Section outline

  • Tip chlorosis of beech

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    Kira Köpke, Susanne von Bargen, Artemis Rumbou, Carmen Büttner

    Humboldt-Universität zu Berlin, Albrecht Daniel Thaer-Institute, Division Phytomedicine, Berlin, Germany

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      • Symptoms

        Chlorosis as chlorotic spot, tip chlorosis, vein yellowing and vein banding.

        Carlavirus fagi-associated leaf symptoms on infected beech. A) vein banding; b) chlorotic spots; c) chlorotic spots vein yellowing; d) leaf tip chlorosis; e+f) chlorotic spots; g) chlorosis, chlorotic spots

      • Biology

        Carlavirus fagi has been detected in the urban forest, as well as in natural and commercial forests. Most carlavirus species are transmitted naturally by aphids in a non-persistent manner; cowpea mild mottle virus is transmitted by whiteflies (Bemisia tabaci), pea streak virus, red clover vein mosaic virus and cowpea mild mottle virus are seedborne in their leguminous hosts. All carlaviruses are mechanically transmissible; some (e.g. carnation latent virus and Passiflora latent virus) are sufficiently infectious to be so transmitted this way in the field (ICTV, 2023). Nevertheless, mechanical inoculation of carlavirus fagi on Nicotiana benthamiana, Chenopodium amaranticolor and C. quinoa was not successful.

      • Actions/ Management Recommendations

        The use of virus-tested plant material is highly recommended, especially if the beech trees are planted as street trees in cities, where growth under adverse environmental conditions have to be expected (Bandte et al., 2022). As also other viruses have been reported to infect Fagus spp. (Winter and Nienhaus, 1989, Büttner et al. 2023) and induce virus-like symptoms on leaves, reliable diagnosis of caralvirus fraxini should be done by molecular means, for instance virus-specific RT-PCR from symptom-bearing leaf material.

      • Geography

        Carlavirus fagi has been confirmed in France (Corsica) at a natural site and in (urban) forest trees in Germany. Chlorotic spots have also been observed in Fagus sylvatica in Croatia. A Europe-wide distribution is assumed.

      • Research & Science

        Carlavirus fagi (genus: Carlavirus, family: Betaflexiviridae) is a single stranded RNA-virus with a positive orientation. Phylogenetic analysis of open reading frames of the polymerase genes and coat protein gene confirm that the virus is a typical member of the genus and a novel species. Many epidemiological questions regarding the disease are still open. The virus is still not confirmed to be the causal agent of the observed tip chlorosis-disease in European beech, although virus detection correlates very well with the described typical symptoms.  Carlaviruses have been reported to infect a wide range of plant species. However, the host range of individual species is usually limited.

      • References

        1.    Bandte M, von Bargen S, Landgraf M, Rybak M, Büttner C. (2022): Neue Erkenntnisse zu Viruserkrankungen an Bäumen und Konsequenzen für die Baumpflege. In: Dujesiefken D. (Ed.), Jahrbuch der Baumpflege 2022, Haymarket Media, Braunschweig, 143-161.

        2.    Büttner C, Landgraf M, Fernandez Colino HL, von Bargen S, Bandte M (2023): Virus diseases of forest and urban trees. Chapter 3. In: Asiegbu F & Kovalchuk A (Eds.): Forest Microbiology. Tree diseases and pests, Volume 3. Elsevier 2023, London, United Kingdom, 61-97.

        3.    Betaflexiviridae | ICTV, https://ictv.global/report_9th/RNApos/Betaflexiviridae.

        4.    Winter, S., Nienhaus, F., 1989. Identification of viruses from European beech (Fagus sylvatica L.) of declining forests in Northrhine-Westfalia (FRG). European Journal of Forest Pathology 19, 111–118. https://doi.org/10.1111/j.1439-0329.1989.tb00241.x