Cornmeal myth busted

As my colleague Fred Hoffman says, the horticultural silly season is upon us. This week I heard from one of our European readers, questioning the use of cornmeal as a fungicide. He referenced an online article entitled “Cornmeal has powerful fungicidal properties in the garden.” He hadn’t been able to find any reliable information and thought it might make a good topic for our blog. So Johannes, this rant’s for you!

If you’ve followed the link to column in question, you’ll see that the original “research” is attributed to one of Texas A&M’s research stations in Stephenville, TX. But it’s not really research – it’s just an observation on what happens when you don’t plant the same crop two years in a row; in this case, rotating corn and peanuts reduces peanut pathogens. This is hardly news – it’s one of the reasons agricultural scientists recommend crop rotation as part of an IPM program. And have for decades.

Then we’re referred to “further research” (at an undisclosed location) where cornmeal was shown to contain “beneficial organisms.” Well, no, cornmeal doesn’t contain organisms, beneficial or otherwise. Microbes can grow on cornmeal, and in fact cornmeal agar is commonly used in labs as a growth medium for many species of fungi. And has been for decades.

Nevertheless, we’re informed that a gardening personality has “continued the study and finds cornmeal effective on most everything from turf grass to black spot on roses.” This is directly refuted by Dr. Jerry Parsons, who by happy coincidence is an extension faculty specialist at Texas A&M. His informative (and hilarious) column on brown spots in lawns states “Lately there have been claims made that corn meal and a garlic extract is effective. This is absolutely false! Everyone trying to do the “environmentally friendly-to-a-fault” thing have been wasting their money. They would have been better off making corn bread and using their garlic for cooking purposes!”

Dr. Parsons continues: “Let me explain how these University tests and recommendations have been misrepresented in a desperate attempt to find an organic fungicide. The corn meal was investigated by a Texas A&M pathologist as a way to produce parasitic fungi used to control a fungus which occurs on peanuts.” (This directly relates to my earlier point that cornmeal agar has a long history of use in fungal culture.)

It boils down to this: if you have a healthy soil, it will probably contain diverse populations of beneficial microbes, including those that control pathogenic fungi. You don’t need to add cornmeal – it’s simply an expensive form of organic material.  So you can ignore the directions in the article on how to incorporate cornmeal into the soil, or make “cornmeal juice” to spray on “susceptible plants.”   Just nurture your soil with (repeat after me) a thick layer of coarse organic mulch.

(As a footnote, let me say how annoying it is when gardening personalities grant themselves advanced degrees or certifications in their titles.  C’mon folks – if your information is so great, do you really need to pretend you’re someone else?)

(Another footnote: I discussed this myth more in 2012. Be sure to check this link out too.)

112 thoughts on “Cornmeal myth busted”

  1. So I followed the link to the article. The article is attributed to one Marie Iannotti. If you follow the link to her bio you are presented with this “Marie is the former owner of Yore Vegetables, an heirloom seedling nursery. She is a longtime master gardener and a former Cornell Cooperative Extension Horticulture Educator, Master Gardener program coordinator, and a member of the Garden Writer’s Association and The Garden Conservancy.”

    She certainly seems like she has the credentials. Perhaps you should pass your information along to her. It would be interesting to see if she withdraws the article from

    1. Hello,
      I wasn’t aware of the anti-fungal property claims of cornmeal but how do you feel about it being an amendment as a slow release nitrogen source? As far as I know all these seed grains are proteins so therefore a part of the nitrogen cycle. Any thoughts on that?

  2. Tim, that’s not a bad idea. I hadn’t looked over her bio at all, and certainly if she is a Master Gardener she should be using science-based information for her column. I’ll do it!

  3. Thank you! I very much appreciate that you have taken up this topic. After not finding any reliable info I had been very curious to hear if there’s a scientific basis to the many claims that cornmeal is “a great, all natural fungicide”.

  4. We would love an opportunity like this for our Southside Grounds Maintenance Conference that is held every January here in our community. We don’t have a big budget but want to educate our community as much as possible!!

  5. Linda, I found your remarks above interesting. Some years ago I stumbled onto a report by UGA in relation to its studies on peanuts/fungus problems. Quote…”Cornmeal encourages Trichoderma which feed on mycelium and sclerotia of Sclerotina minor, Scleratina rolfsii and all Rhizoctina species”. This has led me to experimenting with cornmeal. My trials and errors are too lengthy to post here, however, many have followed my thoughts and tried cornmeal on Brown Patch with success. It is also successful, used in generous amounts, to control difficult Southern Blight. I have not found cornmeal tea to be an effective control for tomato fungi or black spot on roses. Yet, there are some who swear it works. I discovered that cornmeal spread under Gardenias early in the spring prevents the ‘yellowing’ leaf problem so common to that shrub. I have no idea why! Suggest that some of your students research cornmeal and its possible uses in the organic garden. Perhaps someone might want to begin with spreading cornmeal on newly emerging hollyhock foliage in the spring, repeat treating on the soil once a week throughout the growing season to prevent the common rust problem. More cornmeal research needed before we allow the ‘publish or perish’ guys to scoff at those of us who have found it to be effective in certain garden situations.

  6. @Nandina, while I appreciate you may have had success with cornmeal, the fact remains that it does not have repeatable, reliable efficacy (as demonstrated in the scientific literature). That’s the only criterion we Garden Professors can use to guide recommendations on any practice or product. As with compost tea or any other untested material, it is up proponents to demonstrate, conclusively, that it works. It’s not up to skeptics to demonstrate the opposite.

    I’m not familiar with any UGA study (which as far as I can tell hasn’t been published – and I’ve been through that literature exhaustively). When I take your quote above and search in Google, the only place it appears is in gardening forum web pages. Did you obtain the quote from a published paper, and if so, can you give me the reference? What is in the literature is the usage of cornmeal agar as a growth medium for Trichoderma in the lab. One paper grew Trichoderma in soil amended with cornmeal “as a nutrient source.” It’s pretty clear that cornmeal will enhance Trichoderma populations in the lab.

    It’s dangerous taking lab results and applying them to field situations. Dr. Jerry Parson’s article above also comments on extrapolating petri dish science to the field: “He [Dr. Larry Barnes of Texas A&M] indicated that the petri dish test is only an indicator of what might work in the soil and the petri dish test alone SHOULD NEVER BE USED as a positive indicator of effectiveness of a product. Do you wonder why further testing in field conditions have not been performed? Because the product distributors do not want to take the chance of failure. So if you want to waste money on a “snake-oil” product that hasn’t ever been statistically shown to be effective in field conditions just for the sake of organics, step up to the counter-they will be more than glad to take your money!”

  7. The “loam physician-types” have been promoting this stuff in Texas (even to control foot fungus and pond algae).

    Corn meal is a common ingredient in many medias used to culture plant pathogenic fungi and water molds. Furthermore it is a nitrogen source (which can increase plant quality scores in any experiment compared to an unfertilized control).

    Keep up the good work Linda!

  8. Thanks for the laughs Linda! I so appreciate the rant you give for the myths that is so commonly spread around the use of cornmeal as a fungicide! Tim and Linda please follow the link in the article by Marie Annotti to find the originator of the idea of using cornmeal as a fungicide in organic circles. I knew who you were referring to before I even followed the link to the article which is the reason for the laughs. I used to live in Texas and about 15-18 years ago met the good “DirtDoctor” and had even discovered he and I are alums of the same University, which according to Tim on the June 30th posting, so is the author of the article, Marie Annotti. I agree with you though. Further investigation and experimentation using cornmeal needs to be conducted to settle the cornmeal as a fungicide controversy. So far in 30 years working in Horticulture, every article that espouses the use of cornmeal as a fungicide links back to the same person. As of yet I don’t know of any other scientific documentation or experimentation that shows positive results using cornmeal as a fungicide. Until then the question will remain : “is Cornmeal as a herbicide a myth or fact?” Cheers!

  9. “is up proponents to demonstrate, conclusively, that it works. It’s not up to skeptics to demonstrate the opposite.”

    Actually, the scientific method is based on repeatability. If some scientist thinks they have demonstrated something, it is not their job to prove they are correct. It is the job of other perhap skeptical scientists to repeat the work in a rigorous controlled manner in order to disprove the hypothesis.

  10. For someone to strongly argue against something they have not tested and disproved is as ridiculous as someone making a claim for something they have not tested and proven. Since you have zero experience at actually testing this, Linda, your words are meaningless, without experience, hearsay. Do an actual test and report back.
    I am fed up with “experts” who spout strong opinions about something they never validated. I don’t object to your arrogant untested (by you) ranting, but you would have a lot more credibility if you started the rant with, “ I just completed a test which shows…” (And believe me this is an easy test to conduct.) Until you do, that your words are your personal opinion.
    I have no skin in this game; I just ran across your rant when I was doing agricultural research. I showed other researchers and we had a big laugh at your rant. Thanks for giving us a chuckle.

