Pest risk analysis of Meloidogyne chitwoodi for Finland
There is a an ever‐present risk of Meloidogyne chitwoodi extending its range to Finland because of the active import of plant material to the country. If the nematode becomes established in Finland, two factors may limit its pest potential: low temperature accumulation during the growing season and low winter temperatures. On average, the effective temperature accumulation may enable development of 1.5 generations yearly. In warm years, development of two generations is possible in the southern parts of the country. Hatching of the second generation, and infection of potato tubers, is possible in most potato‐growing areas. Low soil temperatures during the winter reduce population densities but may not prevent the nematode from becoming established in Finland. If M. chitwoodi were to extend its range to Finland, it could become a pest of potatoes, especially seed potatoes. For other crops, such as cereals and vegetables, population densities of M. chitwoodi would probably remain at such low levels that yield losses would not occur under current climatic conditions. Scientific information concerning M. chitwoodi populations in Europe is insufficient for a fully reliable pest risk analysis. This will not be possible until the effect of abiotic and biotic factors on the nematode are well known. A data base of the distribution of the nematode, based on a geographical information system, is urgently needed for the whole of Europe. Soil temperature maps interpolated from direct measurements, or derived from air temperatures, should also be constructed because soil temperature accumulation is one of the most important factors which may limit the distribution of this polyphagous nematode.