Circular, scabby lesions on the leaves of an orange tree with citrus canker, caused by Xanthomonas axonopodis pv. citri.

Circular lesions on orange leaves. Credit: University of Florida
Circular, scabby lesions on the leaves of an orange tree with citrus canker, caused by Xanthomonas axonopodis pv. citri. Credit: University of Florida