Howard F. Schwartz, Colorado State University, Bugwood.org

An onion plant leaf showing blight sypmtoms caused by the bacteria Xanthomonas campestris in the field.

Howard F. Schwartz, Colorado State University, Bugwood.org

Field onion plant leaves showing symptoms of bacterial leaf blight caused by Xanthomonas axonopodis pv. allii.

Howard F. Schwartz, Colorado State University, Bugwood.org

Onion plants showing symptoms of Xanthomonas Leaf Blight.

Howard F. Schwartz, Colorado State University, Bugwood.org

Xanthomonas leaf blight of onion (Xanthomonas axonopodis pv. allii) symptoms on onions (Allium spp.)

Howard F. Schwartz, Colorado State University, Bugwood.org

Xanthomonas leaf blight of onion (Xanthomonas axonopodis pv. allii) symptoms on onions (Allium spp.)

Howard F. Schwartz, Colorado State University, Bugwood.org

Xanthomonas leaf blight of onion (Xanthomonas axonopodis pv. allii) symptoms on onions (Allium spp.)

Howard F. Schwartz, Colorado State University, Bugwood.org

Onion plant showing blight sypmtoms caused by the bacteria Xanthomonas axonopodis pv. allii in the field.

Howard F. Schwartz, Colorado State University, Bugwood.org

Onion leaves showing symptoms of Xanthomonas Leaf Blight.

Howard F. Schwartz, Colorado State University, Bugwood.org

A scenic view of an onion field with symptoms of Xanthomonas leaf blight caused by Xanthomonas axonopodis pv. allii.

Howard F. Schwartz, Colorado State University, Bugwood.org

Onion plant showing blight sypmtoms caused by the bacteria Xanthomonas axonopodis pv. allii in the field.

Howard F. Schwartz, Colorado State University, Bugwood.org

Onion plant showing blight sypmtoms caused by the bacteria Xanthomonas axonopodis pv. allii in the field.

Howard F. Schwartz & Jillian M. Lang, Bugwood.org

Bacteriophage plaques in the laboratory - Xanthomonas leaf blight bacteria growing on culture medium.