If a sweet basil plant has fusarium wilt, can the leaves be eaten or are they unsafe? Stems of good size on basil plant - which was grown probably in a greenhouse and which I purchased at supermarket have dark brown spots inside of stems and the plant is collapsing and green leaves just falling off stems.
I'm sorry your Basil plant isn't doing well!
You can still harvest and dry the leaves that don't have any spots on them, but unfortunately there's no remedy for fusarium wilt, so the plant will need to be destroyed, and if it's in the ground, you can't plant other Basil or mint plants in that area for 2-3 years.
This article may give you some additional information: