Maximising returns from stored grain is the key challenge in the coming months with much focus on low specific weight, but grain is already being rejected for pest infestations at huge cost to growers. p>
Rejections for food safety affect well over 75,000t/year of quality milling and malting grain, warns Matthew Read, a farmer from the Hampshire/Wiltshire border and chairman of Red Tractor Farm Assurance Combinable Crops. Such rejections can amount to £30/t, but typically cost £18/t, or £500 per load, when haulage redirection, lost premiums and hassle costs are all accounted for.
The Red Tractor assurance scheme uses a delivery point rejection system to investigate when things go wrong. Top of the list of reasons for rejection is insect infestation, with the first such rejections happening already this year – a month earlier than usual. Vermin typically comes next, followed by mould and associated taint and smell, foreign object contamination and mycotoxins (DON).
Other causes are chemical contamination, such as exceeding maximum residue levels or unapproved chemicals, and bitumen.
He urged growers to take four key steps to combat insect infestation: store hygiene, drying grain to 14.5% moisture, cooling to 5C, and monitoring so any infestation is detected early, in time to deal with it.
If infestation is found, apply an insecticide, or more commonly use fumigation, or apply diatomaceous earth. But be aware the latter is not acceptable to all buyers, so check first, he advises. Using trained operators is important for best results, as is the correct dose. “Don’t go from one problem to another by exceeding the application rate.” Finally, be sure to complete the grain passport.
“Vermin remains a huge problem, and not surprisingly so, given that we provide a 365-days-a-year food source,” he says. Store hygiene is again important, so clean up spills, remove places where vermin live and maintain buildings. Control demands a well-executed vermin control plan, using approved products and trained operators or approved contractors. “We regularly see contamination of good grain with rat bait, so use wax bait and wire bait into boxes in store.”
Moulds are most common where grain is left unchecked after harvest – a risk in a busy autumn. “But it’s an entirely preventable situation.”
In the right conditions the most common Penicillium verrucosum mould will produce the mycotoxin Ochratoxin A, for which there is a 5ppb EU limit at grain intake. At 18% moisture mould can develop quickly to exceed that limit, so dry and cool grain as soon as possible, he advises.
Foreign objects, including concrete grain laterals and even gun cartridges, still get found in grain. Oil, dust, fertiliser and debris on store floors need cleaning up. “Oil on floors is unacceptable these days, there are plenty of products to clean it up.” Keep treated seed in a separate dedicated storage area.
Glass is rarely a problem, but fragments from hard plastic items used to replace glass in the store are a growing concern. “Just because it is not glass doesn’t mean it is not a problem.”
DON risk assessment remains an issue, with a number of loads carrying low risk assessment scores of 10ppb or less, but showing very high levels in the grain, of more than 1,250ppb. “We will follow those up, with visits if necessary, to see whether it is a genuine issue, or poor risk assessment.”
It is an important issue, he says. “If you think you have a high score, get the grain tested and talk to buyers to see where it could go. And be sure to use the most recent assessment form, as updated on the HGCA website.”
Oilseed rape moisture needs particularly careful attention, with an 8% target for storage, but rejections for anything below 6%, because over-dry seed can split, causing fatty acid content to build up.
Polycyclic aromatic hydrocarbon contamination is also appearing regularly above the 2ppb limit. The cause is unclear so far. “It could be badly calibrated oil-fired dryers, or clay pigeon fragments, since they are made from bitumen.” More work is planned for spring 2013.
Contamination with CIPC potato sprout suppressant is also an issue. “It is a very persistent product, which permeates into the fabric of the building, and once it is in there it can come out in the right conditions. It is not approved for use in cereals or oilseeds, so the maximum residue level is set at the limit of detection. So, if it is detected, it is deemed an illegal use.”
One affected farm had to rebuild a grain store because CIPC had been used in the building 10 years previously by a previous farm owner. “So make sure you know the history of your store 10-15 years ago.”
At out-loading check the lorry, check the underside of the sheet and don’t load un-sheeted lorries. “Quite frankly it is not acceptable, if you’ve gone to all the trouble of looking after your grain up to that point.”
Also, don’t overload, check the bucket is clean and keep a sample back. “And load what the buyer is expecting to collect. It is not unheard of for loads to arrive with something different to what was expected, maybe the wrong variety, sometimes even the wrong crop.”