Causes and effects of the occurrence of "Syndrome des basses richesses" in German sugar beet growing areas

"Syndrome des basses richesses" (SBR) is a sugar beet disease, which primarily leads to the reduction of sugar content and yield and thus to large economic losses. Two non culturable and vector transmitted pathogens, a proteobacterium (Candidatus Arsenophonus phytopathogenicus") as well as a phytoplasma ("Candidatus Phytoplasma solani") can cause SBR. SBR symptoms include chlorosis and necrosis of older leaves, necrosis of the vascular tissues of the beet and asymmetries of younger leaves. In 2018, it was shown that in addition to France Pentastiridius leporinus (L., 1761) it is the most important vector in Baden-Wurttemberg. This species has adapted from its natural host (reed) to the agricultural crop rotation of sugar beet and winter wheat. In 2018, P. leporinus was the most commonly caught Auchenorrhyncha species in sugar beet and 44% were loaded with the proteobacterium. The longest flight pattern of P. leporinus in sugar beet (from May 25th to September 5th) was detected. The first proof of a second generation led to the long flight pattern of this species. This article presents the development of the area of infestation and the proof of the two pathogens until 2018. In addition, previous findings as well as own results for the dissemination and control of SBR at Baden-Wurttemberg in 2018 are presented. Differences in susceptibility of sugar beet varieties were shown for the first time. One specific genotype showed no reduction in sugar content despite SBR infection. Variety selection could thus be a promising approach to control SBR in sugar beet.