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Use of Baking Soda as a Fungicide
Agronomy Technical Note

 

Appropriate Technology Transfer for Rural Areas (ATTRA)
PO Box 3657
Fayetteville, AR  72702
Phone: 1-800-346-9140 --- FAX: (479) 442-9842

By George Kuepper, Raeven Thomas,
and Richard Earles
NCAT Agriculture Specialists
November 2001
 

The PDF version of this document is available at
http://attra.ncat.org/attra-pub/PDF/bakingsoda.pdf
4 pages — 367 kb

Abstract: There has been considerable interest in the use of baking soda (sodium bicarbonate, NaHCO3) and potassium bicarbonate (KHCO3) to control powdery mildew and other fungal diseases of plants. This publication provides a brief survey of observations, research, and recommendations on the use of bicarbonates in horticulture.

 

 

Small Leafs Bullet The use of baking soda as a fungicide is not a new idea. In Alfred C. Hottes' A Little Book of Climbing Plants, published in 1933 by the A.T. De La Mare Co. of New York, mention is made of using one ounce of baking soda per gallon of water to control powdery mildew (PM) on climbing roses. The author credits the idea to a Russian plant pathologist, A. de Yaczenski (1).
Small Leafs Bullet In the August, 1985 issue of Organic Gardening magazine, a short article by Warren Shultz entitled "Recipe for Resistance" reports that researchers in Japan obtained effective control of PM on cucumbers, eggplants, and strawberries. They suggested weekly sprays of ¼ ounce baking soda per gallon of water(2).
Small Leafs Bullet An article in the June, 1990 issue of Greenhouse Manager magazine summarizes the results of three years of testing baking soda as a fungicide for roses. Cornell University researcher Dr. R. Kenneth Horst observed suppression of PM and blackspot—both major problems for New York rose growers. Roses were sprayed every 3 to 4 days with a water solution of baking soda and insecticidal soap. The latter was included for its surfactant qualities. (Surfactants are chemical agents that alter the surface properties of a liquid.) The soap improved the effectiveness of the bicarbonate by making it stick to, and spread evenly over, the leaf surface. Further experimentation proved that the insecticidal soap itself was not responsible for suppressing the diseases. While no specific concentration of baking soda is indicated as being most effective in PM suppression, the article states that a 0.5% solution was most effective in preventing blackspot (3).
Small Leafs Bullet PumpkinSome of the work at Cornell has focused on controlling fungal diseases on cucurbits (4). A single spray application (to runoff) of 0.5% (wt./vol. of water) baking soda, plus 0.5% (vol./vol. of water) SunSpray UFP® horticultural oil almost completely inhibited PM on heavily infected pumpkin foliage. Baking soda without spray oil was ineffective, and a 2% (wt./vol. of water) solution of baking soda damaged the leaves. Baking soda/oil sprays also provided good control of urocladium leaf spot in cucumber, alternaria leaf blight in muskmelon, and gummy stem blight in muskmelon (5). Other diseases against which baking soda may prove effective include anthracnose in cucurbits (6); rust, dollar spot, and pythium blight in turf; late blight in potato; rust in wheat; and diseases affecting peanuts, banana, and alfalfa (7).
Small Leafs Bullet Researchers in Israel reported the successful use of baking soda and SunSpray oil in controlling PM on euonymus (8). In this research a 2% baking soda and 1% oil solution proved most effective (9).
Small Leafs Bullet On-farm observations on melon acreage in Virginia resulted in one farm operation switching from synthetic fungicides to a baking soda/oil spray. These growers incorporated a liquid fertilizer into the mix (10).
Small Leafs Bullet Research in Germany evaluated baking soda as a control for PM on `Bacchus' grapes. Three spray applications were made, beginning when symptoms first appeared. Good control was achieved with no loss of grape quality. The optimum concentration was a 1% solution (11).
Small Leafs Bullet An article in the February, 1996 issue of GrowerTalks magazine follows up on the continuing research at Cornell. Testing with a variety of bicarbonates revealed that selecting the correct bicarbonate for a particular disease is important. Dr. Horst's research team found that ammonium bicarbonate had the strongest effect on some diseases, while potassium and sodium bicarbonates worked best against others. Potassium bicarbonate provided the best control of PM. "Sodium bicarbonate is okay, but it's not as good," Horst is quoted as saying. "And ammonium bicarbonate doesn't do the job on powdery mildew." He points out that while conventional chemical controls for PM are preventatives only, bicarbonates can eliminate the disease after it has already appeared on certain crops—he mentions roses and an unspecified ornamental—provided the infection is not severe. The only plant damage associated with bicarbonates applied in the trials was foliar burning when application rates exceeded recommended concentrations. Testing established that sodium bicarbonate does not increase the levels of sodium in plant tissues, soil, or runoff water. While their precise mode of action against fungi is not understood, Horst states that bicarbonates seem to damage the cell wall membrane in PM spores. He also believes pH to be a factor in bicarbonate effectiveness. In any case, bicarbonates are contact fungicides, and kill PM within minutes (7).