  11. Sorry, Bob, that’s the classic pseudoscience argument (which I’ve mentioned before in this blog but will repeat for your benefit). “In science, the burden of proof rests on those making a claim, not on the critic. “Pseudoscientific” arguments may neglect this principle and demand that skeptics demonstrate beyond a reasonable doubt that a claim (e.g. an assertion regarding the efficacy of a novel therapeutic technique) is false. It is essentially impossible to prove a universal negative, so this tactic incorrectly places the burden of proof on the skeptic rather than the claimant.” (see
    I’m surprised, Bob, that as a “researcher” you don’t know this.

    1. Linda,

      Your name in Spanish means beautiful, but your rants aren’t exactly that. There are many who swear by the cornmeal for brown spot- but, depending if the soil had been treated with something else previously (like a commercial fungicide) then it may not work.
      All inventions/discoveries are first ridiculed. Remember, people used to think the earth was flat? How about people used to take mercury & kids played with it in school. That was before ‘science’ figured out it was dangerous. One would think that there are many different factors which contribute to the success or failures of certain remedies. Often pride comes before the fall.

      1. I used to play with mercury when I was a kid! It’s pretty cool how it clings to itself. Hmmm….maybe that’s what’s wrong with me. LOL

        1. Linda I’m pretty sure something is wrong with you! You seem to cling where you think the moneys at! I’d watch her boys she’s crazy about the mercury! Lol.

    2. You use the words but do not follow their meaning in your own work. Note that you as well are making a claim here. Your claim is that their anecdotal evidence is false. As such you move the burden of proof that you argue for from those with anecdotal evidence to yourself. Anecdotal evidence is one of the weakest forms of evidence, but it is more then nothing. Once you provide experimental validation that your theory is better then theirs you gain the upper hand.

      THAT is how science is done. It isn’t just bickering back and forth pretending that one has more moral authority because they claim the right to do so. Science is about observation, and the logical organization of it into something useful.

      1. Unfortunately, you are incorrect in your statement that anecdotal evidence is “more than nothing.” For anecdotal evidence to be considered at all credible, the methodology by which it was gathered must be generally accepted among scientists. A methodology that consists of “I put corn meal on my lawn and it killed the fungal disease” would not qualify as an acceptable methodology. At best, an anecdote might suggest a new hypotheses, but it is never used as validating evidence. And on a more practical note: if this truly was a consistent, effective fungicide, don’t you think the organic companies would already be selling it as such?

  12. How can Scleratinia be prevented in my petunias?

    Is Scleratinia carried in potting containers or only in soil (potting or garden soil)?

    Last year I purchased petunia plugs from a local nursery and I lost quite a few from Scleratinia ….


  13. Janice, Sclerotinia is exacerbated under wet, heavy soil conditions. The spores can be anywhere – in the plugs, in your garden soil, etc. The best solution is to plant something else there for a while that isn’t susceptible. And try to decrease both the irrigation and fertilizer applications.

  14. For several years, tests have been conducted in Texas using corn meal to stimulate Trichoderma development as a way to control the major soil-borne disease fungi. When yellow corn meal is applied to fields in the presence of moist surface soil, Trichoderma builds up very rapidly over 5 to 10 days. The resulting high Trichoderma population can destroy vast amounts of Sclerotinia, Sclerotium and Rhizoctonia.

  15. I too, tripped over this while doing some general research on Google. My goodness Linda – how pompous, whether you are right or wrong. While I see your point, I am certainly glad I do not work with you. And the Wikipedia defense – lame. Whether or not it follows appropriate protocol, it would be more informative for amateur gardeners to hear that test plots were tried with cornmeal, a volume of “organic material” concocted using a replicable “recipe” , fallow, treated soil, or the susceptible crop planted again, with the results provided.. Your remarks were no more helpful than the cornmeal school.

  16. @Steve, as I mentioned in the original posting (and one of the comments), these tests have not been published in any scientific journal. So they can’t be used as a reliable basis for pesticidal recommendations.

    @Jay, the Wikipedia reference is not a “defense.” It’s a definition. If you prefer something from an academic website, you can find one here: And “whether or not it follows the appropriate protocol” is hardly a valid excuse for recommending anything as a pesticide. In fact, it’s illegal.

  17. Linda, you have missed an opportunity to be an ambassador for your institution. I am not suggesting you endorse cornmeal, I am suggesting you exhibit a modicum of self control. Basically what you are saying, is since it is not necessary to disprove the theory, no additional empirical data is necessary from your camp – the obligation rests with Camp Cornmeal to prove that it works, because Robert’s Rules say so. In my own field, I have manned the reference desk for 23 years. I know from these years of experience that using empirical data to educate the public trumps the philosophical constructs of the scientific method, hands down. Perhaps your job does not require you to work with the public or to otherwise dissemination information in a user friendly way.

  18. Jay, you apparently don’t understand my job or what I do. You can easily find out by reading the “who we are” section of this blog or reading my c.v. on my web page. And yes, it is up to “Camp Cornmeal” to prove that it works. The scientific method might have its flaws, but like it or not, that’s what we’ve got. Anything that doesn’t make it through scientific review and publishing is merely anecdotal.

  19. Linda Chalker-Scott,
    I want to thank you for this opportunity to give my little story about “cornmeal”.
    It goes like this:
    Part one – I have used dry cornmeal to exfoliate for my face as a teenager.
    Part two – My new to me house had an ailing Cypress tree. The first year I picked 2- five gallon buckets of bag worms off of it. During this same time I was soaking my feet in what Howard Garrett groupies called “cornmeal tea” and I decided to pour the liquid cornmeal around the base of the tree. Much to my surprise the tree has never had bagworms since and that next year grew five feet.
    Part three – As for me and my results read on.
    I had taken a ten day class in Florida and upon returning realized that I had contracted a fungus on my toe nails and had lost three toe nails and started the corn Meal Soak and the fungal activity ceased and no additional nails came off.
    I am a believer because this does works.
    Some things are true whether you believe it or not.
    Thank you for this forum to support Mr. Howard Garrett and his good work bringing the “Natural Way” Mainstream.

  20. Linda Chalker-Scott, I too suffered dreadfully with toenail fungus as a result of playing tennis for many years. Cornmeal soaks was the only successful remedy. I have also used cornmeal in the garden with excellent results and I have been gardening for 30 years. I originall got the toenail remedy from Howard Garret’s newsletter. Thank you, Howard!. Robin

  21. I go by what the old timers recommend and have found that most of the time they know what they are talking about. I have seneral friends that have used corn meal with success and also peat moss. So, I am going to try the corn meal application on the brown patch in my new sod. It doesn’t hurt to try. I have an appreciation for science and testing but I have found that it isn’t always accurate. 🙂

  22. Jay: I commend you for your comments; well said. Like Mrs. Scott, I also have a Ph.D. and consider myself well educated and experienced in the scientific model and the relationship of such to research and statistically based and professionally published research. As I have read this blog, I see two issues at play: (1) the efficacy of cornmeal as an organic fungicide or preventative and (2)‘the approach of Mrs. Scott in what has been described repeatedly described in this thread as arrogant, dogmatic and less than “user friendly”. I am not passionate about #1, but it has been my anecdotal experience that cornmeal is efficacious in many applications and I have done side by side comparisons here in the Caribbean which support my hypothesis.

    In the case of the second variable, Mrs. Scott is missing a major tenet of the scientific model. It seems that the dogmatic, sarcastic tone of her original “article” demeans the anecdotal reports which stimulated her “rant?”. There is NO scientific proof of anything in any field that was not originally stimulated by anecdotal report, leading to hypothesis and subsequent research. Without anecdote, we would have NO basis for question, the formulation of hypothesis and subsequent research and result. So, to demean those who “have hunches” is contrary to the eventual formulation of factual knowledge.

    With regard to Cornmeal, I might briefly share my “anecdotal” report. I reside in the Caribbean 7 months annually. We have very limited commercial chemical resources here. Due to unprecedented rainfall over the past 12 months, we have an incredible problem with “rust” particularly on Plumeria. I have found that my recipe including baking soda did well with the white powdery and the black mildew. It had no impact whatsoever on the rust. I divided my infected plants into two groups less than 3 meters apart. I sprayed my experimental group with the cornmeal spray daily for three days and also sprayed the ground beneath the plants. I did not spray the control group. At the end of three days, the rust was totally gone on the plants sprayed and the control group of plants were dropping leaves due to the impact of the rust. I have now not sprayed for four days and the experimental group remain rust free.

