Better blight control draws a step closer

19 July 2002

Beet weed headaches

BRITAINS top organic sugar beet grower is on target to repeat last years success, but has faced huge weed control problems after Countryside Stewardship rules restricted management of the previous stubble.

A good plant means the crop is on target to match last years 51t/ha of clean beet, with 17.1% sugar content, said Jean Burke, head of the Duchy Colleges organic centre, during a farm walk around the Duchy Colleges Coswinsawsin stockless organic arable unit at Barripper, Cornwall.

Having to leave cereal stubble over winter, to meet the terms of a Countryside Stewardship scheme to encourage corn buntings, had made weed control a lot more difficult, said farm manager Paul Harris.

"In March there was a horrendous population of aphids on the cereal volunteers and weeds, so we had to use the Green Burner once we got to March 15. Before that we were not allowed to touch anything."

The field was not ploughed until Mar 25 and drilled to Roberta beet on Apr 22. Had it been possible to plough earlier it would have been possible to drill two weeks earlier, giving more time for hoeing in dry weather, he noted.

Instead drilling was followed by wet weather, so no inter-row hoeing could be done until the first week of June. Since then it has been hoed four times.

Had the Stewardship Scheme not been in place Mr Harris would have had time for autumn weed control work and been able to drill vetches to be ploughed in at the end of winter. They would have helped build up soil fertility and smothered weeds, too, he said.

If he has his way, there will be no more over-wintered cereal stubbles at Coswinsawsin. &#42

Duchy Colleges organic beet looks set to repeat last years best-in-the-country results, says organic centre manager Jean Burke.

Blackleg barrage causes concern

WITH over 12% blackleg in an organic crop of Remarka potatoes at Coswinsawsin organic unit there was keen discussion about sourcing low disease seed.

Tom Dixon of merchant MBM said there was a lot of blackleg throughout the country this year, and colleague Stephen North said it was possible for blackleg to get into a seed crop after certification inspections were complete, unless the crop was burnt off straight away.

Rob Clayton of the British Potato Council gave some practical advice for growers. "Bacteria like it wet and warm. So ask your seed merchant how they handled the seed in store. Did they use the right air quality – it can reduce the incidence of blackleg tenfold.

"Did they avoid big temperature differences between top and bottom of the heap? Was the seed harvested wet? If it was dry did it get wet later on? Did they reduce the temperature slowly enough? That will kill a lot of bacteria. Are they warming the seed up before handling it?

"And it can be affected by what you do when you get the seed in bags on your farms. Get it out into trays and keep plenty of air there."

Organic potatoes and sugar beet were the focus of a farmer meeting staged at the

Duchy Colleges Coswinsawsin organic arable unit in Cornwall last week.

South west correspondent John Burns reports

Better blight control draws a step closer

AN EU-WIDE project seeking better potato blight control methods is showing promise, visitors to the Duchy Colleges Coswinsawsin organic arable unit in Cornwall heard last week.

James Welsh of Elm Farm Research Centre, Newbury, Berks, said there were some promising varieties, which combined good eating quality with good blight resistance.

Lady Balfour was one, though it still had to pass the supermarket selection barrier. There were some very resistant Hungarian varieties, and he knew of two as yet unnamed varieties performing well in the trials.

Some trials with a range of "alternative" sprays such as seaweed extracts, and microbial preparations had also shown promise, said Dr Welsh.

At Coswinsawsin last year there was no visual difference in blight incidence between plots sprayed with copper oxychloride and "Biomax GP", a mixture of bioflavonoid complex, organic acids, glycerine, and water, he noted.

But planting a mix of varieties, which worked well in cereals, had so far proved disappointing.

Controlling blight in organic potatoes has long been a challenge. Alternatives to copper oxychloride are now showing some promise in Cornish trials.

&#8226 Some promise on potato blight control.

&#8226 Bad blackleg in potatoes, check suppliers.

&#8226 Over-winter stubble hits beet weed control.

See more