19 November 1999

Nematodes pose rising threat to potato crop

POTATO cyst nematode problems are far worse than most producers realise, according to results from a recent survey backed by the British Potato Council.

Up to 65% of potato fields could be infested, with 92% of those containing the more troublesome white cyst nematode (G pallida).

The findings stem from a study of 500 samples collected and checked by Steven Minnis of Harper Adams University College. Further work by Pat Haydock, also of Harper Adams, and Ken Evans of IACR Rothamsted, used bait plants to identify infestations well below the normal levels of detection.

"Populations have been moving towards pallida ever since the introduction of rostochiensis-resistant Maris Piper in 1966," says Mr Minnis. "Now we know just how serious the situation has become.

"As granular nematicides appear less effective against pallida the problem could accelerate unless growers change control programmes." He urges growers to have fields sampled regularly and to consider a control programme including soil-injected fumigant. &#42