Small Leafs Bullet EggplantThe Federal EPA ruled (as of December, 1996) that sodium and potassium bicarbonates are exempt from residue tolerances (12). This action served to facilitate the development and release of commercial bicarbonate products for horticultural use. It also lent weight to the belief that these materials are largely innocuous from a food safety perspective.
Small Leafs Bullet Connecticut researchers evaluated the effects of a spray solution containing 1% each of baking soda and horticultural oil on PM infection in zucchini, pumpkin, and cantaloupe. Four applications were made and disease suppression was definitely observed, accompanied by reduced insect pest damage. These researchers maintain that the treatment is preventative—not curative; that it is only necessary in years where early outbreaks may threaten yields; and that spraying should accompany proper nutrition and water management (13).
Small Leafs Bullet In 1998, Church & Dwight Co. (14)—the manufacturer of Arm & Hammer™ baking soda—received EPA registration for Armicarb 100®, a potassium bicarbonate formulation, for use against PM, downy mildew, botrytis, and alternaria leaf-spot (15). This product is the direct result of Dr. Horst's research at Cornell, which was funded by Church & Dwight. Armicarb 100 is now available from Helena Chemical Company (16). A similar product is sold under the name FirstStep® by the W.A. Cleary Chemical Co. (17).
Small Leafs Bullet The EPA and the California Department of Environmental Protection have provided registration to Monterey Chemical Co. (18) for a product called Kaligreen®. A potassium bicarbonate fungicide for PM control, it is cleared for use on grapes, cucumbers, tobacco, roses, strawberries, and a wide range of other crops (19, 20, 21). Directions for use include the addition of a sticker-spreader surfactant and a caution against use in acidic spray mixes. Since the product contains 30% potassium it is also touted for its fertilizer value (22). One source of Kaligreen® is Peaceful Valley Farm Supply (23).
Small Leafs Bullet Yet another potassium bicarbonate product, Remedy®, by Bonide™ (24), is now available from Gardener's Supply Co. (25). This formulation, which includes a surfactant oil, is labeled for use on ornamental, nut, and fruit trees, shrubs, and many vegetable plants. Said to control PM, black spot, leaf spot, anthracnose, phoma, phytophthora, scab, botrytis, and many other diseases, Remedy is particularly targeted toward rose growers (26).
Small Leafs Bullet Various carbonates and bicarbonates have been proven effective against gray mold, the number one post-harvest disease of grapes. Researchers found that carbonates were more effective than bicarbonates at reducing gray mold (Botrytis cinerea) spore germination, and that sodium and ammonium bicarbonates were better than potassium bicarbonate (27).
Small Leafs Bullet While industry was in the process of developing bicarbonate products for commercial and home horticulture, a number of recommendations for using kitchen-grade baking soda surfaced in print. These include:
  Small Leafs Bullet J. Howard Garrett—a well-known horticultural columnist and radio personality in the Dallas, Texas, area—recommends baking soda sprays at a concentration of 4 teaspoons per gallon of water for control of PM, blackspot, brown patch, and other fungal diseases. He also suggests that a light soil spray of baking soda solution can suppress fungus gnat problems, while cautioning that overuse should be avoided because of possible negative effects (sodium accumulation and alkaline pH) on the soil (28).
  Small Leafs Bullet The authors of an organic pest control handbook suggest the same concentration mixture as Garrett, but advise the addition of an equal quantity of liquid dish soap or insecticidal soap as a surfactant (29).
  Small Leafs Bullet The P. Allen Smith Gardens website advises mixing 1 heaping teaspoon of baking soda, 1 tablespoon of dormant oil, and ½ teaspoon of insecticidal or dish soap in one gallon of water as a PM spray. Stating that plants should be well hydrated prior to spraying, this source recommends irrigating a couple days in advance (30).

