Why do plants not need vaccination
Vaccination may be defined as protection of the body from communicable diseases by the administration of some agents that mimic the microbe.
The agent can be a suspension of killed or attenuated microbes, or a substance that mimics the disease-causing microbes. This is known as a vaccine.
We cannot say that plants do not need vaccines.
The application of concept of vaccination in plants is under development. When vaccine is inserted into a plant it simply boosts immune system.