What is destroying my gardenia hedge?
I have a gardenia hedge that is well established. It is approximately 6 feet tall and 25 feet long. It consists of approximately 10 plants. Over the past few months the leaves have turned brown and fallen off along a horizontal line in the middle of the hedge. The line did not extend the entire length of the hedge but it is slowly creeping along. It has spread to affect the top and bottom leaves in the area where it started as well. A landscaper friend said that it looked like the area got burned, maybe from the exhaust of a car? However, the issue is getting worse and not better. The main trunk and all branches are still alive and there appears to be tiny new growth trying to sprout out. Can anyone tell me what is going on? I have searched gardenia diseases but nothing seems to fit. Please help! I will never be able to replace this absolutely gorgeous garden.