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PSI Bulletin: Feb23

No. 2/23 SUBSCRIBER EDITION: please go to to sign up

Welcome to your February edition of Synopsis, Potato Storage Insight's monthly publication bringing you news, technical information and developments on potato storage issues.

PSI Potato Store Managers' Course '23: FINAL CALL!

The PSI Potato Store Managers' Course for 2023 will be held on Wednesday 15 & Thursday 16 March 2023 at the Weston Hall Hotel, Bulkington, near Coventry. The venue has easy access from the M1, M6 and M69 motorways and is just a short drive from Birmingham airport (BHX).

Tutors for the course will be Adrian Cunnington and Glyn Harper, both formerly of Sutton Bridge Crop Storage Research, who between them have over 50 years' experience of potato storage research, training and knowledge transfer.

The course is aimed at growers and store managers who are involved in the day-to-day management of potato stores. The course will include talks, group discussions and practical interactive sessions, focusing on all aspects of potato storage. There will be opportunity for delegates to raise specific concerns and for these to be addressed during the course on a 1:1 or group basis. Delegate numbers are limited to 20, so please book now to guarantee one of our final few places. Areas covered will include:

  • Store management principles

  • Storage buildings and control systems

  • Basic physiology for storage

  • Store hygiene and disease control

  • Maintaining skin finish for pre‑packing

  • Drying, wound healing & pull-down

  • Managing processing crop quality

  • Sprout suppression options post-CIPC

  • Condensation control

  • Energy efficiency & cost control

  • Seed store management

An electronic booking form and full details are available on the PSI website. Click here to open the booking form in a new window. For further information call Adrian on 07970 072260.


Last month, Adrian Cunnington was speaking at the SACAPP conference in Dundee, focusing on store efficiency and effectiveness and, specifically, on managing costs.

One discussion point was storage temperature. Since the conference, we have re-visited some AHDB work on the topic carried out at Sutton Bridge which showed no significant difference in blemish disease levels across a range of temperatures below 5.5°C. The silver scurf data is below, with overall means across all varieties summarised in the bottom left:

Adrian has been carrying out some bespoke training in a similar vein over the course of recent weeks and also, whilst in Scotland, was able to visit James Hutton institute for an update on their huge array of potato work.

Of particular interest, since late blight is a potentially serious storage disease, was the latest data from Dr David Cooke and his team on blight population dynamics which showed increased proportions of 36_A2 and 6_A1 strains last year compared with 2021 (see graph below). This work - which underpinned the Fight Against Blight initiative run until its demise by the AHDB - is an example of work which needs continued industry support to combat continuing changes in the blight population and the potential emergence of new fungicide-resistant strains, as recently featured in Farmers Weekly.

Blight population data 2021/22 (courtesy: D Cooke, JHI)

BEST PRACTICE for February/March

Generally, most crops are reported to be storing well but there remains a steady level of sprouting pressure. This is requiring re-treatment of stores at intervals as short as four weeks at higher temperatures, notably for those crops which were unable to be treated with maleic hydrazide.

Sprouts are best controlled when less than 2 mm long. Some shown here are well past that.

It is important, to have the best prospect of control, not to leave treatments too late. The 'peeping' stage (< 2 mm) is recommended as the optimum time for treatment by chemical manufacturers. Whilst some of the products available can take out more extensive growth, this is not a preferred route as more sprouting will result in greater weight loss and can compromise fry colour by contributing to defects such as 'sugar spotting'.

Do remember, if you need to re-treat, to make sure you get condensation under control in the store before the chemical goes on. Recirculation of air at a high speed setting (80% +) is best for this job of moisture removal but may take some time if ambient conditions are colder than the store. It is worth repeating that ANY damp potatoes will be highly prone to scorch by any of the fogged actives we now have available and distribution of the sprout suppressant will be compromised by the presence of any wet crop.

Disease remains a threat in some crops, especially those susceptible to dry rot (see December's edition of Synopsis). Warm conditions at harvest were ideal for its spread and infection takes place through damage so there are always tubers which can be prone to infection, even in the most kindly-handled crops. Don't forget that, over time, dry rot will become secondarily infected with bacteria which will cause breakdown and spread.

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