Add to GuideAsk a Question
To Top

Treating Plants with Powdery Mildew

Category Plant Health
This common fungal disease can affect nearly all types of plants. This guide is about treating plants with powdery mildew.


Share on ThriftyFunThis guide contains the following solutions. Have something to add? Please share your solution!

6 found this helpful
May 10, 2011

If you garden long enough, sooner or later you'll find yourself dealing with powdery mildew problems. This common fungal disease can affect virtually all types of plants. Fortunately, other than slowing down growth, reducing yields, and looking terrible, it rarely kills affected plants. Here are some ways to tackle the problem organically.

Symptoms and Effects

If your plants have a white to grayish powdery coating on the upper surfaces of the leaves, the problem is most likely powdery mildew. Once a plant's leaf surface becomes covered with patches of mildew, its ability to produce food (photosynthesis) is reduced and it becomes weak. Leaves are often shed prematurely, and in severe cases the plant may fail to produce fruit.

There are many types of powdery mildew, all of which spread by microscopic spores. These spores can live for years in leaf debris or in the soil, and are carried to plants by wind, insects, and splashing water. Conditions that favor the spread and growth of powdery mildew include a lack of air circulation around plants (especially in the shade), dry weather, and temperatures between 60 and 80 degrees F.



Organic Treatments

Baking Soda: This homemade remedy is easy and inexpensive to make, and very effective at preventing powdery mildew. Mix together 3 tablespoons of baking soda (sodium bicarbonate), 1 tablespoon of Murphy's Oil Soap (or light horticultural oil) and 1 gallon of water.

Spray a fresh batch of the mixture on the tops and bottoms of leaves every 7 to 10 days. Because oil combined with the heat of the sun can damage plant tissues, it's wise to test the solution on a few leaves before using it in large quantities.

Water: This low-tech approach must be done consistently to work effectively. Unlike indoor mildew, powdery mildew hates water and spreads readily on dry leaves. The spore plugs must embed themselves in leaf tissue to grow, which they can't do on slippery, wet leaves.

Spray down the leaves with the garden hose daily. Make sure you do this early enough in the day so that leaves dry out before evening, otherwise you'll be swapping one fungal disease for another.


Compost Tea: When used as a foliar spray, compost tea has both insecticidal and fungicidal properties. Place a gallon of well-aged compost in a 5-gallon bucket and fill it with water. Stir well and let sit in a warm place for 3 days.

After three days, siphon off the liquid tea by filtering the mixture though a burlap sack. Pour the tea into a hand held sprayer and apply to leaves in the evening.

Remove affected leaves and discard severely affected plants. Use a plastic bag to carry the plant debris out of the garden. Spores can live for years waiting for the right growth conditions, so either burn the waste or discard it in the trash. Don't compost it!

Comment Was this helpful? 6
May 17, 20110 found this helpful

Thanks for the great info. Powdery mildew is an enemy I fight with every growing season. From flowers, to vines, to vegetables.

God Bless

Trish in CT

Reply Was this helpful? Yes
Read More Comments

6 found this helpful
May 28, 2011

A good solution to get rid of this powdery mildew is to make a solution of dry powered milk and spray your plants. This is a tip I learned at a Master Gardener class. It works!

By jeannette from West Palm Beach, FL

Comment Was this helpful? 6
May 31, 20110 found this helpful

What are the measurements for this solution? Powder vs water ratio?

Reply Was this helpful? Yes

August 11, 2014

powdery mildew on plant leaves

There are many articles posted on the Internet reporting that ordinary cows milk diluted with water to about a 10 % solution and sprayed on plants is highly effective as a preventative and as a treatment for various types of powdery mildew.


0 found this helpful
August 6, 2014

leaf covered with powdery mildew

I's that time of year again, the garden and the garden pests are back with a vengeance! This is what white mold looks like. It destroys cucurbit crops such as pumpkins, cucumbers, and peas. To date we have tried everything to rid ourselves of this.



Ask a QuestionHere are the questions asked by community members. Read on to see the answers provided by the ThriftyFun community or ask a new question.

0 found this helpful
November 7, 2009

I am very inexperienced in gardening. There is a white powdery look and white flecks on the underside of a sweet potato vine. Is this powdery mildew? The white flecks are not insects. But I do not know what they are.