    Scientific…of course not. Worthy of respect as a research question…yes! The scientific method, Jay is not a hiding place. Your comments are well founded!

  23. Until someone publishes a controlled, repeatable experiment on the efficacy of cornmeal for any horticultural purpose, it will not be recommended as a pesticide by any reputable Extension specialist. Not only would this be highly irresponsible, it is also illegal.
    If you want sound, reliable information about gardens and landscapes, this blog will provide that for you; the four of us are recognized experts in our fields. If you prefer the home remedy approach to gardening, you’ll have to go to the self-proclaimed experts.

  24. Angela: I will be very interested in the results of your trial. I have now tried this as a spray every three days on my 1/2 of Plumeria and Gardenias. I have merely sprayed the other half of these plants on the same days with rain water from our cistern. The two groups are about 20 ft apart and are both in native soil and get the same amount of sunlight and natural waterfall. The half I have sprayed with the corn meal are now totally free of rust and have new leaves which are also free of fungi. In general, they just look revived and healthy and happy! The other half (sprayed with water) still look very sick–no new growth at all and with the leaves gone, the rust is now moving down the stem. I wondered if I might be mis-identifying the “rust” so I had the head gardener from one of our major resorts (spent upwards of $400,000 on landscaping plants within last two years). He confirmed my diagnosis. I sent a photo of the infected leaves to a friend in the U.S. who I feel knows much more about horticulture than do I. He replied–”Fungus! Looks like rust! Spray it with Corn Meal Tea). My trials are far, far, far from scientific, but then we ALL have a lot to learn! Good luck and if it does not work for you, then that will be valuable info also!

  25. Seems like people need to read the ingredients in corn meal (niacin,ferrous sulfate,thiamin mononitrate(vitamin B1)riboflavin(vitaminB2), Folic acid)I’m not a scientist but I do know what works. I’m a tree hugger been gardening for 20 yrs know thing don’t work all the time because some plant become rezilant to fugisides. That doesn’t mean they don’t work mean u need to use more than one method. As for me I would alternate neem oil & corn meal I don’t need some one to hold my hand and tell me something work test it ur self and know with ur experiance.

  26. Let’s cut through the BS as to the real value of cornmeal in treating plant and lawn diseases. Self proclaimed experts don’t convince me of anything on the subject. For a few dollars one can perform their own tests and draw their own conclusions. So, why not purchase some and give it a try. It will either prove useful or only waste a few dollars. I suppose one could waste an equivalent amount of money by donating to some college where another expert will perform another “test” as it does using Gov. grant funding.

  27. Just tabulating the data from the replies here, it looks like corn meal works every time. What the heck? It is easy to get, can’t cause any harm, and might just work! I’d say it is definitely worth giving a try. In fact virtually nobody has anything to say against it. It doesn’t get much better than that. Since these writers have actual boots on the ground from all over the world, there must be something to this idea.

    Despite her enthusiastic sarcasm and self-proclaimed claim of mythology, Mrs. Scott has no authoritative expertise of her own on this subject. Thus she tags onto the coat tails of Mr. Parsons. Mr. Parsons similarly presents no evidence but does offer his hearty unsupported denial. If the real gardening doctors insist that corn meal is “unreliable,” then there must be several reliability tests somewhere. Because it would be highly unprofessional for professionals to pass out unsupported information in their field of expertise. All you have to say is, “repeated testing at Cornell, Penn State, Georgia Tech, and Texas A&M have found corn meal to be unreliable as an antifungal agent.” …or words to that effect. You don’t have to quote chapter and verse on the amounts used and the soil preparation. Just make it sound like you know what you’re talking about. On the contrary, in the face of an accumulating mountain of successful anecdotes, why have the experts not referenced any studies which back up their claims of unreliability? It sure a heck sounds reliable to me.

  28. I think it’s very unfair that you claim the myth is busted as you haven’t proven such. I understand that you don’t think it’s your job or that it’s impossible to prove a negative but then you can’t title your article claiming you have disproved it.

    I’ve been using cornmeal on my lawn with great results for a number of years and I have researched the topic. It works for me and many others. The original Texas A&M study’s statement regarding cornmeal was that it increased the population of beneficial fungi in the soil which helped control disease.

    The original document that has been referenced by others is no longer online but many references to it are still around. I have quoted the section regarding cornmeal and beneficial fungi in an article I recently published as well as other articles and research which strengthens my belief that cornmeal can help control lawn disease.

    It seems odd that the orginal document would be removed from the website. If the conclusions have changed or some flaw was found in the paper wouldn’t it be updated with those conclusions or another article would correct it?

    I understand you can’t recommend cornmeal for lawn disease because of EPA regulations but the EPA itself has published a document concerning compost and how it can control plant disease and even insects. You can’t sell compost as a pesticide/fungicide or market it as such but most people understand that using compost can solve these problems. Maybe the EPA needs to rethink how it deals with these organic recommendatio

  29. Dr, Chalker-Scott,
    As I said, I’m not disagreeing with you regarding the lack of research and published studies and what that means in reference to claiming cornmeal can treat plant disease. The main issue is with claiming “myth busted”. Over the past few years the bar has been significantly raised in regards to what myth busting entails thanks to the Discovery Channel. 🙂
    You don’t need ballistics gel or explosives for this one. I’m sure you’d know how to conduct a proper test but for completeness this is one way to bust the myth. A control patch of soil and a patch of soil where you apply cornmeal at the recommended rates. The soil needs to have been free of fungicide and pesticide applications as well irrigated without chlorinated water. Some sort of crop (lawn?) should be growing in the soil. Test needs to be done during the growing season and soil must be moist. Irrigation to each patch should be the same only difference is application of cornmeal to one. Count (estimate) the population of trichoderma in control and test soils before application of cornmeal, count the populations each day and see if the population of trichoderma has increased in the cornmeal soil compared to the control and possibly compare population of trichoderma to other fungi for comparison. If not you can say the myth is “busted”. If the levels of trichoderma have significantly increased in the test soil then there might be some validity to the statement though it doesn’t prove anything other than trichoderma populations increased.
    In your second paragraph you stated “But it’s not really research – it’s just an observation on what happens when you don’t plant the same crop two years in a row; in this case, rotating corn and peanuts reduces peanut pathogens.” That’s not what it says at all. The document says “This enhanced, natural biological control process is almost identical to the processes that occur when crop rotation is practiced.” Applying yellow corn meal to peanut crops is clearly not the same thing as rotating corn and peanut plantings each year.
    I’m not trying to be argumentative and I have a lot of respect for your other articles that I’ve read but like I said I don’t believe you busted anything which is a shame because you have the knowledge and equipment to do so in this case.

    1. @OrganicLawnCare: The Discovery Channel has done nothing but lower the bar when it comes to debunking myths, notions, lore, and the like. The show to which you are referring would be laughable in its ignorance if it weren’t so popular. Every episode I’ve watched (scores of them) contains a bare minimum of one absolutely crucial error in how a given test should be executed and even what a given test would actually demonstrate. The people behind that show obviously either know absolutely nothing about how to conduct an accurate test, or – more probably – really don’t care, so long as there are ‘splosions and bangs and a laugh here and there to keep the money flowing in. As a trained professional, it would be, as I mentioned above, laughable, were it not for the fact that it reinforces ignorance among the general public. Because of that popularity and the concomitant impact on the general public, that show and many others on that channel are not only disgusting, but actually irresponsible.

  30. As we’ve pointed out in other posts on other topics, it’s up to proponents of practices and products to demonstrate conclusively that they work – in a peer-reviewed scientific publication. If no one is able to publish a research paper demonstrating that cornmeal does whatever is claimed, then by definition it has no verifiable activity. Anecdotal information can direct further research, but it doesn’t replace research.

    The research at Texas A&M was summarized in 2001 guide on peanut production. You can see it here on page 54: You’ll notice there are no data or references, just the statement that “testing will continue.” To the best of my knowledge, nothing further has been published.

  31. It’s my understanding that Texas A&M continued to research the issue but drew no conclusive results. Human nature being what it is, many scientists don’t publish negative results (which is a shame because it would help lay to rest so many ineffective practices and products).
    Any publishable research requires time and money – not just expertise. I know that my fellow GPs and I would love to conduct research on topics of interest to gardeners – but someone has to foot the bill. Ironically, whenever a company or other interest group steps up to do so, many people are suspicious of the results. It’s a Catch-22: outside money is absolutely required to carry out substantial field research at universities, but when someone donates the money then scientists are often accused of being in the pockets of whomever funded the work.

