Bacterial diseases of maize

Bacterial wilt, or Stewart’s wilt, caused by Pantoea stewartii subsp. stewartii, is a quarantine disease. The pathogen is transmitted by the corn flea beetle and clogs the xylem with bacterial slime, which leads to the appearance of necrotic streaks on leaves, wilting, and the presence of exudate in the stalks.

Bacterial ear rot, caused by Bacillus mesentericus var. vulgatus, affects the crop during the milk stage. Through damage caused by the corn bug, bacteria penetrate the kernels, provoking the appearance of depressed ulcer-like spots with a characteristic discoloration of the tissues.

Other bacterial infections include bacterial leaf spot caused by Xanthomonas campestris pv. holcicola, leaf streak (Xanthomonas vasicola pv. zeae), and bacterial stalk rot, caused by Erwinia species and Enterobacter dissolvens.

Resistance to maize bacterial diseases is predominantly polygenic. Although specific loci are being studied, such as the sw1 gene for Pantoea stewartii, in breeding practice, expert scoring scales of susceptibility are more often used to assess resistance than the presence of specific resistance genes.