5 September 1997

Globodera resistance added to book

POTATO variety resistance to the widely occurring white cyst nematode, Globodera pallida, have been added to NIABs 1998 Potato Handbook.

The move reflects the growing number of varieties showing some resistance to the troublesome pest. Last year eight recommended varieties had partial resistance – this year there are 11, points out NIABs Simon Kerr.

"While none of them has complete resistance, some have much more than others. With the growing need to consider integrated pest management we felt the time was right to include pallida resistance ratings." Resistance is rated 1-5, with low resistance scoring 1. The best rating on the list is 3, denoting moderate resistance, which is given to PBI Cambridges Midas, Rocket and Sierra and Dutch-bred Sante.

A rating of 2 indicates low to moderate resistance for Kestrel, Maxine, Stroma, Swift and Valor from Caithness Potato Breeders. Caithnesss, Nadine and SCRIs Spey both have a rating of 1.

"Even with a pallida rating of 3 a variety still allows nematode multiplication. Some yield loss can be expected at high PCN numbers," Mr Kerr says. "Some other means of control will still be needed to complement varietal resistance." &#42