  32. “Human nature being what it is, many scientists don’t publish negative results (which is a shame because it would help lay to rest so many ineffective practices and products).”
    You mean like you not correcting where you said the experiments with cornmeal also involved crop rotation? 🙂
    The absence of evidence is not evidence of absence, that’s a classic logical fallacy I’m sure you’re aware of but it’s what you used to try and bust this myth.

  33. How come you get to create paragraphs in comments and I can’t? 🙂

    1) If trichoderma were available in all soils in sufficient quantities then plant diseases wouldn’t be an issue, but it is. Corn meal is organic material. From my reading, including an EPA document about compost and it’s use in bioremediation and control of plant pathogens compost can be tailored in different ways based on the needs. Isn’t it possible that corn meal happens to be particularly good at increasing the population of trichoderma compared to other OM’s? That’s one avenue worth pursuing.

    2) I know what cornmeal agar is and what it’s used for but do not know why you bring it up? If you look at the TAMU peanut document they didn’t say they applied cornmeal agar to the peanuts or that they grew trichoderma on the CGA in the lab and then applied it to the soil. They said they applied plain yellow corn meal to the soil which increased the population of trhicoderma. In Dr. Parson’s article he did not dispute that the application of plain yellow corn meal to soil increased the population of trhicoderma in the soil. The only thing he said was that it was for a specific fungal relationship and that it will not work for all plant diseases. In the article I posted on my site I referenced a number of different articles and papers that found different strains of trichoderma to be effective for a large number of plant pathogens. I happen to use corn meal in my lawn in the spring and have found it to be effective for me. The first time I used it I was blown away.

    3) That’s a shame.

    I don’t know what distributors you speak off. Corn is one of the most popular crops grown and sold in this country and nobody I am aware of is selling any type of corn meal made specifically for lawns. It wouldn’t be feasible to do so since it’s something you can by in any supermarket in this country. It’s not like corn gluten meal which is a viable commercial product that can be sold in areas that do not have easy access to a feed store. If people stopped using corn meal on their lawn it’s not like the corn industry would go belly up or any companies specifically selling corn meal for lawns because there aren’t any.

    It wouldn’t be profitable for someone to spend money to research if corn meal would be profitable or not in many cases. It wouldn’t be patentable and it wouldn’t be able to compete with grocery store/costco corn meal in most places.

    I didn’t come here to get in an argument of whether or not corn meal works to control lawn disease I came here to point out that you did not bust the myth. That’s not a matter of opinion. It’s fairly easy to disprove that corn meal doesn’t increase the population of trichoderma. If that’s not something you can get funding for I don’t blame you for not conducting the study but then you can’t publish this article for others to read claiming the myth is busted. Especially when you mixed up the corn meal study with a study on crop rotation.

    Since you’re a well respected researcher in this field why not reach out directly to the person that did the study instead of Dr. Parsons?

    1. @OrganicLawnCare: I’m really not trying to pick on you, but are you really so wildly naive as to actually believe that it would be impossible for someone to package and successfully market corn meal specifically for lawn/plants/organic gardening (if it were proven it worked – or even if that proof were lacking)? Seriously. Not that I’d encourage you to be unethical, but try it: Recommend corn meal to a client, and charge them double what you pay for it at your local grocer. I’d bet that a solid 80% wouldn’t bat an eye, and a goodly number would ask if they could apply it themselves in the future, and if so, would there be any way they could purchase that corn meal directly from you? There is no end to what the public will buy, so long as it’s correctly packaged and marketed.

  34. “The myth as I stated in the original post is that “cornmeal has powerful fungicidal properties in the garden.””
    By the time I found this page the linked to article had already been largely removed and I wasn’t able to read it. That statement is clearly wrong. is just a content mill and they don’t have much of a review process from what I understand. It’s not something I would consider an authoritative source. In this case it just seems like a third hand account. mainly cares about putting keywords on pages, not about accuracy.
    Every credible thing I’ve read about cornmeal for control of lawn disease specifically stated that the cornmeal isn’t a fungicide and that it just helps increase the population of tricoderma which in turn can control lawn pathogens.
    The David that left a comment before me sounds like a person that frequently contributes to lawn care discussions online. If he is, he might be the first person I learned about the TAMU study from. To my knowledge he has never stated corn meal is a direct fungicide. He also frequently comments that he uses cornmeal on his lawn as well as to control black spot on roses and it seemed you were talking about him in part of your article. I think David is the source for spreading the use of cornmeal to the lawn care community and does a good job of explaining it.
    I had the same “aha” moment he had when I first applied cornmeal to my lawn. I got up extra early so that nobody would see me and think I was crazy. Not too long after my lawn was green while other’s were red, brown and orange.
    The person on was just plain wrong. I see now the first article referenced another article from the Dirt Doctor. I don’t know who he is. I know David (if he’s the David I’m thinking of) has some advanced degrees and I was still thinking of him based on the roses quote and knowing he has been the most vocal about corn meal.
    If that’s what you’re calling the myth, yeah you busted it. Most of us that use cornmeal in our landscapes would disagree with those statements made on too. That statement was simply wrong. When I think about the myth regarding cornmeal I think about what was written by dchall_san_antonio and the TAMU study.
    Based on your other writing I still don’t think you would recommend the use of cornmeal even if it was proven effective. If I lived in a more rural area and had access to a pickup I’d probably be spreading compost on my lawn instead. For me it’s cheaper and easier to spread cornmeal and it’s been effective.
    To clarify my position, the page on pseudoscience doesn’t contain the actual phrase myth busting. You can say there’s no verifiable proof all you want and I wouldn’t object but once you say something is not true you have gone from a skeptic to making a claim and now the burden of proof rests on you.
    If Bertrand Russell came up to me and told me there was a teapot orbiting the sun but was too small to see the burden of proof would be on him and I can choose not to believe him until he can prove it then I have no obligation to backup my doubt. If I instead claimed what he said was false now I am obliged to backup my claim if challenged.
    I’ve seen cornmeal work on my lawn and heard of others using it successfully too. Nothing I’ve seen has refuted the TAMU study and the Iowa study that led to the discovery of pre-emergent herbicidal properties has a bit in it to suggest that cornmeal might have prevented the establishment of a different lawn pathogen. I believe there is ample evidence to warrant further study the only thing lacking is the funding to perform the research. That’s obviously not going to come from companies that are currently marketing fungicides, it won’t come from a company hoping to market cornmeal as a treatment for plant disease as there are few ways to make that profitable and no offence but I doubt it would come from many university researchers who probably don’t want to disrupt funding for their other projects from companies that would have their profitability threatened.
    That last part sounds a little bit conspiracy theory-ish but it’s not. I understand the economics of these decisions I’m just not happy about them.

  35. Let’s just cut to the chase. One: Trichoderma is a fungal parasite present in *all* soils. You don’t have to do anything special to encourage its growth, other than to provide sufficient organic matter. Two: Cornmeal agar is used to grow Trichoderma in the lab. Three: no one has published anything (in the scientific literature) showing that adding cornmeal to soil will control fungal diseases.

    To quote Dr. Jerry Parsons again (the link to his column is in the original post): “Do you wonder why further testing in field conditions have not been performed? Because the product distributors do not want to take the chance of failure. So if you want to waste money on a “snake-oil” product that hasn’t ever been statistically shown to be effective in field conditions just for the sake of organics, step up to the counter-they will be more than glad to take your money!”

  36. Trichoderma IS in all soils. Whether or not it’s actively growing is a different matter. Unhealthy soils with little OM and/or fungicidal applications won’t have active Trichoderma. Your soils also contain Phytophthora and other pathogenic species. They’re inactive unless soil conditions are appropriate for their growth.
    The myth isn’t that corn meal will increase Trichoderma (it does, at least in the lab – that’s why I mentioned the cornmeal agar point). The myth as I stated in the original post is that “cornmeal has powerful fungicidal properties in the garden.” That’s not easy to demonstrate in a field study. It requires the ability to follow an undefined number of fungal populations over time, which requires microbial laboratory facilities and equiment that most of us don’t have.
    Because this belief has never been supported with anything other than anecdotal evidence, pointing this out constitutes “myth-busting.” Per Wikipedia, “In science, the burden of proof rests on those making a claim, not on the critic. “Pseudoscientific” arguments may neglect this principle and demand that skeptics demonstrate beyond a reasonable doubt that a claim (e.g. an assertion regarding the efficacy of a novel therapeutic technique) is false. It is essentially impossible to prove a universal negative, so this tactic incorrectly places the burden of proof on the skeptic rather than the claimant.”
    Finally, if I knew who did the orginal study, you can be sure I would contact them directly. But I don’t have a clue. That’s another problem with not publishing in the scientific literature.

