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Update on using cornmeal to prevent blackspot

Posted by Nandina 8b (My Page) on
Sun, Apr 21, 02 at 20:30

All the rose growers report having success warding off black spot by sprinkling cornmeal once a month on the ground around roses. So, I decided to try it this year. To date all my roses here in the south are free of black spot....except for one which has never shown any sign of blackspot over the past five years until now. I am mystified by that!

And I decided to also try the cornmeal sprinkled around my container grown tomatoes to see if it would stop the tomato fungus problems. Usually by this time of the year the bottom stems have browned and are falling off. I wish you could see the tomatoes. Not a sign of fungus problems. Plants are fully branched and touching the soil. And they are a vivid healthy dark green. I attribute this to my second experiment. Once a month I mix 2 tablespoons of old-fashioned blackstrap molasses into a gallon of water and water the tomatoes with this. Our tomato season ends June 21st here because of the heat. It will be interesting to see how well these tomao plants grow through the rest of the season.


Follow-Up Postings:

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RE: Update on using cornmeal to prevent blackspot

i'm headed to the pantry for the cornmeal right now! black spot definitely a problem here and this is exciting news for me :-) thanx for sharing! theresa


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RE: Update on using cornmeal to prevent blackspot

  • Posted by Byron 4a/5b NH (My Page) on
    Mon, Apr 22, 02 at 20:01

What tomato fungus problems?


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RE: Update on using cornmeal to prevent blackspot

Corn meal from the feed store is about $5 for 50 pounds. If y'all decide to go into mass usage, spring for the big bag or else you'll forever be running to the grocery store.


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RE: Update on using cornmeal to prevent blackspot

This is EXCITING!!! I didn't want to bake that darned cornbread anyway:)


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RE: Update on using cornmeal to prevent blackspot

This is straight corn meal or just the gluton?


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RE: Update on using cornmeal to prevent blackspot

We are talking about straight corn meal used for corn meal muffins, etc. It does get confusing! Use regular, edible corn meal scattering it under plants prone to fungus problems once a month beginning in early spring. Corn meal gluten is applied in the early spring as a pre-emergent weed killer on lawns and gardens. Both types should be available at your local feed store.


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RE: Update on using cornmeal to prevent blackspot

I wonder if gluten would work the same way, that way I could kill 2 birds with one stone. Or is it another part of corn that affects blackspot?


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RE: Update on using cornmeal to prevent blackspot

Sorry, here it is again.

Edible cornmeal is used for our fungus experiments. The gluten will not work as it is a processed substance.

Cornmeal gluten is used as a pre-emergent weed killer not as a fungicide.


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RE: Update on using cornmeal to prevent blackspot

I know that the gluten is used as a weed killer. I was just curious as to what part of the corn acts as a fungicide. I think I have some old corn on hand that's past its prime for bread, so I'll grind it up and put it around a couple of roses.
Thanks for this thread. I hadn't heard of using corn meal for a fungicide. Is this a fairly new discovery? I never came across it on the rose forum before, but I haven't been there much for a year or so.


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RE: Update on using cornmeal to prevent blackspot

Nandina, what happened with your tea oil as a fungicide experiments?

I have heard of using a high nitrogen fertilizer sprayed under fruit trees to "consume" the overwintering disease spores. Does the corn meal work in the same way?

On my market farm I have used from time to time soymeal (if from organic soybeans) as a good nitrogen source. I wonder if such a meal, derived from the oil-pressing residue, would have a similar effect?


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RE: Update on using cornmeal to prevent blackspot

Marshall,
I am delighted that you have returned to posting on the garden forums again. Your expertise in organic farming has been missed by yours truly.
Tea tree oil experiments on fungus problems have been discontinued. Yes, I believe that TTO does kill some fungi. However, I found that even light sprayings with it left a very sticky coating on leaves which captured and held whitefly and tiny gnats. Within a few days of spraying the plants, although very healthy, would look unsightly with all these critters attached to them. Not something that the average gardener wants. But, I still soak my seeds in 3 drops of TTO to 8 oz. of water for an hour before planting them to kill off any fungus spores. This method or another of soaking seeds in a 10% peroxide solution seems to work the best. And, both techniques appear to speed up germination by several days.

I am not any good a linking things. But if you will scroll down on this Forum to Dschall's posting titled "Update on my experiment with sugar and cornmeal on lawn"...toward the end he posts the science behind using cormeal. It is very informative reading. But, you raise an interesting question to which I do not have an answer. First, I do not know the nitrogen content in cornmeal. Can anyone dig up that figure? But, if what you say is true that spraying high nitrogen fertilizer in the early spring consumes overwintering disease spores....then spreading cornmeal gluten, which is 10% nitrogen, heavily under fruit trees should do the job and also deter sprouting weed growth. Perhaps you would trial it next year. An early application of cornmeal gluten followed by monthly applications of cornmeal through the growing season.


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RE: Update on using cornmeal to prevent blackspot

Nandina, nice to be back with friends again.

Let me clarify the role of nitrogen in suppressing overwintering fruit tree diseases. Litter from the trees carrying innoculi of these diseases overwinter so that with warming weather and raindrop splashing, the spores end back up in the tree. An early winter application of Urea or other highly soluable chemical can be used to break down the litter quickly and so destroy the overwintering diseases. Other sources of nitrogen, such as manures and blood meal were less effective because they rely on warmer temperatures for maximum soluability through bacterial action.

I rather not add too much N during the growing season because too much N will force excessive growth at the expense of flowering a fruiting. The effect could last through the next year -- I know this well because a worker overfertilized my fig grove last year and now we are still growing massive fig leaves, long branches and few figs.


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RE: Update on using cornmeal to prevent blackspot

Byron- I am trying cornmeal for tomato fungus problems, but it's still too early to tell. I usually don't have problems with tomatoes until around the beginning of July when it really starts getting hot around here. I am using the coarse grind that you get from feed stores rather than the grocery grade. Reportedly, the cornmeal encourages growth of organisms that keep the fungal organisms in check. Won't hurt to try.
Mrs Hunter


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RE: Update on using cornmeal to prevent blackspot

does any one have guinea's and cornmeal? i am getting the birds tomorrow and before i toss my cornmeal out under the tomatoes and roses i wanted to make sure i would not start a bird stampede to them.

thanks
reg


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RE: Update on using cornmeal to prevent blackspot

  • Posted by Byron 4a/5b NH (My Page) on
    Tue, Jun 4, 02 at 19:05

Marsh, Glad to see you back,
Granite state had 3 in of snow on May 18th and near hurricane conditions on the 30th, Wiped out cole, root and leaf crops, Tomatoes and peppers are still in greenhouse.
Still too cold to plant out.

Nandina

Sorry Tea Tree did not work out.


