These types of bacteria are important for plants because they recycle dead material and make the nutrients available for plants. Some bacteria are autotrophic, or they make their own food. These are of limited importance to the plants. Bacteria that live on living plants or animals are called pathogens or parasites. These are the bacteria that must be controlled or your plants will become ill.
Bacteria enter their host through wounds or small openings.
They can easily be spread from one plant top another. Rots attack because of bacterial enzymes that dissolve cell walls. In wilting the bacteria have blocked the vascular systems that transport water and sugar to the plant. These include black rot and ring rot. Gall causes an overgrowth of cell walls.