  37. I’ve been following this thread with interest, due to a serious problem with daylily rust in our garden.

    Tonight, I’m going to start soaking some corn meal, and tomorrow I’ll hand-apply it to one particularly rusty daylily, as well as working some corn meal into the soil around this plant. I’ll report back later as to any effect this treatment has had.

    My daylilies have been sprayed with every recommended fungicide, to no avail.

  38. I don’t need a scientific study to tell me if this works or not. I need 12 bucks, 30 minutes of my time to spread it, and 3-4 weeks to see if I notice a difference in my lawn.

  39. I’m sorry to report that the combination of corn meal juice and cornmeal worked into the soil was not effective against the daylily rust. I wish it had been.

  40. Nancy, thanks for reporting back on this. You might want to try some more reliable organic remedies, such as milk sprays or baking soda. Both have some efficacy on certain types of foliar disease. If you’re interested, my web site has a horticultural myth section that presents the evidence on both of these treatments.

  41. Nancy Barginear–To do a proper research on cornmeal, you would need to have to divide your plot of garden for daylily in say at least 10 little lots. You would need a reasonable size of say 10 square feet per lot (for a small garden). That will be 100 square feet in total (10 feet by 10 feet). In each lot, you will have a control lot without cornmeal , and cornmeal application of 1 oz , 2 oz, 3 oz,….9 oz to each of the remaining 10-sq-feet-lot. Thoroughly mixed in the cornmeal and work the soil in the control lot without cornmeal (make sure the control lot has the same treatment of the other lots without the cornmeal that’s all); give it a good watering everyday. Give it a few weeks for the Trichoderma to grow then plant your daylily. You can then tell whether the cornmeal worked to prevent harmful fungal infection of the plants. The results will also tell you which concentration of cornmeal is optimal to apply. I hope this will help you in your “research” interest into using cornmeal to help “prevent” fungal infection of your plants. “Prevention is better than cure”. Just trying to help you with some research methodoloy. Nothing else.

  42. Valuable advice, Onn Yu – but it applies to *everyone* who has commented here on using cornmeal, not just Nancy. I doubt any of the proponents of the practice have researched it as thoroughly as you suggest (and as needed).

  43. I did use the baking soda and molasses on this rust-prone plant, but that didn’t work either.

    Onn Yu, thank you for the information, but reconstructing our existing daylily beds is not an option. I would need to apply products that would suppress or eliminate rust.

    I think Howard Garret may have an excellent point about not fertilizing with high-nitrogen fertilizers. My original daylily plants (4 clumps) were divided and planted out in front of a board fence along a dirt road. They were growing 8′ apart, and never once fertilized or watered. Surrounded by weeds and native grass, none of them ever developed any rust whatsoever. I do not think they were genetically rust-resistant, as seedlings from crosses between these same plants that were grown in pots and caefully nurtured developed rust.

    When we lived in the country, and first put in large new daylily beds, one end section did have cornmeal incorporated in the soil, along with other organic products. We also used Nutri-Cote fertilizer. This particular bed was planted mostly with very young diploid daylily seedlings in the fall. Next spring, many of our seedlings were already blooming. By the second year, they were is full bloom. The colors were very vivid and spectacular. However, I did have some tetraploids planted in one small section of the bed. About 90% of the diploids developed no rust. The other 10% were not badly affected. The tetraploids did have rust. We had four other sections that developed a lot of rust. It shows up in the spring and fall when the nights are cool and days are warm. Our area of the country is very prone to daylily rust, due to the milder winters and humidity.

    I plan to stop spraying with chemical fungicides altogether, and only fertilize with organic products (i.e. seaweed fertilizer or other). I really don’t know what else to do.

  44. Nancy. You can try using 10 large pots instead of a 100-sq-ft plot. You can also try using commercially available Trichoderma Fungi (do a web search) on those plants that have rusts. Good luck.

  45. Nancy, molasses won’t work and will probably make disease problems worse – it’s a source of sugar. The articles I mention on my web site are based on scientific research, and baking soda does have some efficacy, as does milk spray. Please read the articles to get the science-based information, and don’t rely on recipes found on non-educational sites.

    By the way, you stumbled upon a very good way of controlling the rust – by growing your lilies in biologically diverse groups of plants. I’d encourage you to mix up your lily plantings with plants that aren’t susceptible to rust.

  46. Is there any evidence to suggest that cornmeal increases the level of T. Harzanium more than another high nitrogen organic fertilizer? Soybean meal, for example? Does Trichoderma really like corn for some reason?

  47. Interesting thread, still alive after two years! I still don’t know if cornmeal is effective or not as a fungicide (I was actually searching for toenail fungus remedies).

    It would appear that Ms. Scott also has no evidence as cornmeal’s efficacy. I believe you could have avoided much of this comment hoopla (and thus my entertainment this morning) if you had only said “There is no published evidence that cornmeal is fungicidal” instead of “Myth Busted!”

    Finally, though I admire your academic rigor, all honest scientists admit that new knowledge is ever arising and that “proven, published literature” is constantly being revised, updated, and thrown out. Even Einstein has been trumped on occasion 🙂

    Now I’m on to researching tea-tree oil for my toenails! Wish me luck 🙂

  48. Jay, there are a variety of recipes for culturing Trichoderma spp. All have some sort of cellulosic component, whether it’s corn, wheat, potato, etc. mixed into the agar base. Not being a microbiologist, I can’t tell you if one recipe is better than another. It would be interesting to see a comparison of culturing techniques to answer your question.

  49. By the way, here’s how Mayo Clinic handles similar situations:

    “Fungal nail infection (onychomycosis)
    Although tea tree oil is thought to have activity against several fungus species, there is not enough information to make recommendations for or against the use of tea tree oil on the skin for this condition.”


  50. Paul, if/when there is new published evidence supporting a fungicidal role for cornmeal, you can be sure I will include it on this thread. Because you’re right – science is always evolving. I don’t think you’d find any scientist who would suggest otherwise. But in the meantime, we need practical advice to give to people, and that advice is based on the best available science at the time.

  51. Linda, there are many issues I have with some of your comments within this thread…Right off the bat you stated that the cornmeal “myth” has been busted, since you are the one that made that claim you need to prove it. from what I can tell you have done absolutely nothing with cornmeal, so how can you prove it doesn’t work when you’ve never even tried it? I also can’t help to notice that there are several claims on this thread that seem to atest to cornmeal having helped reduce or eliminate fungal issues on lawns and bedding plants through experimentation and you have no reply to any of these success stories but when 1 person finds that the cornmeal solution does not work on her lily rust you are real quick to thank her for her useful input conveniently disregarding all of the success stories.
    You also mention that trichoderma is naturally occuring in soils and you are correct…That does not mean that it occurs in high enough populations to effectively control pathogenic fungi, especially in this day and age of chemical fertilizers, air pollution, acid rain, and soil compaction due to foot traffic and weekly lawn mowings with heavy equipment. thats like saying that predatory mites exist naturally in the environment so we should never have mite issues on our plants. and finally, at least twice in this thread you stated how it is illegal to recommend the application of cornmeal as a fungicide, (I’m assuming you are refering to FIFRA regulations and EPA reg. numbers), but then you take it upon yourself to recommend the application of milk and baking soda as a fungicide to another contributor. I really don’t get it.
    Now I may not have fancy letters at the end of my name, But I am a state licensed arborist and supervisory pesticide license holder with 30 years of experience under my belt in the world of horticulture ans IPM
    I would bet dollars to donuts that some 400 years ago many of the kings most scholarly and well educated wisemen pranced around claiming that they have busted Christopher Columbus’ “myth” that the world is round.

  52. Ron, if you’ve read this thread then you’ve seen my numerous references to pseudoscience. I’m not going to repeat what I’ve said before. I would encourage you to read the Wikipedia entry on it:

    Unlike cornmeal, both baking soda and milk have shown some fungicidal activity in controlled experiments and these results have been published. So these products can be recommended as science-based home remedies for gardens. You can read more about the science behind these products on my website if you are interested:

    Just now I updated my literature search on cornmeal as a fungicide, using the AGRICOLA, BIOSIS and CABI databases. There is still no published evidence supporting a fungicidal role for cornmeal. (There is one paper, however, that found no effect of cornmeal in controlling Rhizoctonia on containerized grapevines.) So unless there’s a big conspiracy among all the plant and soil scientists in the world to somehow hide the fungicidal wonders of cornmeal, that’s where the science currently stands, and that’s what informs my recommendations. If and when the science changes, then I’ll modify my stand on the topic.

  53. “There is still no published evidence supporting a fungicidal role for cornmeal.”

    Again, the claims that cornmeal is a fungicide are uninformed 3rd hand accounts by people that don’t understand what’s happening.

    Here are two older articles from non US based journals.