Hardiness Zone: 10b

By Lynn from South FL

Answer Was this helpful? Yes
November 12, 20090 found this helpful

One thing that I found helps with powdery mildew is to make a solution of dry powder milk, and spray your plants. Learned this at a mg. class

Reply Was this helpful? Yes
November 12, 20090 found this helpful

I've seen this on my plants. If it's not powdery mildew it's the residue of the bad bugs that the good bugs ate.

Reply Was this helpful? Yes
November 12, 20090 found this helpful

If this white powder is on the bottom side of your leaves, it may be mealy bugs and they are easily washed off. You can use clear water or mix a drop of dishwashing liquid with it. Keep a close watch on this plant as they may show up again and mealy bugs will kill the plant. They will move to other plants they like so watch the neighbor plants.

Reply Was this helpful? Yes
November 13, 20090 found this helpful

I use the milk method but I use skim milk full strength.

Reply Was this helpful? Yes
Read More Answers

0 found this helpful
January 14, 2015

There has got to be something you can do to get rid of the powdery mildew. I have tried compost, mulch, and last year I put in some tomato cages to keep them off the ground. They had the most beautiful vines, some 5 feet tall, but when the fruit set all the vines died! I wish I could send a pic of the vines.

By Vicki

Answer Was this helpful? Yes

0 found this helpful
September 6, 2011

This is the second summer I've grown zucchini and yellow squash in my garden. Both years the leaves become covered with powdery white mildew. Eventually the bottom leaves die and the new leaves soon become mildewy as well.

I have had two different water systems, underground that waters only the roots, and above ground, but only watering in the morning so the leaves get dry. It didn't seem to make any difference, they were covered with mildew with both systems. I don't want to use a chemical fungicide unless there's no other option to get good healthy leaves. I don't want to eat fungicide. I would be grateful for any help.

By LeeAnne67 from Bothell, WA

Answer Was this helpful? Yes
September 10, 20110 found this helpful

I feel your pain. I've been plagued with powdery mildew for over two decades. It is nearly impossible to get rid of because it lives in the soil from year to year and is both air borne and water borne. One of my yards is so infested with it that I cannot grow any vegetables there at all. It is extremely contagious and easily transmitted by the hands and gardening tools.

The only thing I've learned to do is manage it, somewhat, by eliminating flowering plants that easily succumb to it - morning glories and sunflowers, for example. It attacks nearly all soft leaved plants, so your squash is easy prey. Remove infected leaves immediately and harvest very early, not letting the fruit remain on the vine too long, then pull up the plant when the mildew begins to overtake the it. I've managed to grow squash quite successfully with this kind of diligence. Also, areas of the garden that get the longest hours of full sun seem to thwart the invasion. If anyone knows a cure I'd sure like to know about it.

Reply Was this helpful? Yes

0 found this helpful
July 15, 2011

I recently noticed that one of my succulent houseplants, a kalanchoe, has powdery mildew on the leaves. I just moved and it is in a new location, but nothing else has changed. How to I treat the leaves? They now have brown spots where I have wiped it off. Thank you for your suggestions.

By Barbara from Bremerton, WA

Answer Was this helpful? Yes
July 23, 20110 found this helpful

I've never treated succulents for powdery mildew, but have other plants using a fungicide purchased at the garden centre. Check your local extension website, or talk to the staff at the nursery to see what they suggest.

Reply Was this helpful? Yes

0 found this helpful
May 29, 2012

My hibiscus plant has a white powdery substance on the leaves and stems. The leaves turn yellow and fall off. How do I get rid of it? What is it?

By Dawn H

Answer Was this helpful? Yes
Related Content
Home and Garden Gardening Plant HealthMay 30, 2012
Cleaning Chalk Off Upholstered Furniture
Cleaning up Mildew From Wood
Removing Mildew from Wood
Photo of a tent set up in the woods.
Removing Mildew from a Tent
Treating the Soil After Tomato Blight
Treating Soil After Tomato Blight
Father's Day Ideas!
Mother's Day Ideas!
Ask a Question
Share a Post
Desktop Page | View Mobile

Disclaimer | Privacy Policy | Contact Us

© 1997-2017 by Cumuli, Inc. All Rights Reserved.

Published by .

Generated 2017/04/27 01:44:06 in 3 secs.
Loading Something Awesome!