Botryosphaeriaceae Theiss.& P. Syd. 1918

Botryosphaeria dieback (1)
 

Fungi belonging to the Botryosphaeriaceae family are very cosmopolitan and polyphagous; they are reported all over the world, especially on various woody hosts and in a wide variety of ecological niches. They are also reported on vines in many countries in several production areas: Bolivia, Brazil, Chile, Mexico, North America, Canada, United States, China, Australia, New Zealand, Egypt, Lebanon, Spain, Italy, Portugal , Hungary, South Africa .

Several species belonging to this botanical family (long grouped under the species name Sphaeropsis malorum ) are responsible for various symptoms on vines. Their impact on this plant has long been ignored for lack of specific studies, studies rather reserved for eutypiosis or esca. The first descriptions of their parasitism on vines took place from the 1970s and their parasitic status is now well demonstrated on the vine. Currently, 21 species, of which the anamorphs are distributed in 7 fungal genera, are considered to be pathogenic on this plant.

Studies carried out in several production areas around the world show that several species can be found in the same country, or even in the same vineyard. For example, in Australia 8 species have been identified, their prevalence varying according to geography and climate. The same is true in France where a recent study has revealed at least 7 species belonging to different genera: Spencermatinsia , Neofusiccocum , Botryosphaeria , Diplodia, Lasiodiplodia .

On the other hand, the pathogenicity on vines of Botryosphaeriaceae seems to fluctuate according to the species. Three virulence classes have been defined for the moment on this plant: the most virulent species ( Lasiodiplodia spp. And Neofusicoccum spp.), The moderately virulent ( B. dothidea and Diplodia spp.), The weakly virulent ( Dothiorella spp. And S. viticola ).

Let us add that these fungi have behaviors of endophyte type or latent pathogen recognized in many woody species. These behavioral statuses have been studied in grapevine and a number of fungal species have been isolated from symptom-free tissues ( L. theobromae , D. seratia , D. mutila , N. parvum ). These initial studies must be completed, as well as those defining the conditions which influence the transition from the latent state to parasitism, such as water stress, for example: a factor that can promote the expression of wood symptoms.

( 1 ) Given the variety of symptoms caused by Botryosphaeriaceae on vine, it was recently proposed the name " Decline to Botryosphaeria " (Botryosphaeria dieback) to qualify phytosanitary issues where these fungi are involved.

( 2 ) " Black dead arm " is a disease which was first described in Hungary in 1974, characterized by a brown to black band located in the wood of the xylem, and associated with the presence of Diplodia mutila (named in the Sphaeropsis malorum period ). This name "Black dead arm" was used subsequently to indicate various diebacks on vines associated with Botryosphaeriaceae, creating confusion for several years. It should only be reserved for the Hungarian case of "Black dead arm". Note that this name was also used in France to characterize several symptoms on vines, particularly foliar, considered to be different from those of esca, but which would only be a variant as reported by several observers around the world.

Classification : Fungi, Ascomycota, Dothideomycetes, Incertae sedis, Botryosphaeriales, Botryosphaeriaceae

English name : Botryosphaeria dieback

Other names of diseases associated with Botryosphaeria problems on vines: "black dead arm" (2), Diplodia dieback (Diplodia-cane dieback), Botryosphaeria canker (Botryosphaeria canker, "bot" canker).