Several weeks ago, we began noticing yellowing of numerous interior leaves on our gold dust acuba plants. Yesterday, I removed many of the affected leaves from the plants as well as those that had fallen to the ground. They do have significant healthy appearing new growth. They were planted approximately 2.5 years ago. We have sprayed Round Up in their vicinity (with care to prevent any exposure to the gold dust acuba ) to try to get rid of lesser celandine. In addition, since the gold dust acuba were planted, we have used Bonide on the plants to prevent the deer from feasting on the leaves. What is causing the leaves to die? Any suggestions? I have included a picture of several of the affected leaves in various stages. Thank you for your help, Debbie Goldstein