    Canadian Journal of Botany, 1952, 30(5): 652-664, 10.1139/b52-043

    “In natural, unamended soil, a heavy infestation of T. lignorum did not check the growth of R. solani perceptibly, but with the addition of cornmeal it was practically suppressed for several days.”

    De invloed van het toevoegen van organisch materiaal aan de grond op het optreden vanRhizoctonia-ziekte en schurft bij aardrappelen – S. de Boer
    Tijdschrift Over Plantenziekten (European Journal of Plant Pathology) 1962 Volume 68, Issue 5 , pp 268-277

    “After addition of 20 g corn-meal to 1 kg of soil, in most instances combined with Trichoderma, the following effects were obtained: 1. fewer weeds, 2. delayed appearance of the sprouts, 3. fewer (though in a single case more) sclerotia on the crop, 4. less scab, and 5. increased yield”

    1. There may be a hundred other things that cornmeal does to “get results” we do not understand right now.

      Replacing the insulin in a diabetic will keep them from dying “today”, but they are still going to die as a result of having diabetes. The pancreatic cells that produce insulin may also do hundreds of other things we have no understanding of yet…

      The DEBATE is over for global warming!!! LOL

    2. @OrganicLawnCare: OK. Dr. Linda Chalker-Scott wrote this article specifically debunking the widespread (at least on the internet) myth that corn meal is a fungicide. That’s a pretty specific claim, and it’s unfortunately gotten traction, mostly for the reasons given in her article. You then proceed to argue with her, based on what I thought was a misunderstanding (Dr. Chalker-Scott making a specific claim, you taking that very specific claim and broadening it to include related, but ultimately irrelevant, issues, generally muddying the field of conversation in the process, and specifically making some fairly wild – and inaccurate – claims about how science works), and then come to find out you actually not only agree with her specific claim, you bring in other sources to back it up! I’ll ask you to stay off my grass after that.

  54. @OrganicLawnCare, it’s an interesting coincidence that you posted today. I am planning on doing an update on this topic tomorrow, if for no other reason than to stop adding to this thread! My post tomorrow will look at what function cornmeal serves in microbial communities.I too had found the abstracts you mention, but the articles themselves are not available because they are so old (and the second is in Afrikaans, which I don’t speak). I am uncomfortable basing recommendations on abstracts alone, as they don’t include the whole story found in the results and discussion.
    The first article’s abstract isn’t as clearcut as your snippet would suggest. Here it is in its entirety:

    “The effect of the presence of various 21-day-old host and non-host plants, soil amendments, and Trichoderma lignorum [T. viride: R.A.M., 31, p. 271] on the persistence of a heavy artificial infestation (one part inoculum to nine parts soil) of Rhizoctonia [Corticiuiri] solani was studied under controlled conditions at the Dominion Laboratory of Plant Pathology, Edmonton, Alberta, using natural, virgin black loam at optimum moisture content, held at 61° F., in further experiments in this series [ibid., 27, p. 254]. Persistence was assessed from disease ratings, root infestation, and examination of buried microscope slides, the first method being the most satisfactory. “When maize meal was added to the soil, the growth of C. solani was practically suppressed by T. viride for several days. In the presence of living potato plants C. solani persisted as well in natural, untreated soil as with the addition of maize meal, sodium nitrate, or calcium hydroxide. The fungus disappeared from the soil within 120 days when associated with wheat, oats, barley, or maize replanted every 21 days, but persisted for 170 days or longer in soils planted with potatoes, beans, or peas. In the absence of potatoes a heavy soil infestation in late autumn practically disappeared by the following June.
    “It appears, therefore, that C. solani depends entirely on parasitic nutrition for its persistence in the soil. Hyphae commonly inhabited the living roots of host and non-host plants, but there was no apparent nutritional relationship.”
    More tomorrow…

  55. This has been a very interesting thread. I ran across it in my search for a treatment for gray leaf spot on my St Augustine, but I was not prepared for the bias evident in the use of the “Scientific Method”…which it’s very use is supposed to eliminate. Very interesting!

    Apparently, today’s version of the Scientific Method would seem logically to infer that nothing in science is true or factual until it undergoes the rigid filtration processes of testing and scrutiny. Does that mean, for example, that prior to the study of physics and the effects of gravity on the earth air bubbles actually sank in water while rocks were buoyant? Was tobacco smoking a harmless activity until it was proven to be harmful?

    Cultural and personal biases have a way of influencing the way we view natural occurrences. The Scientific Method was intended to eliminate or minimize these biases.

    There is a clear denial present in the current culture of science (and I would wager in most other professions as well) that I feel reasonably sure is meant to insure that the various scientific disciplines are protected from being seen as nonviable, or being unable to justify their existence. It’s also apparent the biases created by money or the potential for the advancement of one’s career or promise of notoriety will never be fully extricated from the “Scientific Method”, because it’s the only logical reason for the categorical refutation of a method (in this
    case the use of cornmeal as a fungicide) because of it’s lack of study and peer-review by other scientists.

    Exactly how many anecdotes does it take to make something true or even viable? Based upon the current interpretation of the SM espoused in this thread, all of humanity could bare witness to an event or occurrence but it would only be an apparition or “myth” without the “blessings” of the scientific community.

    Please excuse me if this sounds pessimistic, but I’ve noticed in my life that most good things humans create or touch end up turning into a form of fertilizer. Science has always had the potential and the ability to benefit us all, but it doesn’t always. The SM is supposed to build upon and improve itself, but that isn’t possible if it denies a flurry of anecdotal evidence that something claimed is viable.

    Personally, I believe there’s not enough money in natural organic methods to justify pursuing scientific results, while there is money to be made in the already established chemical “solutions” on the market today. This reality really gets nasty when the behavior of pharmaceutical companies is studied.

    Additionally, don’t scientists generally agree that theories can never be proved, only disproved?

    1. Thank you! Extremely well said! Will it make it through the “Gosh I have a PH.D and only I know the Scientific Method” Filter. Don’t know but Gosh, you certainly said it very well indeed!

    2. Tobacco has not been proven harmful “scientifically” Because it would be an unethical experiment PERIOD

      I suggest that NO ONE smoke it might be bad! One thing I would bet is that Food as eaten by Americans kills a LOT MORE than tobacco…

    3. Look. Dr. Chalker-Scott wrote that corn meal is not a fungicide. That means that it does not directly kill fungus. She did not write – in fact, she was very careful about not writing – that corn meal not being a fungicide does not mean that it is without benefit. I’m not going to reply to your attempts at sarcasm re: bubbles and smoking, because your vocabulary suggests you know better (although your argument suggests the opposite). I’ll try to break it down: A fungicide is something that kills fungus. Corn meal does not kill fungus. Corn meal is not a fungicide. (That is the entire extent of what Dr. Chalker-Scott wrote in the original post.) Corn meal may encourage the growth of beneficial organisms that may – in turn – help prevent or control fungus, but that does not in any way, shape, or form mean that corn meal is a fungicide. Seriously. Is it really that hard to understand?

  56. This morning, I ordered 150 pounds of agricultural cornmeal, which I will apply to my brown St. Augustine grass every few weeks. – I’ll report back in 6-12 months.

  57. Linda, would you consider adding it to only half your lawn? If so, be sure all other treatments (water, fertilizer, etc.) are identical.

  58. I find this post interesting. The author speaks in absolutes, such as: “This is absolutely false!” There are no absolutes in science, new things are discovered all the time. A test is pretty simple, go out to your lawn and find a patch of brown spot and put some cornmeal and sugar on it. If it gets better; then maybe there’s something to it. If it does not; then it’s hooey. If you must put a name to my experiement; then just call it common sense. As for myself, I live in Charlotte, NC where brown patch is very common. I have tried a lot to get rid of those spots with no avail. I am still early to the process but I am noticing some positive results for the areas that I treated.

      1. No worries Linda, this is not a personal attack. Although I am from NC, most people think I am from Missouri, the show me state. So I am naturally suspicious of anyone who talks about absolutes. I followed a discussion on gardenweb and a test someone carried out, using cornmeal and granulated sugar. I pasted the link below, so I hope it works. It sounds like there’s some really bad root knot nematodes in the south and the mixture of cornmeal helps treat those areas. I am probably doing a very poor job of summarizing a member’s posts named “Nandina.” Don’t take my word for it or anyone elses. Instead, I would encourage anyone in the South with a fungus problem to give the experiment a try. As for me, so far it seems to be working.

