Click here for the latest update on blight - July 2010

Potato News

Potato plantings 2010

The Potato Council's estimate of plantings for 2010 is 126,887 has, down on 2009's final planting figure of 130,200 has. This gives a total production figure of 5.7 million tonnes, assuming an average yield of 44.9 t/ha, compared with a total production of 6.2 million hectares ( with an average yield of 47.6 t/ha) in 2009 and a total production of 5.95 million tonnes in 2008 (with an average yield of 45.7 t/ha).

Top potato varieties in 2010

According to the Potato Council, Maris Piper remains the dominant potato variety, with 18% of planted area or 23,053 has planted. Estima was second-ranked variety, although area has halved since 2005, (15471 has in 2005 and 7993 has in 2010) and the crisping variety Lady Rosette third with 6950 has grown this year. Used mainly for chipping, Markies is fourth and has grown substantially from 1402 has in 2005 to 6832 has this year and the pre-pack variety Maris Peer is fifth, with 5574 has.

The next five most widely grown varieties are Harmony (4112 has grown for the packing market), Hermes (4102 has grown mainly for crisping), Marfona (4061 has grown for packing), Melody (4045 has) and Saturna (3831 has). The top eight varieties account for over 50% of the total market

New chairman for NFU Potato forum

Tim Papworth has been elected as chairman of the NFU Potato Forum. As chairman of the group, he will become vice chairman on the national NFU horticulture board with specific responsibility for potatoes.

Mr Papworth grows 12 varieties of potatoes on more than 650 acres and lifts a further 150 acres under contract at North Walsham, Norfolk. He is joint managing director of L F Papworth Ltd, the contract farming business – responsibilities include potato and vegetable production, marketing and livestock supply and selection. The potatoes are marketed through a number of grower groups including McCain’s and Walkers. Last year the business was runner-up in the Farm Business ’Family farm of the Year’ award. He said: "I am delighted to have been elected to the role of chairman of the NFU Potato Forum and I look forward to representing the interests of potato growers in the industry."

New research facility opened at Sutton Bridge Storage Event

New research stores at Sutton Bridge Crop Storage Research (SBCSR) were officially opened on 2nd September by the government spokesperson for Energy and Climate Change, Lord Taylor of Holbeach.

Potato industry delegates were invited to attend seminars focusing on issues such as long-term energy savings and sustainability as well as looking round the new construction that makes the Lincolnshire centre one of the most sophisticated crop storage research establishments in the world.

Topics on the agenda included a review of the impact of climate change on potato storage with Professor Gareth Edwards-Jones from Bangor University, an industry perspective on sustainability from Dr David Nelson of Branston and optimisation of storage costs with Jay Wootton from Andersons The Farm Business Consultants.

“We are looking forward immensely to the opening of this exciting new facility at Sutton Bridge,” says Adrian Cunnington, Head of SBCSR. “Climate change is already affecting our industry and Lord Taylor, as spokesperson for Energy and Climate Change, is ideally placed to understand issues challenging our industry.

“Understanding sustainability is key to the future and improvements can offer substantial benefits, often after as little as two years. However, growers should also be looking at their long term strategy for storage and contemplating investments like the one Allan Stevenson has just completed on his own farm that will provide for the next ten to twenty years.”

For more information, levy-payers should contact Miya Kotecha at Potato Council on 0247 647 8782, email mkotecha@potato.org.uk or visit www.potato.org.uk/events

Approval of two new potato blight fungicides containing new chemistry

BASF has received approval for two new potato blight fungicides, Resplend and Decabane, based on a new active ingredient from a totally new class of chemistry.

Rob Storer, Potato Product Manager for BASF, explains that Initium is a totally new class of chemistry, the pyrimidylamines and the trade-mark of a new active ingredient with the common chemical name of ametoctradin. “Ametoctradin is a highly effective protectant fungicide, showing premium preventative action against potato late blight. It prevents disease by inhibiting the infectious stages of the pathogen, through preventing zoospore formation, release and motility and through direct effects on the germination of sporangia. It will play a useful role in preventing both foliar and tuber blight.”

