You could solarize the soil.

What I have seen on using corn meal as a disease suppressant came first from Texas A & M about using corn meal to control algae growth in ponds and then a report about corn meal controlling alfatoxin in peanut fields. However Georgia State University and Virginia State University did not get the same results as TAMU and TAMU pulled their report off the web. I can find nothing anywhere except anecdotal statements that it seems to work. Understanding the diseases may simply not appear in a garden can easily explain why some gardeners think it did work.

Johhny,
Southern blight is a miserable fungus! Over the past three years I have conducted numerous cornmeal experiments. Many here on GW have contacted me with their cornmeal trial results. At this point I will make the bold statement that cornmeal may be only control for Southern blight. I have received enough positive reports from others dealing with the problem. Cornmeal will control three types of fungus in the home landscape...
Sclerotina minor
Sclerotina rolfsii
Rhizoctina species.

And...the Latin name for Southern blight is...Sclerotina rolfsii.

However, you must treat your whole yard to have any success. Spread the cornmeal and water in throughly. Treat every six weeks if necessary. It works best during the warm months but you may still be warm enough to get one treatment down this fall. It is certainly worth a try this year. Treatment next year should begin early when the weather warms before there is any sign of the blight.

An important P.S......Many are using cornmeal as a lawn fertilizer which is okay. EXCEPT....in my experiments I have found that repeated heavy doses of cornmeal on Centipede grass kills it. I have had no reports of injury to other types of grasses fertilized with cornmeal. Those with Centipede can certainly sprinkle cornmeal on and around Brown patch spots which will kill that fungus in about three weeks. No problem with that type of treatment.

I don't think I would want to use it on the whole yard, as usually it only infects relatively limited areas (it tends to come in with annuals and perennials grown further south of PA, which has helped me decide never to buy plants from southern nurseries). I've never seen it affect lawns here, but it does get on Hosta, Sedum, Corydalis, Ajuga, and occaisionally daylilies. It's only fatal on the ajuga and sedums.

So Kimm, is it worth a try around infected plants?

I have had success using 200:1 neem oil as a drench, but this is rather expensive, and probably kills a lot of things I don't want dead (but unlike solarization or steaming, it does leave the plants still standing).

If you wish to try it you can always do that, but if it does appear to control the blight then you may need a control study to see if the corn meal actually did control it or it was just happenstance.

To extend Kimmsr's advice a tad further:

And you need a professional lab to ID the fungus you are trying to control.

It's definitely southern blight...the sclerotia are pretty much a giveaway, at least in these parts.

The TAMU website was down over the summer but it's back up now.

http://stephenville.tamu.edu/~clee/pdncr/index.html

Many are using cornmeal as a lawn fertilizer which is okay. EXCEPT....in my experiments I have found that repeated heavy doses of cornmeal on Centipede grass kills it. I have had no reports of injury to other types of grasses fertilized with cornmeal.

This is extremely interesting information to me. I am becoming convinced that there is a symbiotic relationship between certain microbes and the plants that they inhabit. In southern lawns crabgrass is killed out by dusting it with baking soda. The crabgrass turns black and dies sometimes overnight but usually within 4 days. I could be wrong but to me anything that turns black (without being cooked) has been killed by a fungus. My theory is that the baking soda kills an important fungus species on the crabgrass which normally protects it from other fungal diseases. Once the protectant fungus dies, the plant is susceptable and gets sick. It could be the same thing happens with the corn meal on centipede. How long does it take for the centipede to die out? Usually it's hard to get rid of.

You can always biofumigate your soil by growing a brassica crop (mustard greens or seed and some varieties of radish work best), incorporate it into the soil and wait 4 weeks for it to decompose, releasing toxic gases that kill fungi and other pathogens. You can also solarize during this period, which traps the gases and compounds the anti-pathogen effects of the biofumigation. Either way, this should prevent the disease.

I had a bad outbreak of Southern Blight that laid waste to an area planted with various hostas and two varieties of ajuga (Black Scallop and Chocolate Chip).

Almost all the CC rotted. BS was more resistant. Hostas were ok. When I figured out the problem, I used a fungicide and the remaining plants returned to health. But I have been trying to go organic, and I wanted to better understand any ill effects of using a fungicide-as well as to learn alternative treatments. The corn meal treatment is new to me. Do you just sprinkle it around the plant and water it in? And what about organic fungicides?

There is no good organic control of s.blight except solarization and steam. Steam treating is out of the hands of many people, but solarization of the soil to kill s.blight can be done in a single day (or a few days to be extra safe) by getting the temperature up to 140-160F for at least an hour during the soliarization. You may have to use a double-tenting method and/or forgo early planting in order to get this kind of temperature range, though.

Almost all organic fungicides for -soil- (different story, and more effective on plant surfaces) are weak to non-effective. If anyone ever finds a good organic soil fungicide, strawberry producers would be doing backflips.

Lucky this southern blight doesn't attack maize, huh? or there'd be no cornmeal to treat it with.

