Rise in blackleg 'major concern' for Scottish seed potato growers

WORD from the seed potato fields indicates increased levels of the bacterial disease blackleg in crops over the past month.

Yesterday the talk was transformed into figures, with officials from the Scottich Government's Science & Advice for Scottish Agriculture (SASA) revealing 8 per cent of all seed crops had been downgraded during field inspections.

The figures are still provisional but they show the highest levels of blackleg infection in seed crops for almost half a century. In addition to the one in 12 crops dropping a grade, 1.5 per cent of all crops entered dropped out of certification status altogether, thus further reducing the certified acreage of seed in Scotland.

Speaking at Potatoes in Practice, Scotland's main potato field trials event, which was held at a rain-soaked farm outside Dundee, Dr Gerry Saddler from SASA described the increased incidence of the disease as a "major concern".

He attributed the increased levels of blackleg to a number of factors, the main one being the four consecutive wet summers in the seed potato growing areas of Scotland.

However, some growers at the event were also pointing their fingers at the removal of sulphuric acid as a crop desiccant. Graeme Currie, technical manager with Agrico, said he believed the blackleg problem had become worse since the use of acid as a method of burning off a crop was banned four years ago.

He suggested that following this year's experience growers might ask for a derogation so that it could be brought back into use.

However, Eric Anderson, potato consultant for Scottish Agronomy stating that seed growers should use diquat to dessicate the crop. He advised strongly against any use of flail machinery to cut the crop down as he believed all this did was help spread the blackleg spores and further infect the crops.

He also said that immediately after lifting the crops growers should reduce the temperature in their stores to less than 6C to prevent any spread of the disease. That and a positive air flow to help dry the crop would prevent spread.

The blackleg problem comes at a time when export demand for Scottish seed has never been greater. Mark Prentice, head of exports with the Potato Council, reported that more than 100,000 tonnes of Scottish seed hade left these shores from the 2010 crop.

He had previously announced the non-EU export figure of 76,000 tonnes but when exports to mainland Europe were added the total ended up at 101,000 tonnes.

Egypt was by far the biggest customer for Scottish seed last year, importing some 40,000 tonnes. Prentice said the next move was to consolidate rather than go for new markets. There was a great deal of work went into generating export markets as governments were always trying to ratchet up the regulations and requirements, he said.