycle.

The grain weevil and saw-toothed grain beetle are prime examples.

"They dont live in the field, they come in on lorries, can be left in previous harvest residues or manage to travel around in the grain trade."

"There are traps available, which can reveal population trends. Bait bags are very effective and are a good choice after cleaning, to see whether insecticidal treatment is required." Bags must be collected, emptied and counted after use.

Once the grain is in store PC traps can be installed. "Then its important to keep the grain cold, below 12C. That will stop beetles breeding, although it wont have the same effect on mites."

Insecticides

Three chemicals are approved for use on grain and in grain stores. But growers may struggle to get two, reveals Mr Kelly. "They are all OPs, so they must be applied carefully and accurately."

Some residual pyrethroids are approved for treating grain stores, but labels say grain must not touch treated surfaces.

Actellic now comes in a liquid emulsion formulation only, which is applied as grain is conveyed into store. Grain flow rates need to be known.

"Then theres Reldan, which appears to be hardly available, and Satisfar, which has stopped being manufactured."

All three chemicals control all the storage pests, he says. "Theres some opinion that mites are now resistant to OPs. But disappointing control may just be the result of bad application or poor storage practices."

Applying insecticide to the store structure is sensible if problems occurred in the previous two seasons. "Once youve swept and cleaned the store, and the sweepings have been burned, treat all the interior surfaces. Get this done three weeks before you fill the store."

New for this harvest is Silica-Sec, a desiccant dust based on aluminium silicate. It partially absorbs the insects outer wax coating, causing death by desiccation. It is sold for mite control.

"This type of material has been used for a while in public health, against pests like cockroaches," remarks Mr Kelly. "It has an indefinite life and has been shown to work well."

Rodents

Grain stores must be cleared of rats and mice and made rodent-proof while empty, says Mr Kelly. Denying access and removing harbourage helps and rodenticides and bait points are best used pre-harvest.

"Avoid loose grain baits once the store is full, as they are difficult to manage for safety. Rodenticides must be in a safe format, such as lard or wax blocks. And its a good idea to use lockable bait containers, as growers have to consider absolute safety of the food product."

There is also an obligation to search for and remove dead rodents, and clean up excess bait. &#42

Grain store hygiene is vital to prevent already low crop values dipping lower still. Good preparation is the key to success, says Achetas Mike Kelly.

1Structure – check for and fix leaks.

2 Moisture – wet grain attracts mites and fungus-feeding beetles, so dry to 14% moisture.

3 Mites – breed very rapidly once moisture reaches 16% and will taint and spoil grain.

4Beetles – include strays and scavengers, which cause rejections.

5Primary pests – six or so species, all of which thrive in warm grain. Cooling below 12C prevents activity.

6Traps – use bait bags to detect and identify problem species.

7Insecticides – three OPs approved, but availability differs. Use on structure before store is filled if there have been problems in the past two years. Use on grain as a preventative or curative treatment.

8Desiccant dust – new for this harvest, works by absorbing the insects wax coating. Approved for mite control.

9Rodents – tackle and solve rats, mice and birds before harvest.

10Rodenticides – use safe formats and lockable bait containers. Inspect for and remove dead bodies. Keep records of all pesticide treatments.