Fend Off the Fungus An Easy DIY Homemade Garden Fungicide

Controlling The Fungus Among Us

If you’re growing any gourds this year, this easy homemade fungicide recipe might just come in handy for you.  Curcurbits like cucumbers, squash, pumpkins, and watermelon are notoriously prone to a fungal disease that’s known as powdery mildew.

And as you’ll see below, this simple recipe can also be used to treat other fungus issues around the garden.  It is also widely used by rose aficionados to help control the black spot fungus that is a common problem for rose bushes.

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Is Powdery Mildew Consuming Your Cucumbers?

Powdery mildew is easily recognizable in an otherwise healthy garden.  When this fungus goes unchecked, it often looks like someone has used a flour sifter to apply a thin coat of flour across the leaves of affected plants.

Powdery mildew can pop up on other garden plants, too.  Some other plants that are especially prone to this fungal issue include phlox, bee balm, roses, apples, and grapes.

Powdery mildew

Make Your Own Homemade Garden Fungicide

The basic recipe I have had success with comes from The Natural Gardener in Austin.  The recipe they recommend is as follows (link to original recipe here):


4 Level teaspoons or 1 1/3 tablespoons of Baking Soda
1 teaspoon of Mild Soap (Dawn, Ivory, should be biodegradable with no phosphates)
1 gallon of Water


Mix all ingredients thoroughly and keep agitated.  Then spray plants.

Spray all leaves thoroughly, until the solution begins to run off.  Spray the top and bottom of affected leaves, and spray all of the small new leaves, even if they don’t appear to have the fungus yet.

Read More: Colloidal Silver as a Fungicide

Peer Reviewed and Scientist Approved

Gardeners might be infamous for passing along myths and legends, but this simple fungicide has some pretty good academic credentials.  Dr. R. Kenneth Horst from Cornell University led a series of studies to document the effectiveness of baking soda as a fungicide.

His studies found that a 0.5% solution of baking soda is best to control powdery mildew in curcurbits, and he found that using a surfactant (like soap or horticultural oil) is necessary to make the solution effective.  You can find lots of information about Dr. Horst’s work, and other relevant research, in this document from the National Center for Appropriate Technology:

View or Download the Original File Here: Use of Baking Soda as a Fungicide

Natural Alternatives for Controlling Fungal Issues

Before you start breaking out the fungicides, consider whether or not you might be able to control the issue just by adjusting your watering schedule.  Powdery mildew can spring up during exceptionally dry conditions, especially when you have hot, dry days and cool nights.  If you are growing plants that are susceptible to drought stress, make sure that they are getting regular water during summer hot streaks.

Air circulation is one of the biggest factors in many fungal infections, and you might be able to control powdery mildew and other fungal issues by spacing plants further apart and pruning selectively to increase air flow through the affected area.

And if you’ve had problems with powdery mildew in the past, one of the best things you can do is be sure to select plants that are resistant to powdery mildew in the future.  Some varieties are less susceptible to the fungus, and they are advertised as being resistant in seed catalogs and garden centers.



1: Baking Soda Fungicide, The Natural Gardener.  https://www.naturalgardeneraustin.com/baking-soda-fungicide.html
2: The Organic Gardener’s Handbook of Natural Pest and Disease Control. Ellis, Barbara W. and Martin, Deborah L. 2009. Rodale.
3: Use of Baking Soda as a Fungicide. Appropriate Technology Transfer for Rural Areas, National Center for Appropriate Technology, USDA. http://www.attra.org/attra-pub/bakingsoda.html

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Michael Ford


Michael has been the resident editor at The [Grow] Network since January 2015. Michael grew up in St. Louis, where he became a lover of nature - hiking and fishing his way through the Ozark hills in Missouri. He attended Baylor University in Waco, TX, and he currently lives in Austin. Michael has background experience in small-scale farming, commercial growing, vegetable gardening, landscaping, marketing, and software development. He received his Permaculture Design Certification from the Austin Permaculture Guild in 2013.

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  • Softballumpire

    I am confused, you use the term mild soap then mention Ivory & Dawn. Ivory and Dawn come in mild liquid dish detergent. Ivory also makes soap flakes or Ivory bar soap can be easily grated like cheese. Off hand, I am not familiar with Dawn soap so the term soap and detergent could be being used synonymously or erroneously. I am familiar with Fels Naptha soap which may not be classified as gentle. Then there is the Boraxo hand soap in powdered granules which also may not qualify as gentle.

    If soap is to be used exclusively, castille soap is mild, how does it impact the efficacy?

  • This is a very interesting and might be useful right away. Does this recipe also drive away ants? Ants are attacking my peppers, tomatoes and eggplants. The peppers appearances are now very bad with leaves curling because of the ants.

    And, one more question, is the mild soap a liquid soap or bar?

    • Ants are a symptom of the “real” problem. When you see ants marching, take this as a warning, you have pests like APHIDS, which DO suck the sap from a plant. Causing it to shrivel and curl. Ants are there for the “honey” the aphids secrete.

    • Sandy

      The ants are FARMING the aphids. A simple, simple remedy I have used for years is to sprinkle a few handfuls of homemade compost around the base of the invaded plant. You can gently stir the surface a little to help it get to their root systems. By the next day the aphids and the ants will have vanished. WHY?? What I assumed when this worked for me is that something about the nutrients balances and enhances the biochemistry of the plant. Most of my experiences are with curcubits and brassicas, but I have used this with other fruiting plants and leafy greens. It also worked on my dwarf cherry tree this summer (note to self: Use more compost more often on my fruit trees). I just listened to a brief seminar from Elaine Ingram on the Living Soil Web. She explained, among many other points, how helpful soil microorganisms are in moving nutriennts through a plant’s root systems into the plant. I had already understood that soil microorganisms help breakdown composted plant material and mineral components as your pile turns into compost. This experience brought home to me the oft cited comment that bugs tend not to bother healthy organic plants.

  • what is good for preventing worms in apples?

  • Debra

    Why would you not use a small amount of Castille liquid soap instead? Seems a better choice to me. When they mention “horticultural oil” what are they talking about – neem oil or something of that nature?

  • d. henry Lee

    I will try it.

  • Maury

    Please make your posts “pinnable” to Pinterest. I often want to to save an idea of yours to my garden tips board (like this one).

  • Isobelle

    Thank you for the Garden Fungicide recipe. I have struggled with this very thing for a few years.
    It appears on any squash type plant as well as on my tomato plant leaves. I look forward to using this just as soon as I can get some mixed.

  • Gay

    I have used raw whey from clabbering milk with great success for fungus. This recipe will be good to have for when I don’t have raw milk on hand. Thank you!

  • Bill P

    Elaine Ingham’s The Compost Tea Brewing Manual points out that compost tea has been instrumental in preventing the appearance of psychedelic mushrooms where they are unwelcome. It’s wonderful stuff with a great many uses.

  • Thank God you posted this info! I have struggled for years with this stuff on my squash and I’m definitely printing this out to try next year. I sure hope it will work for me!

  • Dr M.DonAvidfz

    I really appreciated and thank Almighty God so well for this released of imapActation to us ward for a better one growth.

  • Al Crockett

    will this work no tomato plants to treat blight?

  • 786177 255347 There is noticeably a bundle to know about this. I assume you created certain nice points in functions also. 307940

  • Jenn

    A few alternatives to using baking soda – hydrogen peroxide, crushed aspirins (salicylic acid), mild bleach solution – 1 part bleach to 9 parts water – FYI the chlorine bleach degrades and evaporates very quickly, does not remain or build up in your soil

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