Plant Fungus: Easy DIY Ways to Prevent and Control It

Written by Priyanka Paul
Published: September 25, 2023
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Plant fungal diseases are every gardener’s bane. From rapid discoloration, sunken stems, wilting flowers, and rots, fungal diseases in plants manifest in many different ways. A research study published by the Ohio State University has found that fungi and fungal-like organisms (FLOs), in fact collectively account for more plant diseases than any other group of plant pests.

Plant fungus can undoubtedly be a stealthy adversary that jeopardizes the health and beauty of your garden. But don’t feel defeated if you find fungus invading your plants. Understanding what causes plant fungus and dealing with it effectively can prevent and control the growth of common fungi in your garden.

Plant Fungus: How to Spot Them

Diagnosis is a crucial part of plant fungus treatment. Plant fungal diseases typically spread through infected seeds, soil, transplants, or garden equipment. Also, fungi surviving in weeds and plant debris can make your plants sick. Airborne fungal spores and spores carried by water and insects are other common garden offenders. 

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When fungi penetrate a plant and the plant organs, there is an enormous range of disease symptoms that become visible. White mold on plant soil, blights, rust, root rot, wilt, scabs, canker, and yellowing of leaves, also referred to as downy mildew are some common complaints. Learning to recognize symptoms of plant fungus early on and taking quick action will reduce the likelihood of fungi devastating your garden.

Leaf of Lettuce, which was destroyed by powdery mildew

The picture shows patches of powdery mildew on the leaves of a sick lettuce plant. Powdery mildew is one of the most common plant fungal diseases, characterized by talcum powder-like growth that is white or grayish.


Ways to Prevent Plant Fungus: Effective DIY Hacks

The following is a collection of effective plant fungicides that will protect your plants and keep the tapestry of your garden green and healthy. From solutions to problems like how to treat powdery mildew to dealing with that stubborn blight, these simple do-it-yourself solutions can come in handy. What is great is that these organic solutions are also frugal and incredibly easy:

1. Milk Spray

 In the last few years, milk has been widely touted as an effective alternative to conventional fungicides. Numerous scientific reports indicate that milk is particularly effective in controlling powdery mildew and leaf black spots. The reason milk works as an antifungal agent is still unclear. But in general, it appears that milk works as a great preventative measure for plant fungus.

So then, is this quick fix for powdery mildew worth trying? From a practical standpoint- Yes! It is non-toxic and definitely won’t hurt your plant.

How to use: Dilute 30-40% full-fat milk in 60-70% water, depending on how concentrated you want the solution to be. Pour the solution into a spray bottle and wet both sides of the leaf. 

Diseases controlled: Powdery mildew, blackspots

How often to use: Every 10 to 14 days

Precautions: Higher concentrations of this solution can sometimes induce black rot and may even produce unpleasant odors as they break down. Spray the solution on in the afternoon so that it dries out quickly without hurting your plant 

2. Cinnamon 

Plants love cinnamon. As shown by a study, this pantry staple, apart from having powerful anti-fungal properties also has a wide array of benefits for plants and the soil. If you want to prevent fungal diseases like damping-off especially, cinnamon can come in handy. Apart from that, cinnamon can act as a great repellent for aphids too.

How to use: Simply sprinkle ground cinnamon on the soil surface. This will kill any fungal spores in the soil and prevent them from infecting your plants. Another effective way to alleviate symptoms of fungal infestations is to mix a teaspoon of cinnamon powder with approximately four cups of water and spray this solution onto affected plants.

Diseases controlled: Damping off disease

How often to use: Once every couple of weeks.

Precautions: Test a small area first to prevent any direct damage to the plant.

3. Baking Soda

This basic ingredient has long been known to be a promising alternative to commercial fungicides. Baking soda a.k.a sodium bicarbonate works by creating pH conditions that are hostile to the growth of fungi. General research, however, indicates that this D.I.Y fungicide is probably more effective in preventing fungal disease rather than treating it.

How to use: Combine one tablespoon of baking soda with a gallon of water and a spreader sticker or one-half teaspoon of liquid, non-detergent soap, and spray this solution liberally on your plants.

Diseases controlled: Certain black spots and powdery mildew.

How often to use: Once every couple of weeks

Precautions: Do not spray this on your plants during the heat of the day. Frequent use of this solution may also lead to slower plant growth and can even prevent plants from absorbing iron, leading to chlorosis.

