Powdery Mildew: powdery mildew can infect a wide range of plants – from houseplants to trees to roses- powdery mildew can affect different plants at different times of the growing season. Some plants can tolerate this fungus and continue to thrive while others can be severely injured by a minimal infection. Powdery mildew appears as a gray powdery substance that covers the leaf surface and other plant parts. It will slowly accumulate to a light dusting. Usually circular powdery white patterns will appear. As these spots continue to grow they will eventually cover the entire plant if not treated. The fungus is most visible during hot humid conditions or in plants that are close together. Powdery mildew injury can cause the plants to present yellow leaves or leaf drop. This also can include the deterioration of buds, blooms, leaves and sometimes complete death of the plant. Select the proper fungicide to get the best control. Not all fungicides are labeled to control all fungus problems. On outdoor plants always make sure all fallen, infected leaf and plant material around the plants are gathered and destroyed during the growing season. The 1st time the fungus is noticed begin a fungicide applications immediately. Continue to use as needed during the humid weather as per label. Contact your nearest plant shed for questions or concerns.