Again, fusarium is in the bark, not inside the stem and it will make the bark slimy and comes off easily if you rub it.
BT is to try and stop some pests eating your plants, it is not for fungal issues. Like using a respirator when you broke your leg.
Trichoderma is anti fungal, so that would be the one to go to, but it's more for prevention than cure.
Let your soil dry back between waterings, keeping the soil damp can lead to more fungal issues, so let your practices avoid making the right environment for the fungus to come.
To make the most out of BT and Trichoderma, start using them as you start veg. I know I have pest and fungal pressure every season, so rather than react when I see it (which is too late), I anticipate and it helps a lot more.