  59. I wish to respectfully refer those posting on this topic to my post of Feb.12, 2012. It seems to me there are two themes to this thread. The first has to do with the efficacy of corn meal as a fungicide. The second has to do with the lack of appreciation by Linda of the potential worth and significance of “anecdotal reports” related to this topic. The latter is the larger problem from my perspective for the reasons I expressed in my post of Feb. 12. Having a Doctoral Degree (as does Dr. Scott) I deeply share her love and enthusiasm for the “scientific method”. HOWEVER, arrogant disregard for the formulation of hypotheses by those with direct experience with an issue’ reported with “dirt under their fingernails” rather than “monitor eye fatigue”, is not in the best interest of any of us. I would only add that I have found my own, “controlled” experiments with corn meal here in the Caribbean to strongly support the efficacy of this as a fungicide in certain applications. I also spent five months back in Iowa this sumer and found the efficacy in terms of white powdery mildew on our K. Blue Grass to be remarkable. Of course, as a retired Professor, I no longer have the Ivory Tower in which to conduct the “Perfect” controlled tests. At any rate, for those of you who are in good faith and open mind, giving this corn meal a try–good for you and trust your results.

    1. Rick, you don’t need an “ivory tower” in which to conduct research – look at Gregor Mendel’s groundbreaking genetic research on common peas in a monastary garden, for example. Lots of home gardeners and other nonacademics have contributed to the field, using the accepted scientific method in which to set up the experiment and analyze the results.

      So please – write up your results and have them reviewed by your PhD peers. When you’ve done so, then I’ll be more than happy to read and respond to the article. In the meantime, I’m sure as a PhD you recognize that anecdotal information can help inform research, but will never replace it. It’s not “arrogance.” It’s the way that science works.

      1. Thanks, Linda. My comments stand. Your recommendations as you have offered them are appreciated, but totally inconsistent with the tone/message of your “Myth Busting” treatise. I would respectfully refer you to a review of the “second theme” I referenced. With one exception, I do not find in your replies in this thread any encouragement to field research; however crude and well intended (and ultimately, worthwhile) it might be. Science only works when all persons asking questions, contributing anecdotal information, “hunches” as well as those who do the formal research proceed with mutual respect; otherwise, it is “arrogance”.

  60. I have been reading these thresds with interest. Most brown patches on lawns in this country seem to appear where dogs have urinated.and probably have an effect on the populations of trichoderma in the soil. Not being an academic in the sciences, I would suggest that cornmeal application probably neutralises the the adverse effects of dog urine in the soil. Lawns by a nature tend to be a monoculture without the benefits of crop rotation so any organic matter that you can add to the soil will benefit it. Organic principle feed the soil not the plant. I am a great believer in mixing plantings because what one plant takes out another could put back and thereby prevent a build up of particular pathogens and maintain a balance of microbial activity and nutrients in the soil (working in harmony with nature). On my plot here in the Uk ( London) it works quite well for me and the more organic matter you can work into a soil the better and helps to prevent a build up of pathogens and helps to maintain a balance of microbial material within the soil. to stop dogs from urinating on your garden put chili pepper down if its a dry day. they are creatures of habit and always sniff the area that they are marking need I say more, we all know what chili in the mouth and nostrils feels like and you will probably get rid of your brown spot on the lawn problem too. That’s impirical enough for me having tried it outside my front door with a problem dogowner who used to allow his animal to defacate there. Unfortunately it was the dog that learned the lesson not the owner. What I am trying to say is horses for courses and I don’t think that anyone is right or wrong here and yes don’t hold your breath for a rigorous scientific study cos! it ain’t going to happen. Too many vested interests preventing it from happening. So all we have is hearsay and old adages to rely on in our organically orientated world. Bottom line, if it works for you stick with it, if it doesn’t move on to the next thing. Understanding why something might work is always nice and helpful, but not always necessary.

    1. First, corn gluten meal is NOT the same thing as corn meal. Second, corn gluten meal has herbicidal properties, not fungicidal properties. You are mixing apples and oranges in the above post.

  61. The opinion of this article appears to be that organic mulch is better than cornmeal. This is a testable hypothesis, but it has not been tested by the author.So this is also just an opinion piece. It is common for certain academics to equate truth with anything that has been published in a peer reviewed journal. The reality is though that the truth ( ie one is better than the other) still exists independent of whether or not the fact is published in a journal. While anecdotes can sometimes confuse cause and effect they are still very useful. Most people, (scientists included) for example base their idea of what foods and substances are safe for humans to eat, and what are not, purely on anecdotes. It has worked pretty well for us as a species. Certainly,occasionally people may get it wrong ( though they are more likely to declare a safe food poisonous than the other way round, due to the obvious consequences of eating poison).Still in the absence of academic proof one way or another, anecdotal evidence is not to be sneezed at. And the fact that something is based on anecdotes,is not the same as saying you have proof that it is incorrect.

  62. healthy soil does away with most plant problems in garden…along with learning how and when to water plants…with healthy water…tks to all

  63. It is apparent from the comments above, and from what scientific research (as opposed to anecdotal evidence from a few, who had some measure of success, which they then attribute to the use of an ingredient promoted by enthusiastic but ill-informed and careless gurus like the Dirt Gardener)I have been able to locate that cornmeal is nearly useless as a horticultural pesticide, that so-called corn gluten meal (which contains no gluten) can be use as a pre-emergent herbicide under certain conditions, and that most people who use either in the garden are wasting their money, unless they have a really cheap supply or either. BTW, cornmeal is really great for feeding snails, so if you want healthy snails in your garden or greenhouse, just try Tbsp. sized heaps of cornmeal in the pots or on the ground. I note that Mr. Garrett, the Dirt Gardener is quite an entrepreneur, who sells memberships for his organic gardening newsletter. If you want to post a disagreement in his newsletter, it’ll cost you. Also, the gent apparently is not a critical reader, and knows no difference between cornmeal and corn gluten meal.

  64. A book/resource named Pathogenesis-Related Proteins in Plants (CRC Press, Dec 12, 2010) by Swapan Datta and Subbaratnam Muthukrishnan talks about anti-fungal activity from proteins. Corn has a protein named zeamatin that is a known fungicide. This is not controversial. According to this source, “The TLP’s known to have anti fungal activity include osmotin and PR-S from tobacco, AP-24 from tomato, zeamatin from corn, trimatin from wheat and protein R and S from barley. The susceptible fungi included Phytophthora infestans, Candida albicans, Neurospora crass, Trichoderma reesei, Trichoderma viride, Verticilium albo-atrum, Verticillium dahliae, Cercospora beticola, Fusarium Oxysporum, and Alternaria solani and included fungi belonging to the classes Oomycetes, Hyphomycetes, and Ascomycetes. The effects were both at the spore germination level and inhibition of hyphal extension.” Another quote about this research: “A great deal of research has been focused on the isolation, characterization, and regulation of expression of pathogenesis-related proteins since the discovery that several of the PR-proteins had antimicrobial or insecticidal activity and can delay the progression of diseases caused by several pathogens belonging to diverse genera. This is an exciting period of research where constitutive (or inducible) expression of PR-proteins at effective levels could be used as a tool to enhance or stabilize yield in areas where pathogens and pests are endemic. Pathogenesis-Related Proteins in Plants analyzes the practical aspects of employing PR-proteins for plant protection, in a possible role as the first or last line of defense against pathogens and pests. In addition, PR-proteins expressed in apparently healthy tissues during normal plant growth such as seed development and flowering, may have additional unsuspected roles in morphogenesis or in symbiosis.’ In fact, if one does a internet search for zeamatin, you’ll find many links to research papers on this topic. It would appear that corn meal’s anti fungal properies aren’t what I would call a myth per se. More research of course needs to be done, but to throw it out as a myth does seem short-sighted.

    1. Zeamatin has been extracted from corn meal, but its known antifungal activities seem to be limited to post-harvest fungi (i.e., those that affect harvested grain) and human pathogens. There is no evidence in the literature that this protein has any effect on soil-borne plant pathogens. And it’s a real stretch to take this lab-based research to application of corn meal to soil. As we like to stress, extraordinary claims require extraordinary evidence. We’re still missing the evidence for this claim.

      1. I believe Fusarium Oxysporum is the cause of Fusarium wilt. As far as I know it’s a soil-borne plant pathogen. In any event, the lab is where one typically starts. Any interest in carrying on the work to the field?

  65. Yes, that’s true, but the research was done on Fusarium moniliforme, which causes grain mold. There’s no publication on the species you mention and zeamatin.

    1. The publication I first mentioned, page 114, section 5.4.2 Anti Fungal Activity. It mentions oxysporum specifically. I already quoted it earlier.

      1. Matt, the problem with your quoted reference is that there are no data. It’s just a statement without any support. Do the authors refer to a particular study they reviewed for this bit of information? If not, then it’s hardly credible.

