ABSTRACT Citrus canker (caused by Xanthomonas citri subsp. citri, Xcc) is an important bacterial disease of citrus that is spread naturally by rain and wind. Feeding damage to citrus leaves by the citrus leafminer (CLM), Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae), has been shown to promote infection levels of citrus canker in a number of citrus-growing regions around the world. We conducted 2 studies to document that CLM damage exacerbates canker in Florida citrus. In 1 study, young citrus trees of 5 cultivare commonly grown in Florida were inoculated with a culture of Xcc. Two groups of trees were studied, 1 group with leaves damaged by CLM and 1 group that was treated with a pesticide to prevent CLM damage. Over all 5 cultivars, comparisons between the 2 groups of trees indicated that CLM damage resulted in 6-fold increase in the number of lesions. No difference was found between the 2 groups with respect to numbers of canker lesions on leaves without CLM damage. In the second study, ...