This is my 2nd year cascade. I have been noticing the brown spot on a lot of the leaves. At first I though it was nute burn because I had given it some 10-10-10 about two weeks ago, only about two table spoon sprinkled around the base of the plant. But I'm also seeing similar spots on a different cascade plant that hasn't been fertilized. So I'm not sure what the problem is and would like to correct it as soon as possible

