A ProMED-mail post
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Date: October 2012
A new disease of sugar beet (_Beta vulgaris_) called "syndrome des basses richesses" has emerged in eastern France since 1991. Affected sugar beet roots present a reduction of sugar content leading in some cases to serious economic consequences for the growers. Similar symptoms were also locally described in Hungary in 2005.
For a long time, the aetiology of the disease remained unclear, although stolbur phytoplasma and an unknown proteobacterium both transmitted by ciixid insects were found to be associated with the disease. Recent studies have shown that the main pathogen associated with "syndrome des basses richesses" was a gamma-proteobacterium [closely related to] species [which] are usually insect endosymbionts and that stolbur phytoplasma only played a marginal role. It was also demonstrated that the main vector of the disease was _Pentastiridius leporinus_ (Hemiptera: Cixiidae). Many aspects of the biology and epidemiology of this disease remain uncertain.
The disease has recently been found in Germany [see link below]. The [EPPO] Panel on Phytosanitary Measures decided that the "syndrome des basses richesses" should be added to the EPPO Alert List.
[Syndrome des Basses Richesses (SBR) was 1st described on sugar beet crops in the Burgundy and Franche-Comte regions of France. Symptoms on sugar beet include yellowing and curling of older leaves leading to new growth of central leaves which show chlorosis and distortion.
Roots are of normal size, but vascular bundles are brown. Sugar content of the beets suddenly decreases before harvest in autumn.
Yield losses resulting in up to 50 percent loss of income from the crop ("basses richesses") have been reported from France.
Two phloem-restricted prokaryotes which cannot be cultivated, a phytoplasma (Stolbur SBR phytoplasma, 16SrXII taxonomic group) and a
gamma-3 proteobacterium (SBR proteobacterium), have been found associated with the disease. Phylogenetic analysis showed a close relationship between the SBR proteobacterium and several bacteria in the arsenophonus clade, which contains secondary symbionts of hemipteran insects. It appears that final taxonomy remains to be resolved since 2 tentative names are currently in use for the SBR proteobacterium, _Ca._ Phlomobacter betae and _Ca._ Arsenophonus phytopathogenicus. Both the SBR phytoplasma and proteobacterium are transmitted by the same plant hopper vector which was recently identified as _Pentastiridius leporinus_.
Disease management for both SBR pathogens may include vector control, removal of pathogen and/or vector reservoirs (volunteer crop plants, weeds), use of clean planting material and crop rotation with non-host species. The inclusion on the EPPO alert list can be expected to encourage sugar beet producers to introduce phytosanitary measures for prevention of SBR spread to new areas.
In Germany, SBR was detected for the 1st time in 2008, but no diseased crops could be detected by 2010. A new outbreak occurred in 2011 in the southwestern state of Baden-Wuerttemberg, which borders on France.
The phytosanitary risk for the country as well as the rest of Europe has been declared as high, and crop monitoring has been recommended for areas under threat.
The related _Ca._ Phlomobacter fragariae has been found to be associated with the Marginal Chlorosis disease of strawberry in France and Japan. More work is needed to clarify the epidemiology of these recently identified pathogens as well as the taxonomic relationships of species within the arsenophonus clade.
Regions of France:
Germany (with states):
Characterisation and description of the SBR proteobacterium:
SBR vectors and epidemiology:
Recent detections of SBR in Germany (in German):
_Ca._ Phlomobacter betae taxonomy:
Stolbur SBR phytoplasma taxonomy:
EPPO alert list:
A HealthMap/ProMED-mail map can be accessed at:
Phytoplasma, new, sugarbeet - France 20020324.3812]