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Storage Bulletin - December 2010

Publication Date: 
20 December 2010

Growers are urged to check their crops in store carefully to ensure they are not suffering from the current cold weather.

Most stores are well insulated to help isolate the storage environment from the impact of the conditions outside. But stores should be checked for any leakage or spots where cold air may get inside the building. Even small gaps in the insulation ‘envelope’ can lead to localised chilling, especially when there is wind pressure to assist the penetration of cold into the store.

Cold weather heightens the risk of condensation in the roof of the store as the warm, high humidity air coming from the crop will condense on the cooler roof above.  Processing stores are most at risk. Condensation can be managed by using roof space heating if this fitted or a combination of heaters and air movement in the roof space.

Temperature gradients will also be created in store by cold weather so there is a greater risk of condensation within the crop. Use of recirculation can help to alleviate this.

Where ambient air is used for ventilation, check that the louvres are opening and closing correctly. Ice can often form around louvres and result in them sticking. A stuck-open louvre could have catastrophic effects at this time of year… Speaking of which, double check that there is a back-up thermostat covering the air delivery that will shut down the fan in case of a problem where air that is too cold risks being blown into the crop. This override thermostat should be entirely independent of the control system to guard against any faults with dodgy sensors or similar.

Cold air will usually also affect the flushing of stores. Those using manual flushing must take care to balance the need for fresh air with the risk of chilling. Automated flush systems should have a minimum temperature set for air delivery in the duct, but remember that, in very cold weather, this may mean there is little or no mixing of ambient air taking place.

Fry colours should be tested regularly to identify any impact of the cold conditions on market acceptability. If quality has been affected it may be possible to take some corrective action by conditioning the crop; it is recommended to seek the agreement of your market and specialist advice before doing so. You can call SBCSR free on 0800 02 82 111 for assistance.

CIPC timing is critical to get the most from this important chemical.

Sprout control treatments should be have been applied by now. Please see the accompanying article at the end of this bulletin on timing of CIPC application for further guidance.

Energy & sprout suppression on the agenda for our storage forum.

Thursday 3 March is the date for your diary when we will be holding our winter storage forum at Sutton Bridge. Half of the day will be devoted to energy management, the other half to sprout suppression. Further information will be released shortly; please register your interest by emailing mkotecha@potato.org.uk.

Bookings now being taken for store management training.

The PCL Store Managers’ Course is being held at Sutton Bridge on Thursday 17 and Friday 18 February 2011. Contact Kate Balloch for details, email kballoch@potato.org.uk.

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Getting the timing of the application of CIPC correct is crucial to ensuring no MRL exceedance, warns Dr Mike Storey, head of AHDB Potatoes R&D.

“Stored crops will have received an initial CIPC treatment and now consideration has to turn to managing the correct timing of subsequent applications,” he continues.

“If you don’t get the timing of these right, you could reduce the time your potatoes can be stored and you may risk exceeding the 10mg/kg MRL residue limits.”

Dr Storey, who chairs the CIPC Stewardship Group, goes on to explain that some eye movement does not necessarily mean that the initial application was ineffective as CIPC needs some active growth to be taken up effectively.

“Often the eyes just open, then take up available CIPC and growth is suppressed again,” he explains. “It is worthwhile waiting, say a week, to see if the sprouting moves on a bit further, rather than just jumping straight in with an additional CIPC application.

He also recommends growers not to make early re-applications.

“It is also vital that records of the total CIPC application to a crop are available,” he continues. “It would be disastrous if a crop that had been intended for the processed or chip shop market and received corresponding levels of the suppressant, were then sold to the fresh market. This could easily be prevented if merchants, processors and packers all have access to application records – this should be part of their due diligence.”

The cross industry CIPC group recently won the prestigious international Agrow Award for Best Stewardship programme to promote best practice and protect the availability of this crucial sprout suppressant.

“Despite this recognition, there is definitely no room for complacency,” warns Dr Storey.

CIPC residues are being very closely monitored by the Pesticide Residue Committee and any evidence of incorrect total application or MRL exceedance will have serious consequences for the whole industry.

 He goes on to remind store managers that over the whole season, potato crops destined for the fresh market can only receive up to 36g CIPC/tonne and processing potatoes up to 63.75g/tonne.  

 “CIPC is crucial and we all have a responsibility to use it properly,” he declares. “There is no alternative sprout suppressant, especially in the potato processing and chipping sector. We are in our third season of CIPC stewardship and we must keep doing all we can to ensure best practice is followed or we will lose it!”

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