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RE: Update on using cornmeal to prevent blackspot

Hey, Byron, bet you wish you were here... (ha!) I gambled successfully on the Spring weather, guessing that Spring would be drier and warmer than usual. Last year I guessed the opposite and saved myself some grief. The previous year I planted my summer stuff early and ended up replanting because of widespread mildews and blights.

So I am looking at pole beans, peppers, tomatoes close to harvestable stages while still picking snow and sugar snap peas.

Your experience reminds me of a Spring in early 1950s when we got a foot of snow about the first week of May in middle Conn. Valley of NH and VT. We still planted the garden in the last week of May/first week of June, hoping that Indian Summer would not be kicked off by a killing frost in Sept.


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RE: Update on using cornmeal to prevent blackspot

Nandina wrote:

First, I do not know the nitrogen content in cornmeal. Can anyone dig up that figure?

Hi there...just a wild guess, but I'd wonder if regular cornmeal is in the same ballpark as corn gluten meal for nitrogen content, i.e. 10-12 percent. Just a thought...

Jason


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RE: Update on using cornmeal to prevent blackspot

Jason,
I am going to guess that cornmeal has less than 10% nitrogen. I have been spreading it over and around a few sections of brown spot in my Centipede lawn and note no increased greening and/or vigor of growth in those areas. I would expect to see this if dealing with 10% nitrogen. But, I can happily report that the cornmeal applications, to date, are working and the lawn is filling in and regrowing in the brown spot infected areas.

As I reported in an earlier post, I am noting that my roses are free of blackspot with a monthly application of cornmeal around them. But........those roses that I purchased because they are very disease resistant and have never shown any signs of blackspot are covered with it this year for the first time. I am anxious to know if anyone else trying the cornmeal experiment is noticing a similar situation. I will not treat those specific roses next year and see what happens.


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RE: Update on using cornmeal to prevent blackspot

  • Posted by Byron 4a/5b NH (My Page) on
    Thu, Jun 6, 02 at 7:16

I read one report claiming cornmeal had a N = 9

Marsh, I just barely remember that 50's storm

I think as the canoe floats Brattleboro was about 50 miles
downstream


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RE: Update on using cornmeal to prevent blackspot

This is what Texas A&M University says about corn meal...

Biological Control of Soilborne Fungi
It is known that certain fungal species in the genus Trichoderma feed on mycelium and sclerotia of Sclerotinia minor. Sclerotium rolfsii and Rhizoctonia sp. All peanut fields in Texas tested to date have a natural population of Trichoderma. For several years, tests have been conducted in Texas using corn meal to stimulate Trichoderma development as a way to control the major soilborne disease fungi. When yellow corn meal is applied to fields in the presence of moist surface soil, Trichoderma builds up very rapidly over a 5 to 10 day period. The resulting high Trichoderma population can destroy vast amounts of Sclerotinia, Sclerotium and Rhizoctonia. This enhanced, natural biological control process is almost identical to the processes that occur when crop rotation is practiced. The level of control with corn meal is influenced by: 1) organic matter source 2) soil moisture, 3) temperature, and 4) pesticides used. Seasonal applications of certain fungicides may inhibit Trichoderma. Testing will continue to determine the rates and application methods that will give consistent, economical control.

Here's the link to the whole article...

2002 Peanut Disease and Nematode Control Recommendations

Our local (San Antonio) organic gardeners are reporting that corn meal is working for many more fungi (including toenail fungus). A few (very few) ranchers and vets are reporting on the use of corn meal spilled into horse and cattle bedding to reduce the time leg wounds take to heal.

Regarding the nitrogen content of grains: I'll have to bookmark it and save it next time I see it. I've found websites that report that stuff for oats, alfalfa, wheat, corn, soy, sorghum, rice, etc. and, as I recall, all of them were in the area of 10% protein. I don't know how protein converts to nitrogen. Corn gluten meal was also listed and was in the 10% range. Corn is the product that seems to be the most highly processed. Not all processed corn products have all that nitrogen, but most that retain the corn kernal in some ground or cracked form retain the N. Certainly corn cobs don't.

I think the point about the nitrogen is really off the theme of this thread. Any ground grain can be used as a fertilizer applied at a rate of about 10 pounds per 1,000 square feet. Twice as much won't hurt anything (maybe your wallet). Less will give you less results.


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RE: Update on using cornmeal to prevent blackspot

When I was a kid I remember people using corn flour dusted in shoes and boots to control foot fungus...even dusting the stuff in more private places...


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RE: Update on using cornmeal to prevent blackspot

Any idea if corn grits would be as effective as corn meal? I'm not sure what difference, if any, there is between grits and meal. I am looking for organically grown corn meal but can only find organically grown grits and flour.


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This is making me VERY hopeful, but does anyone know if the corn meal will help when the black spots have already started? I have many small fruits that still appear ok, but I've also plucked a half dozen or so bad fruits already. If I start using the corn meal now, do I have a chance of at least SOME healthy tomatoes?
Thanks!


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RE: Update on using cornmeal to prevent blackspot

Freaky, I'm waiting for an answer to that myself. I have some strawberries that already have black spot, and I was wondering if I should use corn meal or something stronger.

Debbie


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RE: Update on using cornmeal to prevent blackspot

A few thoughts in response to some questions asked above........

1. Yes, I would suspect that grits could be substituted for cornmeal. Remember, this is all an experiment we are trying. So, trial and error is important, as in any experiment.

2. Will cornmeal applied later in the growing season stop fungus problems? I don't have an answer to this question. Try it and see. Generally, when one is dealing with a known, annual fungus problem it is best treated with any type of fungicide early in the growing season onward.

3. Just to report my latest observations. All my roses, including those that were showing signs of blackspot, are blackspot free as of today. However, the tomatoes are now showing signs of fungus problems. Remember, I am growing in a very difficult hot, humid climate where the tomato season ends in June. I would urge northern gardeners to keep experimenting with cornmeal around tomatoes to see what results you notice.


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This is a fascinating thread and I thank you for supplying such useful information. I will try it and report back later in the season. Reports from people all across the country, or around the world, would be interesting reading.

Mary


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RE: Update on using cornmeal to prevent blackspot

  • Posted by Mikie z9 St.Pete.FL (My Page) on
    Mon, Jun 17, 02 at 21:50

nitrogen content of grains
percentage of crude protein divided by 6.25 = percent N

ie;
10% protein / 6.25 = 1.6% N


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RE: Update on using cornmeal to prevent blackspot

Hi All,
Just my 2 cents worth. I used cornmeal last season on my Cecil Brunner climbers. Only one application, so far no black spot this year.
Dev


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RE: Update on using cornmeal to prevent blackspot

It has now been about 3 weeks since I first used cornmeal. All the leaves on my fig had rusty spots all over them. New leaves became speckled well before they were full sized. Within a few days of applying the cornmeal (I even sprinkled it on the leaves), the plant put out a huge flush of new leaves. To date, these leaves are perfect. The old leaves with the spots and cornmeal are still in place, so I can tell the before and after leaves. There has been no change in the weather since I applied the cornmeal. We have had daily rains since the beginning of June!