 

References:
1) Williams, Greg and Pat Williams. 1993. Baking soda vs. powdery mildew: Not a new idea! HortIdeas. June. p. 62.
2) Williams, Greg and Pat Williams. 1985. Baking soda for powdery mildew control. HortIdeas. September. p. 101-102.
3) Anon. 1990. Baking soda can ward off fungus. Greenhouse Manager. June. p. 24.
4) Ziv, O. and T. A. Zitter. 1992. Effects of bicarbonates and film-forming polymers on cucurbit foliar diseases. Plant Disease.
Vol. 26, No. 5. p. 513-517.
5) Williams, Greg and Pat Williams. 1992. More on baking soda/horticultural oil vs. fungal disease. HortIdeas. June. p. 69.
6) Hofstetter, Bob. 1993. Homemade pesticides. The New Farm. February. p. 14-16.
7) Moore, Sallyann Roberts. 1996. Bicarbonates offer effective disease control. Grower Talks. February. p. 72.
8) Ziv, O. and A. Hagiladi. 1993. Controlling powdery mildew in euonymus with polymer coatings and bicarbonate solutions. HortScience.
Vol. 28, No. 2. p. 124-126.
9) Williams, Greg and Pat Williams. 1993. Baking soda and horticultural oil vs. powdery mildew. HortIdeas. May. p. 51.
10) Byczynski, Lynn. 1995. New ideas for a new year. Growing for Market. January. p. 1, 4-5.
11) Williams, Greg and Pat Williams. 1997. Sodium bicarbonate for control of mildew on grapes. HortIdeas. June. p. 70.
12) Otten, Paul. 1997. Can kitchen products control powdery mildew? Northland Berry News. Fall. p. 20.
13) Elmer, Wade H. and Frank J. Farandino. 1997. Managing powdery mildew of cucurbits. The Natural Farmer. Summer. p. 26-27.
14) Church & Dwight Co., Inc.
469 N. Harrison St.
Princeton, NJ 08543-5297
609-683-5900
800-221-0453
15) Anon. 1998. EPA approves reduced-risk fungicide. The Grower. December. p. 8.
16) Helena Chemical Co.
225 Schilling Blvd. Suite 110
Collierville, TN 38017
901 537-7280
http://www.helenachemical.com/sales.html
Armicarb® is available in 5 and 25 lb. bags, for about $5/lb. Call the number above or visit the website to locate the Helena Chemical dealer nearest you.
17) W. A. Cleary Chemical Co.
1049 Corporate Rt. 27
Somerset, NJ 08875
800-524-1662
FirstStep® is available in 5 lb. bags and 20 lb. cases. Call the number above for price information.
18) Monterey Chemical Co.
P. O. Box 35000
Fresno, CA 93745-5000
559-499-2100
http://www.montereychemical.com
Kaligreen is available in 5lb. and 10lb. bags. Prices vary from dealer to dealer.
19) Anon. 1998. Powdery mildew fungicide. The Grower. March. p. 6.
20) Anon. 1999. EPA expands Kaligreen label. The Grower. August. p. 10.
21) Anon. 2000. Label Changes (Kaligreen) American Vegetable Grower. March. p. 14.
22) Anon. 1998. Peaceful Valley Farm Supply 1998-1999 Main Catalog. Peaceful Valley Farm Supply. Grass Valley, CA. p. 92.
23) Peaceful Valley Farm Supply
P. O. Box 2209
Grass Valley, CA 95945
530-272-4769
888-784-1722
http://www.groworganic.com
24) Bonide Products, Inc.
Oriskany, NY 13424
315-736-8231
25) Gardener's Supply Co.
128 Intervale Rd.
Burlington, VT 05401-2850
800-863-1700
http://www.gardeners.com
e-mail: info@gardeners.com
26) Anon. 1998. Fungus remedy. B.U.G.S. Flyer. Vol. 12, No. 1. p. 5.
27) Anon. 1999. Baking soda and gray mold. Conference notes: ESA and APS joint meeting. IPM Practitioner. April. p. 10-11.
28) Garrett, J. Howard. 1989. J. Howard Garrett's Organic Manual. Lantana Publishing Co. Dallas, TX. 104 p.
29) Ellis, Barbara W. and Fern Marshall Bradley. 1992. The Organic Gardener's Handbook of Natural Insect and Disease Control. Rodale Press. Emmaus, PA. 534 p.
30) Anon. 1997. Garden lore—Baking soda solution. P. Allen Smith Gardens. Hortus Ltd.
http://www.pallensmith.com/features/highlights/h1709c.htm.

