Progress on the etiology of the new disease of sugar beet ‘Syndrome des Basses Richesses’
As reported in EPPO RS 2002/017, a new disease of sugar beet called ‘syndrome des basses richesses’ appeared in France, in Bourgogne in 1991. Roots of affected plants present a loss of sugar content which may have serious economic consequences for the growers. The aetiology of the disease remained rather unclear although a phytoplasma of the stolbur group was found associated with the disease. A newly described planthopper species, Pentastiridius beieri (Homoptera: Ciixidae), was shown to carry the phytoplasma and transmit it to sugar beet. However, several observations and studies indicated that the phytoplasma did not play a major etiological role in the disease (the rate of stolbur-infected plants among all diseased sugar beet never exceeded 12%). Preliminary microscopic observations of affected roots suggested that another phloem-limited organism (a bacterium-like organism: ‘BLO’) was involved. Further experiments confirmed that a BLO, related to Candidatus Phlomobacter fragariae (causal agent of marginal chlorosis in strawberry), was naturally infecting sugar beet and could experimentally be associated with disease symptoms at both macroscopic and microscopic level. In addition, it was observed that P. beieri was an effective vector of the BLO. In the present state of research, it appears that ‘syndrome des basses richesses’ is associated with two phloem-limited pathogens (BLO and/or stolbur phytoplasma) which are both efficiently transmitted by P. beieri in the field.
Gatineau, F.; Jacob, N.; Vautrin, S.; Larrue, J.; Lherminier, J.; Richard-Molard, M.; Boudon-Padieu, E. (2002) Association with the syndrome ‘Basses Richesses’ of sugar beet of a phytoplasma and a bacterium-like organism transmitted by a Pentastiridius sp.
Phytopathology, 92(4), 384-392.