Latest Edition
(March/April 2010)
Variety trait a useful tool against PCN
The search for alternatives to conventional chemical nematicides made up a significant part of Greenvale AP’s programme of field trials in 2009. Technical director Paul Coleman was particularly pleased with the results of a small-scale investigation in which prepack variety Vales Everest was grown with or without a granule treatment (Mocap). Cara was planted in an adjacent plot to provide comparative data on PCN numbers at the end of the season.
The trial, conducted by John Keer of AgroChemex on a sandy silt loam at Estuary Farm, North Wooton, near King’s Lynn, seems to have confirmed earlier observations that Vales Everest offers a useful combination of tolerance to nematode attack and resistance to Globodera pallida (see Potato Review, November 2006).
Dr Coleman explained. We asked John to try and measure how effective Vales Everest was against PCN. We know it has very good pallida resistance but to put that in perspective we wanted to know whether we could effectively drop the use of a nematicide.
He set up a simple trial looking at figures for pf/pi [population increase] because we know from work conducted three of four years ago that the variety was effective. He started with quite high egg counts but what was really interesting was the final numbers. If you consider Cara with Mocap application as the standard, it produced a five-fold multiplication rate and without nematicide the increase was 15-fold. Growing Vales Everest with the nematicide the population came down by around 80% but what was really interesting is that even without Mocap the PCN numbers still declined.
We knew the variety had a good resistance rating but to get an effect like that in the field and to see a pallida reduction is pretty surprising,’ Dr Coleman observed. ‘So we now have evidence that we can grow it without a nematicide and we don’t have to worry about an increase in the nematode population.
We are using Vales Everest as a general purpose potato with some of the retailers though, to be fair, it is a tool for growers who have a problem with PCN,’ he commented. ‘But we are also crossing it with a number of commercial varieties and selecting purely for PCN resistance. We’ve now got quite a lot of successful crosses which have been tested at SCRI, though they are a few years away from the market.’
Paul Coleman appeared equally excited by the results of trials last summer using naturally occurring compounds to suppress PCN activity. While giving no clue as to the precise nature of the products involved he confirmed that investigations would continue in 2010.
For the full story see our March/April edition
In-furrow aphid control
The application of an aphicide at planting could improve prospects for reducing early virus spread in potatoes. Trials in the Netherlands identified the potential for in-furrow treatments using Syngenta’s Actara (thiamethoxam) which provided up to six weeks post-emergence control. The product is already approved for foliar applications in the UK but a new label recommendation means that the in-furrow option has been made available for seed growers just in time for planting this season.
The Dutch field trials showed good control of Peach-Potato aphids (Myzus persicae) on experimental plots 40 days after crop emergence when insect populations on untreated plants were multiplying rapidly. Eric Anderson of Scottish Agronomy Ltd has also been evaluating Actara in-furrow treatments. He points out that nearly a quarter of seed crops entered for certification in England last year were downgraded because of virus infection, over 90% of cases involving PVYn, PVYo and PVA.
‘Clearly there is an underlying problem which demands a new approach to counter the threat,‘ he told Potato Review. ‘Seed growers have shown they can effectively manage PLRV with foliar systemic fungicides, but we need to develop the techniques to eliminate the rapidly transmitted Poty-viruses.’
Over recent years aphid migration has started earlier in the season, at a time when many seed crops are just emerging and the young plants are most susceptible to virus spread.
Crucial timing
‘When there are aphids present sprays may need to go on from the rosette stage, with just 10% ground cover,’ Mr Anderson advises. ‘That poses a significant problem for operators to target the foliage without significant over spraying. The in-furrow application could provide crucial early season aphid control, as part of the ongoing virus protection programme,’ he adds.
Seed growers should be paying greater attention to all aphid species, he warns. Cereal aphids can be migrating in huge numbers during June and July when crops are vulnerable to infection. The feeding aphids can quickly pick up potato viruses from infected leaves and when they move to another plant the problem can be transmitted within five seconds. As the insects move on in search of food, they will continue to spread the virus.
‘If we can reduce the early aphid movement with in-furrow treatment, there is a better chance that the subsequent season-long control programme can achieve the desired result,’ Mr Anderson suggests.
For the full story see our March/April edition
Ocado offer was ‘just too good to miss’
Sandra Ziles, who took over as director of the Potato Council in autumn 2009, departed in mid-February. She has joined Ocado, a grocery retailer trading solely on-line and with direct home deliveries, as a senior manager in charge of its ‘Everyday’ fresh produce division. It may be that she found the culture of PCL somewhat at variance with that to which she had become accustomed among the grocery multiples.
During her short tenure in the job she is said to have made a good impression on council staff and her performance at British Potato 2009 last year, meeting levy payers and the farming press to explain the corporate plan for the next three years, was judged a success. A double act with council chairman Allan Stevenson, himself a relatively new appointment, inspired a degree of confidence in the team at the top.
The organisation could now be faced with a fresh recruiting exercise. Mrs Ziles was a central AHDB appointment and the cost of advertising the post and interviewing candidates was born out of the relocation funding jointly supplied by the levy organisations. The search for her replacement will be financed out of funds raised from potato levies.
The process could be accelerated – and the cost reduced – if the council decides to recall one or more of those who made up the short list from which Mrs Ziles was selected. One of the applicants then, Rob Clayton, head of knowledge transfer, has been appointed interim director. His career spans 20 years in potato science with a doctorate in plant pathology, and stints at SAC, Sutton Bridge Experimental Unit and the British Potato Council at Oxford.
‘Appointing Rob as interim director is an opportunity for him and it’s a low-risk option for us,’ said Allan Stevenson. ‘The staff know him, the levy payers know him and it is relatively easy for us to carry on absolutely as though nothing has happened. Although it was a disappointment, I don’t think Sandra’s departure has harmed the Potato Council at all.’
Sandra Ziles’ new job will present her with some interesting challenges. Ocado is the first example, in the UK, of a ‘warehouse-based’ grocery retail model. The company has no expensive retail premises to maintain and no managers, check-out or shelf-stacking staff to employ. The idea behind this method of retailing is that consumers like supermarket products and service but they don’t much care for visiting the stores, and with an ever-expanding use of on-line ordering, a rapidly growing number of them no longer feel they need to.
For the full story see our March/April edition
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