Use of resistant and susceptible potato cultivars in the trap cropping of potato cyst nematodes, Globodera pallida and G-rostochiensis

The effects of planting date and growing period of potato cultivars on thei r efficiency as trap crops for potato cyst nematodes (PCN) were studied. Pl ots were planted with susceptible or resistant cultivars in April, June and August and these were grown for 5, 6 or 7 wk before removal of the plants by hand lifting. Crops planted in June provided the best overall reductions in PCN population density of up to 95%, with cv. Sante significantly more effective than the other cultivars. Population reductions from the August p lanting were only slightly less than from planting in June but the tuber yi elds obtained were much greater: Maris Piper and Maris Bard produced 16.4 a nd 21.4 t ha(-1) respectively, with 37% and 43% respectively, of a size use ful for canning (i.e. between 20 and 40 mm diameter).