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UK - Mycotoxin Hazard on Crops Storage

Published: September 12, 2007
Source : Farmers Guardian
Poor storage continues to be potentially a weak link for quality in the cereal supply chain. However a new £1.3 million LINK project, funded jointly by Defra and industry, is aiming to find solutions to current storage challenges.


Facing up to storage difficulties and finding solutions is Link project’s goal

Results from a survey conducted in 2006 by English Food and Farming Partnership (EFFP) revealed that almost one-quarter of farmers surveyed felt their businesses were constrained by their grain storage facilities.

Furthermore, more than two-thirds believed that their returns were being diluted by claims and allowances on grain deliveries.

According to Rob Sanderson, deputy grain groups director with Grainfarmers, rejections cost milling wheat growers over £3 million a year and almost half are as a result of grain condition, rather than quality. The average rejection rate for milling wheat deliveries, according to industry body nabim, is 4.2 per cent.

Against this backdrop a new £1.3 million LINK project led by the Central Science Laboratory got underway in July 2006 to look at the key issues relating to grain storage and food safety, with the aim ultimately of enabling the grain industry to comply with more stringent legislation and demonstrate due diligence via the implementation of HACCP (Hazard Analysis Critical Control Points), which is already in place a short way along the supply chain and is expected to be extended to include primary production at some point in the future.

According to CSL business development manager and LINK project co-ordinator Dean Cook, the new project has three major drivers. The first is the introduction of new legislation setting limits for the storage mycotoxin Ochratoxin-A. Legal limits now in place impose standards of five parts per billion (ppb) in grain intended for human consumption and three ppb for finished cereal products.

One of the key aims of the project is to determine how the development of Ochratoxin-A is affected by store hygiene and other management practices. OA is formed in store by a penicillium fungus, which has never been found in the field. Inoculum must therefore originate within the store but little is known about this process.

Early indications from the LINK research are that elevator and conveyor systems are an important source of penicillium verrucosum and as a result growers and storekeepers are being advised to pay particular attention to their cleaning procedures for these systems.

The project will also evaluate the efficacy of different store hygiene measures in reducing inoculum levels and examine their effect on grain contamination during the storage period, with the aim of establishing best practice recommendations.

The second driver, says Mr Cook, is the continuing loss of insecticide products available for use in grain stores. Malathion (co-formulated with bifenthrin in Prostore) has recently failed to achieve Annex 1 listing, leaving
pirimiphos-methyl (Actellic/ Fumite) and chlorpyrifos-methyl (Reldan) as the remaining surface application or admixed chemical options for storage pest control. Fumigation options have been limited to phosphine following the withdrawal of methyl bromide.

Mr Cook points out that there is a need to determine the current status of grain pests in UK stores and to establish what limits of infestation might be appropriate.

In addition to the direct physical damage caused by pests, there is evidence that some insect species may also act as vectors in transmitting micro-organisms – scientists will be trying to find out if this process takes place in stored grain.

In common with other sectors of the plant protection industry there is little in the way of new active ingredients or products coming forward, adds Mr Cook, although approval is being sought for the use of spinosad, an insecticide derived from naturally-occurring soil fungi, for storage pest control and the Mycopest project underway at CSL is developing the use of entomopathogenic fungi for insect and mite control in store.

Driver three is climate change, which is important for several reasons, says Mr Cook. A warmer climate may compromise the industry’s ability to cool grain, affecting the extent of infestations of the three key storage pests: saw-toothed grain beetle, grain weevil and flour mite, as well as the type of infestation.

“Climate change could mean warmer and earlier harvests, which in turn will affect the minimum night-time ambient temperature we have available. It could take longer to get the first cooling front through and so the risk of insect attack will be increased. We may also see greater pest pressure overall as pests will be able to survive over-winter in store structures,” he comments.

In addition, in reducing the overall carbon footprint of agriculture, there is a need to look at the energy costs associated with grain drying, he adds.

The predicted increase in extreme weather events may also pose a challenge for storage. Wet harvests may become more commonplace, in which case the industry will need to assess whether its grain drying capacity is sufficient to dry grain quickly enough to prevent the formation of storage mycotoxins.

Work on climate change and storage is taking the form of computer modelling to determine the potential implications of a range of climate change scenarios. This season CSL is also undertaking live demonstration work at stores across the country with the aim of demonstrating to farmers how well the stores cool and also comparing manual and automatic control cooling systems.


Three tips for this harvest

1. Avoid drying backlogs - get wet grain through a hot air dryer as quickly as possible.
2. Try not leave grain in an unventilated heap.
3. Grain coming into store at 20 per cent moisture content is at risk from Ochratoxin-A formation.
Source
Farmers Guardian
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