 

By George Kuepper, Raeven Thomas, and Richard Earles
NCAT Agriculture Specialists
November 2001

ATTRA is the national sustainable agriculture information service operated by the National Center for Appropriate Technology under a grant from the Rural Business-Cooperative Service, U.S. Department of Agriculture. These organizations do not recommend or endorse products, companies, or individuals. NCAT has offices in Fayetteville, Arkansas (P.O. Box 3657, Fayetteville, AR 72702), Butte, Montana, and Davis, California.

 

 

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APPROACH

Harmon Distributing Systems uses Soda or Sand to remove most coatings from almost any surface. The equipment & media is combined for a wide use of applications to remove paint, rust, dirt, carbon, oil and grease from steel, stainless steel, aluminum, galvanized metal, concrete, glass and more.....

SODA BLASTING
SANDBLASTING

Cob blasting

What is it?
Uses

Why It Works
Examples

Advantages

Examples

SODA BLASTING EXAMPLES

WHAT IS SODA BLASTING?
It is a process where a surface is cleaned or paint is removed or coatings of any kind are stripped from a substrate. It is very similar to traditional sand blasting yet has the significant advantage of cleaning the surface without causing any harm to the substrate or the environment.

APPLICATIONS

From the removal of graffiti from brick and concrete to the cleaning of boat bottoms, from the removal of carbon, char, and odors from buildings damaged by fire to refurbishing stainless steel kitchen equipment, from removing oil and grease from engines to removing offensive odors in stairwells, from cleaning washrooms in manufacturing facilities to removing paint from brick and steel, from removing rust and paint from cars to the line removal off highways, this approach has proved to be successful time and time again. The system has been used for:

Paint Removal
Engine Parts
Brick & Concrete
Hard Wood
Odor Elimination
Cleaning Boats
Anilox Rolls
Fiberglass
Rust Removal
Cars-Paint/Rust
Airplane Parts
Stain Removal
Graffiti Removal
Fire Restoration
Conveyor Systems
And More!

WHY THIS APPROACH

Equipment is easy to use
Equipment is transportable, in many cases a one-man operation
Short set-up time
Media is environmentally sensible (USDA Approved as an A1 cleaner)
Media is water soluble, gentle yet effective
Safer than solvents, caustics and acids
Media is an odor-eater
Clean up is relatively easy


WHY IT WORKS...

