29 November 1996

Early action can nobble nematodes

PATCH treatment of nematodes within potato fields can be effective, if the problem is caught early. That is the perception in the Netherlands, where growers are offered a precision mapping service to track the pests development.

"The key is to catch infestations in the very early stages, just as the field is going from nematode free to having a very small number," says Tom Stolte, head of the seed potato laboratory at the Netherlands NAK independent agricultural testing service.

"Our service is an early warning, so growers can use fumigation, rotations and resistant varieties to tackle a very low population"

All fields destined for seed production must be certified nematode-free by NAK. That service checks three 200g samples or one 600g sample from each hectare and costs £24/ha (£9.70/acre).

But NAK will also take 20 400g soil samples a hectare. That detects populations as low as one cyst in 50kg of soil, says Mr Stolte. What is more the samples are collected on a 5 x 100m (984yd) grid, so results can be plotted across the field, allowing targeted use of control measures, he says.

The intensive sampling service costs £140/ha (£56/acre) and is proving popular among progressive ware growers as well as seed producers. By catching populations when limited treatments can prevent a full-scale problem, it also ties in with the governments goal of reducing pesticide usage.

Government has banned one-in-two year rotations, and one-in-three year rotations are only permitted if land is certified nematode free. Routine fumigation is outlawed – Plant Protection Service confirmation of the need is required before treatment. That has brought a 60-70% reduction in fumigation, says Mr Stolte.

The race of Globodera pallida can also be checked at a cost of £26. That helps direct choice when looking for a resistant variety.

Charles Abel


&#8226 20 x 400g samples/ha.

&#8226 Detects 1 cyst/50kg soil.

&#8226 5x100m grid for mapping

&#8226 Targeted controls.

&#8226 Costs £140/ha.