3 July 1998

This store is not rat-proof.Repair-damaged or corroded sheeting before the smell of fresh grain attracts rats at harvest.

Tell-tale signs of high-level mouse activity. Baits placed on runs will intercept and control numbers effectively, even in a full store. notes Mr Kelly.

Protecting operators is essential when store cleaning. Air-filtering masks are a minimum, says Mr Kelly.

Clear ground around grain stores so rodents have to break cover. Cut or kill undergrowth.

Use bait bags after cleaning to lure any bugs out of hiding. If none are found spraying is not necessary.

Inspect and clean out elevator and conveyor bases (inset) – or residues will contaminate the first grain at harvest. If there are inaccessible areas, flush the system with a grain/insecticide mix and dispose of it like other store cleanings.

Remove temporary structures such as walling and ducting. Clean out potential insect havens such as floor recesses. Damaged ducting should be repaired or replaced before the hectic harvest period begins.

Immediate removal and burning of cleanings is essential to reduce risks of re-infestation. Inset: Mites half an inch deep on a small spillage of OSR between bins. Such spillages harbour pests and lead to infestations and rejections of later loads. A clear-up after outloading should be standard practice.

A meticulous

clean-up to start is so vital

Infested grain can hit farm

profits hard, and in too many

cases basic errors in pre-

harvest cleaning are letting

growers down.

Andrew Swallow provides a

step-by-step guide to help

growers eradicate the risks

before this harvest

RECENT MAFF surveys show about 10% of farm stores in England and Wales are infested by a primary grain pest. Many growers are let down by gaps in their pre-harvest hygiene programme, believes Mike Kelly of independent storage specialist the Acheta partnership.

"Hygiene is all about thorough cleaning. That means brushing or vacuuming walls and floors, in ducting tunnels, behind bins and temporary bulkheads, even if they are a devil to get behind. It is the long-term residues that cause the problems," he stresses.

Cleaning methods must be safe however. "The Health and Safety Executive are not keen on compressors to blow stores clean as grain dust has a high hazard rating. Operators must be kitted out with suitable breathing apparatus and personal protective equipment. Besides, compressors tend to redistribute, rather than remove, debris," he notes.

Elevators, conveyors and dryers can all harbour pests too. Inspection hatches should be taken off and remnants of last harvest removed. And that should include the combine, he says.

Efforts cleaning the store can all be in vain if sweepings are not disposed of immediately, preferably by burning. "If you are keeping sweepings for game-feed, store them at least a quarter of a mile away. And make sure the sacks are taken out of the store that day – pests will crawl out and seek cracks and crevices to hide in as soon as the sacks settle."

After cleaning many farms routinely treat stores with insecticide, against the ethic of only applying pesticides where a need is justified, says Mr Kelly. "Storage pests are not going to come in from the field. If the store is clean, then I have to question the policy of automatically spraying."

To ensure the store is pest free, bait bags should be placed in and around the store, lowered into position on a string in inaccessible areas, such as behind bins. After a week, remove the bags and shake them out over a large white surface to see if any grain bugs have been attracted.

If no bugs are detected, then spraying is not needed. When bugs are found, then the whole store should be treated, paying particular attention to the area where the bait bags became infested, he advises.

Immediately after cleaning is also the best time to wage war on mice. Loose baits such as calciferol on canary seed are particularly effective, and stocked by most agro-chemical suppliers. "But be sure to clear them up before harvest starts."

Actellic (pirimiphos-methyl), Satisfar (etrimfos) and Reldan (chlorpyrifos-methyl) are the only three products approved for use on surfaces which will come into contact with grain, says Mr Kelly. They should be applied either with a conventional high volume sprayer, or a mister, at label application rates. As a rule of thumb, surfaces should be sprayed just to the point of run-off.

"Spray a 1-2m strip at a time, starting from the top. Take care not to make a lake at the bottom of walls – the target dose per sq m would be far exceeded, and grain could pick up the chemical."

Smoke-bombs or Ultra-Low-Volume sprays are not stand-alone treatments, he warns. "Smoke-bombs do not penetrate the cracks and crevices, and insecticide only settles on horizontal surfaces. Ultra-low volume sprays are designed for flying insects – they do not give the necessary continuous surface coating of material, and often use pyrethroids, which are not approved for surfaces coming into contact with grain."

However, both have useful disturbance effects, which can force sheltering beetles out of hiding and into contact with already treated surfaces, he notes.

Ideally three weeks is required between treatment and store-filling with one week the absolute minimum, says Mr Kelly. "Less than a one week interval and spraying is pointless. Any pests present will not need to come out to feed, so will not contact chemical treatments."

The job is not finished with spraying as attention should turn to the store surrounds. "Rats in the fields will be attracted by the smell of fresh grain at harvest, so take time beforehand to clear at least a 10ft strip round the whole store. It should be cut to lawn height or less, to make an area the rats will not feel safe crossing. Over-hanging trees and bushes must go too, and the structure of the buildings should be surveyed and repaired where necessary.

"Finally, having taken the trouble to keep your own store clean, do not allow lorries collecting grain to sweep out on your yard – they may have just tipped off a rejection for infestation!"

KEYPOINTS

* 10% of stores infested.

* Brush/vacuum all areas.

* Avoid compressors

* Clean elevators, dryers, conveyors & combine too.

* Burn sweepings immediately.

* Use bait bags to check.

* If pests found use insecticide.

* Clear 3m strip around store.

* Dont let lorries sweep out.

PRE-HARVEST CHECK

&#8226 10% of stores infested.

&#8226 Brush/vacuum all areas.

&#8226 Avoid compressors

&#8226 Clean elevators, dryers, conveyors & combine too.

&#8226 Burn sweepings immediately.

&#8226 Use bait bags to check.

&#8226 If pests found use insecticide.

&#8226 Clear 3m strip around store.

lDont let lorries sweep out.

Pre-store sample safe and accurate

SAMPLING grain on its way into store is more accurate than sampling in store – and safer.

Accidents in confined spaces cause an average of 15 deaths a year across all industries. And the risks to farmers, farm workers and trade representatives mean working practices must change, says trade body UKASTA.

Regulations which came into force on 1 Jan 1998 require workers, including visiting grain samplers, to avoid entry into confined spaces if an alternative working practice is available, explains UKASTA marketing manager Jamie Day.

"Traders are concerned about their staff, frequently working alone, drawing samples from stores that are often badly lit and guarded. Silos and stores can be very dangerous. These new regulations mean fewer samples will be collected in this way."

The trade is encouraging farmers to take their own grain samples as crops go into store this year, says Mr Day.

Such sampling also produces more representative results. "It is an ACCS recommendation. A six-foot grain spear can not give a sample that accurately reflects the crop in store. Similarly, taking samples when a store is full fails to distinguish between crops from different fields or those harvested under different weather conditions."

More representative sampling at store loading will help reduce costly crop rejections when delivered crops fail to meet contract specifications, he adds.

&#8226 Safe work in confined spaces: approved code of practice, regulations and guidance, priced £7.50 and a free leaflet Safe work in confined spaces are available from Health and Safety Commission Books (01787-881165).