Detection of Xanthomonas axonopodis pv. phaseoli and Pseudomonas savastanoi pv. phaseolicola on bean seed using a Milk-Tween medium

Bean production is threaten by phytopathogenic bacteria causing agents of blights, Xanthomonas axonopodis pv. phaseoli (Xap) and Pseudomonas savastanoi pv. phaseolicola (Psp). Since there is no satisfactory chemical control for the disease, the recommended measures are preventive and include use of healthy seed, crop rotation, deep plowing and use of resistant cultivars. In this work we involved a detection method for isolation of Xap and Psp from bean seed to semi-selective medium Milk Agar Tween (MT). On this medium, Xap formed yellow, mucoid and convex colonies with two hydrolysis zones (less milk and more enlightened), and Psp formed whitish-cream, flat and round colonies. The identification of Xap and Psp was confirmed using the ELISA and PCR. Due to its selectivity, easy preparation and possibility of simultaneous detection of bacteria Xap and Psp, MT medium can be recommended for routine test of seed health for local seed or seed from import.