I'm putting cornmeal around all of my plants now.

I will keep you posted about the fig.


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RE: Update on using cornmeal to prevent blackspot

I haven`t tried this yet, but I heard on a radio gardening show that common grits spread on the ground would eliminate carpenter ants. Anyone else heard or tried this?


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RE: Update on using cornmeal to prevent blackspot

I have had mixed results with cornmeal to prevent blackspot. I suspect that I may have applied the meal after some blackspot had already started to develop so I will have to wait until next year to apply it early in the spring. We have 6 hybrid teas (1 climber), 1 floribunda, 5 David Austin's and 6 mini's in the test area. Other hybrid teas and mini's in another part of the garden have never had blackspot so I didn't treat them.

Here is what has happened so far. I put name-brand cornmeal around the roses, leaving 1/2 of one bush(David Austin Othello) and one entire bush (David Austin Heritage) untreated around June 15. Within a few days a hybrid tea - Medallian, had blackspot on some lower leaves which I promptly removed. Medallian continued to develop blackspot, so I put more cornmeal around it. This continued and I quickly ran out of cornmeal so I spread some yellow corn grits that we had in the cupboard around it. I happened to watch a cooking show later that day where the chef was making polenta. According to the chef, corn meal has the germ removed so it is preferable to grits for polenta because the germ contains oil that becomes ranacid.

The second week in July, Smokey, a hybrid tea next to Medallian that has historically suffered the most from blackspot had numerous infected leaves. I removed the infected leaves and spread yellow grits. Last week Othello had blackspot on the untreated side. By now I was out of yellow grits so used the white grits from the cupboard around all of the bushes except Heritage.

None of the other roses have had signs of blackspot so far. Medallian has endured and has only had a couple of bad leaves since the application of yellow grits. Othello hasn't had anymore blackspot since the white grits so far. I think Smokey is a lost cause but provides a good tesing ground for my next experiment - Blue Corn Tea.


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RE: Update on using cornmeal to prevent blackspot

I am amazed ,I just went thru the Master Gardening program
and all they ever told us was that there was nothing you could do about black spot.
Just goes to show you that the experts really don't know everything.
Thanks for sharing will try that next season.
Sharyl


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RE: Update on using cornmeal to prevent blackspot

Difference between corn meal and grits is that the corn is turned into hominy, dried and then ground. My mother used to make it annually. It is soaked in lye water to remove outer coating (hull) and the germ....seems like there was also cooking and I remember lots of rinsing to remove lye.

My box of girts calls it Hominy Grits in the ingredients list.


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RE: Update on using cornmeal to prevent blackspot

Degerminated cornmeal is like white flour. Stoneground cornmeal is like whole wheat flour. But both are cornmeal, i.e. ground-up corn. Corn flour is just very finely ground cornmeal, of either type. And for polenta, it's traditional to use coarsely ground cornmeal, of either type. Grits and masa harina are different, being corn treated with lye and then ground up to different consistencies. You can check if it's whole-grain or degerminated by seeing if there's fiber listed on the nutrition label. No fiber = degerminated.

In any case, I've been using whole-grain cornmeal around the blackspot-prone roses, with neither rancidity nor blackspot so far. Though with the drought, it's possible there wouldn't have been any blackspot anyway.


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RE: Update on using cornmeal to prevent blackspot

Another success story here - one newly planted rosebush lost all it's leaves to blackspot, and another started developing spots. Used the cornmeal treatment - they are both now flourishing.

THANK YOU!!!!


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RE: Update on using cornmeal to prevent blackspot

  • Posted by Byron 4a/5b NH (My Page) on
    Mon, Aug 12, 02 at 16:22

If grits works, best place for them.


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RE: cornmeal for yellowing leaves?

I just noticed some yellowing of leaves on 4 of my tomato plants, no black spot. Wondering if cornmeal would benefit.


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RE: Update on using cornmeal to prevent blackspot

Byron,
You be wrong.....best place for grits is with my eggs (sunny side up) and bacon on saturday morning....Ain't nuthin' finer in Caroliner....

See ya in the garden,
Joe B.


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RE: Update on using cornmeal to prevent blackspot

Byron, your regionalism is showing :). Truly, I"m Southern born and bred and I'm not fond of grits either (except the cheese variety,) much prefer yankee hash-browns with lots of ketchup. But I'm interested in the report that grits might be effective against carpenter ants. So far nothing seems to get rid of them ...


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RE: Update on using cornmeal to prevent blackspot

Joe B you could be wrong, too. Let's not limit the bacon, eggs and grits to Saturday morning! ANY morning is good and here in Alabama, that's a fine supper, too...I'll SHARE my grits, but even the garden doesn't get them all!


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RE: Update on using cornmeal to prevent blackspot

I have a question, did anyone have a problem with ants after using the corn meal? and if so how bad was it. Thank you for your time.
Kelly


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RE: Update on using cornmeal to prevent blackspot

Hi all
First off I would like to thank you for having such a usefull thread. You all seem to be so into this. My next question is why no one deemed it important enough to answer my question. Sorry if this offends anyone, just wondering. I do work in this field and felt confidant you would have some answers for me. Sorry to have bothered you, thanks for your time.
Kelly


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RE: Update on using cornmeal to prevent blackspot

Sorry, Kelly,
I was waiting to see what others might report on the subject of ants and cornmeal. I have not seen any increase in ants in my yard, including fire ants. I did note one spot where some type of ant had dragged and piled up grains of cornmeal near a hole. However, it just remained on the surface and it does not appear that they took it underground. If anything, they helped to disperse it.


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RE: Update on using cornmeal to prevent blackspot

  • Posted by Mikie z9 St.Pete.FL (My Page) on
    Sun, Sep 15, 02 at 20:45

3 handfulls of corn meal in water growing fungus in gallon milk jugs attracts worms & slugs
no ants


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RE: Update on using cornmeal to prevent blackspot

Thanks guys the reason for the question was I had devoloped black spot on a shrimp plant,(JUSTICIA brandegeana), I used the corn meal and had an infestation of the small black ants the first two days , although they seem to be disapearing now and the black spot is getting a little better also? I appreciate everyones help and look forward to lurking and occasionally posting on this thread. The plant was also in my greenhouse and I had not seen signs of ants in there before??
Thanks Kelly


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RE: Update on using cornmeal to prevent blackspot

Kelly, we have always had alot of ants in the garden, so I couldn't say if cornmeal attracted ants.

Here is an update on my cornmeal experiment. I tried spreading regular yellow cornmeal under the roses, then corn grits (yellow & white), then sprayed blue cornmeal tea, then yellow corn meal tea, spread more yellow cornmeal on the ground. We still have blackspot on the roses that developed it early on. The bushes in the main rose garden that didn't have any bs early on had very minor bs that the teas took care of. Those that have never had bs outside of the main garden didn't have become infected.

