There is a molecular battle that takes place during the infection of plants by pathogens. Some of the weapons in the pathogen’s arsenal are known as “effectors;” these are secreted proteins that enter host cells to alter their physiology and suppress the immune system. Effectors can also be a liability for pathogens because potential hosts have evolved ways to recognize these effectors, triggering a defense response leading to localized cell death, preventing the spread of the pathogen. Our research focuses on the identification and characterization of RxLR effectors encoded in the genome of Phytophthora parasitica, the pathogen causing black shank disease in tobacco and root/stem rot in citrus. In addition to contributing to our understanding of the mechanisms of pathogenesis, this study of effectors facilitates breeding for disease-resistant plants, which will decrease agricultural reliance on fungicides.