![]() ![]() ![]() ![]() The objective of this review is to describe the present situation regarding the pathogen and integrated control strategies in The Netherlands, the Nordic countries and the UK. In the context of EuroBlight network ( recent results regarding the pathogen and integrated control strategies are presented and discussed. To achieve control of this pathogen population, it is essential to exploit the range of available control measures in an integrated programme. infestans population by a new, more diverse and presumably fitter population containing strains of both the A1 and A2 mating types. The situation has been further complicated by major pathogen population changes which have occurred since the late 1970s, resulting in the displacement of the apparently clonal ‘old’ A1 mating type P. Production is thus reliant on the application of fungicides despite pressures from governments, supermarkets, and consumers to reduce inputs of pesticides. Varietal choice is dictated by end users who demand cultivars with specific agronomic characters, and these are difficult to combine with blight resistance. Subsequent breeding efforts have produced cultivars with substantial levels of race-nonspecific resistance (also known as horizontal, partial, or field resistance), but the great majority of European potato production remains devoted to susceptible varieties. In the first half of the twentieth century, breeding programmes concentrated on introducing major genes for blight resistance, but this approach was largely abandoned after the 1960s when it was found that even multiple R-genes were soon overcome by the pathogen. Over 160 years later, it continues to pose a major threat to potato production, particularly in the cooler, wetter northern European countries despite the efforts of potato breeders and fungicide producers. (de Bary), first occurred in Europe in the 1840s when it led to the devastating Great Irish Potato Famine (Bourke 1991). Potato late blight, caused by the oomycete pathogen Phytophthora infestans Mont. infestans in the UK is currently being evaluated. The validity of Smith Periods for the new population of P. In the UK, commercially available DSSs are used for c. In the Nordic countries, a new DSS concept with a fixed 7-day spray interval and a variable dose rate is being tested. In The Netherlands, it is estimated that almost 40% of potato growers use recommendations based on commercially available DSS. The development and use of decision support systems (DSSs) in NW Europe are described. The spray strategies in NW Europe and a table of the specific attributes of the most important fungicides in Europe are presented. Fungicides play a crucial role in the integrated control of late blight. From the grower’s perspective, the savings in fungicide input that can be achieved with these varieties are not compensated by the higher (perceived) risk of blight. In NW Europe, varieties with greater resistance tend not to be grown on a large scale. The relative importance of the different primary inoculum sources and specific measures for reducing their role, such as covering dumps with plastic and preventing seed tubers from becoming infected, is described for the different regions. infestans has increased in the past 20 years. Although it is difficult to find direct evidence that new strains are more aggressive, there are several indications from experiments and field epidemics that the aggressiveness of P. The population characteristics of recently collected isolates in NW Europe show a diverse population including both mating types, sexual reproduction and oospores, although differences are observed between regions. It is widely believed that new strains migrated into Europe in 1976 and that this led to subsequent population changes including the introduction of the A2 mating type. infestans outside Mexico appeared to be asexual and to consist of a single clonal lineage of A1 mating type characterized by a single genotype. Before 1980, the worldwide population of P. Phytophthora infestans, the causal agent of late blight, is a major threat to potato production in northwestern Europe.
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