Biological control of Plasmopara viticola: where are we now?

Grapevine downy mildew, caused by Plasmopara viticola, is one of the most critical diseases on grapevine worldwide, causing relevant economic losses. Nowadays, the management of grapevine downy mildew relies mainly on the application of copper and synthetic fungicides. However, due to the occurrence of P. viticola populations resistant to fungicides and the impact of chemicals on humans and the environment, the development of eco-friendly plant protection products is highly requested. Biocontrol agents are effective in controlling P. viticola on grapevine and represent an important alternative to the use of synthetic fungicides and copper in viticulture. Several bacterial and fungal biocontrol agents have been evaluated for their ability to directly control P. viticola or by stimulating defense mechanisms in grapevine plants. In the future, the progressive reduction of the chemical input in viticulture and the current lack of commercial microbial biopesticides active against P. viticola will make the management of grapevine downy mildew a compelling challenge in the field of biological control of plant diseases.