Has it really been that long since this topic was discussed?

I absolutely rely on cornmeal as a fungicide in my lawn. It is the only thing that works, chemical or organic. If you apply at a rate of 20 pounds per 1,000 square feet (or 2 pounds per 100), and reapply in 3 weeks, it should take care of your fungal diseases. You do not water the cornmeal in. You moisten it and let it do it's thing. If you water it in, you might wash it away.

Organic fungicide? Can anyone name one? I guess I've heard of neem oil being used that way. Sulfur? I consider sulfur a chemical. Corn meal is organic but it is not a fungicide in the way chemical fungicides work. Cornmeal works by preparing a good foundation to repopulate the soil with the Trichoderma fungus. Trichoderma (try koh DER ma) is a predatory fungus that feeds on the cell walls of other fungi. Cornmeal may come with Trichoderma already "installed" but otherwise, it just promotes the proliferation of the Trichoderma.

The problem with using a chemical fungicide is that soil health absolutely depends on a healthy population of fungi. If you use a fungicide, you will have to start over with new fungi. Fortunately by using simple compost you can do that. I would give the fungicide 2-3 full weeks to dissipate before adding the compost back.

I believe TAMU took their cornmeal/fungus page down because it generated so much grief among the organic folks. TAMU is almost completely anti-organic - hence the issue with it. All I can say is that cornmeal has worked to eradicate brown patch for me every time I've tried it since 2002. In fact the performance of cornmeal against disease is what convinced me to try organic fertilizers.

Regarding Nandina's findings on centipede grass: I believe the problem is with increased fertility. Centipede does poorly in a well fertilized soil.

If you don't already have a healthy population of Trichoderma fungi in your soil you can do more harm than good by dumping a bunch of carbs into your soil.

Many people have a hard time reproducing the observations made by the TAMU peanut field observation (not experiment).

Usually the worst that happens is a battle between good/bad that gets fed and you've wasted some money on corn meal to dump into the ground rather than ruining anything. In some soils it evidently works. In some soils it makes the situation worse.

If you know what kind of fungi you're working with in your soil to begin with it'd help, but that's a bit out of most people's gardening scope.

It seems to have more positive results in dry/arid areas. Parts of the North-West and South-East US have seen a lot of the negative effects.

If you choose to play around with it, make sure you use a true corn meal and not corn gluten/corn meal gluten. That's just going to be a mess.

Good points, nc. One of the first things that happens when you apply corn meal for the first time is the preexisting population of trichoderma builds up. The reason I suggest the second application 3 weeks after the first is to pile on once the population is built. I have never needed it as my lawn is always in full recovery at the 3 week stage.

I agree that many people cannot reproduce the observations. Nandina, one of GardenWeb's more studious members, has tried corn meal and found that it worked very well. Still, that is only a few trials. What needs to happen is someone needs to test it on a large scale. But first they need to become familiar with the concerns, issues, and underlying concepts. I think part of the problem is it is hard to find soil that is not already in affected by prior applications of various chemicals which work against the corn meal approach.

I cannot think of what circumstances would make corn meal a wasted effort. It is an organic fertilizer by itself. If nothing else the protein in the corn improves the health of the soil microbes. What negative effects are you talking about?

One of the reasons corn meal is beneficial is the user does not have to have a Ph.D in mycology to identify the disease. The trichoderma do that for you. If you don't see any improvement in 3 weeks, it is time to apply the chemicals. I would start with baking soda or maybe sulfur before going to the bottled fungicides.

There are two popular corn products. One is ordinary whole grain corn meal. That is what we're talking about as an anti fungal material. The other one is corn gluten meal (CGM). CGM is an ultra high protein organic fertilizer. Again, I cannot think of circumstances where you would create a mess by using CGM...unless you are referring to the delay in attacking the disease. I am about to apply both products so if I see a mess, I'll let you know.

I've broad spread organic cornmeal & baking soda in my small garden lot. NJ is known for high humidity. I put it to prevent Blumeria graminis (PM). We had a very hot, wet summer, however, there was no PM on any of my plants (flowers & roses). Whether this was due to cornmeal & BS, I don't know. I'm not that well knowledged in soil mycology.

This is my question to you all. For those of us that use micronutrients or organic fertilizers, by adding the cornmeal and/or BS are inadvertently killing off the good fungi and soil microbes? Is this a Double Indemnity?

When cleaning out the flower garden, I noticed the soil especially the top 2 inches had become very dry and sandy, and I believe this is the after effect of the cornmeal and BS. So I am adamant about repeating this process again this season particularly since I've added Azomite & Gaia Glacial rock dust to get my soil back to the way it was.

Are there more reports out there on organics and mycology?

PS: I did not use this on the vegetable garden because the soil needs to be seriously amended.

Is the corn meal genetically modified? Unless it states it ISNT, then it probably IS and we all know what they did to make it that way.

