Tree of Life

Healthy Home Gardening
Powdery mildew

Plant Disease Type:


This Disease attacks:
Leaves and steams of plants.

General Information:
Powdery mildew is a fungal disease that affects a wide range of plants. Powdery mildew diseases are caused by many different species of fungi in the order Erysiphales. It is one of the easier diseases to spot, as its symptoms are quite distinctive. Infected plants display white powder-like spots on the leaves and stems. The lower leaves are the most affected, but the mildew can appear on any part of the plant that shows above the ground. As the disease progresses, the spots get larger and thicker as massive numbers of spores form, and the mildew spreads up and down the length of the plant.

Powdery mildew of grape

Erysiphe necator (or Uncinula necator) causes powdery mildew of grapes. It produces common odors such as 1-octen-3-one and (Z)-1,5-octadien-3-one.

Powdery mildew of wheat and barley

Blumeria graminis, the fungus that causes powdery mildew of grasses, can persist between seasons in wheat stubble that is left in the field, or in wheat that is left to overwinter. It thrives in cool humid conditions. Controlling the disease involves eliminating those conditions as much as possible. Wheat plants should not be overcrowded in the field. This allows better air circulation among the lower parts of the plants, which lowers the humidity levels. Nitrogen fertilizers encourage lots of leafy growth, and in farming systems that use them they should be used sparingly to control powdery mildew. Crop rotation with non-host plants is another way to keep mildew infection to a minimum. Reducing splash from contaminated soil also helps control spores. Chemical control is possible with anti-fungals such as triademefon and propiconazole. Some farmers are experimenting with spraying plants with waste milk, with varying degrees of success.

Powdery mildew of onions

The fungus causing powdery mildew of onions is Leveillula taurica (also known by its anamorph name, Oidiopsis taurica). It also attacks the artichoke.

This plant disease was found in these places:

How to treat this disease:

What Causes Powdery Mildew?
Powdery mildew fungi seem to be everywhere. They overwinter in plant debris begin producing spores in the spring. These spores are carried to your plants by wind, insects and splashing water. Conditions that encourage the growth and spread of powdery mildew include:
•Dampness or high humidity (Not common during rainy seasons or in extreme heat)
•Crowded plantings
•Poor air circulation
Controlling Powdery Mildew
•Choose healthy plants and keep they growing healthy
•Try and find a powdery mildew resistant cultivar, if your area is susceptible
•Don’t plant non-resistant varieties in the shade
Once Your Plants are Infected:
•Remove and destroy all infected plant parts
•Improve air circulation by thinning and pruning
•Don’t fertilized until the problem is corrected. Powdery mildew favors young, succulent growth
•Don’t water plants from above

•Apply a fungicide: There are many fungicides available. Check the label to be sure they are safe and effective on the type of plant that is infected. Look for ingredients such as: potassium bicarbonate, neem oil, sulfur or copper. There are also chemical fungicides, such as triforine, that can be used on ornamental plants. There is also a home remedy made from baking soda that is effective.
Most fungicides will need repeat applications every 7 - 14 days, for continuous protection. Always follow the label instructions for both application and waiting period before harvest

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Comment: Powdery mildew

Page Posts: 8


Bl.Pra., MN usa October 12, 2010
My mock orange bush, all my peonies and even the leaves on some seedling maple trees have thick coats of powdery mildew. We have had a wet year and now a dry fall. I cut them back, except for the mock orange. I have several price roses I do not want to get this mildew. What care should I give them next year?


Sayreville, NJ, US October 01, 2010
I have the Holy basil (Tulsi) plant which has developed powdery mildew in back and white colors on leaves. Since this plant is edible, is there a natural remedy to cure this?


Dickson, Tennessee June 05, 2010
Discovered the spots on some of my cucumber leaves today. Have removed those leaves and plan to treat. Thanks for the info.
June 04, 2010
Thanks for the info. I have always wondered what this was!


Van Nuys,Ca. USA April 26, 2010
My begonia plants were hugh and beautiful, then leaves started falling off and I noticed spots on them and powder spots. I tried a spray but I don't think it helped. I don't want to lose them they belonged to my sister. Is there a natural way to help them?


hillsboro, oregon.usa July 24, 2009
some of my garden plants have this white powder look, please tell me how to get rid of this. thank you . TR

JoAnn LaFave

Fort Meyers, Fl 33920 July 19, 2009
My Hybiscus and mandevilla plants are being taken over by powdery mildew. What can I do. If I cut the Hybicus way down will they come back???


Miami, Florida May 04, 2009
we have this powdery mildew on our cucumbers and squash. how do you get rid of it?


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