We also have an heirloom yellow pear tomato sprawling through the main rose garden. I read on I think the organic rose forum, that tomato plants prevent blackspot.I planted the tomato before I read this and didn't intend for it to be part of an experiment. The roses that had bs first are in the middle row of the garden. The roses that had the least bs have the tomato forming a barrier between them and the middle row. Those that developed bs in the other rows had no tomato barrier early on. So the tomato may have been another factor.

Next year, I'll put cornmeal out very early. I'll never plant another indeterminate tomato plant. It is huge! I've never seen anything like it. It's an especially bad choice for a rose garden if you want to pick the tomatoes.


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I've been following this posting and one by dchall with a lot of interest, although I found it too late to save 3000 sq.ft. of lawn from brownspot, crepe myrtles from sooty mold...you get the drift! My question is: If the cornmeal works so well, is there any reason to wait instead of applying it now? If it encourages the growth of beneficial, fungus eating organisms in the soil, would it do any harm to start early and work it right through the growing season? I'll be more than happy to be the "experimenter" to give it a shot, but if anyone knows of reasons not to do this, please let me know! I want to do a throrough "blanket" application, to cover lawn, roses, trees that are susceptible and garden areas. Please share your thoughts...


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RE: Update on using cornmeal to prevent blackspot

FlwrLdy,
We are still in the learning mode concerning the uses of cornmeal as a fungicide. You are in zone 7 which means a mild winter. You certainly can spread cornmeal now while your weather remains warm. And repeat the treatment early next spring when the weather warms. If you wish to do monthly treatments next year, go ahead. But, at this point I think, based on my research, that a spring application and another about the end of August should be sufficient.

The sooty mold on your crape myrtles has been caused by whitefly. Whitefly is very difficult to control. But, you say you are willing to experiment, so I would ask you to try the following. Next year when your crape myrtle leaves have reached almost full growth, treat them with the following spray. Place 1/2 cup of cornmeal in a gallon jug of water. Let this sit two days until it smells yeasty. Strain through a coffee filter and put the corn liquid in your hose end sprayer. Put the dial setting to its highest number and spray the tree heavily. Repeat once a month during summer months. This treatment will not stop the whitefly problem, but it will be interesting to see if the fungus which is caused by the 'honey' they exude can be controlled using this type of spray. I have no idea if this will work. Let's find out.

The important thing to remember about fungicides, be they organic such as cornmeal or one of the commercial types is that you must begin treatment each year in early spring. This is also true of seedlings you are raising that are prone to fungus problems, such as tomatoes. Treatment must start when they first pop up from seed to have complete protection from fungus problems.


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RE: Update on using cornmeal to prevent blackspot

I get started early in the season. I scatter a cup of corn meal under each rose when I prune it on Valentine's Day. If I had tomatoes, I would put the corn meal down on the day they were planted.

I like Nandina's suggestion to use corn tea on crepe myrtles.


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RE: Update on using cornmeal to prevent blackspot

Most often, though, the sooty mold on crape myrtles is caused by the honeydew exuded by aphids, not by whitefly. Therefore, the better control is to get rid of the aphids at an early stage.


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RE: Update on using cornmeal to prevent blackspot

Thanks for all the input. I will put down some cornmeal now and then again in the early spring. Nandina, I thought you had said you were putting it under your roses every month...I didn't see any whiteflies around the crepe myrtles, but will be more than happy to try the spray.
This was certainly a fungus year...lost the whole fescue lawn to brown spot. We had/still have a phenomenal number of mushrooms of incredible size and colors sprouting all over the place, including places we never water. A large bag of cornmeal from the feed store is a small price to pay!
I will keep you updated.

And dchall, would this be a good time in my area to put the cornmeal gluten down on the lawn? Lawn isn't my "thing", but, boy, would I make some wife points if I found a way to give the honey that green, thick healthy lawn he wants to mow! Thanks. Pat


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RE: Update on using cornmeal to prevent blackspot

FlwrLdy52,
If you're in northern Alabama, this would be a good time. I understand y'all have had a little rain recently. Wait for it to dry a little.

If you're in southern Alabama, you can probably wait as much as 4 weeks.


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RE: Update on using cornmeal to prevent blackspot

How much corn meal did you sprinkle around your rose bushed? And how much gluten for the weed pre-emergent? Thanks!


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RE: Update on using cornmeal to prevent blackspot

I use about a half cup scattered around the bottom of each rose bush.

CGM is applied at 15 pounds per 1,000 square feet as a preemergent.


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Hmmm....I'm wondering if corn meal would be good to sprinkle around newly potted cuttings and seedlings overwintering in a cool greenhouse?


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RE: Update on using cornmeal to prevent blackspot

Since reading about this earlier this year I started using the cornmeal around my roses, with great results. A couple of roses that had blackspot no longer have it and none of the others have had any sign of it. I tried spreading the word on another forum and was more or less told that since I was not an "expert" I probably shouldn't be sharing this. But I thank you and my roses thank you. You are all experts to me.


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RE: Update on using cornmeal to prevent blackspot

mrskjun,
Thanks for posting. This is the type of information we need and I hope gardeners are trying these cornmeal experiments on various fungus problems. At the moment I am experimenting using cornmeal and cornmeal tea on Camellia japonica to see if we can get control of the petal blight problems that plague these beautiful shrubs. They will be coming into bloom soon. If the cornmeal treatments are effective the Camellia growers will celebrate.


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Has anyone tried cornmeal around or corn tea sprayed on plants with powdery mildew, since that's a fungus also (but I don't know how closely related to blackspot.) I have an old house with old lilacs that are quite mildewy. I'd like to keep them, but also have them look a bit less disreputable during the summer. If no one has tried it, I'll give it a go next spring.


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RE: Update on using cornmeal to prevent blackspot

  • Posted by Byron 4a/5b NH (My Page) on
    Fri, Dec 13, 02 at 16:50

Folks, I had interesting results.

I brought in a potted chile pepper.

The leaves developed what looks like fly spec fungus.
I lost maybe 5% of the old leaves.

I place a 1/4 cup of cornmeal on the soil surface.

The spread of this fungus has stopped. The plant is developing new growth and new blossoms.

Thanks Nandina
Byron


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RE: Update on using cornmeal to prevent blackspot

Pepperjack: Try instant (must be instant) grits or dry molassis on ants. It really works.

On the cornmeal question, I've been mixing dry cornmeal, kelp, molassis and alfalfa togeher for years and using it on everything and I have had incredible results! In the fall, I dump some on the veggie and berry garden, flowers, whatever, and then dump some compost on top and let it sit until time to plant the spring garden. I'm telling you, it's the best kept secret in gardening. I think of it like giving the plants a B-12 shot each season, and healthy plants better resist disease and pests. Try it this season on a small section of the garden for an experiment. All of this stuff can be bought very cheaply at feed stores. The kelp is a bit pricy, but everything else is dirt cheap. I just love hearing about everyone's experiments!