The cleaning effectiveness of blast soda is a direct result of its physical properties. These qualities allow the media to be used in a wide variety of applications.

The magic of baking soda is due to: Granulation resulting in consistent sizing of the cleaning media
Shape is multi sided leads to an improved cleaning capability
Hardness is such that it will not damage delicate substrates
Friability (easily crumbled) enhances the cleaning process
pH of media (8.2) greatly reduces any
caustic effect


These properties provide the cleaning power of media:
1. High friability with consistent angular fractures results in smaller, uniformly angular cleaning particles. This feature ensures that all surfaces of a part can be cleaned effectively.

2. media is very soft (2.4 on Mohs Scale of Hardness) and is a friable cleaning agent. This means that blasting with soda is like throwing a snowball at a fence whereas other less friable media (plastic at 3.5 and glass at 5.0 on Mohs Hardness Scale) is like throwing a stone at a fence.

3. media imparts a cleaning effect where other abrasives use a hit and cut method to clean or chop away the coating.

4. soda crystals begin at less than 70 microns. At impact the crystal crumbles and gently imparts the energy into a cleaning mass. Much of this energy is transferred perpendicular to the angle of the blast across the entire structure. The result is a clean surface.

5. Easily remove carbon, grease, oils, gasket material, surface corrosion, paint and coatings from a variety of alloys, plastics and composites without substrate damage or distortion, even leaves hard anodized coatings intact.

6. Reduce cycle time by cleaning, de-greasing, de-painting in one step. Unlike glass beads or plastic media, soda requires no pre-wash and its water solubility allows for complete rinsing, eliminating the risk of spent media lodging in tight spaces or critical passageways.

ADVANTAGES...

Cleaning & De-Coating in One Step
Standard abrasive blasting is a dirty process, often loading and even embedding the surface with contaminants (grease, oil, tar & abrasive particles) in the process of removing the coating. Recycled abrasives compound this problem by loading increasing amounts of contaminants into the substrate. Soda blast media's effectively de-coats and cleans the substrate in one step; producing a level of surface cleanliness not seen with most processes. The media is not reusable thus eliminating the issue of blasting with re-used media. Coating adhesion relies heavily on surface cleanliness and a surface profile has been used to offset this lack of cleanliness.

Unique Cutting Action
Soda blast media offers the unique properties of sodium bicarbonate, the primary ingredient. The softness (Mohs Hardness = 2.4) and friable nature of this crystal produces a unique cutting action with little or no effort on most substrates. For example, thick coatings can be removed from glass without any etching effect. With proper care, delicate substrates can be cleaned without damage.

No Pre-Cleaning Required
For projects where the coating is covered with grease, carbon, salt or other contaminants, the more traditional blasting methods require the coating to be fully cleaned before blasting. This is required so that the contaminants on the surface of the coating not be driven through the coating and into the surface of the substrate, causing future coating failure.

No Need To Re-Profile Steel
Standard grades of soda media (without any hard aggregates) do not profile steel. soda have a Profile grade of baking soda that imparts a profile on steel. When an operator removes a coating from a metal surface, he or she exposes the existing anchor pattern under the coating. Unless corrosion has occurred, there is no reason to re-profile the surface.

Reduced Solid Waste
soda blast media can be dissolved in fresh water. By dissolving the media and filtering out the contaminants the solution can generally be discharged to POTW treatment systems or open waterways, with proper discharge permits. Waste volume is generally reduced to less than 5% of the original waste volume. With increasing landfill costs and liabilities, this advantage becomes more important every day.

Natural Rust Inhibitor
As long as soda is on a ferrous metal surface, rust will not form. For rust to form, free moisture and an acidic condition must exist. In most cases, free moisture combines with carbon dioxide in the atmosphere to form carbonic acid. This acid releases a free metal (ferrous) ion which combines with oxygen (oxidizes) to form rust. soda buffers acids, prevents the release of free metal ions and prevents rust.

