PSI Bulletin: September 2024
No. 9/24 SUBSCRIBER EDITION: please go to potatostorageinsight.com/subscribe to sign up as a Synopsis subscriber.
Dear Subscriber,
Welcome. You are reading the September edition of Synopsis, your monthly potato storage update from Potato Storage Insight.
This month has seen a new event in the potato calendar and the UK Potato Days working demonstration held at Lincoln on 4/5 September certainly grabbed the attention of many judging by the strong level of attendance, particularly on day one.
And, as we head into a new storage season, after a couple of tough years for many potato store managers, you'd be justified in expecting an easier journey over the coming months. Time will tell, but we have to be ready for the next challenge. Reports from the field suggest there's a high degree of variability across crops around the country and, given some already exceptional weather, there are a variety of issues to cope with for some…
Best practice
A NEW STORAGE SEASON BEGINS…
Bruising risk (see also Technical Insight below) is a major concern with crops seemingly exhibiting a high degree of susceptibility to the problem. Recent rain where it has been received [in moderation] will have helped to improved the level of cushioning on the harvester, but this needs to be extended right through to box filling or the store elevator; minimising drops is crucial to limit the problem.
In some parts of the country, notably the Midlands and north west, there have been excessive and, in some cases, unprecedented levels of rain in recent days that mean any crops affected will need to be assessed very carefully for their suitability for storage. Having adequate drying capability will be paramount – forced ventilation is always the best for removing excess moisture either in bulk storage or in a positively ventilated box storage setup. Don’t try to store waterlogged or ‘rained on’ potatoes.
Reports have also been received of disease issues with pink rot (Phytophthora erythroseptica) amongst the most concerning. This fungus is often linked to soils with a history of waterlogging (so that will be quite a lot after last year) and is encouraged by warm and wet field conditions as many have already experienced this month. Pink rot can rapidly break down to soft rot in a matter of days.
A forecast reduction in ambient temperatures may be a boost in reducing risk of rots developing but care will be needed if night-time temperatures fall away too fast as we head into October, especially given the high bruising risk and the need to maintain processing quality in many crops.
From a storage perspective, it is important to remember some basic rules of best practice:
· Always ensure skins are fully set before loading.
· Get crops into store as reasonably quickly as possible. Avoid extended loading periods which tend to compromise the quality of the first crops that went into store.
· Make sure forced draught ventilation is initiated on any crops where there is moisture present or soil contamination, so that drying can be achieved quickly.
· Be aware that, as moisture is evaporated, the temperature will fall.
· Avoid creating large temperature differences across stores as this makes condensation much more likely.
· Stack boxes carefully to ensure air can circulate freely; leave adequate space at row ends rather than creating a bottleneck which will limit air flow.
· If air can't get to the potatoes, it can't do the job you want it to, be that drying or cooling – or both. Or, if it can take an easier route, the same applies. Take a look at the example below to see how we can improve evenness of flow in a box store.
Technical insight
Factors influencing bruising in potato
The bruises found in potato tissue result from the production of melanin pigment following the injury of cells and these give that tissue a black, brown or grey appearance. The pigment is formed when substrates derived from the amino acid tyrosine and an enzyme called polyphenyl oxidase (PPO) come into contact with each other as a result of the injury*.
Bruises usually occur in the peri-medullary tissue just below the vascular ring. Whilst turgid or firm tubers tend to be more prone to mechanical damage, flaccid or soft tubers are more likely to suffer from bruising. Temperature is key with greater risk of bruising associated with cold temperatures (below 8°C). Extra care should be taken with harvesting early in the day if tuber temperatures have dropped overnight.
Varietal susceptibility is a major factor. Large tubers bruise more easily than small ones as the larger weight means that more energy must be absorbed on impact. The size of cells in the tuber also affects cell strength and elasticity. Generally, larger cells are more easily damaged.
Within a variety, seasonal conditions which result in high dry matter content can increase susceptibility to bruising but any cultural practice that ages tubers such as stress, poor nutrition or delayed harvest can do so too.
*Reference: Brook, R.C. (1996) Potato bruising. NPAC, Lansing, Michigan, USA. 117 pp.
Seed and salad storage
Many seed and salad stores will already be loaded or approaching that position by now. A key consideration with these is the respiration rate of the crop when the potatoes came into store (which can often be very high) so care needs to be taken when entering these stores to guard against carbon dioxide accumulation, especially in well-sealed buildings. Use a CO2 monitor if you have any concerns before entering a store. The high CO2 levels can also get the crops themselves quite agitated (a circular self-driving reaction) so regular venting and steadily dropping the temperature is recommended wherever possible.
Remember too that, by virtue of the smaller tuber size in seed and salad lots, more fan power is needed to drive air through the crop as the tubers pack more tightly when they are small. This can make the drying and cooling process relatively slow and more difficult to regulate evenly. The combination of high tuber respiration and less airflow through the crop (unless positive ventilation is available) can also make seed and salad crops more prone to condensation.
Potato Days UK
Potato Days UK was a new initiative from DLG, the organisers of many of the world’s major agricultural events and shows, including AGRITECHNICA. The event was held on 4 & 5 September at the Nocton Estate, near Lincoln, LN4 2GR, courtesy of Dyson Farming Ltd.
It is understood that there are plans for the new event to run every two years although no dates for future shows have been confirmed.
Snippets
New PPA Board Chair
John Sedgwick of Wisbech-based processor Lamb Weston has been elected the new Board chair of the UK Potato Processors' Association.
DMN harvest interval reduced in France
DormFresh has announced that its harvest interval (HI) - the minimum time permitted between last treatment and sale - for its DMN sprout suppressant Dormir (known in the UK as 1,4 SIGHT®) has been reduced from 30 days to just three with immediate effect.
PSI understands that there is a similar application to reduce the HI in process with the Health & Safety Executive in the UK, but no changes to the conditions of use have taken place as yet. The interval therefore remains at 30 days.
Peter Craven
NIAB/CUPGRA have advised that Peter Craven, their Potato R&D Manager, has accepted a new position as the Head of Agriculture at Natural England with effect from 30th September. We wish him well in his new role. Elizabeth Stockdale will provide cover until Peter's replacement is appointed.
Forthcoming events
If you are hosting a potato or agricultural industry event, please send details to admin@potatostorageinsight.com. Key dates with relevance to the potato sector in the coming months in the UK include:
November
Wed 6 Agri-Tech E REAP conference, Cambridge
Wed 27 - Thu 28 CropTec, NAEC, Stoneleigh
December
Tue 12 - Wed 13 CUPGRA Conference, Cambridge: SAVE THE DATE!
February 2025
Fri 7 SACAPP Potato Conference, Apex Hotel, Dundee.
Contact is kyran.maloney@sac.co.uk
March 2025
Tue 4 - Wed 5 PSI 2-day residential Store Managers' Course: provisional date.
Prospectus to be released shortly. Will include BASIS Stored Potatoes
option. Join our waiting list by emailing adrian@potatostorageinsight.com
International Events
6-8 Nov POTATO VARIETY DAYS, Emmeloord area, The Netherlands
24-26 Nov INTERPOM '24 Kortrijk, Belgium
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Synopsis is published by Potato Storage Insight Ltd., 45 Main Street, Gedney Dyke, Spalding, PE12 0AJ. UK.
© Potato Storage Insight Ltd. 2024
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