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RE: Update on using cornmeal to prevent blackspot

EarthAngel, how do you mix this? What proportions do you use. I've been using alfalfa pellets for a couple of years with outstanding results and just started using the cornmeal this year for blackspot on my roses, so far it's working very well. It would be much easier to mix everything together and apply once. How often do you use this?


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RE: Update on using cornmeal to prevent blackspot

mrskjun,
I haven't been very scientific with the measurements but it doesn't seem to matter. I have 4 x 8 foot raised beds in a large garden and I put a 1 lb. coffee can of each of those four ingredients in each row and mix it in. My original plan was to use the formula when I felt the garden needed it, but after growing fall and spring gardens year around, I decided to use it every year, applying in the fall. I'm applying the formula in a different way this year (experimenting!) On vacation in NM, I found an organic formula which has all of these natural products plus a lot more and the price is comparable. Apparently, it's a Northern product because I can't get it any closer to Texas than NM. If you're interested, go to www.espoma.com and check it out. Good luck!


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RE: Update on using cornmeal to prevent blackspot

Around here the organic gardeners use corn meal every 3 months under roses.

Ask around at your feed store. Ask them what products they have containing corn meal. If you have a feed mill, shop there. I just found a product at my mill that I really like. It's called calf mix and has corn, cottonseed, milo, and oats all ground/mixed together. Another product called cattle mix has the same ingredients with salt added. I opted for the calf mix.


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RE: Update on using cornmeal to prevent blackspot

Would it be beneficial to make a mild cornmeal tea to water seedlings with? Would this help with dampening off?


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RE: Update on using cornmeal to prevent blackspot

If you are rooting in compost, it might help. If you are using a soiless mixture, you should just leave it alone.


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RE: Update on using cornmeal to prevent blackspot

  • Posted by jkom51 Z9 CA/Sunset 17 (My Page) on
    Wed, Feb 5, 03 at 22:58

What a great thread! I've been having fungal problems on my lantana - they're very xeric and the winter rains seem to be hard on them.

I'll be cutting them back soon, and shall try the cornmeal treatment to see if it works. Will report back.


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RE: Update on using cornmeal to prevent blackspot

This is very interesting, I will try the cornmeal on my 100 or so tomatoes and my wifes roses this year, as far as ants whole cloves spread around where you want to keep the ants out of works great, it seems to totaly disrupt their
scent(?) trails and they abandon their missions.


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RE: Update on using cornmeal to prevent blackspot

The following thread is discussing why cornmeal works:

http://forums.gardenweb.com/forums/load/organic/msg0315483014278.html?23

Here is a link that might be useful: why cornmeal works


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RE: Update on using cornmeal to prevent blackspot

Thanks for all the usefull information. Would it matter if the corn meal has lots of weavils? LOL Actually, I think they are dead, but maybe not. Also, I'm going to give the corn meal the supreme test....I have a New Dawn Rose that is coming out with first leaves with blackspot and a Climbing Peace that gets it so badly every year.I spray & spray with no results. I will let you know if this does the trick. I was about to dig up that darn Peace rose.


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RE: Update on using cornmeal to prevent blackspot

I was doing a search on cornmeal when I found the posting...after reading them all, I'm more convinced than ever....so count me in. I live in Southeast florida...black spot is a major problem...for roses and everything else. I'm off to the feed store..I'll let you know the results.


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RE: Update on using cornmeal to prevent blackspot

Hi all,

I found this thread last fall after fighting off black spot on several of my rose bushes. March of year I sprinkled about a handful of plain cornmeal under each of my rose bushes. One already had some black spot started. As of today, April 19, 2003, I am proud to say that none of my rose bushes have any sign of black spot. YEAH! ! !
I also used the dishwater trick on my ant piles. Yep! It works too. Had an ant pile I have been working on getting rid of for 3 years. GONE!!!
I am a believer.


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RE: Update on using cornmeal to prevent blackspot

This has been a very helpful thread. Just this morning I had to cut away allot of my two climbing roses due to black spot mold.

We have tried everything over the market that is suppose to work and nothing seems to do the trick. I am off to the store to get some cornmeal right now.

Thanks so much ya'll,
laura/Louisiana flower bug


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RE: Update on using cornmeal to prevent blackspot

Hi Louisianaflowerbug,

I live in zone 8 of Louisiana and am so happy to find out about the cornmeal too. I sprinkle once a month about two handsfull around each rose bush and don't care if it drops on the leaves some. My bushes are big and beautiful. Just a tad here and there of some black spot. Make sure you remove all leaves that have dropped off the bush or take off with clippers. Sterilize your clippers with 10% bleach and water solution between each cut on an infected plant. I am sure you will love the eventual outcome. I also put down a bit of epson salt on my plants. It encourages them to grow a strong root system. Good luck and if I can help you with any questions, feel free to ask.

Mary


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RE: Update on using cornmeal to prevent blackspot

I skimmed thru most of these, but think I only saw that cornmeal was suggested for fungus on plants and feet. It also works great for other skin problems. I heard about it on the radio. I put some in pantyhose and tie off the end and soak in the tub with it. If you squeeze it the "milk" comes out without the cornmeal itself. It has worked on my family for several skin irritations. I've also made a liquid and sprayed it directly on plant leaves. What a great, cheap discovery!


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RE: Update on using cornmeal to prevent blackspot

To Hippiechick,
Thanks for idea of making cornmeal tea by enclosing the cornmeal in panty hose. We are finding that one cup of cornmeal to one gallon of water and left to ferment slightly for 48 hours seems to be the most effective proportions. Perhaps it would be best for those planning to apply (spray) the cornmeal tea to also drip it through a coffee filter to prevent possible clogging of the sprayer nozzle...which is a pain in the neck to clean. To date I am finding that cornmeal spread on top of mulch (or soil) once a month and spraying cornmeal tea every two weeks on very fungus prone plants such as roses and tomatoes is very effective.


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RE: Update on using cornmeal to prevent blackspot

Glub..glub.. from my ARK on rain swollen creeks in the NC Piedmont..
Just found this forum. WOW! Am willing to buy the stock of an entire mill if necessary.


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RE: Update on using cornmeal to prevent blackspot

Boy am I glad I found this site. Corn Meal! I will go out and try it now. I never had blackspot before moving here. My neighbor in Virginia always had it. But I agree, Grits are made to be eaten, as long as the whites are done. Thanks guys! I will let you know what happens.
Mrst53


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RE: Update on using cornmeal to prevent blackspot

not for nothing but...i have a holly bush that had black spots on its leaves for 4 yrs in a row.

sprinkled , well poured corn meal under it twice in a months time. now a while has past and no blackspot.amazing!
dawn


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RE: Update on using cornmeal to prevent blackspot

Wish me luck! I just found this thread and am thrilled at the idea of something so simple and organic to treat blackspot. I recently put in several new rose bushes. The first batch has been fine until I brought the 2nd set home. I picked off all the effected leaves of the first one with black spot and sprayed all of the bushes. Now well into our wonderfully hot and humid summer all the bushes have blackspot. I hate the spray fungicide, which apparently doesn't seem to work to well on already established blackspot. Time to break out the cornmeal! Do you think if I dust the leaves it will help even more?