Reduced Clean-Up Costs
soda blast media performs roughly the same level of work (somewhat slower) as sand blasting while producing 1/5 to 1/7 of the total waste volume. Although media costs per square foot are higher, site clean-up and residue disposal are significantly lower. The net balance id that total cost per square foot are about the same for both approaches.

Benefits In Waste Disposal
In most non-hazardous applications, the residue from blasting with soda can be rinsed into sanitary drains or sewers which flush the residue to a water treatment facility, greatly reducing the clean-up time. Sodium bicarbonate is actually beneficial to waste water treatment systems.
For industrial treatment systems, where chemical neutralization is a major cost in water treatment, soda blast media can often save significant dollars in waste treatment.

Increased Worker Safety
The safety of sodium bicarbonate to workers is well understood, since it has been in use for some 160 years. The bicarbonate buffer system is the major extracellular buffer in the human body, thus sodium bicarbonate is part of the body's normal chemistry.
Sodium bicarbonate and thus, soda is not toxic via ingestion, inhalation or dermal contact, nor is it a skin or eye irritant as defined by EPA and OSHA. Any risk to workers is primarily the containment or coating removed during the blasting operation. Removes Odors
The same odor absorbing effect seen in the refrigerator at home is present when blasting with soda media. It not only removes the contaminants, it also reduces the unfriendly odors.

Replaces Dangerous Solvents
soda formula is an excellent de-greasing media that eliminates the uses of solvents in most cleaning processes. Hydroflex does not "dissolve" or "emulsify" grease and oils, it simply coats them causing the grease or oil to release from the surface. It also eliminates the translocation of oil and grease.

Does Not Produce Sparks
Standard grades of soda blast media (without hard aggregate) will not produce thermal sparks and are suitable for use in explosion proof areas; including refineries, chemical plants and grain elevators as long as proper grounding techniques are used to prevent a static charge build up.

Improved Crack Detection
When cleaning metal surfaces for crack detection, standard abrasive blasting tends to peen the crack closed or pack the crack with abrasive, making crack detection more difficult. soda media actually cleans out the crack, leaving it exposed and easy to find.

No Residue Problems In Small Passageways
Standard grades of soda blast media (without hard aggregate) are 100% water soluble. They can be used to clean critical engine components including those with small passageways. Once cleaned, the soda residue can be thoroughly rinsed off by dissolving in water.
Traditional blast media are not water soluble and if left after cleaning, can pack into small passageways and possibly damage an engine while on operation.

Reduce Surface Acids
As a strong buffer for acids and alkalis, soda eliminates acidic conditions on the surface of the substrate. For conditions with high acid levels, acid rain or boiler fly ash, blasting with soda will reduce coating failures.

SSPC-NACE Standards
soda will attain a level of clean that will meet the standards of both NACE and SSPC.

NACE 1 (SP-5) White Metal Blast Cleaning
NACE 2 (SP-10) Near-White Blast Cleaning
NACE 3 (SP-6) Commercial Blast Cleaning
NACE 4 (SP-7) Brush-Off Blast Cleaning

Hardness Scale
soda has a hardness of 2.4 on Mohs' scale of Hardness. The softness of this media means that it can be used to remove most materials without harming the substrate.

Benefits Of Process

Environmentally Sensible
Non-Hazardous to Workers
Non-Toxic Media
Water Soluble Media
Low Blasting Pressure
Does Not Generate Explosive Dust
Does Not Pose A Threat Of Silicosis

Where Used

Industrial Maintenance
Chemical & Petro-Chemical
Oil & Gas Production
Pulp & Paper
Food & Beverage Processing
Textile Mills
Foundries & Steel Production
Printing Industry
Electrical Utilities
Mining
Aviation, Military & Commercial
OEM's, Automotive, Electronic
Marine
Transportation, Transit, Highway.