Use of Baking Soda as a Fungicide

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Use of Baking Soda as a Fungicide

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Use of Baking Soda as a Fungicide

  1. 1. USE OF BAKING SODA AS A FUNGICIDE HORTICULTURE TECHNICAL NOTE 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.By George Kuepper, Raeven Thomas, soda as a fungicide for roses. Cornelland Richard Earles University researcher Dr. R. Kenneth HorstNCAT Agriculture Specialists observed suppression of PM and blackspot—November 2001 both major problems for New York rose growers. Roses were sprayed every 3 to 4• The use of baking soda as a fungicide is not days with a water solution of baking soda anda new idea. In Alfred C. Hottes’ A Little Book insecticidal soap. The latter was included forof Climbing Plants, published in 1933 by the its surfactant qualities. (Surfactants areA.T. De La Mare Co. of New York, mention is chemical agents that alter the surfacemade of using one ounce of baking soda per properties of a liquid.) The soap improved thegallon of water to control powdery mildew effectiveness of the bicarbonate by making it(PM) on climbing roses. The author credits stick to, and spread evenly over, the leafthe idea to a Russian plant pathologist, A. de surface. Further experimentation proved thatYaczenski (1). the insecticidal soap itself was not responsible for suppressing the diseases. While no specific• In the August, 1985 issue of Organic concentration of baking soda is indicated asGardening magazine, a short article by being most effective in PM suppression, theWarren Shultz entitled “Recipe for Resis- article states that a 0.5% solution was mosttance” reports that researchers in Japan effective in preventing blackspot (3).obtained effective control of PM oncucumbers, eggplants, and strawberries. • Some of the work at Cornell has focused onThey suggested weekly sprays of ¼ ounce controlling fungal diseases on cucurbits (4). Abaking soda per gallon of water (2). single spray application (to runoff) of 0.5% (wt./vol. of water) baking soda, plus 0.5%• An article in the June, 1990 issue of (vol./vol. of water) SunSpray UFP®Greenhouse Manager magazine summarizes horticultural oil almost completely inhibitedthe results of three years of testing baking 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 © 2002- www.arttoday.com effective include anthracnose in cucurbits (6);ATTRA is the national sustainable agriculture information center operated by the National Center for AppropriateTechnology under a grant from the Rural Business-Cooperative Service, U.S. Department of Agriculture. Theseorganizations do not recommend or endorse products, companies, or individuals. ATTRA is located in theOzark Mountains at the University of Arkansas in Fayetteville (P.O. Box 3657, Fayetteville, AR 72702). ATTRAstaff members prefer to receive requests for information about sustainable agriculture via the toll-free number800-346-9140.
  2. 2. rust, dollar spot, and pythium blight in turf; provided the infection is not severe. The onlylate blight in potato; rust in wheat; and plant damage associated with bicarbonatesdiseases affecting peanuts, banana, and applied in the trials was foliar burning whenalfalfa (7). application rates exceeded recommended concentrations. Testing established that• Researchers in Israel reported the sodium bicarbonate does not increase thesuccessful use of baking soda and SunSpray levels of sodium in plant tissues, soil, or runoffoil in controlling PM on euonymus (8). In this water. While their precise mode of actionresearch a 2% baking soda and 1% oil solution against fungi is not understood, Horst statesproved most effective (9). that bicarbonates seem to damage the cell wall membrane in PM spores. He also• On-farm observations on melon acreage in believes pH to be a factor in bicarbonateVirginia resulted in one farm operation effectiveness. In any case, bicarbonates areswitching from synthetic fungicides to a contact fungicides, and kill PM withinbaking soda/oil spray. These growers incor- minutes (7).porated a liquid fertilizer into the mix (10). • The Federal EPA ruled (as of December,• Research in Germany evaluated baking 1996) that sodium and potassiumsoda as a control for PM on ‘Bacchus’ grapes. bicarbonates are exempt from residueThree spray applications were made, tolerances (12). This action served tobeginning when symptoms first appeared. facilitate the development and release ofGood control was achieved with no loss of commercial bicarbonate products forgrape quality. The optimum concentration horticultural use. It also lent weight to thewas a 1% solution (11). belief that these materials are largely innocuous from a food safety perspective.