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RE: Update on using cornmeal to prevent blackspot

not happy with the rotting smell of cornmeal on my roses, when will that be gone? I dumped all my pots and am removing the clumps of garbage.


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RE: Update on using cornmeal to prevent blackspot

labrador,
I am mystified by your report of a "rotting cornmeal smell".
You are the first to report such an occurance. How much cornmeal are you applying to each plant? It only takes a handful sprinkled on the ground around each. Are you certain that you purchased pure cornmeal/ground corn and not the packaged self-rising cornmeal? Many times both package types look alike and you have to read the labels carefully. Personally, I have buried my yard and those of others with cornmeal (here in my hot, humid climate) conducting many experiments and have never had any odor from the cornmeal. Sorry, can't help you with an answer except to say that the odor, perhaps, might be coming from compost or some other soil additive you have used.


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RE: Update on using cornmeal to prevent blackspot

Do you need to reapply more often if you get a lot of rain, or will once a month still be ok?


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RE: Update on using cornmeal to prevent blackspot

WOW! This is my first time to lurk on this fourm, usually hang out at veggie & harvest fourms. I am a first year gardener with a desire to go organic and am learning so much. I just pulled out my 5 ft. tomato plants because of a fungas problem that I was determined not to put a chemical spray on. Wish I had read this first! New tomato plants were put out yesterday for fall, and as soon as daylight gets here I will be out with the cornmeal. Does anyone know if the cornmeal gluten with work as a preemergent for poison ivy?
Carrie


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RE: Update on using cornmeal to prevent blackspot

  • Posted by Talis W OR z8 (My Page) on
    Sun, Jun 13, 04 at 7:39

Just this morning my daughter was grumping about blackspot on her roses - talk about prayers being answered! Thanks - looks like we need to try this. & I'd been thinking of using alfalfa & maybe kelp on my gardens, (just moved into a 1900 'farmhouse' last fall, nice gardens, but tilth to build) so the cornmeal, molasses, kepl & alfalfa mix sounds great, too. THANKS, all of you.


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RE: Update on using cornmeal to prevent blackspot

I saw someone say that cornmeal will attract the worms and keep the ground fertile and airated, and it reminded me of when I was a kid :)

As a teenager I used to keep a rod and reel in the trunk of my car to go fishing any chance I got, so I bought a couple of "Worm Farms" from K-mart (a styrofoam cooler with the words "worm farm" printed on it and a bag of soil-less mix LOL!). I Just had to buy a carton of red wrigglers from the bait shop and drop them in, they were definately fruitful and multiplied... EXPONENTIALLY!

I used to feed them plain old cornmeal (I forget now how much or how often) but I always had a lot of happy worms hee hee. They dearly love the stuff, and the castings are pure gold for the garden. :)

Best Wishes
Amino-X


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RE: Update on using cornmeal to prevent blackspot

I tried the cornmeal (a small handfull at the base of each rose) about 6 weeks ago. 3 of 6 roses DEVELOPED blackspot after the application and the cornmeal became a hard, MOLDY mess! I used Goya brand yellow cornMEAL, NOT cornFLOUR or cornbread mix. Is there more to it than just "tossing" the cornmeal at the base of the plants?

An interesting aside: I decided to sprinkle a tad on a couple of emerging blooms that were being attacked my thrips and found no evidence of thrips the next day. They actually stayed away long enough for the buds to open with minimal thrip damage.

The roses I used the cornmeal on were: Mr. Lincoln, marmalade skies, angel face, french lace, dr. huey, and goldilocks. These are all in large (20" +) containers. Is the problem I'm having because they're in containers? Maybe it's the worms that help. I'll track some down and add them to the containers. Or, should I? SHEESH! I'm new to all this and don't quite know what to do! HELP! LOL

Thanks
Dee


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RE: Update on using cornmeal to prevent blackspot

Dee,
In general, we have concluded that cornmeal is not an effective plant fungicide for roses and tomatoes. Yet, some have reported success using it on both types of plants. In those cases these are gardeners who garden organically and use heavy amounts of compost and compost teas in their plantings. There have been some reports of success using cornmeal tea sprayed on tomatoes and roses, but these have been sketchy.

However, I do want to stress that positive reports of success are pouring in re using cornmeal for all lawn fungus problems and many other types of plant fungus problems. Just remember that when you scatter cornmeal on lawns or under affected plants it must be watered to activate it. This is very important.

Dee, your thrip report was very interesting. Okay, all you rose growers....try putting a pinch of cornmeal in each rose blossom when the thrips begin to attack. Let's see if Dee has made an important observation.


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RE: Update on using cornmeal to prevent blackspot

  • Posted by RacerD z7 TX (FW) (My Page) on
    Wed, Jun 30, 04 at 23:33

Interesting thread and I've learned more about this by reading tips on dirtdoctor.com as well. There are several "recipes" on the site. I'm curious if anyone has had results trying the cornmeal on powdery mildew on verbena. It seems the raised beds with mulch are promoting mildew and the verbena look awful despite their blooms. I'm so disappointed in the leaves and stems that I'm thinking of removing them and trying something else in the beds that likes moist soil. The Gazania in the beds are doing great. Thanks.

Deanne


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RE: Update on using cornmeal to prevent blackspot

I have 4 lilac bushes which tend to develop powdery mildew every year. This year it's worse than usual, and it appears that I may lose one of the bushes. There is fungus growing on the bark and the leaves are turning brown. Is there anything I can do to reverse the damage and prevent the fungus from spreading to the other lilac bushes? Will cornmeal help?

Amyhlr


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RE: Update on using cornmeal to prevent blackspot

Very recent evidence that scientists are actively investigation this fungus. The following is a quote from the introduction of a paper published in the December 2004 issue of Soil Biology and Biochemistry, volumn 36, pages 1955-1965.

