| Two years ago I purchased a Monrovia plumbago plant from Atlantic Gardens (the only local retailer of your plants). The plant was in a terrible state at the time- nearly dead, and with a gritty substance under the leaves. The store explained that with the extreme winter temperatures that year many of the plants had suffered, that the grittiness was merely the residue of a pesticide spray and that the plant would quickly return to health given good conditions. I believed this, as I was very familiar with plumbago from my time spent in California and in Australia, and knew it to be a highly pest-resistant plant. And since I had been searching for a plumbago plant here in Canada for some time, I bought it anyway. But unfortunately it did have some pest- a pest resistant to all the usual household plant sprays, and a pest which infected the |
| Plumbago is usually trouble free so there is no "usual suspect" you are right. Based on your description I think you might be seeing evidence of a cottony scale insect problem which eventually does cause yellowing, the stickiness could be caused by the sucking and the black spots could be mildew -- and there would be no webs as with spider mite. Without seeing the plant however it is hard to say for certain. Here is a photo, note the white dots ... http://www.upenn.edu/paflora/p... Scale can be treated in the crawler stage with insecticidal soap or can be sprayed with horticultural oil to smother it. I'm sorry you are having trouble with your plant. |
