Yield losses caused by potato cyst nematodes: a review of the current position in Britain and prospects for improvements

Studies of the yield losses caused by potato cyst nematodes (PCN) in Britain are reviewed. The main conclusions either drawn from or supported by the literature, are:- 1) The models/equations used to relate yield losses to pre-planting densities of PCN are not entirely satisfactory. 2) There is considerable variation between sites in the damage caused by PCN and hence the yield response to nematicide treatment cannot be reliably predicted. 3) Oximecarbamate nematicides, if well applied and if other damaging pests are absent, will prevent most of the loss at infested sites but do not increase yields at most uninfested sites. 4) PCN decreases yields by reducing the effectiveness of the root system, and hence leaf area duration and the amount of light intercepted by the crop canopy: in some circumstances PCN may also decrease the efficiency of assimilation. 5) Several factors interact either to increase or to decrease the damage caused by PCN; some of the more important are soil type, interactions with micro-organisms, differences in husbandry, differences between cultivars in their tolerance of damage, the weather and differences in yield potential between sites. 6) Both the yield losses caused by Globodera pallida and the amounts of nematicide used may be decreased by planting tolerant and partially resistant cultivars. New results are used to show that yield losses may be decreased by applying extra fertiliser and that low rates of nematicides may be adequate to prevent damage to tolerant cultivars. Further research may lead to an improved basis for advice relating to the control of PCN and the damage it causes.