Experts and BHG readers answer.
white spots on leaves turn yellow then die
"It sounds like you have powdery mildew on the leaves of your roses indoors. This is very common and is a real nuisance. There are lots of chemical preparations on the shelves of garden centers to treat this, but before you start spraying chemical indoors, try to get rid of the problem with more benign methods. First be sure that any diseased leaves are picked up or removed from the bush and destroyed - NOT on your compost pile. Then make a solution of 1T Bicarbonate of soda and 2teasp. dishwashing liquid in 1 gallon water. Put some of the solution in a spritzer bottle and spray both sides of the leaves regularly. This should slow the disease down and it will gradually clear up. I would hesitate to plant it outdoors till after you have controlled the disease, in case it spreads to other rose bushes.