This project looked at the in vitro sensitivity of Guignardia citricarpa, causal agent of citrus black spot (CBS) for demethylation inhibitor fungicides (DMI; FRAC 3), succinate dehydrogenase inhibitor fungicides (SDHI; FRAC 7), an aniline-pyrimidine (FRAC 9), and a phenylpyrrole (FRAC 12). This allowed for the establishment of baseline sensitivities for those fungicides registered for citrus along with estimating whether it was worth placing them in a year-long field trial. Three DMI fungicides showed promise: difenoconazole, fenbuconazole, and propiconazole. The difenoconazole and fenbuconazole were found to be efficacious in the field trials and were recommended for CBS management. Imazalil is used post-harvest but did not have great in vitro efficacy or an ability to suppress lesion development post-harvest. The three SDHI fungicides were all efficacious in vitro and boscalid was recommended for CBS management based on field trial results. The two newer SDHI fungicides have not been field tested as of this date. The aniline-pyrimidine and the phenylpyrrole were not pursued further based on in vitro results. There was a spatial distribution study of G. citricarpa in the field and it was found that there was a clustered distribution of the disease in groves. There were several post-harvest studies undertaken. One looked at the effect of heated fungicides. It was found that heating the fungicide solution did not improve the efficacy nor did hot water treatments by themselves. Chitosan was also tested as a post-harvest control but did not have any particular effect on lesion development.