4. Vegetable Oil

Wondering how to treat powdery mildew? Here’s another great organic fungicide-cooking oil. Salad oils and cooking oils work great as a preventive fungicide, especially against powdery mildew. These solutions or oil sprays repel water and moisture which tends to invite moisture-loving fungal diseases. What’s even better-they are biodegradable and rarely cause any long-term problems for plants.

How to use: Combine 3 tablespoons of oil with one gallon of water plus 1/4 to 1/2 tsp of liquid soap or detergent and spray this solution over your plants.

Diseases controlled: Powdery Mildew

How often to use: Every 7-14 days

Precautions: Test on a small area first to check for any plant damage.

5. Phosphate Salts

One other organic fungicide that deserves special mention is phosphate salts. It doesn’t just prevent fungal disease, but also provides nutrition to plants and improves plant growth. Phosphate salts are usually available at horticultural nurseries or chemical supply stores.

How to use: To use phosphate salts for plant fungus treatment, make a foliar spray by combining one tablespoon of phosphate salt plus about 1/4 to 1/2 tsp of liquid soap or detergent with a gallon of water.

Diseases controlled: Leaf blight, powdery mildew, rust 

How often to use: Every 12 to 15 days

Precautions: Test the spray on a small area to ensure that there is no direct damage to the plant 

6. Garlic

Garden folklore suggests that this culinary ingredient is a quick fix for many plant problems, including white mold on plant soil. The Sulphur compounds in garlic are central to the antibacterial and anti-fungal powers of garlic as a plant fungicide.

How to use: Peel and puree a whole head of garlic with one quart of water in a food processor or blender. Add a few drops of liquid soap to this solution and leave it to steep overnight. Strain it with a cheesecloth and spritz on plants as needed. If you’re using this spray only as a deterrent, then it is advisable that you dilute one part of this solution in 9 parts of water and then use it.

Diseases controlled: black spots, blight, rust, fruit rot, and mildew 

How often to use: Every 7-14 days

Precautions: Spray over a small area to check for any plant damage first.

7. Aspirin

Aspirin is not just a great drug to ease your headache but is apparently good for treating plant disease too. Trials done by scientists and research bodies, including the United States Department of Agriculture have theorized that the salicylic acid present in aspirin also helps boost plant immunity and will give you big, lusher yields in your garden.

How to use: Dilute one tab of aspirin in a gallon of water and spritz on the plant.

Diseases controlled: blight 

How often to use: Every 10-14 days

Precautions: Avoid using this spray in very hot weather and do not use this solution on very young seedlings.

To sum it up:

Preventing problems and managing disease is an important step in building a healthy garden. Follow simple ground rules like appropriate garden hygiene, proper spacing for airflow, and deeper watering of plants. When trying to combat plant diseases such as white mold on plant soil, it is also always a good idea to use combination treatments rather than rely on a single plant fungicide as most pathogens tend to develop resistance to certain substances over time.


  • Is Dawn dish soap good for powdery mildew?

Soap sprays are being widely used to treat plant fungal diseases like powdery mildew, cankers, black spots, and rust. But when improperly applied, there is always a risk of damage to your plants. It is, therefore, important that you test the solution on a small area before you treat the plant.

  • What is the best natural fungicide for plants?

Turmeric is a great natural fungicide for plants, owing to a component called curcumin. Organic turmeric can be brewed into tea and used as a foliar spray for plant fungus treatment.

  • Can vinegar be used as a fungicide on plants?

Vinegar can be safely used in plant fungus treatment. Simply mix one tablespoon of vinegar with a gallon of water and spray it on the affected area.

  • Is hydrogen peroxide an effective fungicide?

Hydrogen peroxide can work as an effective plant fungicide in treating serious bacterial and fungal diseases in plants. The recommended ratio for a homemade solution of hydrogen peroxide is three parts water to one part peroxide.

  • How to prevent and treat powdery mildew effectively?

Plant fungal diseases such as powdery mildew can be prevented by practicing good garden habits such as watering your plants at the base, spacing your plants appropriately for good airflow, following proper garden hygiene, and treating the infected plant with an effective plant fungicide. Also, practice watering your plants in the a.m. to give them sufficient time to dry during the day; roots and foliage that sit in water are usually sitting ducks for fungal infections like powdery mildew.

The photo featured at the top of this post is © foto_molka/

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About the Author

Priyanka Paul is a writer at A-Z Animals where her primary focus is on plants, geography, and insects. Priyanka has been working as a writer for over 5 years and holds a Master’s Degree in Public Administration. A resident of Buffalo, New York, Priyanka enjoys gardening, hiking, and spending time observing nature’s little creatures.

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