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PSI Bulletin: March 2022


A new potato storage update from Potato Storage Insight, exclusively for our subscribers

This is our second free bulletin. Along with last month’s edition, I hope it is sufficient to give you a flavour of the product we are offering. From next month, the monthly bulletin will only be available to subscribers. Storage cost management will be featured. You can find subscription prices and sign-up information here. Alternatively send an email confirming you wish to subscribe to If you have already signed up, thank you for subscribing. We will be in touch very soon.


Thank you to everyone who has given feedback on Synopsis, this new, monthly potato storage bulletin from Potato Storage Insight (PSI).

The bulletin is based around an established model of many years standing, informing you about news and developments from research but with added commercial relevance to keep you informed about what’s going on in the potato storage world.

It's a regular monthly prompt of topical issues too and a reminder of the issues that you may need to consider as a leading potato store manager.

As with all our work, PSI provides this from a standpoint that is professional, specialist and independent.

Adrian Cunnington

Potato Storage Insight Ltd.

Potato Storage Insight activity

Potato Storage Insight Ltd (PSI) is a new company specialising in potato storage expertise and know-how. PSI has been set up by Adrian Cunnington, former head of AHDB’s Sutton Bridge Crop Storage Research facility that closed in December.

PSI is available to offer support and advice to all parts of the British potato industry, building on Adrian’s many years of experience, on technical issues and best practice adoption. It is now a member of the Association of Independent Potato Consultants, an alliance of industry-leading agronomists working across the potato sector, co-ordinated by John Sarup of Spud Agronomy.

February has been a busy month with extensive interaction with a wide range of supply chains on storage matters.

A trip to Scotland to provide input to the SRUC Potato Store Managers’ Course in Perth was a highlight, working alongside Stuart Wale, Philip Burgess, Kyran Maloney and colleagues. The course included a visit to seed grading taking place at Glenfarg (below), courtesy of Rob Doig.

PSI’s training work extends this month into delivery of our own two-day course for store managers at Retford, Notts on 15 & 16 March. Places have all sold out but, if you are interested in discussing dedicated training options for your company, please call Adrian on 07970 072260 today!

Technical Insight: STORAGE CONTROL

Cornerstone Systems Limited

This month, PSI visited Cornerstone Systems Ltd, a company based in Stone, Staffordshire who market computer-based store control systems.

Cornerstone Systems is operated by Richard Priestley and Liam Redmond, who have a long track record of working in the control business across a range of industries. Agricultural store control has been a lynchpin of the company’s work dating back to the late 1980s when Cornerstone were one of the first to introduce PC-based control to our sector and today their work extends to, not only potatoes, but grain and biomass storage too.

More ‘experienced’ subscribers will perhaps remember the introduction of the almost bullet-proof ‘Teletext’ format controllers over 30 years ago (some still remain in use), but when Richard and Liam took over control in 2015, the company was moving to introduce a new, more up-to-date product line which they called Crop Sense.

Today’s offering is even more sophisticated and capable, with bespoke configurations of the sleek, PC-based Crop Sense controllers available to suit individuals’ needs. These have a very varied but easy-to-use capability with multiple features being able to be built into each controller on a modular basis.

Cornerstone Systems’ directors Richard Priestley and Liam Redmond (right)

Temperature control, of course, remains the core element of the potato storage system and Cornerstone offer novel cable-free, radio-based thermistor sensing in many of their installations. A single controller can be used to monitor multi-store sites and outputs can be sent to multiple remote sites or mobile devices. And carbon dioxide sensing can be linked in to fully automate fresh-air flushing requirements.

Beyond this, they offer interlinking with ethylene systems to control ventilation and minimise chemical loss. Power management capabilities aim to offer cost savings through use of inverters, minimise consumption at high tariff periods and optimise use of on-site generation. But you don’t need a complex site to use the system; Liam says some of their clients have just “one or two stores”. Cornerstone claims it can link its controller into almost any climate control equipment to provide an independent and common-format monitoring capability. Find out more at or call 01785 818020.


Peter Dade (right), stores manager at Winters Lane Storage (WLS) has extensive experience of using Cornerstone controllers across the thirteen store, 12,500 tonnes capacity, co-operative site in Lincolnshire since 1995. He says: “In many ways, our stores almost run themselves. Having a single system like this on a site like ours is a no-brainer.”

Their newest Cornerstone controller was installed with the latest Crop Sense software just over two years ago, although it was able to use a lot of the infrastructure – such as probe wiring – that was already there from the earlier system.

As an independent system, the versatility coupled with remote notification and alarms across the WLS site is its attraction to bring together control of multiple processes in a single unit. Peter says the system is user-friendly and generates regular outputs that are suited to day to day control. “It has a bespoke program that is very precise and takes account of a lot of different inputs to run the stores exactly how we need them to. This includes temperature, Biofresh ethylene, electrical metering and PV energy availability as part of the 4-tariff management control. It also looks after fan speeds through the inverters we now have and regulates defrost on demand.”

Thanks to Richard, Liam and Peter for their help with this article.

Topical tips for March

This month, attention turns to getting ready to deal with the next crop to go in the ground – but don’t get complacent with what’s still in store…

Seed handling

This is an area that needs your attention not least because it is all too easy to put your crop at a disadvantage from the outset if attention to detail falls short.

Seed in one tonne bags needs to be stored carefully. Even if they have ventilation strips in the sides, one tonne bags can very quickly develop condensation within them and this can become an ideal breeding ground for bacteria – such as blackleg-causing Pectobacterium atrosepticum (Pba) and fungi like silver scurf (Helminthosporium solani).