The two new approved products, to be test marketed in the UK this year, consist of co-formulations with two other blight fungicides. Resplend contains ametoctradin and dimethomorph and is formulated as a suspension concentrate, Decabane contains ametoctradin and mancozeb formulated as a water dispersible granule.

“Developing two new coformulations with complementary active ingredients with different modes of action will enhance the anti-resistance position. This new class of chemistry has been shown to have no cross-resistance to phenylamides (e.g. metalaxyl), QoI inhibitors (e.g. strobilurins) or carboxylic acid amides (e.g. mandipropamid). Both Resplend and Decabane will be important new tools in the fight against blight as well as in resistance management,” he says.

Resplend contains 300 g/litre ametoctradin and 225 g/litre dimethomorph and is formulated as a suspension concentrate. It is recommended at a dose rate of 0.8 l/ha, delivering 240 gms ametoctradin per hectare and 180 gms of dimethomorph per hectare, in 200- to 500 litres of water. It is applied from early leaf extension to start of leaf senescence at 7 to 10 day intervals. Up to 4 applications per crop can be made. Resplend is rainfast within 1 hour and it is not subject to a LERAP. It is packed in the new 5 litre Eco Pack.

Decabane contains 80 g/kg ametoctradin and 480 g/kg mancozeb and is formulated as a water dispersible granule. It is recommended at a dose rate of 2.5 kg/ha, delivering 200 gms ametoctradin per hectare and 1200 gms of mancozeb per hectare, in 200- to 500 litres of water. It is applied from early leaf extension to start of leaf senescence at 7 to 10 day intervals. Up to 4 applications per crop can be made. Decabane is rainfast within 1 hour and it is subject to a category B LERAP. It is packed in a 10 kg pack.

Signum has recently received a new and significant off-label approval for use against early blight or Alternaria in potatoes, in time for the season. Growers will need to obtain a copy of the notice of approval to use Signum in potatoes via the Chemicals Regulation Directorate (CRD) web site, ADAS offices or NFU. The SOLA reference number is 1942 of 2010.

The SOLA relates to the use of Signum (boscalid and pyraclostrobin) for the control of strains of Alternaria (early blight). It should be applied at a maximum individual dose of 0.25 kg/hectare in 200 to 400 litres of water per hectare. Up to 2 treatments per crop/year can be made. The latest time of application is 3 days before harvest.

The important requirement for control is to ensure that applications are applied in a protectant situation at the start of the disease epidemic. As the SOLA is for two applications, it is suggested that the first treatment is applied when the weather conditions are conducive for disease development. To ensure late blight protection is maintained, it may be necessary to apply with an appropriate late blight fungicide.

Signum is highly rated for Alternaria control by Euroblight and is given a 3* rating, which is the highest rating awarded.

Background on Alternaria in potatoes:
The disease can be caused by two species – Alternaria solani and A. alternata. Although disputed by some authorities, A. solani is understood to be a truly pathogenic species, while A. alternata is saprophytic to weakly pathogenic. An early infection resulting in heavy disease pressure can result in a yield loss of 20 – 30%.

The typical concentric-ring symptoms appear principally on the leaves, with smaller lesions expanding into larger ovoid lesions, often with a yellow margin. The disease symptoms can be confused with manganese deficiency, magnesium deficiency and ozone damage, which can also produce lesions with concentric-rings.

The disease survives the winter as mycelium and spores which are found in crop and alternate host trash, as well as in the soil or infected tubers. Spores released in the spring act as the primary inoculum source and these can be carried by wind and water, resulting in further disease build up and spread. The disease needs warm wet weather for an epidemic to fully develop as spore production is favoured by alternating wet and dry periods.

