Chemical agent that destroy vegetative pathogens?

Fumigants

These are volatile chemicals that are toxic to living organisms and are used to control pests in soil, such as nematodes, fungi, bacteria and insects. Some common fumigants include methyl bromide, chloropicrin and dazomet. Fumigants are typically applied by injecting them into the soil, where they vaporize and spread through the pores. They can also be used in greenhouses or other enclosed spaces to control pests.