indoor fungicide

Use Baking Soda Spray to Cure Plant Fungal Problems

The Spruce / Anastasiia Tretiak

Fungal problems are some of the most persistent issues facing gardeners. Even indoors, a variety of fungal organisms can affect your plants, ranging from common problems like anthracnose to opportunistic infections that attack weakened plants. If your plants start to suffer from unusual spotting or funny colored growths, the problem is likely a fungus.

Issues Caused by Fungi

Fungi thrive on the energy from the plants on which they live. As the fungus grows, the plant withers. Plant fungus can quickly damage and even kill plants. Different types of fungi have a variety of appearances that include wilting, scabs, moldy coatings, blotches, or rotted plant tissue. Some come through the air via spores and attach onto the plant’s leaves. Other types live in the soil and can enter a plant through the roots. Root-based fungi can kill the roots or block the water-conducting cells, causing the plant to wilt and eventually die.

Effectiveness of Baking Soda

Outdoors, gardeners can use a variety of antifungal agents to control fungal problems on plants. Popular antifungal agents contain copper and sulfur, which are both toxic materials. These chemicals can be used indoors, however safety instructions must be followed very carefully. These chemicals are toxic to mammals, so avoid ingesting them and wear protective clothing when applying them to your plants. If any pets or children will be interacting with the treated plants, it may be best to avoid using these chemicals or move the plants to a location where they cannot be disturbed.

If you prefer a gentler solution, try using baking soda. Baking soda (sodium bicarbonate) is an antifungal agent and can even kill some established forms of fungus. Research has shown it’s effective against some kinds of black spot and powdery mildew. Best of all, baking soda is completely non-toxic for mammals, readily available in any grocery store, and inexpensive.

Making the Spray

Make a typical baking soda spray by dissolving 1 teaspoon of baking soda into one quart of water. You can add a few drops of insecticidal soap or liquid soap to help the solution spread and stick to the leaves. Only use liquid soap, like Ivory, and not laundry detergent. Stir this mixture around and then pour it into a clean, empty spray bottle.

Spray the plant completely, reaching both the upper and lower leaves, and let the plant dry. Repeat the application as necessary to control the fungal problem. If the fungus continues despite the repeated application of baking soda, consider using a stronger antifungal agent. Baking soda sprays should be labeled and stored out of reach of children. If you have leftover spray, it can be left sealed and used next time. Give the spray bottle a gentle shake prior to use.

Negative Outcomes

Constant use of a baking soda spray on plants will eventually seep through to the soil below. Bicarbonate can accumulate in the soil, impact the nutrients in the soil and may lead to slower plant growth. There are so many factors impacting a plant’s ecosystem that it is hard to predict what outcome a baking soda spray will have on a particular plant. If you notice plant damage or lower quality blooms, stop applying the baking soda spray to your plant.

Learn how to make and use a simple baking soda spray to prevent and cure fungal issues on houseplants.

How to Treat Fungus on a Houseplant

Related Articles

The bad news is that your houseplant has fungal leaf spots. The good news is that the poor thing’s prognosis for recovery with reasonable treatment is excellent. Even better, you’re not going to have to resort to dangerous chemicals to save your beloved houseplant. Powdery mildew is a common headache for indoor gardeners, particularly during the cooler months of the year. Caused by a variety of fungi, these infections respond well to treatment with the combination of sound cultural practices and a few simple, eco-friendly household products. You’ll have that ailing plant restored to its former happy, spotless beauty within a few short months.

Examine your houseplant daily for the presence of fungus, particularly during the fall and winter. Leaf spots produced by fungal infections vary in color, shape and size depending upon which of several different fungal organisms may be infecting the plant. Look for yellowish margins surrounding small brown spots on leaves. These spots may look like targets with concentric rings. Numerous diseased spots often enlarge and join together, forming large blotched areas. Some fungi infect leaves and cause them to wither and drop. Dead or dying leaves may be marked with a series of small black dots.

Move the sick plant to another room in your home at the first sign of fungal infection. You’ll need to isolate it from your collection to keep the fungus from spreading to healthy plants. With several months of intense therapy, you should be able to return the specimen to its rightful spot in your foliar display.

Pick off infected leaves as soon as you notice any spots on them. If the houseplant is full, trim out a little of the excess interior foliage to promote good air circulation, which is crucial for fighting fungus. Seal the diseased leaves and other trimmings in a plastic bag, and dispose of them in the trash. Do not add infected foliage to your compost heap.

Pour 1 cup of vegetable oil such as corn, canola or soybean into a clean plastic container with a tight-fitting lid to create a fungicidal concentrate. Add 1 tablespoon of non-degreasing liquid hand dishwashing soap. Pop the lid tightly on the container, and shake vigorously to combine the oil and soap thoroughly. Use a permanent marker to label the container clearly. Store the fungicidal concentrate indefinitely in a cool, dark spot.

Funnel 1 cup of hot tap water into a plastic spray bottle. Add 1 1/2 teaspoons of baking soda. Shake the container briskly to dissolve the baking soda. Add 1 1/2 teaspoons of the fungicidal concentrate. Shake well to combine the ingredients thoroughly. Use the solution the same day you mix it. Discard any leftover fungicide.

Set the infected houseplant in the shower or bathtub. Spray the fungicidal mixture directly onto the plant’s dry foliage. Coat all surfaces thoroughly. Be generous and saturate the plant completely to the point of runoff. Give leaf undersides and the stalks where they attach to each leaf — known as petioles — extra attention as these are areas where active fungal spores are often overlooked. Shake the spray bottle every few squirts to keep the ingredients from separating. Treat the houseplant every five to seven days thereafter throughout the remainder of the growing season.

Give the infected houseplant all the bright, indirect light possible. Keep the room warm, preferably above 75 F. Move multiple plants farther apart to facilitate increased air circulation. Cool temperatures near or below 70 F, low lighting and inadequate air circulation are the main factors that contribute to fungal disease development.

Modify your watering practices to keep the foliage of infected plants as dry as possible. Many types of fungus can’t develop if foliar surfaces aren’t moist for extended periods. Try not to splash water on the leaves, which accelerates fungal spread. Do not mist houseplants with signs of fungal disease.

Things You Will Need

Vegetable oil such as corn, canola or soybean

Plastic container with tight-fitting lid

Non-degreasing liquid hand dishwashing soap

How to Treat Fungus on a Houseplant. The bad news is that your houseplant has fungal leaf spots. The good news is that the poor thing’s prognosis for recovery with reasonable treatment is excellent. Even better, you’re not going to have to resort to dangerous chemicals to save your beloved houseplant. Powdery mildew …