In 2009 there was an increase in reported cases of the disease. This may be due to more susceptible varieties being grown. Varieties which have been noted as being susceptible include: Markies, Mimi, Hermies, Vivaldi, Saturna, Maris Piper, Lady Clare and Maris Peer. Or it may be due to weather conditions, with warm days and cool nights during the growing period being conducive to the disease. Other factors that may have contributed to higher risk of Alternaria are reduced nitrogen usage or reduced mancozeb usage.

Dow AgroSciences has introduced the second of its innovative concepts in plant protection technical transfer in the form of a new e-learning module for the potato sprout suppression product, Fazor. Designed for potato growers and advisors, the e-learning module can be found on-line at www.dowagroadvice.co.uk/fazor and will help improve understanding of how the product works, what it does and how to get the best from it.

“This unique e-learning system has been updated and improved. Whilst it retains the essential information on integrated methods of volunteer potato control and sprout suppression in store, there is in addition a wealth of product information to optimize its use. Those completing the Fazor module will be entitled to a CPD BASIS point,” says John Sellars, Marketing Specialist for Dow AgroSciences.

“Fazor is the only in-potato field application solution for the control of volunteer potatoes, which can be important source of blight, viruses and potato cyst nematodes. Applied correctly, trials show that Fazor significantly reduces potato volunteers in following crops. It also suppresses sprouting in store and can be used in an integrated programme with CIPC. In order to optimize the performance of Fazor, there are a number of application timing criteria that need to be met and the updated e-learning module ensures that advisors and users of Fazor are fully briefed and understand how to get the best results from it,” says John.

Fazor contains 60% w/w maleic hydrazide, formulated as a water-soluble granule. It is recommended on second earlies and maincrop potatoes (but not on seed or first earlies) as well as bulb onions. In potatoes, Fazor is recommended at a dose rate of 5 kg/ha in 350-500 litres of water. It should be applied to actively growing foliage, typically around 3 to 5 weeks before burn down. It has a maximum number of treatments of one per crop and a latest time of application of 3 weeks before harvest. It is packed in a 2.5 kg bag. Fazor is fully approved for use on bulb onions and also has a specific off-label approval for use in garlic, shallots, carrots and parsnips.

Walkers crisps pioneer water efficient potatoes
Walkers crisps are pioneering water efficient technology to make their potato production process more environmentally friendly.

PepsiCo, which also produces Tropicana orange juice and Quaker Oats, source all Walkers Crisps potatoes from UK farmers. Walter Todd, vice president of operations at PepsiCo, said water shortages could hit UK yields and force the company to import potatoes if nothing was done. He said areas such as East Anglia were already under intense water stress and the problem was certain to get worse.

This year the company will spend £250,000 on a probe, the i-Crop, that monitors the moisture in the soil then sets the amount of water used to irrigate the fields.
“This not only means we use water more efficiently but also reduces the impact on the environment in other ways such as reducing fertiliser and pesticide run-off, which has a benefit for biodiversity.

“Also when too much water is applied to the soil, the potatoes shut down so this system also improves our yields. Given that water is a local issue, it will help farmers create environmental strategies that are bespoke to their farm,” said Mr Todd.
The company is also carrying out large scale trials on new crop varieties that require less irrigation, produce higher crop yields and can be stored more easily. Within the next 10 years the company also hope to remove its four crisp factories from the water mains, instead running them on water extracted from potatoes.

“Water is the poor second cousin of carbon - it is still an emerging issue,” said Mr Todd.

'Zero tolerance' on Dickeya in Scotland to protect potato crops
Scotland has introduced a "nil tolerance" on Dickeya solani, a new more aggressive form of blackleg, to protect potato crops . The zero tolerance policy has been incorporated into the Scottish Seed Potato Classification Scheme (SPCS), following a consultation. The new law covers all classes of potato seed entered under the scheme.

The main threat comes from the 1% of potato seed imported into the country, says Mark Prentice, head of seed and export at the Potato Council. Fortunately, Dickeya has never been found in potato seed of Scottish origin.
"Imports are a potential introductory route for Dickeya. The risk, albeit small, is there," he warns.

