Rubber Plant (Ficus Elastica)
The leaves on my rubber plant have these black looking spots. Last year I had my plant out on my patio, and I found ants had invaded my plant. Could these black looking spots be from the ant invasion? If not, how do I get rid of them?
I am always reluctant to use a treatment of any kind if I don't know what I'm treating. While it is true that the most likely cause for spots - black, brown, or yellow - on most any plant, is some sort of fungus, the causal condition is soil that is too wet, or stays too wet for too long. Excessive soil moisture allows fungi to grow unchecked, and invade the plant. The wet conditions also impair the health of the roots, and limit the plant's ability to use its own natural defenses. So the first treatment for any kind of spots is to back off on the water, and allow the plant to dry sufficiently between waterings. Rubber trees like to be very slightly damp to almost dry, all the way to the bottom of the pot. You can use a kebob skewer, like testing a cake, to be sure of the soil moisture before you water again. A couple of videos that might be of interest to you regarding watering are http://www.youtube.com/watch?v=YBBh0RPPqu0 and http://www.youtube.com/watch?v=Tf-8InSamYQ
The following link takes you to an informative chart about ficus leaf spots: https://extension.psu.edu/plant-disease-factsheets/all-fact-sheets/ficus-diseases
The spots probably are not related to the ants. Almost any all-purpose fungicide should help with the problem, use according to package directions.