Expert: nick mccann - 6/19/2009

Question
I recently potted (clay pot with potting soil) a Madagascar Jasmine vine and it is on my patio with partial sun - it seemed very happy until a few days ago when I noticed yellowing leaves and a few leaves with round purple spots that have dark centers.  A friend suggested I might be over-watering it so I have cut way back on watering....any suggestions about how to keep this nice plant healthy?  thanks for any help/suggestions!

Answer
Hi Susan, from what you describe, it sounds like it could indeed be too much water, but in a clay pot, it is unusual for water to be retained on the roots (because of the porous nature of the clay...); the spots sound like a fungal condition brought on by night moisture on the leaves. When a plant goes into the night with wet leaves, fungal spores use the droplets of water to develop, albeit it is difficult to prevent this from common occurrences, like rain and dew, you can help by not watering after late afternoon. Hopefully you lined the bottom of your container with some drainage medium, so any excess water can collect there instead of the roots. Spray it down with a fungicide, like "Daconil" or "funginex", this will help abate the fungal spores from developing. Nick