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Alternaria alternata (Fr.) Keissl. (1912)

Brown spot


- classification : Fungi, Ascomycota, Dothideomycetes, Pleosporomycetidae, Pleosporales, Pleosporaceae
- synonym : Lewia sp. (teleomorph)
- English names : Brown spot, Alternaria leaf spot

Alternaria alternata occurs worldwide but with varying degrees of severity in different countries. This fungal disease is particularly damaging in warm and humid regions such as southern China, Malawi, Zimbabwe, Argentina and northern Brazil. In many other countries, disease outbreaks are sometimes severe, such as in various Asian countries and America. North Africa and the Mediterranean regions are only slightly affected. This is true for European countries, except perhaps for Germany, Hungary and Poland.

In France brown spot cannot be considered as a limiting factor to tobacco production. Confusion in diagnosis may impute more damage to this disease than it actually produces. Furthermore, although the symptoms of brown spot are usually associated with the action of Alternaria alternata, other species of Alternaria spp. whose parasitic potential on mature tobacco leaves is not well known may be present on the spots. Are they secondary invaders of spots? Are they less severe towards tobacco leaves of advanced maturity? In our experience all species of Alternaria spp., including Alternaria alternata, isolated from spots and inoculated to susceptible varieties showed low severity on tobacco, not comparable to that expressed by the American reference strain.


China situation

A new Alternaria species causing leaf spot on tobacco in China.

During disease surveys conducted in tobacco fields at later growing season (summer) in Zhangjiajie city, Hunan province in 2016, some plants exhibited symptoms quite similar to those caused by Alternaria alternata and included near round lesions, concentric rings surrounded by a yellow halo. But there were also differences between the two symptoms, for example, intervals of concentric rings of spots were narrower and the spots were smaller than those caused by A. alternata and other species. Based on morphology, multi-gene sequencing and Koch's rule method, the scientists identified it belonged to Alternaria section Alternaria, but as a new Alternaria species. And they named it Alternaria zhangjiajieense sp. nov..Fig.1 and Fig. 2 are symptoms of cv. Yunyan 87 naturally infected in June, 2016 in Zhangjiajie, Hunan Province, China.




Last change : 05/28/19
  • Author :
  • D Blancard (INRA)
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