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 application immediately. Continue to use as needed during the humid weather as per label. Solutions to this gnarly beast after the break...
This is probably the most common problems indoor gardeners face. The key here is more AIR FLOW and less shade. Increase air flow through the stagnant areas and don’t leave any parts of your plant shaded. Powdery mildew HATES to be in full light and also does not like to be sprayed with water. Spray off any visible powder the instant you see it, early in the day when its cool and never let water sit on the leaf surface. If your not too far into flowering, you can apply a copper or sulfur fungicide. A sulfur burner will also help tremendously. Another very helpful tool is sodium bicarbonate. The most effective way to use this is by actually using a sodium bicarbonate-based fungicide, like GreenCure.
Be vigilant, this is something not to take lightly, it can DESTROY your crop!