What are the differences between viruses, bacteria and fungi?

A wide variety of plant diseases, including this fungus, exist in the Sunshine State. The most obvious plant pathologies are fungi, since they are larger than bacteria and viruses

What are the differences between bacteria and viruses … or viruses and fungi … or bacteria and fungi? Are these similar in any way? We studied these plant pathologies during Week 6 of my Florida Master Gardener program in Broward County.

  1. A fungus might not be a plant at all; a bacterium is definitely not a plant; a virus might not even be alive.
  2. A virus is so small, you need an electron microscope to see it; a fungus is often easily visible; a bacterium is smaller than a fungus.
  3. A virus, to reproduce, must have a host; a bacterium can survive on its own; a fungus might survive on its own for a long time.
  4. Many fungi have spores, which aid in dispersal and reproduction; bacteria lack spores and thus rely on outside agents for dispersal.
  5. Fungi and bacteria lack chlorophyll, the pigment responsible for the green color of many plants and algae; but both have cell walls.

Source: Disease Diagnosis Guidelines for Master Gardeners, by Kenneth Pernezny