PSI Bulletin: October 2024
No. 10/24 SUBSCRIBER EDITION: please go to potatostorageinsight.com/subscribe to sign up as a Synopsis subscriber.
Dear Subscriber,
Hello! This is the October edition of Synopsis, your monthly potato storage update from Potato Storage Insight.
Potato harvest has been very much in focus this month for everyone as growers and store managers are challenged by a variety of weather conditions around the country. Generally, the overall picture has been one of continued but slow progress, albeit in far from ideal conditions for many, with sharp showers or longer spells of rain disrupting work for significant periods. Take a look at our best practice advice below for dealing with wet crops...
PSI activity
A new season has meant another round of work on a small amount of storage trials forming part of the GB Potatoes Strategy Potato Storage project which is continuing into 2024/25. Working with Simon Faulkner of SDF Agriculture and the University of Greenwich, we have successfully loaded a couple of respiration pods (right) into stores at the south Lincolnshire trials site. These will be monitoring tuber respiration in one fresh market and one processing store and data will be presented as part of the project output in spring 2025.
Adrian Cunnington will be involved in two UPL potato storage webinars being planned for October 22 and November 5; the events are part of a weekly series being run by the agchem company (see Forthcoming events).
Adrian will also feature in a storage efficiency workshop being held at the pre-Christmas CUPGRA conference (see Forthcoming events).
Best practice
Dealing with wet crops coming into store...
At the risk of repeating myself, I want to stress the importance of having positive ventilation available if you want to have any hope of keeping crops that have been harvested out of wet fields, like the one pictured above. The recent deluges have raised the prospect of very wet crops entering store and it is important not to turn a 'blind eye' to the weather if it has resulted in very wet or even waterlogged crops coming into stores.
Get the air onto the crop as fast as you can and keep the fans running until the crop is totally dried out. Run the fans at close to maximum speed for any drying operation; if inverters are fitted setting these at 95% (45 Hz) will mitigate the cost but should keep plenty of air moving. If possible, put boxes on a drying wall or, as an alternative, stack the boxes one or two high on a bulk store floor such as a grain store, if there is one available.
If conditions have turned cold (sub 7°C), look at adding a bit of heat to enhance the drying capability - i.e. the moisture-carrying capacity - of the air. You don't need much! Air at 12°C will work better, with less risk to the crop, than air at 20°C...
Waterlogging or rain on the trailer is bad news for stored potatoes. As previously discussed in these articles in Synopsis, water quickly blocks the breathing pores of the potato skin (known as lenticels) and - unless there is plenty of air available to dry it up - it's downhill from there, really. Not only do blocked lenticels prevent the tuber achieving good gaseous exchange to keep it alive, it also offers a great opportunity, as the lenticels ‘erupt’ and invert, for bacterial infection to set in.
This can result in rapid tuber breakdown in a matter of a few days - or less - and the crop cannot be stored. Keep waterlogged or 'rained on' potatoes separate at the front of the store or in an adjacent building, so they can be turned round quickly after harvest.
There's a lot more information on tuber lenticels in this review which is freely available on the 'net:
Bethke, P.C. (2023) Potato Tuber Lenticels: A Review of their Development, Structure, Function and Disease Susceptibility. American Journal of Potato Research, 100 253-264.
Technical insight
Sprout suppression options
This month’s technical insight looks at the myriad sprout suppression options that are now available in the post-CIPC era.
The first thing to say is that you do not always have to use a sprout suppressant for potato storage. The potato is pretty good at regulating its growth through natural dormancy, especially at low temperatures.
There is also the option, of course, notably for the fresh market, to use temperature as a sprout control. Maintaining an even temperature in the store that is sub-4°C will suppress many varieties.
Before we consider products to be applied to the crop in storage, it is important to consider maleic hydrazide (MH), as this has become a key component of many sprout control strategies. MH is applied to the growing crop in late summer can provide background control through the early part of the storage season and, depending on temperature, even into the following calendar year. It also has a role to play in controlling groundkeepers and, in some susceptible varieties, can help to reduce the risk of internal sprouting.
When it comes to looking at products for suppressing sprout growth in storage, there are many options, which are broadly summarised in the table below.
Of the many different products now available, there is a group of options which act as dormancy enhancers whilst other products offer a more direct impact on any sprouts that have developed.
