Esca: devastating “trunk disease” of grapevines

Grapegrowers are dealing with several different diseases, among them “trunk diseases”, which in most cases cause sudden death of grapevines. There are several known trunk diseases of grapevines, but lately, esca seems to be the most devastating. In recent years, it has become a real problem in several European wine countries, such as France, Italy and Spain, although it is also well-known in other grape-growing areas of the world. Unfortunately for the winegrowers, the disease has not been thoroughly studied, and there seems to be no cure.

According to existing studies, esca is caused by several different fungi, such as Phaeoacremonium aleophilum, Phaeomoniella chlamydospora and Fomitiporia mediterranea. Since symptoms of esca appear on mature grapevine in vineyards 5 to 7 or even 20 years old, it seems that intensive pruning, frost and other mechanical injuries can contribute to disease development. Even though esca appears in older vineyards, grapevines can be affected already in a nursery. The first symptoms of esca appear as dark red (for red cultivars) or yellow (for white cultivars) stripes on leaves, which eventually dry and become necrotic. When the disease progresses, it causes a dieback of the entire grapevine. Sometimes, there are even no “warning” symptoms, and the whole grapevine suddenly dries out. Read more about Esca in Jancis Robinson post: Esca and friends.

Dimensions of grapevine trunk diseases have become so problematic for grape growers in France that even Hennessy, with his famous Cognac house, invested 600.000€ in the INRA research centre to explore and find a solution for those devastating diseases; read more.

Sources:

• Esca, UC Pest Management Guidelines; University of California
• What if esca disease of grapevine were not a fungal disease?, 2012 , Hofstetter, et.al.
• Esca and friends; Jancis Robinson
• Feature image by Daniele Barbacovi; via Wikimedia Commons