Development of multilevel monitoring systems for the identification of phytoplasma diseases in German viticultural areas

"Flavescence dorée" (FD) and "bois noir" (BN) are the most important phytoplasma diseases of grapevine. While BN is widespread in German winegrowing regions, only one single grapevine plant infected with FD phytoplasma has been reported and eradicated in 2020. Although the main vector of FD, Scaphoideus titanus, is not present in Germany, the FD phytoplasma is classified as quarantine pest because of its epidemic potential and a systematic monitoring of the disease and the vector is mandatory in Germany. Furthermore, a non-epidemic strain Palatinate grapevine yellows (PGY), with the same symptomatology as FD and BN is present in Germany. For large scale monitoring digital multilevel monitoring systems for grapevine yellows (GY) are being developed. Reference plots with infection by either BN or PGY in risk zones in southwestern Germany and Württemberg have been visually monitored and symptomatic grapevines were analysed by molecular means. In parallel, the same samples were examined with different sensor-based methods to define a correlation between phytoplasma presence and specific spectral signatures. A spectral distinction to similar symptoms due to virus infection, insect damage, and nutritional deficiencies was investigated for the system validation.