Spud storage: Keep on top of disease control

Take extra care when lifting and storing this season’s crops, urges Stuart Wale (left)

Tight blight management will be crucial if this year’s crop is to survive in store, warned specialists who joined a record 500-plus visitors to the BPC-sponsored event hosted by SCRI, SAC and CSC PotatoCare.

“It’s a diabolical situation and the worst in Scotland since 1963, when the vast majority of the crop in the Lothians couldn’t be stored,” said the latter’s Jim Rennie.

Tuber blight was the biggest immediate issue facing the industry, according the SAC’s Stuart Wale.

“Greater care is needed when lifting crops or there’ll be problems with rotting and breakdown in store.”

Growers should pick off all rotting and blighted tubers from harvesters and grading lines, he advised. “Then get as much ventilation into the harvested crop as possible.”

Blight–hit crops early and continual Smith periods and unsuitable spraying conditions helped it spread, explained BPC’s Rob Clayton.

“However, the higher pressure means we have plenty of samples coming through from scouts as part of our Fight Against Blight programme monitoring populations.”

Initial SCRI testing suggested the rise of the A2 population would continue, said the institute’s Dave Cooke.

“We’re monitoring the attributes of different genotypes, including aggressiveness to both foliage and tubers to assess how this may affect future blight management.” Full results would be presented at the British Potato 2007 event in November.

Further BPC-funded SAC work was exploring adjusting doses and spray intervals to variety.

“The aim is to give agronomists hard data they can use to tailor recommendations without compromising effectiveness,” said SAC’s Ruairidh Bain.

“We know there is significant potential in a low–risk year to save money and meet future EU requirements on justifying pesticide use.”

Mr Rennie’s advice was to keep spray intervals tight with cymoxanil-based products to dry up foliar infections.

“Mix in a good tuber blight fungicide, such as Shirlan (fluazinam), and add this to both your desiccant applications if using Reglone (diquat). Then apply another dose of Shirlan five days later if the crop is not completely desiccated.”