Bacteria are dependent on outside agents for dispersal. Splashing water is the chief means by which bacteria are disseminated. Another important means of dispersal is through human contact. Many bacterial diseases can be spread simply by touching an infected plant and then touching a healthy plant. Bacteria cannot penetrate the cuticle of plants, but must enter the plant through a wound or natural opening.
Viruses are the smallest of the three pathogens mentioned here.
They can only be seen with an electron microscope. They must have a living host in order to reproduce. Viruses are usually vectored from diseased to healthy plants by insects. In Florida, most viruses are vectored by aphids. Symptoms and Signs Symptoms are abnormal states that indicate something is wrong.