Powdery Mildew

Does something not look right on your plants or in your lawn and garden? 

What if I told you that it could possibly be a fungus that is infecting them all?

 Powdery Mildew could be the suspect we are looking for. Powdery mildew looks like white to gray spots with a talcum powder like growth. The mildew is host specific, i.e., the mildew that can be affecting your lilac and elm trees would not affect your grass, or mildew on grapes would not affect your lilac. Mildews thrive in warm dry climates. When plants have high humidity, poor air circulation, or are located in shaded areas, it allows the mildew to have an ideal growing environment.

What can we do to fix it?

The simplest and easiest option is to buy plant/seed varieties that are resistant to powdery mildew, i.e., roses, cucumber, squash, and beans.

 Not everything we want to plant will have an available resistant variety; therefore powdery mildew needs to be managed culturally and chemically.

Cultural practices:

·         Prune with good air circulation in mind.

·         Do not over fertilize and possibly look into slow release fertilizers for future applications.

·         Do not overhead water to help reduce humidity and reduce chances of spread of other fungus problems.

Chemical practices:

●   Fungicides- function as protectants, eradicants or both.  A protectant fungicide is a preventative to protect against new infections from occurring. An eradicant fungicide kills an actively growing infection. For highly susceptible plants, apply protectant fungicide before disease appears. Eradicants should be applied at earliest appearance of disease.

 ●    Horticultural oils- can be an effective eradicant in plants with mild to moderate symptoms and has some protectant effects with products such as Saf-T-Side Spray Oil, Sunspray Ultra-Fine Spray Oil, neem oil or jojoba oil.

●    Sulfur- usually a spray that is only effective before the symptoms have appeared. Copper may also be used in the same manner. It has a lower effective rate.
●    Bacterial Fungicides- made of a pathogen that kills the fungus and helps prevent future infections. These are also safe for beneficial insects, pets, and people. 

 With applying any chemicals, you want to make sure that you are reading the labels and ensuring that you have correct target pest on plants, proper protective equipment, and applying at correct rates. The label is law and we do not want to damage the environment with an application applied incorrectly. Now with our new knowledge on how powdery mildew works, we can better manage it in our gardens going forward.

 Consider signing up for land and garden pest alerts at the Pest Alert Network in order to find out about pests as soon as they are found in our area. These are the alerts for Powdery Mildew.