SCHEDULE 12SPECIAL MEASURES FOR THE CONTROL OF POTATO CYST NEMATODE(COUNCIL DIRECTIVE 69/465/EEC)(OJ No. L323, 24.12.69, p.3)
6. A potato variety shall be regarded as being resistant to a particular pathotype of Potato Cyst Nematode if, when that variety is grown, a natural and annual decrease in the population of that pathotye is found to occur.