The corn will continue to produce the killing ingredient it was made to in the lab. Whether it be a pesticide which is LETHAL to MOTHS, BUTTERFLIES in the larval stage and is now a known problem to BEES. This corn does not NEED a bee to pollinate. The gmos will spread to other areas and contaminate.

Please due diligence here. RESEARCH. Our globe needs help and so does our food. Say no to gmos. They aren't that great. Even though the Trillion dollar corp that makes it and the government agencies paid to keep quiet will not let that out.

http://www.dirtdoctor.com/newforum/root/cornmeal-for-fungal-control-gmo-corn-t19684.html

This post was edited by worriedone on Thu, Jan 17, 13 at 13:40

Moth, butterflies, and bees aren't going to dig in the dirt to mess with corn meal...it's not pollen.

This should be laid to rest, but folk continue to waste their money on inappropriate uses of cornmeal. BTW, the Texas study which some can't seem to find was about crops rotation and peanuts, and had nothing to do with lawns. I believe that it was also about the use of corn gluten meal, which is what is milled off of whole grain corn, so that organic farmers can pay a great deal more for a product that is ineffective in most turf situations, and is sold cheaply to pet foods manufacturers, is a mess when misapplied (if you must do it, use a rolling hopper fertilizer spreader rather than one of those rotary crank hand-held devices that fling the stuffs to the wind), and is a great food for snails, some rodents, some insects, and is not a good substitute for a good soil base built up by conventionally composted organic materials mixed in with your local soil (if you need to do that where you live). On the plus side, as a fertilizer in a healthy turf, it (the corn gluten meal) decomposes slowly, so releases nitrogen at a rate beneficial to your turf...just expensively.
Now then, if you were trying to grown peanuts in your lawn, then do a bit more work and find the original research.
For more info, look up the WSU garden notes from WSU extension in Puyallup, WZ.

I do not recommend the WSU extension in Puyallup, WA if the link below is the intended site (I feel the comments to the link do a sufficient job of explaining why I do not recommend it.):

https://sharepoint.cahnrs.wsu.edu/blogs/urbanhort/archive/2010/06/30/cornmeal-myth-busted.aspx

--------------------------------------------------
cornmeal application come under the heading of "biological control".

In the article cited below, my cut and paste will not work. Use the PDF "Find" command to see how cornmeal was used.

------------------------------------------------------------------------

A second article that you may find of interest is:
"USING TRICHODERMA SPECIES FOR BIOLOGICAL CONTROL OF PLANT PATHOGENS IN VIET NAM"

http://www.issaas.org/journal/v16/01/journal-issaas-v16n1-03-tranha.pdf

Here is a link that might be useful: cornmeal - biological control literature example

Thank you, Henry, for the above link. I respect Henry for his research. He's a retired chemistry professor, and got his Ph.D. when I was still in my diaper.

Roses are known for fungal diseases: rust, black spot, mildew. I have 55+ varieties of roses. I dusted them with WHOLE-GRAIN corn meal in late fall (non-stop rain).

At first I tried refined corn meal, but that didn't work, WHOLE-GRAIN corn meal works because of the fatty germ layer, which is documented in a lab to be anti-fungal, due to the Proprionic acid produced. Google that and you'll see.

I was happy with the result: clean roses, while my annual impatients flowers got black spots. I posted pictures as proof in the English Roses forum. See link below:

Here is a link that might be useful: Whole-grain corn meal to prevent black spots on roses

This post was edited by Strawberryhill on Sun, Aug 25, 13 at 0:01

Here's an excerpt from an ABSTRACT in below link of the anti-fungal effect of whole-grain corn meal (has the fatty germ layer):

"The effect of mixing varying amounts of soybean meal, fish meal, poultry by-product meal, corn gluten meal, fat, and limestone in corn meal on the antifungal activity of propionic acid was assessed by measuring the production of CO2 by fungi in the mixtures. Antagonism was observed with soybean meal, fish meal, poultry by-product meal, and limestone. Corn gluten meal was without effect while the addition of fat to corn meal enhanced the activity of propionic acid."

Below is a picture of my 6 Austin Roses in front (Wise Portia, Golden Cel., Christopher Marlowe, Pat Austin, Lilian Austin, and Queen of Sweden). They are clean, no fungal diseases whatsoever for the past 3 years.

The key? Keep soil surface dry and alkaline to prevent fungal germination. pH of cooked corn is 7.3, and the pH of dry corn is alkaline, above 7.5. The pH of baking soda is very alkaline, from 8.3 to 8.5. In my college microbiology lab, fungal growth is minimal when it's dry and alkaline.

Another rosarian wrote in his blog that alkaline soil produce pale roses, while acidic soil produce roses prone to black spots fungal infection. I have alkaline clay soil, pH 7.7 (tested by EarthCo.), my roses are pale-in-color, but have very little fungal diseases.

Here is a link that might be useful: Antifungal activity of Proprionic Acid

This post was edited by Strawberryhill on Sun, Aug 25, 13 at 0:16