This bacteria class holds more than 20 genera. And not all of them are completely harmful, but it will be hard to describe all of them, so we focus on the most important. Citrus Canker is caused by Xanthomonas axonopodis pv., and Pseudomonas syringae is caused by other gammaproteobacteria. Mentioned pathogens affect the plant’s appearance; they enter the plant through holes and wounds mostly. Their activity is shown in the suppression of the plant’s immunity. As a result, we can see how plants lose their vigor.