OCCURRENCE AND CHARACTERISATION OF Xanthomonas axonopodis pv. glycines, CAUSING BACTERIAL PUSTULES ON SOYBEAN IN GUINEA SAVANNA OF BENIN

To improve soybean (Glycine max L.) production in Benin, knowledge of bacterial diseases is needed. The objective of this study was to establish the disease occurrence and to identify Xanthomonas axonopodis pv. glycines, the causal agent of soybean bacterial pustule. Soybean bacterial pustule disease was studied during the flowering and at pod maturation, in thirty four sites of the main soybean cultivation areas in eight districts of the Guinea Savanna in Benin. Twenty and 10 soybean plants were randomly inspected for incidence and severity, respectively, on two diagonals through the field. Seven isolates from 6 different locations with highest severity, were submitted for virulence tests. The most virulent was characterised by Polymerase Chain Reaction. Bacterial pustules were present in 33 of 34 sites. Incidence and severity per district ranged from 15.8 to 70%, and 6.0 to 26.14%, respectively. Severity was highest at Binassi (34.33%) in Perere and Baka (33.2%) in Parakou. Among the seven strains isolated, UP-PK-S3 from Baka (Parakou) was the most virulent, and was characterised as Xanthomonas axonopodis pv. glycines.