Xanthomonas campestris pv. campestris (Xcc) causes black rot of crucifers, the most important cabbage disease worldwide. We built a collection of Xcc strains isolated between 2004 and 2016 in New York to test varietal susceptibility and strain aggressiveness in field trials. There is no known major gene resistance to black rot in commercial cabbage varieties. Understanding of cabbage susceptibility is vital and can be gained via study of pathogen virulence mechanisms. Transcription activator-like effectors (TALEs) are a large family of type III secreted effectors present in some Xanthomonas species. They specifically target and directly upregulate plant susceptibility (S) genes. By PCR, and western and Southern blotting, we surveyed 124 New York Xcc isolates from our collection and found that 30% express TALEs. Assays of TALE knockout strains in cauliflower revealed that across strains, different TALEs contribute to virulence. Long read sequencing of 20 Xcc isolate genomes identified TALE repeat sequences, allowing us to computationally predict TALE binding sites in cabbage and Arabidopsis promoteromes. In addition, we compared transcriptome profiles of cabbage inoculated with an Xcc strain containing cloned TALEs or an empty vector to determine TALE specific gene upregulation. Intersecting these computational and experimental data sets resulted in S gene predictions that we are testing via qRT-PCR and designer TALE effectors that target the candidate S genes. Identification of S genes could inform breeding of brassica crops for reduced susceptibility to black rot.