CS20ABN has been developed by Chang et al. to isolate Xanthomonas campestris pv. campestris (Xcc) from crucifer seeds. The original medium recipe allowed the quick isolation of most isolates of Xcc. However, the recovery of some isolates of Xcc was poor due to pH-dependent sensitivity to neomycin. In the modified version, the pH is lowered to 6.5 by the addi-tion of extra potassium dihydrogen phosphate. This modification improved the recovery of some neomycin-sensitive isolates considerably.Contaminated seed lots can be detected by dilution plating of the bacterial extract on mCS20ABN and mFS. Suspected isolates are then transferred to YDC. Finally, the identity of the suspected isolates can be determined by a pathogenicity test using brassica seedlings.The colonies of Xcc and Xanthomonas campestris pv. armoraciae are yellow, mucoid and surrounded by a zone of starch hydrolysis. For detailed information about DuchefaÂ’s Phytopathological media have a look at our specialized brochure about this topic. Brochure can be found at the Â“Brochure sectionÂ” at the home page of this website.