First report of Xanthomonas oryzae pv. oryzae in Madagascar
Until recently, bacterial leaf blight caused by Xanthomonas oryzae pv. oryzae (EPPO A1 List) was considered to be absent from Madagascar, as shown by regular monitoring for rice diseases carried out since the 1980s. In December 2019, symptoms resembling those of bacterial leaf blight were observed in 2 rice (Oryza sativa) fields in Vakinankaratra, the Central Highlands of Madagascar. Affected plants showed yellow to greyish, water-soaked lesions starting from the leaf tip and progressing along the central vein or leaf margin. At a later stage, leaves became completely desiccated and sometimes had droplets of yellow exudate at the leaf margin. Symptomatic leaf samples were collected from these 2 fields. Laboratory analysis (morphological, PCR, pathogenicity tests) confirmed the presence of X. oryzae pv. oryzae. Further surveys conducted in the regions of Vakinankaratra and Menabe from 2020 to 2022 confirmed the presence of the bacterium in Madagascar and a sharp increase in disease incidence.
The situation of Xanthomonas oryzae pv. oryzae in Madagascar can be described as follows: Present, not widely distributed.
Sources
Raveloson H, Rabekijana R, Rakotonanahary NM, Szurek B, Muller B, vom Brocke K, Hutin M (2023) First report of bacterial leaf blight disease of rice caused by Xanthomonas oryzae pv. oryzae in Madagascar. Plant Disease 107(8), 2510. https://doi.org/10.1094/PDIS-03-23-0411-PDN