|My Ficus Melany is generally healthy, but one of the big leaves has developed a black spot along its edge. Any thoughts on what could be causing this and how to solve the problem?
|I'm not familiar with this particular cultivar of Ficus, but in general there are a few possibilities. A common problem with Ficus is scale. Scale insects look like small, oval bumps. They secrete a sweet substance called honeydew, which then attracts something called sooty mold, which is a black powdery substance. If you can wipe the black away, this is likely the problem.
If you can't wipe the spot away, my next guess is chill damage. Houseplant ficus are tropical plants and cannot withstand freezing temperatures. If the plant is near a door where it could get cold drafts, this could be the problem. Also, overwatering can cause leaf margins to turn brown/black.
Finally, have you sprayed anything unusual on the plant--either a pesticide or cleaner? These tend to collect on leaf margins and may have been a factor.
I hope this helps you figure out the problem.