• An article in the February, 1996 issue ofGrowerTalks magazine follows up on the • Connecticut researchers evaluated thecontinuing research at Cornell. Testing with a effects of a spray solution containing 1% eachvariety of bicarbonates revealed that selecting of baking soda and horticultural oil on PMthe correct bicarbonate for a particular disease infection in zucchini, pumpkin, andis important. Dr. Horst’s research team found cantaloupe. Four applications were madethat ammonium bicarbonate had the strongest and disease suppression was definitelyeffect on some diseases, while potassium and observed, accompanied by reduced insect pestsodium bicarbonates worked best against damage. These researchers maintain that theothers. Potassium bicarbonate provided the treatment is preventative—not curative; that itbest control of PM. “Sodium bicarbonate is is only necessary in years where earlyokay, but it’s not as good,” Horst is quoted as outbreaks may threaten yields; and thatsaying. “And ammonium bicarbonate doesn’t spraying should accompany proper nutritiondo the job on powdery mildew.” He points and water management (13). out that while conventional • In 1998, Church & Dwight Co. (14)—the chemical controls manufacturer of Arm & Hammer™ baking for PM are soda—received EPA registration for Armicarb preventatives only, 100®, a potassium bicarbonate formulation, bicarbonates can for use against PM, downy mildew, botrytis, eliminate the and alternaria leaf-spot (15). This product is disease after it has the direct result of Dr. Horst’s research at already appeared Cornell, which was funded by Church & on certain crops— Dwight. Armicarb 100 is now available from he mentions roses Helena Chemical Company (16). A similar and an unspecified product is sold under the name FirstStep® by ornamental— the W.A. Cleary Chemical Co. (17).PAGE 2 //USE OF BAKING SODA AS A FUNGICIDE
  3. 3. • The EPA and the California Department of problems, while cautioning thatEnvironmental Protection have provided overuse should be avoided because ofregistration to Monterey Chemical Co. (18) for possible negative effects (sodiuma product called Kaligreen®. A potassium accumulation and alkaline pH) on thebicarbonate fungicide for PM control, it is soil (28).cleared for use on grapes, cucumbers, tobacco,roses, strawberries, and a wide range of other ! The authors of an organic pest controlcrops (19, 20, 21). Directions for use include handbook suggest the samethe addition of a sticker-spreader surfactant concentration mixture as Garrett, butand a caution against use in acidic spray advise the addition of an equalmixes. Since the product contains 30% quantity of liquid dish soap orpotassium it is also touted for its fertilizer insecticidal soap as a surfactant (29).value (22). One source of Kaligreen® isPeaceful Valley Farm Supply (23). ! The P. Allen Smith Gardens website advises mixing 1 heaping teaspoon of• Yet another potassium bicarbonate baking soda, 1 tablespoon of dormantproduct, Remedy®, by Bonide™ (24), is now oil, and ½ teaspoon of insecticidal oravailable from Gardener’s Supply Co. (25). dish soap in one gallon of water as aThis formulation, which includes a surfactant PM spray. Stating that plants shouldoil, is labeled for use on ornamental, nut, and be well hydrated prior to spraying, thisfruit trees, shrubs, and many vegetable plants. source recommends irrigating a coupleSaid to control PM, black spot, leaf spot, days in advance (30).anthracnose, phoma, phytophthora, scab,botrytis, and many other diseases, Remedy is References:particularly targeted toward rose growers 1) Williams, Greg and Pat Williams. 1993.(26). Baking soda vs. powdery mildew: Not a new idea! HortIdeas. June. p. 62.• Various carbonates and bicarbonates havebeen proven effective against gray mold, the 2) Williams, Greg and Pat Williams. 