A ProMED-mail post
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International Society for Infectious Diseases
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Date: Mon 2 Oct 2023 16:13 CET
Source: Proplanta [in German, transl. & summ. Mod.DHA, edited]
https://www.proplanta.de/agrar-nachrichten/pflanze/zuckerrueben-stolbur-phytoplasma-erreger-jetzt-erkennbar_article1696255989.html


In addition to sugar beet basses richesses [SBR; ProMED post 20231009.8712531], a massive occurrence of stolbur rubbery taproot disease [ProMED post 20201012.7856600] is being reported in the region, particularly from the warmer grapevine growing areas with a high density of beet cropping.

The plant hopper vectors of both the stolbur and the SBR pathogens transmit the disease by feeding on the leaves. They then lay their eggs into the soil around the emerging beets; nymphs can be detected in late summer, feeding on the maturing beets and continuing to spread the pathogens. Currently in affected fields a nymph can be found virtually on each and every beet. It is not yet known why in affected crops some of the beets appear to be healthy and without visible symptoms.

It remains to be seen how the rubbery beets will fare during continuing growth in the soil or later during storage. Currently there are no insecticides to control the vectors. The insects prefer warmer environments, making their occurrence and the risk of crop diseases spread by them more likely with the warming climate.

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Communicated by:
ProMED

[_Candidatus_ Phytoplasma solani is the type member of the stolbur (16SrXII) phytoplasma taxonomic group. A stolbur strain has been identified as the cause of sugar beet rubbery taproot disease in Serbia (ProMED post 20201012.7856600). Stolbur phytoplasmas, alone or in coinfections, have been reported to affect a range of dicotyledoneous crops (including tomato, potato, capsicum, aubergine, grapevine, sugar beet), as well as a few monocot hosts such as maize and sugarcane (ProMED posts 20070607.1844, 20080303.0869).

The main pathogen for SBR in France and Germany is considered to be _Ca._ Arsenophonus phytopathogenicus (gamma-3 proteobacterium). Both pathogens are vectored by the same plant hopper species, such as _Pentastiridius leporinus_. Further information is needed to clarify the role of each of the pathogens and any potential interactions in causing disease.

Disease management for both pathogens may include vector control, removal of pathogen and/or vector reservoirs (volunteer crop plants, weeds), use of clean planting material and phytosanitary measures for prevention of spread to new areas; crop monitoring has been recommended for areas under threat.

Maps
Europe, overview:
http://www.edinphoto.org.uk/0_MAPS/0_map_europe_political_2001_enlarged.jpg

Pictures
Symptoms of sugar beet stolbur rubbery taproot disease:
https://apsjournals.apsnet.org/cms/10.1094/PDIS-07-20-1602-RE/asset/images/medium/pdis-07-20-1602-ref1.gif
SBR symptoms on sugar beet:
https://bisz.suedzucker.de/wp-content/uploads/2018/10/Schadbild3-1024x595.png (affected field),
https://bisz.suedzucker.de/wp-content/uploads/2018/10/Schadbild2-1024x589.png (tuber, healthy on left) and
https://bisz.suedzucker.de/wp-content/uploads/2018/10/Schadbild1-1024x645.png (crown, healthy on left)
Rubbery taproot & SBR vector insects:
https://bisz.suedzucker.de/wp-content/uploads/2018/10/Zikade1.jpg

Links
Information on sugar beet stolbur rubbery taproot disease:
https://doi.org/10.1094/PDIS-07-20-1602-RE
Information on SBR and associated pathogens:
https://gd.eppo.int/download/doc/985_minids_ARSEPH.pdf,
https://doi.org/10.1094/PHYTO-97-0072 and
https://doi.org/10.1094/PHYTO.2002.92.4.384
Phytoplasma & Arsenophonus taxonomy and species lists via:
https://www.uniprot.org/taxonomy/33926
Information on phytoplasma vectors (with pictures) via:
http://www.psyllids.org/index.htm
- Mod.DHA

ProMED map:
Baden-Württemberg, Germany: https://promedmail.org/promed-post?place=8712769,4181]

See Also

Basses richesses, potato - Germany: new global host record 20231009.8712531
2020
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Rubbery taproot disease, sugar beet - Serbia: cause 20201012.7856600
2012
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Basses richesses, sugar beet - Germany: 1st rep. 20121205.1439837
2002
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Phytoplasma, new, sugarbeet - France 20020324.3812
and additional items on stolbur diseases in the archive

Website: http://www.isid.org

Published: October 24, 2023