Risk Assessment of Occurrence and Spread of the Phenomena of Degeneration to the Vitis vinifera Produced by Fitoplasma, in Tarnave Vineyard

Abstract

We conducted a multiannual analysis regarding the evaluation of the occurrence risk of degeneration phenomena in grape vines as well as phenomena that cause the leaves to turn yellow as a result of phytoplasma induced diseases such as Flavescence doree and Bois noir. This analysis allowed the establishment of precise correlations between the manifestation of disease specific symptoms and the presence of vectors involved in the transmission, such as Scapoideus titanus and Hyalestus obsoletus. Studies revealed two severe phytoplasma caused diseases, affecting the grapevines from the Tarnave vineyards. These are Flavescence doree and Bois noir, which belong to a complex generically called “the yellow turning of the grapevine”. Symptomatically the two diseases are very similar and can be distinguished by performing serological and molecular analysis. Other indicators for a correct diagnosis are: the presence of the vector specific for each phytoplasma disease or the focused aspect of the Flavescence doree attack in comparison to the diffuse attack of the Bois noir. The symptoms of the attack are often mistaken for mineral deficiencies or the effect of herbicide treatment. These symptoms are: the yellow turning of the leaves, flower sterility, malformations, hypertrophy, dead buds. The symptoms begin to show in early summer, they gradually become more evident and reach the maximum state in september-october.