The MT (Milk-Tween) Medium is a semi-selective medium for the detection of Pseudomonas syringae pv. syringae (Pss), Pseudomonas savastanoi pv. phaseolicola (Pspha) and Xanthomonas axonopodis pv. phaseoli (Xap) in bean seed. The medium relies on the ability of the micro-organisms to hydrolyze casein. Suspected isolates are transferred to YDC (Xap) or KB (Pss and Pspha). Finally, the identity of suspected col-onies is determined by PCR or a pathogenicity test.The colonies of Pspha and Pss are cream white, flat circular, 4-5 mm in diameter and produce a blue fluorescent pigment under UV light. Xap colonies (3 – 3.5 mm in diameter) are yellow, non fluorescent and typical two zones surround colonies: a bigger, clear zone of casein hydrolysis and a smaller zone of Tween 80 lipolysis. Xap var. fuscans (1 – 2 mm in diameter) produces a brown pigment within 5 days. For detailed information about Duchefa’s 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.