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Storage Bulletin - January 2015

Publication Date: 
16 January 2015


For the 2014/15 storage season, like last year, approval holders have limited the use of CIPC in low temperature stores (those operating at storage temperatures of 5°C or less) to a single application, early in storage. This is because decline in CIPC residues is reduced at low storage temperatures because the volatility of the chemical is low and it is therefore less readily lost from cold stores. The risk of exceeding the MRL for CIPC is therefore increased in such stores especially if best practice has not been followed.
A single, even application of CIPC results in good sprout control efficacy if best practice is followed, but it is recognised that re-growth may occur in some situations. Where this does occur, options include the use of ethylene or spearmint oil. In the longer term, looking at variety dormancy characteristics, use of maleic hydrazide and different marketing strategies may also be useful for reducing dependence on CIPC as regulation is unlikely to be relaxed. 
The maximum dose of CIPC is being reduced annually and, by 2017, all CIPC product labels will be limited to a total dose of 36 g/tonne (or less). Users of CIPC need to be aware of this and begin to plan changes to stores (see below) that will accommodate the lower usage rates, without impacting crop quality. Keep up to date with developments at
The time has come for those with deficient stores to upgrade them or, at the very least, think carefully about how they are going to be used in future. A number of areas are causing concern at the moment and may affect ability to compete effectively in markets which have recently been over-supplied. but if a choice has been made to continue with potato storage (and clearly that may not be a straightforward decision), there may be a need to address some or all of these issues. Clearly any such changes need to be cost-effective but there are compelling cases for change in these situations:
  • Bulk stores without speed-controlled fans
Most bulk stores are used for holding crop for the processing sector and require treatment with CIPC. If that is the case, the application of CIPC should be carried out with the assistance of low speed fans to circulate the fog evenly throughout the stack. Unless additional fans are to be fitted to a store, the easiest way to achieve this is to fit an inverter (or variable frequency drive) to allow the main fan(s) to be slowed down. 
An inverter also allows energy savings to be made in many stores. Running a fan at 80% capacity costs half as much to run as at full speed so, once a store is down to temperature and providing it is kept dry, there is plenty of scope to recoup on the investment. Most inverters pay for themselves within 2-3 years.
  • Overhead-throw box stores without air dividers
The vast majority of box stores in GB are of the overhead-throw type. These stores were mostly built in the 1980s and 1990s but some are more modern than that. Unless particular measures have been taken to address the airflow, they are likely to suffer from unevenness of air distribution. The ease with which discharged air can return to the fan without passing through the crop (or even the boxes) has been demonstrated in AHDB Potatoes research to contribute significantly to poor efficiency of operation.
An air divider can address this problem in an affordable way. Our Air Divider information sheet shows how these can be fitted into a store to force air to travel along the pallet slot bases and improve the effectiveness of ventilation and temperature control. Closer regulation of temperature also reduces the risk of condensation and associated disease development.
  • Leaky stores 
Wherever there is uncontrolled air exchange in a potato store there is scope for inefficiency. Air that penetrates into a building changes the temperature or humidity of the store and this requires energy for ventilation or mechanical cooling to rectify. Many stores suffer from unregulated air leakage and this can contribute significantly to running costs.
SBCSR is now offering an air leakage test as part of its new, improved StoreCheck auditing service which will be re-launching in February for stores as they are unloaded in 2015. See our StoreCheck leaflet for further details.
  • Stores where there is an expectation to store both cereals and CIPC-treated potatoes 
We are receiving reports of an increased level of auditor activity on this topic as they seek to establish compliance with the latest Red Tractor Combinable Crops protocol. This requires an assessment of risk of CIPC contamination in cereals especially if there is a history of shared storage. The MRL for CIPC in cereals is set at the limit of detection (0.01 mg/kg). CIPC is a persistent chemical and the risk assessment also states that ‘If a comprehensive record of storage is not available and you cannot be sure that CIPC has not been used, then testing of the fabric of materials within the building should be carried out before any other crops are stored.’ 
It is likely that these measures will preclude many stores used for long term storage of CIPC-treated potatoes from also being used as cereal stores. From a potato perspective, this may well affect the availability of buildings for storage so requires consideration before planting.

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