Powdery mildew is a grayish-white powdery fungal growth, usually on the upper surfaces of leaves. Powdery mildews flourish when days are warm and nights are cool. Because of the wide variety of mildews, one plant may be infected while other susceptible plants remain healthy.
POWDERY MILDEW -- CONTROL OPTIONS
There are usually several management options for solving any pest or disease problem. Use the non-pesticide approach whenever possible, saving pesticide use as the last line of defense. If a pest is identified at a damaging level, select a control targeted to the problem. This decision-making process is called "Integrated Pest Management" or "IPM".

GROWING HEALTHY FLOWERS AND SHRUBS
Powdery mildew is a fungal disease found on roses, bee balm, lilacs, phlox, zinnias, and other plants. Powdery mildews affects appearance and may weaken a plant so that it is more susceptible to pest or disease problems.

To minimize powdery mildew, select mildew-resistant varieties and space plants to allow open air circulation. Do not over-water. Monitor plants in the early spring and prune off infected leaves and stems.

ALTERNATIVE CONTROLS
Control options include highly refined horticultural oil, formulations with bicarbonate of soda (baking soda), potassium bicarbonate, and/or fungicidal soap. Apply to top and bottom of leaves as soon as a problem is spotted. Reapply after rain. Follow label instructions.

CHEMICAL CONTROLS
If you have decided to use a chemical fungicide, read the precautionary statements on the label before making your selection.
 
READ THE LABEL BEFORE BUYING ANY PESTICIDE.
Re-read the label before using, storing or disposing of the pesticide — the label is the law. Following label instructions will help reduce risks to human health and the environment.
Sources of information:
Greg Patchan, Horticulture Agent, Oakland County MSU Extension.

Ellis and Bradley, Natural Insect and Disease Control, Rodale Press

Ellis Taylor ’s Weekend Gardening Guides:

Organic Pest &Disease Control, Houghton Mifflin

FOR ADDITIONAL INFORMATION:
Oakland County Garden Hotline:248/858-0902

National Pesticide Telecommunications Network (NPTN):1-800-858-7378
(Information about environmental and health effects of specific chemicals)

Household pesticide disposal: If you live in one of the SOCRRA communities, call for an appointment:248/288-5153
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