Seed crops will undergo testing for blackleg symptoms in late June or July, with government inspectors also concentrating on ware crops grown from imported seed crops. Plants showing blackleg symptoms, such as plants wilting and tuber rots, will be sent to the government agency SASA, for testing.

"If Dickeya is picked up in a seed crop, it will be removed from the classification scheme and will only be allowed to be marketed as ware. Restrictions on subsequent handling and marketing of ware are also anticipated," Mr Prentice says.
"Protection measures will be put in place to prevent any cross-over from infected stocks and clean stocks."
The exact measures that will be put in place have yet to be decided.

But Mr Prentice says there is no single standard and diseased crops, including those grown for ware, will be assessed on a case-by-case basis depending on risk and plans for the crop. Meanwhile, early indications suggest that Dickeya is more aggressive than traditional blackleg.
"Dickeya appears to operate in warm and cool conditions," Mr Prentice says. "It would be harder to manage and causes problems in the growing crop from yield loss - up to 30% - and storage."

And the impact of Dickeya, a non-quarantined disease, could be more serious if it infiltrates British crops, he warns.
"Without quarantine status there is the potential for the disease to spread unchecked," says Mr Prentice. "So regulations have been put in place in Scotland to give British seed growers and their customers at home and abroad some protection."

Need for blight fungicides with proven tuber blight activity

As the maincrop develops, growers should be using fungicides with proven foliar and tuber blight activity, says Gowan Comércio.

“Once tubers start to form, they are at risk from zoospores that are the causal agents of tuber blight. Each infected plant can release millions of zoospores when the conditions are right. These zoospores are released or are washed down by rainsplash from the foliage into the soil and cause infection by germinating close to the tuber and entering access points such as buds, lenticels and wounds. The blight fungus spreads within the tuber and starts to breaks down cellular tissue. You only need a few zoospores to reach potato tubers to suffer significant and damaging blight infections. Symptoms are usually seen one month of lifting, but the disease must be prevented in the field well before it gets into store and as soon as the crop is vulnerable to attack,” explains John Edmonds, European Technical Manager for Gowan Comércio.

“Not all blight fungicides have proven zoospore activity, but those that do need to be used in a specific way according to how they work. Zoxium® in Electis® and Roxam®, for example, stops zoospore formation and release, resulting in non viable spores, which are incapable of infecting tubers. By reducing the zoospore loading in the crop as early as possible, Electiswill optimize the activity of other fungicides that have more direct zoospore activity,” says John.

John explains that other blight fungicides such as fluazinam, cyazofamid or fluopicolide + propamocarb act directly on zoospores once they are released, preventing them from reaching tubers. Such products would be beneficial once Electis has been applied, he says.

According to John, growers cannot and should not rely on just foliar blight control to prevent tuber blight. “Crop foliage must be protected by robust blight fungicides that have proven zoospore activity. This is particularly so as tubers are vulnerable from tuber initiation, which is defined as when the tuber is twice the diameter of the attached stolon, onwards. This vulnerable stage normally starts around three weeks after crop emergence.”

He warns that many crops have shown signs of Alternaria or early blight and that Electis® has one of the highest ratings for the control of this disease, as well as one of the best ratings for protectant activity against late blight plus a very acceptable rating for tuber blight. “So there is no need to go to the trouble or expense of a separate treatment.”

“Even with lower blight pressure r, it remains important to keep spray intervals tight right up to desiccation. Electis® can be used up to 10 times in the season, important when regular applications are being made. It also gives growers much better flexibility as to how they integrate this fungicide into their programmes for effective foliar and tuber blight control, additional Alternaria activity and as a resistance management strategy.”

For further information, please contact John Edmonds, European Technical Manager for Gowan Comércio on 01223 506 606 or 07764 268 199 (mobile).

Electis® contains 8.3% w/w Zoxium® (zoxamide) and 66.7% w/w mancozeb, formulated as a WDG. It is recommended on all varieties of potatoes at spray intervals of 7 to 14 days. It has a dose rate of 1.8 kg/ha in 200-600 litres of water per hectare. It has a maximum number of treatments of 10 per crop and a harvest interval of 7 days. It is packed in a 3-ha pack (5.4 kg).