Title: A duplex-PCR bioassay to detect a Trichoderma virens biocontrol isolate in non-sterile soil

Authors: Sarah L. Dodds, Robert A. Hill, Alison Stewarta

Authors affiliation: 'The National Centre for Advanced Bio-Protection Technologies, Lincoln University, P.O. Box 84, Canterbury, New Zealand and the Horticulture and Food Research Institute of NZ Ltd, Private Bag 3123, Hamilton, New Zealand

"Introduction

The biological control capabilities of species belonging to the fungal genus Trichoderma have been well documented over the past few decades (Hjeljord and Tronsmo, 1998). In particular, isolates of Trichoderma virens (formally Gliocladium virens) have demonstrated good biocontrol activity against a wide range of ornamental and vegetable fungal pathogens (Mishra et al., 2000; Nemec et al., 1996; Howell, 1991; Lewis and Lumsden, 2001; Rabeendran et al., 1998; McLean and Stewart, 2000; Prasad et al., 1999; Krauss and Soberanis, 2002). In addition, T. virens has also been reported to be active against root-knot nematode (Meyer et al., 2001) and responsible for reduced emergence of weeds in the glasshouse (Hutchinson, 1999).
However, regardless of the numerous successes there are still relatively few commercial products available with T. virens as the active ingredient (e.g. SoilGard", Grace Biopesticides, Columbia, MD, USA). The main reason is the high variation in the level of disease control achieved with the agent. To address this issue researchers are now focussed on understanding the mode of action and the ecology of the biocontrol agents with a view to manipulating conditions to achieve more consistent disease control."

Also of interest relative to using cornmeal. In the abstract they state: "soil was amended with cornmeal, as a nutrient source, and a mix of antibiotics to favour Trichoderma growth."


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RE: Update on using cornmeal to prevent blackspot

Ok, so I've been thrilled to death reading ALLLLL the way through this post only to see that.....cornmeal DOESN'T work for blackspot??? Is that right, Nandina?

Everyone seemed so excited about it for the last two years and now kaplooey?

I'm reaaally bummed. :( My roses are a MESS and I absolutely won't use the chemicals because of wildlife, insects...not to mention that you can't even get near the roses to smell them with that junk on! Ick! :)


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RE: Update on using cornmeal to prevent blackspot

ademink, the following thread has a subthread that discusses blackspot and friendly fungi (including the one that cornmeal encourages):

http://forums2.gardenweb.com/forums/load/roses/msg1013193422635.html?37

Here is a link that might be useful: link for above


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RE: Update on using cornmeal to prevent blackspot

Thanks for your time, Henry! :)


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RE: Update on using cornmeal to prevent blackspot

I note that this thread is reaching its 100 message limit. As it ends I would like to add a few thoughts.
It has been a very interesting adventure of discovery as many of you have trialed cornmeal and cornmeal teas as a plant fungicide. Your e-mails to me have been very helpful as you report your successes and failures. Thank you, Henry, for your latest postings. I am delighted that cornmeal is now undergoing further research. Although I have contacted a number of institutions begging them to undertake more research on the subject, the answer has always been the same...not interested if it cannot be patented and turned into a money making project.

Here's what I know to date on the subject of cornmeal as a plant fungicide:

1. The average gardener reports that cornmeal does not control blackspot on roses or tomato fungus problems. My trials have yielded the same observation.

2. Cornmeal, when dampened allows Trichoderma fungus, which is the 'good one', to feed on the mycelium and sclerotia of the bad, unwanted fungi Sclerotina minor, Sclerotina rolfsii and Rhizoctina sp. and kills or controls them. So....if fighting a fungus or mildew problem, try cornmeal. If it doesn't work....it doesn't. Simply put, the fungus which is your problem is not in the family of fungi listed above.

3. The posters over on the Lawn Forum have really been giving cornmeal a workout. Many are now buying it in bulk from feed stores and even local bakeries will order it in for you if asked. They are spreading it on lawns because cornmeal contains 10% slow release, non burning nitrogen. Also, it does control lawn Brown Patch when spread on and around the infected spots and watered in once a week for three weeks. To date no reports of injury to lawn grasses using cornmeal. Others are working cormeal into garden beds and appear pleased with the results. Just a reminder, use food grade, cooking type cornmeal (as from a bakery or grocery store) on vegetable gardens, please. Those who have trialed using cornmeal to control lawn rust and red thread infections do not report that it is a successful cure to date. Several other organic ideas are being trialed on those two problems.

And so, we have found that cornmeal is an effective plant fungicide for a number of situations. We still do not have all the answers, but we have some. It is an inexpensive, organic method which every gardener should try when dealing with a fungus problem. Success using it depends upon the type of fungus infection causing the problem.
We are making progress!


4.


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RE: Update on using cornmeal to prevent blackspot

For those with a scientific background: a recent (2004) scientific review of Trichoderma beneficial behavior by a very impressive group of scientists is given at:

http://www.weizmann.ac.il/Biological_Chemistry/scientist/Chet/NR.pdf

You may be interested in looking at the list of who supported this research on page 56. It appears that a number of scientific groups are taking biocontrol by trichoderma seriously.

Of course you can probably spread all of the cornmeal in the world on a waste chemical dump (i.e. a garden that has been routinely sprayed with chemical fungicides) and short term you will only see a fertilizing effect as the cornmeal is only the food for the trichoderma fungi - which probably will not be present if residual chemical fungicides are present.

Here is a link that might be useful: link for abive


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RE: Update on using cornmeal to prevent blackspot

New research supports the trichoderma model.

Http://www.publish.csiro.au/nid/39/paper/AP03070.htm

Title: Monitoring the survival and spread of the biocontrol fungus Trichoderma atroviride (C65) on kiwifruit using a molecular marker

Authors: S. L. Dodd, R. A. Hill and A. Stewart

Published in: Australasian Plant Pathology, volumn 33, pages 189 - 196, (2004).

Abstract: "An isolate-specific restriction fragment length polymorphism (RFLP) marker previously found for the Trichoderma atroviride (formerly T. harzianum) isolate C65, an isolate with biological control activity against the kiwifruit stem-end rot pathogen Botrytis cinerea, was modified into a dot blot assay to facilitate the screening of large numbers of leaf and flower/fruit samples for the presence of C65. To increase sensitivity, the dot-blot assay was used in conjunction with a Trichoderma semi-selective medium. This modified diagnostic assay was used to track the survival and spread of C65 on kiwifruit leaves in the shadehouse and flowers/fruit in the orchard over two consecutive growing seasons in the Canterbury region of New Zealand. Results showed that isolate C65 could survive on both leaves and flowers/fruit over an entire growing season. The fungus, applied once in early summer (late November/early December) to coincide with bud burst, was detected on both leaves and fruit through to harvest in late summer (March). In addition to its ability to survive, isolate C65 was shown to spread to uninoculated leaves and fruit on the same plant and plants at least 3 m away. It is postulated that the high population of thrips present in the orchard at flowering was responsible for spread of the fungus within the orchard and that resident insects or wind currents could be responsible for spread in the shadehouse. The ability of C65 to survive and spread in the phylloplane and fructoplane of kiwifruit vines over an entire growing season makes it an ideal candidate biological control agent for reducing B. cinerea inoculum in the orchard at harvest and, consequently, post-harvest fruit rot."

