Here we describe a versatile multiplex method for both the serological and molecular detection of plant pathogens. The Luminex MagPlex bead system uses small paramagnetic microspheres ("beads"), either coated with specific antibodies or oligonucleotides, which capture respectively viruses and/or bacteria or PCR products obtained from their genetic material. The Luminex MagPlex bead system allows true multiplex detection of up to 500 targets in a single sample on a routine basis. The liquid suspension nature of the method significantly improves (1) assay speed, (2) detection limits and (3) dynamic range. It can also considerably reduce labor and consumables costs.