16 February 1996

Better nematode control is

vital, potato growers told

Root crop management came in for close scrutiny at two grower conferences last week. Alan Barker reports from Wetherby, Yorks and John Alan from Peterborough, Cambs. Brown rot, irrigation, nematode control and weed control were key topics

POTATO growers need to improve their nematode control to prevent problems developing in future.

That was the message Eric Hutchinson, technical director of Yorkshire-based Farm Supply Company, had for a Wetherby farmer conference last week.

Applying nematicide granules when a stone separator is used may result in granules being buried too deep, so reducing their effectiveness, he said. "The only problems we had with PCN control last year was where this technique was used."

Separator advice

His advice was to avoid using stone separators, except where absolutely necessary, and then to find an alternative method of granule application and incorporation. Application of granules with bed tillers had produced some very successful results, he said.

The challenge is to persuade growers to treat with granules when egg counts are low, he continued. Multiplication rates are far higher at low counts, he said. Potatoes planted into soil with a count of 5 eggs/gram without granular control would see PCN numbers increase to 50 eggs/gram by harvest. On a five-year rotation, allowing natural decline, the count would have reduced to only 30 eggs/gram by the time the next crop was planted – well on the way to an "irretrievable" situation, he argued.

Until trap cropping could be done on set-aside land he considered it an unrealistic nematode control measure.

Telone II (1,3-dichlorpropene) remains the only practical method of returning high nematode soils to potato production. But applications should be planned well ahead in the rotation and not left until the autumn before potato planting.


PCN POINTERS


&#8226 Separators may hit efficacy

of nematicide granules.

&#8226 Use of bed tillers better.

&#8226 Use granules at low egg counts for best effect.

&#8226 Mapping and trap cropping not yet practical.

&#8226 Telone only remedial option.

Nematode control needs sharpening up if populations are to be checked, says Eric Hutchinson (inset) of the Farm Supply Ccompany, Thirsk