1985.number one post-harvest disease of grapes. Baking soda for powdery mildew control.Researchers found that carbonates were more HortIdeas. September. p. 101–102.effective than bicarbonates at reducing graymold (Botrytis cinerea) spore germination, and 3) Anon. 1990. Baking soda can ward off fungus. Greenhouse Manager. June. p. 24.that sodium and ammonium bicarbonateswere better than potassium bicarbonate (27). 4) Ziv, O. and T. A. Zitter. 1992. Effects of bicarbonates and film-forming polymers on• While industry was in the process of cucurbit foliar diseases. Plant Disease.developing bicarbonate products for Vol. 26, No. 5. p. 513–517.commercial and home horticulture, a numberof recommendations for using kitchen-grade 5) Williams, Greg and Pat Williams. 1992. More on baking soda/horticultural oil vs.baking soda surfaced in print. These include: fungal disease. HortIdeas. June. p. 69. ! J. Howard Garrett—a well-known 6) Hofstetter, Bob. 1993. Homemade pesti- horticultural columnist and radio cides. The New Farm. February. p. 14–16. personality in the Dallas, Texas, area— recommends baking soda sprays at a 7) Moore, Sallyann Roberts. 1996. concentration of 4 teaspoons per Bicarbonates offer effective disease control. Grower Talks. February. p. 72. gallon of water for control of PM, blackspot, brown patch, and other 8) Ziv, O. and A. Hagiladi. 1993. Controlling fungal diseases. He also suggests that powdery mildew in euonymus with polymer a light soil spray of baking soda coatings and bicarbonate solutions. solution can suppress fungus gnat HortScience. Vol. 28, No. 2. p. 124–126. //USE OF BAKING SODA AS A FUNGICIDE PAGE 3
  4. 4. 9) Williams, Greg and Pat Williams. 1993. 20) Anon. 1999. EPA expands Kaligreen label. Baking soda and horticultural oil vs. The Grower. August. p. 10. powdery mildew. HortIdeas. May. p. 51. 21) Anon. 2000. Label Changes (Kaligreen)10) Byczynski, Lynn. 1995. New ideas for a American Vegetable Grower. March. p. 14. new year. Growing for Market. January. p. 1, 4–5. 22) Anon. 1998. Peaceful Valley Farm Supply 1998–1999 Main Catalog. Peaceful Valley11) Williams, Greg and Pat Williams. 1997. Farm Supply. Grass Valley, CA. p. 92. Sodium bicarbonate for control of mildew on grapes. HortIdeas. June. p. 70. 23) Peaceful Valley Farm Supply P. O. Box 220912) Otten, Paul. 1997. Can kitchen products Grass Valley, CA 95945 control powdery mildew? Northland Berry 530-272-4769 News. Fall. p. 20. 888-784-1722 http://www.groworganic.com13) Elmer, Wade H. and Frank J. Farandino. 1997. Managing powdery mildew of 24) Bonide Products, Inc. cucurbits. The Natural Farmer. Summer. Oriskany, NY 13424 p. 26–27. 315-736-823114) Church & Dwight Co., Inc. 25) Gardener’s Supply Co. 469 N. Harrison St. 128 Intervale Rd. Princeton, NJ 08543-5297 Burlington, VT 05401-2850 609-683-5900 800-863-1700 800-221-0453 http://www.gardeners.com e-mail: info@gardeners.com15) Anon. 1998. EPA approves reduced-risk fungicide. The Grower. December. p. 8. 26) Anon. 1998. Fungus remedy. B.U.G.S. Flyer. Vol. 12, No. 1. p. 5.16) Helena Chemical Co. 225 Schilling Blvd. Suite 110 27) Anon. 1999. Baking soda and gray mold. Collierville, TN 38017 Conference notes: ESA and APS joint 901 537-7280 meeting. IPM Practitioner. April. p. 10–11. http://www.helenachemical.com/sales.html Armicarb® is available in 5 and 25 lb. bags, 28) Garrett, J. Howard. 1989. J. Howard for about $5/lb. Call the number above or Garrett’s Organic Manual. Lantana visit the website to locate the Helena Chemical Publishing Co. Dallas, TX. 104 p. dealer nearest you. 29) Ellis, Barbara W. and Fern Marshall Bradley.17) W. A. Cleary Chemical Co. 1992. The Organic Gardener’s Handbook of 1049 Corporate Rt. 27 Natural Insect and Disease Control. Rodale Somerset, NJ 08875 Press. Emmaus, PA. 534 p. 800-524-1662 FirstStep® is available in 5 lb. bags and 20 30) Anon. 1997. Garden lore—Baking soda lb. cases. Call the number above for price solution. P. Allen Smith Gardens. Hortus information. Ltd. <http://www.pallensmith.com/ features/highlights/h1709c.htm>.18) Monterey Chemical Co. P. O. Box 35000 Fresno, CA 93745-5000 IP130 559-499-2100 The electronic version of Use of Baking Soda as a http://www.montereychemical.com Fungicide is located at: Kaligreen is available in 5lb. and 10lb. bags. HTML Prices vary from dealer to dealer. http://www.attra.org/attra-pub/bakingsoda.html19) Anon. 1998. Powdery mildew fungicide. PDF The Grower. March. p. 6. http://www.attra.org/attra-pub/PDF/bakingsoda.pdfPAGE 4 //USE OF BAKING SODA AS A FUNGICIDE

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