Arable News

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CIPC reminder at East of England Potato Day

The Potato Council-organised East of England Potato Day in Suffolk went ahead in glorious late summer weather

The Potato Council-organised East of England Potato Day, staged near Bury St Edmunds in Suffolk, went ahead in glorious late summer weather. Dominic Kilburn attended.Review your need and use of CIPC treatments in potato stores and start working towards a lower maximum dose rate. That was the clear message given out to growers and the trade attending the East of England Potato Day staged in Suffolk in late August.The Potato Council’s Adrian Briddon (left), of the Sutton Bridge Crop Storage Research (SBCSR) unit, pointed out that while CIPC Stewardship had been in existence for five-and-a-half years, there was a clear need for anyone involved in CIPC use and application to adhere to the latest advice and best practice guidelines if Maximum Residue Levels (MRLs) exceedances were to be prevented from occurring in the future. He highlighted the fact that there had been seven exceedances in the past five years.
Earlier this year, the Potato Industry CIPC Stewardship group submitted a report to the Advisory Committee on Pesticides (ACP) reviewing progress made, and an expected response from ACP is due this autumn.
Adrian said that there was likely to be a change in regulation in terms of a reduction in the maximum permissible dose of CIPC per season from 63.75g/t (the current maximum) to 36g/t by 2017. “The maximum rate of 63g/t is not being supported in the UK anymore and growers and store managers need to get used to the idea of the new limit which is coming in,” he warned.
“There are already label changes for use of CIPC for this coming season and it’s only going to get more difficult,” he added.
According to Adrian, of the seven exceedances recorded, only one occurred in a bulk store (crop for the processing market), while the remainder were attributed to box stored potatoes. “Bulk stores are relatively easy when considering CIPC management,” he commented. “Best practise is to use the store fans to apply the CIPC using the ventilation system to move the fog around the store. This provides a predictable residue level.
“If fans are not used then chemical is not distributed evenly and there are places in the store where a lot of CIPC residue and sprouting control is found and other areas where there is no CIPC and no control.”  Box stores
Most exceedances are in box stores, pointed out Adrian. “Unfortunately few box stores have positive ventilation. There’s a large use of overhead throw stores – about 90 per cent – where refrigerated air is thrown on top of the boxes and the air returns to the fan between the boxes and not through the crop.
“The majority of the residue ends up on the top boxes and it’s not an effective way of using CIPC,” he added.
Adrian suggested that a solution was to modify the box stacking pattern to create a plenum which acts as a main duct, preventing fog rising into the roof space and providing an improved residue distribution.
According to Adrian, some of the more recent exceedances have been in low temperature stores for pre-pack potatoes. “We are still learning about the effect of colder temperatures but we do know that the ability of the atmosphere to carry the CIPC is more limited.”
New advice for cold store CIPC applications has been released (see box) and Adrian said that an early application on dormant potatoes during the first month of storage is best, before temperature is reduced below 7C.
“It’s important that everyone reviews their need for CIPC,” he continued. “All applications have to be justified and it’s key that we think about dose rates which is not the contractor’s job,” he stressed. “Review it with him. It’s the crop owner’s responsibility if there is an exceedance and not the contractor applying it but I wouldn’t advise anyone to go with a single application above 12-14g/t for pre-pack or processing crops,” he said.
“There are other things that can be considered too such as alternative suppressants like maleic hydrazide, ethylene or spearmint oil, as well as segregating cultivars by dormancy. “Whatever happens there must be no unnecessary applications of CIPC,” added Adrian.
The Potato Industry Stewardship Group (PISG) is a collaboration between key industry organisations that have come together to promote the stewardship of the sprout suppressant CIPC. The Group comprises all the companies that hold the approvals for the CIPC formulations as well as the Potato Processors Association; the Fresh Potato Suppliers Association; the National Association of Agricultural Contractors (NAAC); Red Tractor Farm Assurance, and the research institutes Sutton Bridge CSR and Cranfield University. 
For more information see the ‘CIPC Q&A’ in last month’s edition of Farmers Guide (page 101), or go to advice for CIPC applications:
Timing of first application:
First treatment recommended within three weeks after harvest (or earliest occasion thereafter) even in the absence of signs of breaking dormancy.Treatments in cold stores (holding temp 5c or below):
Only one application of CIPC up to the maximum individual dose per season recommended. The application should be made before the temperature is reduced below 7c. Recirculate store air for at least six hours without cooling prior to application.Ventilation management during application:
Positive ventilation is recommended in all store types.Nitrogen and seed rate trials
Trials work looking at a reduction of nitrogen applied to potato crops has shown that reducing rates can provide a small yield boost in addition to cost and environmental savings.
In addition, trials focusing on reducing seed rates at planting have shown no detrimental effect on yields but also bring financial savings to growers.
These were the findings presented at the event by Cambridge University Farm (CUF) head of agronomy, David Firman (left) as part of the organisation’s Grower Collaboration Project.
In 2012 trials on the variety Melody at Co-op Farms, Coldham in Cambridgeshire, the standard rate of nitrogen applied (190kg/ha) was compared with CUF’s reduced rate recommendation of 150kg/ha.