Ethylene provides control by extending dormancy. It is a plant hormone so it can trigger significant physiological responses in the tuber. Treatments therefore have to be introduced carefully and, for the most part, this has been achieved by using a slowly increased dose at the outset (often referred to as a ‘ramp’). The ethylene companies have been working to refine this process and the recently-introduced PET process from Restrain is an example of this.
Ethylene can influence fry colour in processing varieties, so it isn’t suitable for all markets. Nevertheless, McCain has taken it on across much of its variety portfolio, choosing to adjust any adverse colour as part of its frying process. Do you speak to your market before choosing the ethylene route.
1,4-dimethylnaphthalene (DMN) Is another dormancy enhancer and has rapidly established itself as a key product in the processing sector. Typically, where MH has been used, first applications would go on in November. Second and even, if necessary, third doses can be used to take crops through to spring or summer deliveries. DMN does have a 30 day harvest interval so it may be appropriate to use an alternative for a final application.
There are two essential oils which are established in the marketplace, offering preventative and corrective sprout control.
Spearmint oil has been used in the fresh market for over 10 years and can be deployed at any stage of the season. It can be used as a routine treatment at the standard dose in fresh or processing markets or to remove existing growth at a 1.5X rate. Crops can be moved to market in 12 days after treatment.
Orange oil is a similar option and is well suited to use in conjunction with MH. It is particularly effective in bulk storage application in the processing/chip shop sectors but can be used in box stores too. A 21-day interval between successive applications must be observed.
Costs of these treatments vary appreciably and there are users who have spent time over the past few seasons refining combination or reduced dose techniques. This has to be done at the user’s risk.
Another important point to note is that most of the products have limited or no residual effect which means that growth can potentially restart soon after treatment. This is especially the case where apically-dominant sprouts are checked but secondary buds are not - and can result in the need for a second follow-up dose.
As always, it is important to consult your BASIS-qualified advisor and/or your NAAC-accredited applicator in relation to all sprout suppressant usage and to secure their written BASIS recommendation for any treatments.
Information and independent advice is also available through Potato Storage Insight. Contact Adrian Cunnington at adrian@potatostorageinsight.com or call him on 07970 072260.
Snippets
Store Managers' Training and BASIS (Stored Potatoes) course
Plans are being formulated for this two day, residential event to be held in March 2025. Get your name on the waiting list by emailing adrian@potatostorageinsight.com
EU bans metribuzin herbicides
The European Union has announced plans to ban the commonly-used pre-emergence herbicide active substance metribuzin:
Non-Renewal of Approval for Metribuzin.
Amendment to Implementing Regulation (EU) No 540/2011 & Implementing Regulation(EU) No 2015/408.
Member States must withdraw authorizations for plant protection products containing metribuzin within six months from the regulation’s entry into force.
Any grace period granted by Member States under Article 46 of Regulation (EC) No 1107/2009 must expire within 12 months from the regulation’s entry into force.
This regulation enters into force on the 12th day following its publication in the Official Journal of the European Union and is binding in its entirety and directly applicable in all Member States.
CIPC residue data under review in Europe...
The European SCoPAFF Committee will meet next month to review a number of maximum residue levels, including chlorpropham.
...whilst in the UK, more data will be needed in 2025
The UK CIPC Residues Monitoring Group will be meeting in early November to plan its 2025 campaign to secure data in support of the on-going temporary MRL for chlorpropham, currently set at 0.35 mg/kg. If you can supply CIPC residue (or multi-residue test) data from any potato store previously-treated with CIPC, please email adrian@potatostorageinsight.com
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:
October
Tue 22 UPL storage webinar featuring Adrian Cunnington & Simon Faulkner
Tue 29 UPL storage webinar: second in the series (link above)
November
Tue 5 UPL storage webinar: third in the series (link above)
Wed 6 Agri-Tech E REAP conference, Cambridge
Wed 27 - Thu 28 CropTec, NAEC, Stoneleigh
December
Tue 12 - Wed 13 CUPGRA Conference, Cambridge: Potato Crisis? What Crisis?
Now booking.
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
Please note that you, or a colleague, can subscribe to Synopsis at any time by going to potatostorageinsight.com and clicking on SUBSCRIBE. We can also now take payments by credit card. Call Adrian on 01406 364795 or 07970 072260 if you have any questions.
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Synopsis is written by Adrian Cunnington and published by Potato Storage Insight Ltd., 45 Main St., Gedney Dyke, Spalding, PE12 0AJ. UK.
© Potato Storage Insight Ltd. 2024
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