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.
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.