5 May 1995

Scientists promise green end to nematode problems…

SCIENTISTS have not been slow in tackling the nematode problem, as delegates attending a conference on the topic heard at the Society of Chemical Industries in London last week.

Estimating yield loss and predicting future pest levels so management can be fine-tuned is almost a reality. Enviro-friendly control methods are on the cards. And delegates were reassured that chemicals would remain in the armoury for the foreseeable future.

That is good news for potato growers, who face tough times, reckons Melvyn Askew, head of alternative crops and biotechnology at Wolverhampton ADAS.

By the year 2000 there will be 10 or fewer major buyers, he says. Each will look for an edge on their competitors, and high specification processing markets will continue to rise. "Buyers dont want to know about the problems. All they want is their spec on the shelves."

Green pressure on pesticides, as in the Netherlands, where pesticide use has to be cut by 60% by 2000, will affect UK growers. "Most buyers will buy from both countries. They will want to ensure a uniform product, and that one hasnt an edge over the other."

The UK industry will be faced with controlling nematodes but with less agrochemical input. "In essence we have a challenge to apply integrated pest control. Time alone will tell whether we have sufficient knowledge."

Rhone Poulencs David James says nematicides will be needed to fulfil the demand for quality food, given the lack of bio-control at present. He foresees them having a place in integrated crop management on a range of crops, although he admits their use might need refining.

A big step in that direction will come from better yield loss predictions and knowing the effects of management on future populations, according to David Trudgill of the Scottish Crop Research Institute at Invergowrie.

Damage from potato cyst nematode is "density dependent", he says. "The more juveniles you have in the soil, the greater the yield loss.

"We have been trying to predict what sort of yield loss will occur in different situations and what the response to nematicides will be."

A yield loss equation has now been established which does just that. Commercial funding is now being sought to bring it on farm.

A simple and quick way of identifying and assessing nematode populations in the field was revealed by Keith Davies, one of the project researchers at IACR-Rothamsted. Work has shown that ELISA tests, which visualise protein markers can be used to identify both species of PCN present in the UK.

Further work has shown the colour change relates to the number of juveniles and eggs present. This will form the basis of a test for the density of each species of PCN present in the soil. These tests should be available on farm "in the near future", he says.