Plasmopara viticola: a review of knowledge on downy mildew of grapevine and effective disease management

The oomycete Plasmopara viticola is native to North America and was accidentally introduced into Europe at the end of the 19th century, where it caused widespread damage to the grape industry. Since that time, the damage caused by this plant pathogen has generally been controlled with multiple fungicide applications. Modern fungicides applied as prescribed by weather-based warning systems can effectively prevent any damage that might be caused. Alternatives to chemical treatments, such as the use of biocontrol agents or resistant cultivars, currently play a marginal role in controlling this disease. Until the middle of last century, research efforts were mainly concentrated on optimizing the application of copper fungicides and developing new molecules and formulations for controlling the disease. During the second half of the last century, highly efficient products for control were available, so research efforts moved toward optimizing and minimizing chemical control, mostly through the use of weather-based warning systems based on complex biological models. In the last 20 years, parallel to the development of technologies for genomic and transcriptomic analyses, host-pathogen interactions and population genetics have captured the interest of researchers in this field. Breeding for resistance against downy mildew has always coexisted with chemical control. However, the results of these breeding programmes have traditionally been cultivated only in marginal areas and organic production systems. This review traces the history of European knowledge of P. viticola.