Potato growers must treat blight and Alternaria separately
Potato growers are being warned not to compromise blight control programmes during high risk conditions when tackling the threat of Alternaria.

“During the current high blight risk periods, growers need to be maintaining the best possible control with Revus-based programmes, and addressing the threat of Alternaria as a separate issue,” advises Glenn Wilkinson of Syngenta.

Mr Wilkinson highlights the potential risk of using less effective blight fungicide’s that also claim some activity on Alternaria. “Independent UK trials by Eurofins and Agrisearch have shown that mancozeb-based fungicides were significantly weaker in controlling blight, compared to Revus. Compromising blight control at the crucial time of rapid canopy development would be entirely counterproductive.”

Norfolk agronomist Simon Alexander say that in the past we have seen Alternaria coming into the crop late in the season, typically as it is beginning to senesce and hitting older lower leaves. “More recently infection has occurred far earlier in the season and affected larger patches of the crop. It can quickly spread across the whole field and lead to early leaf loss.”

Attacks can lead to yield loss, smaller tubers, variable dry matter and potential skin damage that reduces marketability.Alternaria infection typically occurs after periods of dry weather initiate spore release, followed by humid conditions leading to infection. Crops under water or nutrient stress are typically more susceptible. Markies has proven the most susceptible variety, but infection has also been identified on other varieties, including Hermes, Saturna and Maris Piper.

This season Syngenta is piloting a new AlternariaCAST forecasting system with a group of growers and agronomists in the eastern counties and Shropshire, where the most severe disease attacks have been recorded. Mr Wilkinson added: “For the optimum Aternaria control treatment should take place before the typical leaf spotting signs of infection are visible. The aim is that AlternariaCAST will give a reliable forecast of conditions conducive to disease, and enable growers to time applications more effectively.”
Building on the success of Syngenta’s web-based BlightCAST, the AlternariaCAST service will be evaluated during the 2010 season, with the intention to make it freely available to growers for following years.

Slug control timings critical for potatoes

New metaldehyde guidelines for 2010 further restrict use but will not impinge on potato growers deploying the Draza forte backbone approach.

A trial by Scottish Agronomy last year set out to discover what could be achieved from a backbone of just two full rate applications of Draza forte to the slug-susceptible variety Maris Piper. Pellets were applied on 14th July just before canopy closure and again on 19th August at the onset of senescence; the trial was lifted on 25th September.

Tuber assessments found 9% from the untreated plots had slug damage compared with only 3% from the Draza forte treated plots. Scottish Agronomy’s Eric Anderson says: “Most packers apply a gross defects limit of 5% so the sample from the untreated area would certainly have been rejected. The two timings chosen proved critical in reducing slug damage.”

“In practice, the actual number of treatments needed has to be based on risk assessment and that’s not just trapping. If you’re growing a slug susceptible variety on a heavy soil with oilseed rape in the rotation – as was the case with this trial – you’re into a high-risk situation before you’ve set a trap.”

This view is borne out by trap catches at the trial site. In eight traps only two slugs were found just prior to the second application but the damage level in the untreated control showed it was clearly a high-risk situation.

“In low risk situations two well-timed applications of Draza forte may be sufficient, but in high risk situations repeat applications are warranted,” Mr Anderson says.

Previously he has recommended the initial application at 50 to 75% canopy closure be followed by fortnightly treatments until burn-down. However, he is thinks that, with a quality methiocarb pellet, the treatment interval can be extended to three weeks.

“Shorter duration crops should only need two half rate methiocarb applications between the initial and final full doses. Longer duration crops that may not be burnt down until late September are likely to need one or two metaldehyde applications adding in mid season.”

However, he points out that under the new metaldehyde guidelines for 2010 the total dose applied from 1st August to 31st December is restricted to 210g a.i. per hectare so any ‘mid season’ applications will need to be planned carefully to comply with this.