Paul M. Cook wrote:
Planted 3 bunches of basil 22 days ago.

Do you mean cuttings or seedlings?

In the last 48 hours I have
lost one bunch and another has started to die. What appears to
happen is that the roots die and I see about an inch of the plant
stem at the base turn brown and woody. It happens very quickly. What
could be the cause of this?

Where did you plant them, in what conditions, what have done other than
water?

David