Here is a link that might be useful: link for above


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RE: Update on using cornmeal to prevent blackspot

Well I have certainly enjoyed reading this thread all the way through and now I will put cornmeal on my calendar for March to scatter under all my azaleas and rhodos. Have had terrible problems the last 2 years with all the rain. We're getting various fungal infections and black spot type production on them. I just finished tonight putting down Hollytone under all the azalea, rhodo and pieris, which is an Espoma product somebody else mentioned. This is my first year doing this but I've heard fantastic results from other people.

I do have a question which may not get answered on this thread - lets see. Due to an illness, my DH couldn't blow all the leaves this fall from our 2 acres back here in the woods. I can't even start the darn blower so I finally started just mowed the lawn every few days with a composting mower and left the chopped leaves in place. I also put down an application of pelletized lime. Our soil is very very hard compacted clay over granite. We have a continual problem with acid pH, mushrooms, moss, etc. I was going to have the soil aerated again and then spread a dusting of mushroom compost. Would cornmeal do just as good a job at a fraction of the cost?


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RE: Update on using cornmeal to prevent blackspot

Title: Biological control of black spot of rose caused by Dipocarpon rosae .


Authors: Prasad, R. D.; Rangeshwaran, R.; Sunanda, C. R.; Vinita, J.

Authors affiliation: Project Directorate of Biological Control, Post Bag No. 2491, H.A. Farm Post, Bellary Road, Hebbal, Bangalore 560 024, India.

Published in: Annals of Plant Protection Sciences,volumn 10, pages 256-259, (2002).

Abstract: "Fungal biological control agents (Trichoderma harzianum , T. viride and Chaetomium globosum ) were used either alone or in combination with fungicides (chlorothalonil and mancozeb) to manage black spot of rose caused by D. rosae under greenhouse conditions. Black spot incidence in biological control agent and/or fungicide treatments was significantly low (disease ratings from 0.33 to 3.33) compared to the control at all observation dates. After 100 days of spraying, defoliation was lowest with chiorothalonil, Trichoderma harzianum +chlorothalonil, C. globosum +chlorothalonil and T. harzianum +mancozeb treatments. The highest mean vigour index was recorded in T. harzianum treatment. The highest flower production was recorded in C. globosum +chlorothalonil treatment (4.33) followed by T. harzianum alone and T. harzianum +chlorothalonil treatment (4.00)."


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RE: Update on using cornmeal to prevent blackspot

I had blackspot on my August Beauty gardenia, read the postings here and sprinkled uncooked instant grits under the bush. Ha ha, I didn't have any plain old cornmeal and was too lazy to go to the store. I pulled off the infected leaves also.
This was one month ago. Haven't seen a spot since.


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RE: Update on using cornmeal to prevent blackspot

I know this is an old thread. I have a 5 lb bag of masa harina, I was going to throw out. Would it be ok to use instead of reg. cornmeal. It says in the ingredient panel corn lye, and water. I know the lye is used to de-hul the corn and then rinsed off well. I'm scared , I might kill my plants.


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RE: Update on using cornmeal to prevent blackspot

I haven't seen any improvement after using the corn meal around my roses. I noticed on the corn meal box that it says "enriched and degerminated". Is there another kind of corn meal that I should be using?


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RE: Update on using cornmeal to prevent blackspot

Hi,
VERY interesting forum (I just joined). I live in Kenya (africa) and I would like to use the corn meal method for fungus. We, in Africa grow maize (and maize meal). Is this what you are calling corn meal?


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RE: Update on using cornmeal to prevent blackspot

Kenyacowgirl, welcome! Yes, maize meal is another name for corn meal. Although it does not solve all plant fungus problems it still is worth trying, on the off chance it might. There are a number of fungi families, some of which maize meal will control. Hope it works for you.


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RE: Update on using cornmeal to prevent blackspot

What kind of cornmeal do I use? Do you use the plain cornmeal at the grocery store or the self rising?


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RE: Update on using cornmeal to prevent blackspot

Hrrannie, use regular cornmeal from the grocery store. In some parts of the country feed stores carry cornmeal in 50# bags inexpensively. You might want to check and see if yours does.


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RE: Update on using cornmeal to prevent blackspot

Ye gads!
I wonder why some of this stuff stays around.
There is a difference between corn gluten (not gluton) meal and cornmeal; the corn gluten meal is the (somewhat effective) proteins plus other materials milled off whole cornmeal, and which actually contains no gluten. It does work as a pre-emergent herbicide in some situations. Do your research to find how, and rather than doing it the lazy way on most organic gardening forums, read abstracts from university research papers and university horticulture forums (I suggest the WSU Extension forum from Puyallup, WA). You can also find whole grain cornmeal at some better grocery stores. It has the corn gluten intact, if you want it.
Corn meal is good food for snails, some rodents and insects.
Cornmeal and corn gluten meal are both good substrates for growing some kinds of fungi for research purposes. Just get some moist, perhaps on a pot of wet soil, leave in the shade, keep it moist and/or covered, and see what grows.
As a pre-emergent herbicide, cornmeal is not so effective, and under just the right conditions (look up elsewhere how to do it right) corn gluten meal is a good pre-emergent herbicide, even if a bit $$.
There is not much guarantee that your corn gluten meal would be OMRI certifiable, for most of it is made from GMO field corn. After all, since most of it goes into animal feed, and the feed producers care mostly about the bottom line, why ask for non-GMO corn sources?
net-net: do better research in finding the papers and abstracts, and read critically. Then you won't be panicking about where to find cornmeal or corn gluten meal for your garden. As for tomato spot disease, just try to find supporting studies on cornmeal for preventing that...you'll likely only find anecdotal reports from some home gardeners who have been successful one season, and attribute that success to the cornmeal, but have no control against which to compare.


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RE: Update on using cornmeal to prevent blackspot

Hi y'all! I've been hunting all over the Internet for some hope to deal with blackspot on roses--and you guys have finally given me some! We tore out out our front yard completely (clay, broken glass, and weeds), and put in brick paths, a pergola, and rose beds. I have 45 roses, of which about two thirds are Knockouts & the rest are own-root heritage roses. All of them are SUPPOSED to be resistant to blackspot. Ha! They're planted 3-4 feet apart, they get a good amount of sun, but there are a number of oak trees that provide partial shade, and last year they were DECIMATED by blackspot. By June, I didn't have a single flower for the rest of the season. So sad!

This spring I started spraying weekly with a mixture of water, kefir (better than milk, I'd hoped?) & neem oil (but not the 100% stuff, apparently). No go. The blackspot is back. I'm going to try baking soda & 100% neem (any reason NOT to try them together?) and run out and get CORNMEAL ASAP!


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RE: Update on using cornmeal to prevent blackspot

3 years ago I put cornmeal around my crape myrtles to try to control the black mold on the leaves. This took care of it and I haven't had any more problems with it. Another thing I did after reading this hint on the forums was using flour to control leaf rollers on my cannas it too worked great. Used it 3 years ago and haven't had to use it again. Great, easy and cheap solutions.


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