So, wherever possible, decant seed into boxes, especially if storage is going to be for more than a fortnight. Hitch those boxes up to a fan to keep them ventilated and dry before planting. Avoid using old CIPC-treated stores for this; you could still have residue in the ventilation tunnel which could contaminate your seed.

If seed has to stay in bags, at the very least place each bag on a pallet so air can be drawn up by the respiring crop to reduce the risk of infection (below).

Better still, place bags where air can be blown around or, ideally, through them to discourage condensation. The bottom slot of a drying wall can be used for this if the other slots can be closed off or blocked with 'sponges'.


In ware stores, there has been a surge of sprouting activity over the past six to eight weeks or so and the contractors applying sprout suppressants have reported that they are extremely busy.

This seasonal peak seems to be a little later than usual, but may be indicative of pre-harvest maleic hydrazide ‘running out of steam’. Residues are reported to be more variable and, if anything, down on average a little compared with last year.

Once that residual effect from MH starts to fade, all the chemical control options available are essentially now provided by contact action. Ethylene is continual treatment and will already be underway. It will suppress sprouting whilst the ethylene level is maintained.

Others, eg spearmint oil and orange oil, will be applied as fog treatments which need to be kept in the building for at least 48 hours after application. Also, when it comes to applying these more volatile sprout suppression products as fogs, there are some key actions needed irrespective of the specific active chosen.

First of all, make sure the fans are recirculating air (but not cooling the crop) for 24 hours before the application. This is very important to even out the temperature as much as possible throughout the store before the chemical is applied.

Use the fans to ‘actively recirculate’ the fog when the application is made. This is not quite the same as it was for CIPC. We need a bit more air now to move the volatile ‘essential oils’. Inverters should be fitted to the fans and used at about 30 Hz (perhaps double the rate used for CIPC) in most scenarios to keep a steady even flow of fog. Avoid concentrated fast jets of air or the opposite, static airflows in corners or eaves, which can lead to over-treatment.

Do, in all cases, liaise with your contractor and/or product manufacturer for up-to-the-minute advice to get the best from your chosen product.

New pesticide usage survey for potato storage published

Fera has published on behalf of Defra for England & Wales, SASA in Scotland and DAERA in Northern Ireland, its latest survey of pesticide use in potato stores. The data is for the crop year 2020/21 and, as such, represents the first season of storage without the use of CIPC (chlorpropham).

A total of 173 stores (82% box and 18% bulk) were surveyed with a marked shift away, since the previous (2018) check, from farm stores to more merchant/rental stores. This may have been affected by accessibility to businesses during the pandemic.

Nevertheless, the authors report a “massive change to the biopesticide spearmint oil” had taken place and the use of maleic hydrazide in the field had increased by 69% in terms of active substance applied.

This step-change in usage was to be expected following the loss of approval of CIPC with just spearmint oil and ethylene remaining as store-applied chemicals for suppressing sprouting.

The survey indicates that untreated tonnage rose from 57% of the stored crop in 2018 to 62% in 2020. This left just over 1 million tonnes of potatoes receiving chemical treatments in store.

In ware storage, some 76% of treated ware received at least one spearmint oil treatment, whilst 23% were treated with ethylene, which is applied continuously to prolong dormancy.

The total quantity of seed and ware stored was 3,097,000 tonnes. Of this, just over 500,000 tonnes was seed and 32% of the seed was chemically-treated with fungicide. Of all seed treatments applied, 88% received imazalil and 7% thiabendazole for disease control. The other 5% was treated with ethylene which can increase stem number.

The trends observed in this latest release of the biennial survey will inevitably be quite transient, as the market has already seen the introduction of orange oil in 2021/22 as a new active for sprout suppression. Other, similar ‘essential oil-type’ products are known to be being prepared for market if approval requirements can be met.


Changes afoot in Cambridge for both CUPGRA and NIAB CUF

John Chinn, the long-serving CUPGRA president and Philip Kingsmill, the organisation’s Chair, both stood down from their posts at the recent AGM.

Their roles have been taken on by former Head of NIAB, Tina Barsby, as the new President, who is joined by Sophie Bambridge as the new CUPGRA Chair.

Meanwhile, at NIAB CUF, lead agronomist Marc Allison has announced that he will be taking retirement in April and Simon Smart has also recently left the agronomy research team. New roles are being recruited for.

WPC platform for storage

Storage is set to feature prominently at the forthcoming World Potato Congress to be held in Dublin, Ireland in three months’ time. Prof Nora Olsen from the University of Idaho; Kurt Demeulemeester of Inagro, Belgium; Ireland’s Derek Roulston and PSI’s Adrian Cunnington are all due to be on the rostrum during the four-day conference being held from 30 May to 2 June. Registration details are at

Synopsis subscription

Finally a reminder that, if you have found this Synopsis bulletin informative and would like to access further copies, they will be published monthly on the Potato Storage Insight website from April on a subscription basis. Next month's edition will include a feature on storage cost management.

You can subscribe by visiting our website at, clicking on SUBSCRIBE and signing up. An annual subscription is just £99 + VAT.

Alternatively send an email to


Synopsis is published by Potato Storage Insight Ltd. 45 Main St., Gedney Dyke, Spalding, Lincs. PE12 0AJ. Tel: 07970 072260. Views expressed are not necessarily those of PSI. No responsibility is taken for views reported nor are endorsements of any products featured made or inferred. © PSI 2022


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