Rosemary stem has bumps
This is not a disease. This looks like adventitious roots on the stems. This can be a response to any type of stress and the plant will survive. You can eat the leaves.
This perennial is not usually hardy here. It should be taken indoors and kept as a container plant during winter. It can be tricky to grow indoors. See more on rosemary https://extension.umd.edu/hgic/topics/rosemary