If the growth looks like fine white cotton and is kind of sticky to touch it is the residue of white aphids, you can usally control the aphids by mixing 2 tea spoons dish detergent, 2 tea of white vinegar and 2 tab veg oil with 1 qt of water and put in hand held spray bottle and spray 2 to 3 times a wk for about 2 wks this usally does it and is better tthan chemicals if not kept in check these bad boys will ruin your plant