[Extra love]

Photosynthetic organisms are rarely pathogenic. Why?

And my answer is "  It would be difficult to infect many other organisms as a pathogen if the infective agent required light to survive. Hair, feathers, or basic shade would prevent the survival on the outside of a host organism, and inside the organism."

I don't know if i am right or no!

[Yggdrasil]

That's a decent answer.  There is another reason.  Why do pathogenic organisms invade other organisms?

[Mitch]

So the other organism produces its energy for them?