The mXCP1 (modified Xanthomonas Campestris pv. Phaseoli) medium is a semi-selective medium for the detection of Xanthomonas axonopodis pv. phaseoli (Xap) in bean seed. Both the fuscans and non-fuscans type of Xap grow on mXCP1. However the production of the fuscous pigment only becomes visible after a relatively long incubation. Modification of the medium was necessary because of poor recovery of isolates of the Xap var. fuscans type. Recognition of putative Xap colonies relies on the ability of the Xanthomonas axonopodis pv. phase-oli to hydrolyze starch. The colonies of Xanthomonas axonopo-dis pv. phaseoli on the mXCP1 plate are surrounded by a clear zone of starch hydrolysis.Detection of Psp and Xap is often performed in combi-assay. Xap is detected by dilution plating of bacterial extract from seeds on mXCP1. Then suspected colonies from mXCP1 should be transferred to YDC. Finally, the identity of suspected iso-lates is confirmed by a pathogenicity test or PCR.Xap colonies are yellow mucoid, convex and surrounded by a clear zone of starch hydrolysis. Colonies of var. fuscan are distin-guished by brown pigmentation. For detailed information about Duchefas Phytopathological media have a look at our specialized brochure about this topic. Brochure can be found at the Brochure section at the home page of this website. For detailed information about Duchefas Phytopathological media have a look at our specialized brochure about this topic. Brochure can be found at the Brochure section at the home page of this website.