7 November 1997

Blight-prone chip variety here to stay

ONE of the most blight-prone potato varieties available is set to remain a cornerstone of the frozen chip market, despite consumer fears over excessive pesticideuse.

Intense fungicide use is inevitable to protect Russet Burbank, which rates just 3 and 1 for foliage and tuber blight resistance respectively on NIABs 1-9 scale, admits Peter Harkett, agronomist for McCain Foods GB.

"We fully appreciate concerns over pesticides and hold those concerns ourselves. But having said that we must produce a product we can sell."

Spray advice for the widely-grown variety is based on specific risk assessments not a set programme, he says. A range of factors, including hygiene on the holding and neighbouring farms, and the presence of ground-keepers, is considered.

With most fungicides preventative, rather than curative, spray intervals remain the key to control, Mr Harkett adds.

Watch out-grades

But the knock-on effects of blight-hit out-grades also need considering. "If you are grading out and dont successfully and completely deal with affected tubers to avoid further growth you could have problems next year." Potential blight sources need burying, spraying or covering with black polythene, he advises.

"It seems quite difficult to get it across that what you and your neighbour do this year could have a significant effect next season."

The weather eventually saved the day for Burbank this year, Mr Harkett concedes, allowing farmers to catch up on delayed spray programmes.

&#8226 More blight-resistant varieties equally suited to McCains needs are being assessed. Some lines, from its own breeding programme, are said to be close to commercial development.