Question
We live in Spain and have had a beautiful bougonvilla plant on our terrace for 3 years. Suddenly, it has bunches of white cotton-looking fungus on it, particularly under the leaves and in the center of the flowers. We had to throw away a bougonvilla plant at our other apartment because it was infested. What is it and how do I treat it. I sprayed it with a fungicide and insecticide.  

Answer
Hi Mary, what you are describing sounds like white fly larvae; if you look closely at the "cotton looking substance" you will find a small worm inside the packing. The best way to eradicate this is with a horticultural oil, (not dormant oil). There are various brands, ie. Ultra Fine Oil, Organicide, to name a few; soak the cotton with this and it will suffocate the larvae. Before you do this, cut back any severely infested branches first, then treat what's left...good luck Nick