Powdery mildew is appearing on lilacs in many areas of the state. This a very common disease of lilacs but powdery mildews (usually different fungi as these mildews are host specific) can occur on many different plants including grapes, roses and Virginia-creeper. Powdery mildew appear as white to grayish spots or patches on the leaf that often contain small pin-size black dots. These symptoms usually occur on the upper leaf surface. They also are more common on plants that are crowded and shaded, locations that provide the high relative humidity needed for the disease to develop. Since the disease occurs mostly on crowded plantings, the best solution is to selectively prune out (or even remove) plants to provide better air circulation and lower the humidity. There are also many fungicides labeled for control of this disease, but these need to be applied every 10-days throughout the growing season or at least throughout the hot, humid summer weather.