First report of Xanthomonas phaseoli pv. phaseoli and Xanthomonas citri pv. fuscans in Belgium
In late August 2019, symptoms resembling those of common bacterial blight* were observed on several varieties of bean plants (Phaseolus vulgaris) in a trial plot (varietal selection experiment) in Hesbaye, Belgium. Irregular brown spots surrounded by a yellow halo were observed on bean leaves. On pods, water-soaked spots developed into reddish-brown spots. Symptoms were scattered throughout the experimental plot (approx. 100 m²), and harvesting was abandoned due to pod infection. Laboratory analysis (MALDI-TOF mass spectrometry, PCR and pathogenicity tests) revealed the presence of Xanthomonas phaseoli pv. phaseoli (EPPO A2 List, EU RNQP) and Xanthomonas citri pv. fuscans (EU RNQP) in diseased leaf samples. In the affected experimental plot, a portion of the plants were destroyed by burning and the rest were buried in the ground. The NPPO of Belgium has confirmed this first finding of common bean blight on its territory.
The pest status of both Xanthomonas phaseoli pv. phaseoli and Xanthomonas citri pv. fuscans in Belgium is officially declared as: Present, locally; only in some areas where host crops are grown.
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* It has recently been shown that common bacterial blight of bean is caused by two distinct bacteria: Xanthomonas phaseoli pv. phaseoli and Xanthomonas citri pv. fuscans (= X. fuscans subsp. fuscans) (Constantin et al., 2016).
Sources
Bultreys A, Gheysen I (2020) First report of Xanthomonas phaseoli pv. phaseoli and Xanthomonas citri pv. fuscans causing common bacterial blight of bean in Belgium. New Disease Reports 41, 6. http://dx.doi.org/10.5197/j.2044-0588.2020.041.006
Constantin EC, Cleenwerck I, Maes M, Baeyen S, Van Malderghem C, De Vos P, Cottyn B (2016) Genetic characterization of strains named as Xanthomonas axonopodis pv. dieffenbachiae leads to a taxonomic revision of the X. axonopodis species complex. Plant Pathology 65, 792-806. http://dx.doi.org/10.1111/ppa.12461
NPPO of Belgium (2020-02).