The citrus leafminer (Phyllocnistis citrella) has increased the vulnerability and susceptibility of citrus trees to canker. Leaves and stems damaged by the citrus leafminer are more likely to be infected because the wounds allow the bacterium to easily penetrate the tissue (Fig. 2). When leafminer feeding galleries become contaminated with the bacterium, the number of lesions and the area infected greatly expand and result in enormous inoculum production. The leaf lesions sometimes fall out, leaving holes. This is known as the shot hole effect and is most common with old grapefruit lesions.