Question
I just purchased a Massangeanna in Dec 2006. However it has been by the living room window on those cold Ohio nights I decided to move it. The thing is I have noticed mold on the top surface of the soil. What can I do. I also noticed the tips are turning brown...WHY? I appreciate your help.
Thank You,
J. Silvers

Answer
Hi John,

I was surprised to see your question still in the "unanswered questions" section.  I prepared an answer on the 5th of February, and I thought all was well.

I will try again.  I am not convinced by your description that you have "mold" on the surface of your soil.  With application of hard water, nutrients, etc., a white mold-like crust can appear on the surface of the soil and along the edge of the pot slightly above or at the soil line.  This white, crusty substance is the result of the accumulation of organic salts that become concentrated over time.  Usually these deposits appear as white to off-white in color; they are fairly irregular in shape with no true structure of their own.

If that is the case, you should soak the plant in its pot overnight in a bucket or tub of water to cover the entire rootball.  This will dilute the salt concentrations, and the remaining dried salts can be removed from the side of the pot with any kind of knife or other hard tool.

If, upon closer examination with a magnifying glass, you notice any threadlike structures extending from the "mold", it is most likely a fungus of some sort. The colors of these fungi may vary in color, but are usually brown, some shade of grey to pale yellow.  The true molds may appear in any number of colors, especially bright yellow; they have a shiny, plastic-like appearance, and can be damaging to plants.

Most soil-borne fungi function as decomposers, and they are not harmful to the plant.  So unless the "mold" is unsightly, I would not worry about it.  If you simply want to make the plant look better, scoop the "mold" off the top and replace with more potting mix.

The browning on the leaf margins suggests to me that the problem may be one of salt rather than disease.  Keep an eye on the plant after you have given it the soak.  In addition to salt, chlorinated water can also cause leaf margins to "burn".  Chlorine is easily removed from tap water by allowing it to remain overnight in a jug or bucket.  The dissolved chlorine with dissipate.

Good Luck and Good Gardening.