OEM-A new medium for rapid isolation of onion-pathogenic and onion-associated bacteria

► We developed a semi-selective medium (OEM) to facilitate isolation of bacterial pathogens of onions. ► OEM supports the growth of bacterial pathogens of onion and associated bacteria. ► Distinctive colonies grow on OEM to a usable size within 24-48 h after plating. ► A broth version of OEM supports rapid growth of onion pathogens-associated Gram-negative bacteria.. ► OEM is effective for samples from onion bulbs, foliage, seed, sets, transplants, soil and water.