Leaf Septoria is it worth treating it if it's on an extra plant or should it be culled

Hey bro! In simple words, remove any leaves and areas with rot or disease. Skip a couple of waterings! Do some pruning on the lower branches to make the area more airy and prevent excess cold and humidity from building up... I would also recommend using "diatomaceous earth," which will help keep pests away and keep the area free of risks, providing micronutrients for a good recovery... you can spray the diatomaceous earth with water or sprinkle it dry... I recommend never watering in the dark, only at the beginning of the day; if you water in the dark, you might get "downy mildew," which comes with cold and humid nights! ;) Cheers, king!

I honestly don't think that's leaf septoria. All the septoria I have seen makes perfectly round circles, and most of the time there perfect yellow circles making the leaf look like it has dots all over. To me that looks like the leaves are dying, I have gotten those markings from overwatering and root rot. Honestly I'm just guessing so feel free to ignore me.