4 April 1997

Checks recommendedfor nematode control

POTATO growers who apply nematicides should have the effectiveness of their application method checked, says DuPont.

Vytest, developed at Harper Adams, and now available through distributors, is used to check the first run up the field after it has been planted.

The top 22.5cm (9in) of the planted ridge is split into three equal layers. Soil from each is tested to ensure there is enough Vydate (oxamyl) present to prevent nematode invasion.

Each test takes 15 minutes. Several may be needed to account for different soil types, the company adds. Cost is about £30 a test, or free for large product orders.

DuPont recommends incorporating granules with rotary tined equipment rather than reciprocating harrows or clod separators. L-shaped blades should also be avoided as these can smear some soils, exacerbating nematode problems, it adds.

&#8226 Surveys conducted over the past two years show that about 20% of machines have been under-applying nematicides, warns DuPont.n