        1. You’re correct. This publication doesn’t possess the hard data. They refer to Stintzi et al (29), as a reference, but I don’t have access to the table of references. The data appear to be out there, it’s just a question of finding them.

          1. Having now conducted a pretty exhaustive search for Stintzi and zeamatin and/or Fusarium in the literature, I feel safe in saying that this research group did not study either zeamatin or Fusarium. They studied other pathogens and other bioactive compounds.

            The snippet you gave us, I believe, is a laundry list of bioactive compounds and another list of affected pathogens. Let’s look at it again:

            “The TLP’s known to have anti fungal activity include osmotin and PR-S from tobacco, AP-24 from tomato, zeamatin from corn, trimatin from wheat and protein R and S from barley. The susceptible fungi included Phytophthora infestans, Candida albicans, Neurospora crass, Trichoderma reesei, Trichoderma viride, Verticilium albo-atrum, Verticillium dahliae, Cercospora beticola, Fusarium Oxysporum, and Alternaria solani and included fungi belonging to the classes Oomycetes, Hyphomycetes, and Ascomycetes.”

            I don’t think this states that zeamatin has efficacy against Fusarium oxysporum. And since I can’t find a single published paper that links those two search terms together, then there’s no supporting evidence at this point.

  66. best advice is try it on a few tomato plants and see for yourself….not going to lose, cause cornmeal is a fertilizer…i choose to believe howard garret, the dirtdoctor, his advise is best on internet…he will also admit if he is wrong about something…

    1. You, of course, can believe what you like. But this is a science-based forum, and Howard Garrett’s advice is anything but scientific. (And cornmeal is not a fertilizer. Corn gluten meal, yes. Corn meal, no. It’s just another source of organic matter, and a heck of a lot more expensive than compost.)

      1. In response to those who believe that corn meal is a fertillizer: there is only one paper published on this topic. Here is the abstract:

        Gaskell, M.; Smith, R. 2007. Nitrogen Sources for Organic Vegetable Crops. HortTechnology 17, no. 4, p. 431-441. “Fertilization is the most expensive cultural practice for the increasing numbers of organic vegetable growers in the United States. Nitrogen (N) is the most important and costly nutrient to manage, and cost-effective N management practices are needed for efficient organic vegetable production. There is a wide array of organic N sources available, but they vary in cost, N content, and N availability. Compost and cover crops are commonly used sources of N for vegetables because they are relatively inexpensive and offer additional nutrients or soil improvement qualities in addition to N. Studies have shown that compost quality factors that affect N mineralization vary by source and among different batches from the same source. Compost carbon to N ratio should be equal to or less than 20:1 to assure net short-term mineralization. Cover crops also vary in N content and mineralization rate after incorporation. Leguminous cover crops decompose and release N more rapidly than grass or cereal cover crops at the preheading stage typically incorporated. Even the most efficient N-supplying composts, cover crops, or other organic N sources do not release appreciable N to a subsequent crop beyond 6 to 8 weeks from incorporation, and this burst of early N may not synchronize with N requirements for many vegetable crops. Other potential organic fertilizer N sources have been evaluated for vegetables, and they vary in N cost and N mineralization rate. Materials evaluated include seabird guano, liquid fish, feather meal, corn meal (Zea mays), blood meal, and liquid soybean meal (Glycine max) among others. Of those evaluated, feather meal, seabird guano, and liquid fish stand out as more economical organic sources of available N. Organic sources generally lack uniformity and are bulky, unstable, and inconsistent as a group, and this contributes to additional hidden management costs for organic growers. Liquid organic N sources for use in microirrigation systems may have additional disadvantages caused by loss of valuable nutrient N that is removed by filters.”

        So published research has demonstrated that corn meal is not a economical organic source of N. There are better choices.

  67. Jaymee, that article simply reports on the types of fungi in cornmeal. The cornmeal itself is not inhibitory. From the abstract: “A survey of different batches of corn meal for the inhibition of their fungal flora by propionic acid, benzoic acid, potassium sorbate, and Mold-X, a commercial inhibitor composed of four organic acids, revealed differences in inhibition so extreme that the batches of corn meal could be categorized as sensitive or resistant to the effects of an inhibitor.”

  68. The irony is this post is based on scientific proof that To every action there is an equal and opposite reaction! By trying to “bust the myth” you actually helped reinforce the fact that cornmeal has some anti-fungal qualities based on those that actually have tried it, seen the results first hand. I own a irrigation company and with over 400 plus accounts I’ve seen my fair share of fungus, including brown patch, dollar spot, leaf spot, phythium, fairy etc. Corn meal works! In fact I’ve gone 100% organic in my fertilizer regimen partly because of it. I grew up on a 800 acre grain farm, we always had the greeniest, healthiest lawn and the tastiest vegetables I ever had. Once a month like clockwork dad and I would load up the spreader with corn meal and spread it on the lawn. Then we’d head over to the bunny hutches, scoop up a couple shovels of poo and spread it in the garden! When I asked my dad why we spread cornmeal his reply was simple, it works!
    Linda, I respect scientific data, I respect your knowledge on gardening, but all though it’s not published in any scientific literature, IT WORKS! I’ve proved it!
    It also works great to make cornbread, pretty sure my great grandma used it before there was any scientific data to prove it!
    Excellent for killing ants as well, so give me your address I’ll personally ship you 100 lbs apply it to your home lawn at 20lbs/1000 to your lawn and report back tell let me know what you think! Sound good?

  69. Oh. My. God. Corn meal doesn’t directly kill fungus. How is that difficult to grasp? There’s really nothing to argue about. Corn meal may encourage the growth of other organisms that in turn kill or reduce fungus, but on its own corn meal is not a fungicide, if anything it’s just food for organisms which in turn kill fungus – maybe.

  70. Some new stuff from Garden Web June 2014 about cornmeal:

    Why corn meal is a better fertilizer than bone meal?

    clip this post email this post what is this?
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    Posted by Strawberryhill 5a IL (My Page) on
    Sun, Jun 8, 14 at 13:31

    Last fall I experimented with WHOLE-GRAIN corn meal as fertilizer … was impressed at how DARK GREEN plus leaves became shiny and glossy. Didn’t realize that whole-grain-corn-meal has 23% iron, 1% calcium, only 2% sodium, plus high in B-complex vitamins that boost plant growth.

    NPK of corn meal is 1.6 / 0.65 / 0.4 …. that’s better than horse manure NPK of 0.44 / 0.17 / 0.35. The biggest drawback of horse manure is the salt-content, plus the de-worming medications given to horse.

    Whole-grain corn’s minerals profile is impressive, with 39% magnesium, 23% iron, 29% phosphorus, 10% potassium, 30% manganese, 37% selenium, 12% copper, and 15% zinc. Iron deficiency cause yellowing of young leaves, versus manganese deficiency of diffused yellowing. I have both: iron deficiency in my pot plants, and manganese deficiency in my native clay.

    I checked the nutritional profile of bone meal: zero values on most, except for 90% calcium at 900 mg, and 36% phosphorus at 360 mg. My soil is limy alkaline clay, and I’m next to limestone quarry, with manganese deficiency in plants. There’s no need for me to use bone meal high in calcium, when my soil is rich in calcium carbonate.

    I used Epsoma Tomato-Tone for 10 tomato plants … these are dark-green. But the last 3 plants I used high-bone meal Jobe’s tomato fertilizer NPK 2-7-4, plus extra bone meal. These 3 plants are yellowish.

    I did a research on bone meal and chlorosis, one nursery reported yellowing of hibiscus with bone meal. Also found a second report of bone meal causing chlorosis and nutritional deficiency. See link below for pictures of purplish streaks on corn leaves with bone meal, plus yellowing of young leaves.

    Here’s the conclusion of Haiwaii County Extension: “With bone meal, there were purpling on the stems and yellowing of the early mature leaves. The leaves of higher rate of bone meal displayed chlorotic symptoms similar to manganese deficiency.”

    Below is William Shakespeare 2000 rose with manganese deficiency in my alkaline clay, pH 7.7 … The picture is taken years ago, now it’s greener since I fixed the hole with cracked corn ($2.99 for 10 lbs. from the feed store). You can see manganese deficiency with green veins, but yellow background. That’s different from iron deficiency, where the young leaves are pale.

    Here is a link that might be useful: Bone meal on bean and corn seedlings

    This post was edited by Strawberryhill on Sun, Jun 8, 2014 at 13:50

  71. *ahem*
    Does anyone know if cornmeal is really effective against slugs?
    Seriously, I read a great many of the comments and I thoroughly enjoyed watching how Dr Scott has stayed on point! Bravo, and jeez, people– what part of ‘we deal with science and you folks appreciate home remedies and that’s ok but we just can’t endorse that’??????
    Now, what about the slugs?

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