“If crops are nitrogen deficient you can find there is a slower increase in ground cover and the canopy can die off earlier at the end of the season, but in this case we found that both ground cover development and persistence were very similar between the two rates,” said David.
“In practise, yield with the reduced rate was higher but it was a split field trial and so we have to be careful how we look at these individual results, but we do know that applying too much nitrogen can reduce yield in potatoes.
“In this example however our rate saved nitrogen costs, as well as being environmentally better, and we were no worse off in terms of yield,” he added.
David pointed out that trials the same year in North Yorkshire where the standard rate applied was 210kg/N ha, compared with CUF’s recommended 180kg N/ha as well as a higher rate of 240kg N/ha.
“In this trial there was no difference in yield between the standard and CUF rate but, if anything, the higher rate of nitrogen reduced yields,” suggested David. “Over the course of the Grower Collaboration Project the more modest nitrogen applications have, on average, increased yields by 3t/ha,” he added.
 Data from a seed rate trial staged during 2009 at Mease Valley Potatoes, in Nottinghamshire compared Lady Rosetta at rates of 47,000 plants/ha with a reduced CUF rate of 35,000 plants/ha.
According to David there was no change in the timing of ground cover for each crop and there was no significant difference in yield. “There was no change in ground cover development in this instance, although the development of leaf area will change as stem numbers are reduced below a certain point, and with yields unaffected we have saved the cost of some seed,” he commented.
“Looking across all the seed rate trials there is no evidence of any difference in gross yields but using seed rate differences in specific crops it is possible to target and improve optimum tuber size distribution while saving seed costs.”
On-going work as part of the Grower Collaboration Project is also seeking to determine the effects of de-stoning at different depths. A standard depth of 12-inches is being compared with shallower alternatives potentially resulting in a reduction in soil damage, faster working speeds and less energy use.
According to David, initial test digs this season at East of England Potato Day host farm Frederick Hiam (also involved in the Grower Collaboration Project) has shown no evidence to suggest that shallower de-stoning results in a poorer crop. What is the CUF Grower Collaboration Project?
Started in 2007, Cambridge University Farm’s Grower Collaboration Project aims to collaborate with growers in planning the agronomic components of their potato production systems using current agronomic knowledge and documenting the process and differences from previous practice.
Key areas of focus to date have been the efficient use of nitrogen and seed. Other aspects of production including de-stoning depths, the retrospective analysis of irrigation practices and the use of models to understand the loss of yield potential to PCN for example, are also being considered.
A range of farming organisations including growers and processors are involved in the project. The Potato Agronomy Unit at Cambridge University Farm (CUF) became part of NIAB at the start of this year in a move which strengthened the future of potato agronomy research at the Cambridge-based unit, while opening up promising new areas of collaborative research to meet the future needs of UK potato growers and their customers.  Weed control of volunteer potatoes is spot on
An alternative method for weed control of volunteer potatoes in vegetable row crops, including carrots, onions and parsnips, providing big savings in herbicide use, is now available to growers or contractors on a commercial basis, according to one of the project’s developers.
Speaking at the East of England Potato Day, NIAB TAG’s Professor Paul Miller of the Silsoe Spray Applications unit, said that the LINK project-developed, vision-guided weed detection and spot treatment system was based on technology already used in hoes.
Built by Garford Farm Machinery, similar to the company’s Robocrop guided hoe, this latest machine has vision guidance for direction but the hoe blades are replaced by special ‘Alternator’ nozzles which can provide the necessary spray footprint in the short time that the nozzles pass over their weed target.
“It’s a specialist machine designed for band or spot spraying with glyphosate between vegetable crop rows,” said Professor Miller. “Why? – because onion and leek growers have lost most of their selective herbicide options in recent years and for two weeds in leeks there is now no alternative treatment available,” he stressed.
“We started by looking at volunteer potatoes which are important, but any large weeds in a row crop could be considered for control,” he added.
The 6m machine is built in three, 2m sections with a guidance camera mounted in the centre of each section. Typically, trial work operating speeds have been at 5kph and the machine is steered down the rows while it “looks for”, and targets by spot spraying of glyphosate, large weed patches outside the crop row itself.
“Part of the project was the testing of the nozzle,” continued Paul. “The Alternator, designed by Hypro, is not a conventional nozzle; it is over the weed target for a very short time and in 0.2 seconds it has to be able to switch on, spray, and switch off – that’s not long at all,” he emphasised.
“We don’t, of course, want drift and so it produces relatively large droplets. The nozzle produces a fine pencil stream through an oscillator and the big droplets are retained well on the larger leaves of volunteer potatoes and not on the leaves of onions or leeks.”
Use of glyphosate herbicide as a band and spot spraying method was approved by the Chemicals Regulation Directorate (CRD) earlier this year in most vegetable crops and an Extension of Authorisation for Minor Use (Eamu) was granted for glyphosate use in peas to take out volunteer potatoes with this system.
“The herbicide savings are, of course, dramatic; only using 1-2 per cent of the amount used in conventional herbicide applications,” concluded Paul.
Funded by the Horticultural Development Company (HDC) partners in the LINK project included NIAB TAG, BPC, Garford Farm Machinery and Hypro.

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