Fungal diseases are a common issue for many gardeners. A variety of fungi can attack our plants, causing unsightly spots, wilting, dieback, and other symptoms. While commercial fungicides are available, baking soda provides a safe, natural, and low-cost fungicide option for treating many types of plant fungi.
What Causes Fungal Disease in Plants?
Fungi are organisms that survive by absorbing nutrients from living or decaying organic material. Unlike plants, they lack chlorophyll and cannot generate their own food through photosynthesis. When conditions are right, fungal spores germinate and the thread-like fungal growth penetrates into plant tissues, robbing them of vital nutrients and causing disease.
Excess moisture is the primary factor that allows fungal diseases to take hold. Excess irrigation, high humidity, poor air circulation, overcrowding, and rainy weather all provide an ideal environment for fungal growth. Stress, pest damage, and poor nutrition also make plants more vulnerable to fungal infections.
How Does Baking Soda Work as a Fungicide?
Baking soda, or sodium bicarbonate, provides an effective natural fungicide that can treat a variety of fungal diseases. It works in several ways:
- It increases the pH on plant surfaces, creating an alkaline environment that inhibits spore germination and fungal growth. Most fungal pathogens prefer acidic conditions.
- The abrasive texture of baking soda damages fungal cell walls and disrupts metabolic functions.
- As baking soda breaks down, it releases carbon dioxide and bicarbonate compounds that interfere with fungal growth.
This multipronged activity makes baking soda a broad-spectrum fungicide suitable for many types of plant fungi. It’s also gentle on plants and safe for edible gardens when used properly.
Mixing a Baking Soda Fungicide Spray
Making a baking soda spray is quick and easy:
- Add 1 teaspoon baking soda to 1 quart of water. Using warm water helps dissolve the baking soda.
- For better coverage, add 1/2 teaspoon of insecticidal soap, horticultural oil, or liquid dish soap to the solution.
- Shake or stir the ingredients to fully combine and dissolve the baking soda.
- Pour the solution into a spray bottle for easy application.
The baking soda does not remain suspended for long, so agitate the spray bottle periodically while spraying plants. Reapply the solution every 7-14 days while disease symptoms persist. It washes off with rain, so reapply after heavy rains.
How to Use Baking Soda Fungicide on Plants
Baking soda spray works best as a preventative measure before fungal diseases take hold. Begin spraying plants vulnerable to common fungal problems, like black spot on roses or early blight on tomatoes, as soon as the first symptoms appear.
To treat actively infected plants:
- Inspect plants and remove any infected leaves, dead twigs, and dropped fruit with disease symptoms. This limits sources of reinfection.
- Spray both upper and lower leaf surfaces until dripping wet. Also spray stems and fruits if susceptible to fungal attack.
- Allow plants to dry completely before watering again. Wet plant surfaces spread fungal spores.
- Repeat spraying every 7-14 days. More frequent spraying, up to twice a week, may be needed for high disease pressure.
Baking soda spray can also be used as a periodic maintenance spray to disinfect greenhouse benches, gardening tools and equipment. Don’t let the solution sit in metal sprayers for long periods, as it can corrode metals over time.
Baking Soda Fungicide Uses for Common Plant Diseases
Baking soda spray is effective against many common fungal pathogens:
Anthracnose – Mix 2 tablespoons baking soda per gallon of water and apply to affected plants every 7-10 days. Good for tomatoes, melons, cucumbers and other crops prone to anthracnose.
Black spot – Start spraying roses at first bud emergence and reapply every 7-14 days. Increases flowering and reduces leaf spotting.
Powdery mildew – Spray susceptible plants like lilacs, phlox and squash every 10-14 days during disease-prone weather. Coats fungal growth to inhibit spreading.
Rust – Apply every 7-10 days to treat rust on snap beans, hollyhocks and other plants. Spray undersides of leaves for best results.
Early blight – Start spraying tomatoes, potatoes and peppers when plants are 6 inches tall. Make successive applications every 7-10 days.
Baking soda is not effective for controlling certain fungal wilt diseases, like verticillium wilt. Consult extension resources for fungicide recommendations for specific diseases in your area. Always follow label directions.
Benefits of Using Baking Soda Fungicide
Compared to commercial fungicides, baking soda offers a safer, cheaper and more sustainable option for home gardeners. Key advantages include:
- Low toxicity to humans, pets, beneficial insects and wildlife when used as directed
- No re-entry interval – harvest edibles immediately after treatment
- Does not induce resistance in fungal populations
- Readily available and very inexpensive
- Degrades quickly without leaving toxic residues
- Can be used up to day of harvest on food crops
- Multi-purpose uses around the home and garden
- Can help correct high soil acidity when used over time
By taking a preventative approach and carefully monitoring for disease symptoms, baking soda allows you to harness the power of this common kitchen staple to keep your garden thriving. Sustainable, earth-friendly fungal disease control is as close as your pantry.
Frequently Asked Questions
Can baking soda damage my plants?
When diluted properly, baking soda does not harm most plants. Test spray a small area first. Some foliage, like peach leaves, can be sensitive to high alkalinity. Avoid excessive use on seedlings.
How often should I reapply baking soda spray?
Every 7-14 days is recommended for active infections. Use as a preventative every 2-3 weeks on vulnerable plants. More frequent spraying is needed in wet conditions.
Is it okay to use baking soda on my vegetables and herbs?
Yes, baking soda fungicide is safe for edibles when used as directed. It breaks down quickly and does not leave toxic residues. Always follow label instructions.
Should I alternate baking soda with other fungicides?
You can. Alternating with traditional fungicides helps prevent resistance. But this is not a major concern with baking soda as multiple modes of action inhibit fungi.
What is the best way to use baking soda on roses?
Start spraying roses at first bud emergence, before disease appears. Cover leaves, stems and buds. Reapply every 1-2 weeks and after rain. This provides season-long control.
Conclusion
Baking soda provides a simple, safe, and highly effective natural fungicide for home gardeners. By spraying plants preventatively, you can stop many common fungal diseases in their tracks and avoid the need for chemical fungicides. Be sure to cover leaf undersides, stems, and developing fruits for best protection. With proper timing and coverage, baking soda empowers you to harness this pantry staple to keep your garden going strong.