Brown Patch Experiment

skoot_catJanuary 31, 2008


I live in the Clearwater, FL area. I have St.Augustine Floratam that has been maintained organically for 3 years. I feed microbes with SBM, CM, Alfalfa Pellets and UCG.

The brown patch area started to show in late November and is roughly 18ft diameter and "slowly" spreading. Every year the brown patch is in a different shaded area of the lawn. This year its in lower lying shaded area. It never kills the lawn, it just looks horrible through winter/dormant season.

I put Corn Meal down in mid September and again in mid October @ 15lbs per 1000. I was hoping it would act as a preventative.


I started this experiment (suggested by nandina) using Corn Meal and Granulated Sugar 4 weeks ago.(approx Jan, 1) The Brown Patch area is roughly 300sqft. I put down 10-lbs of cornmeal on and around the affected area. I also put down 5-lbs of granulated sugar on half the area (roughly 150sft) and hand watered in with a hose. Since then we've received rain 3 times, and I have not need to irrigate.

In the pic below (taken yesterday) I've outlined the affected area. Above the red line is CM only. Below the red line is CM/Sugar. Ive noticed a slight increase in recovery in the CM/Sugar half opposed to the CM only half. Im estimating 20-30% better recovery in the CM/Sugar section. The entire area has stopped spreading and is slowly improving.

So, the question I have is.

Why did the CM/Sugar half have better recovery?

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lou_midlothian_tx(z8 DFW, Tx)

Molasses worked just as good. I still do not see the point in granulated sugar at all since it is very simple sugar which does not feed wide range of microbes. Molasses has over 100 complex sugars and feed significantly more diversity of microbes including fungi.

That is what I have done to combat my friend's st augustine's problem with BP. It worked.

I don't know why Nandina never bothered to explain that in details so as of now, I still think molasses is a better choice over granulated sugar. Molasses has traces of nutrients including potassium, iron, magnesium, and other elements. Granulated sugar does not have anything.

Maybe I look at it differently because I've studied extensively in nutrition and refined sugar isn't very nutritious. Refined food is the worst type of food because of lack of nutrients... This obviously applies to soil biology as well.

    Bookmark   January 31, 2008 at 10:43AM
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Im not exactly sure either. I figured it wouldn't hurt and I thought it was an interesting experiment. Hopefully Nandina will chime in and give us a full explanation.

I Tell ya what Lou, I have a bottle of BlackStrap Molasses at home. Tonight I will apply it to the other half of the BP area and let you know the results. How much and how often should I apply for a 150sqft area.

    Bookmark   January 31, 2008 at 11:35AM
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lou_midlothian_tx(z8 DFW, Tx)

The bottle has 12 oz so I suppose that's how much I used on 2500 sqft. The usual rate is 2oz per 1000 sqft so obviously, I use a lot more but i use ortho dial sprayer and it sucks up a lot of liquid from the container in short time even at 2oz setting. I couldn't move fast enough to apply 2 oz over 1000 sqft and supposedly 2 oz per 1000 sqft doesn't seem very much... Still does a lot faster job than 2 gallon pump sprayer.

    Bookmark   January 31, 2008 at 11:59AM
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skoot cat...Thanks for the update. One of my many horticultural interests/experiments over the years relates to the heavy infestation of root knot nematodes in south eastern soils, especially the Florida problem. I have a quiet hunch that any plant under stress for whatever reason attracts root knot nematode and its feeding activity further reduces the ability of that plant to survive. As I have worked with home owners whose lawns have a heavy nematode infestation I find that granulated sugar is a better treatment than molasses based on nematode counts taken before and after treatment. But, molasses is a less expensive treatment and is somewhat effective. These two 'sugars' are the only products that I know of that have any ability to control nematodes.

Here is what I am trying to say to you...
1. You mention repeated, annual brown patch problems. This leads me to think that part of your problem may be the FL root knot nematodes. Suggest that you send off a soil sample from non-treated areas and ask for a root knot nematode count. I think you will find that the count is high. Keep using cornmeal about every six weeks and keep trialing granulated sugar and molasses treatments. See what happens. When your soil sample nematode count comes in please update us on that. As you work with these ideas and repeat nematodes counts next year to see if the treatments are working, again update us. Let's see if you can add some additional imput into some ideas I have been working on.

    Bookmark   January 31, 2008 at 9:17PM
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dchall_san_antonio(8 San Antonio)

Great explanation, Nandina. Thanks.

Molasses is often suggested for an organic treatment of root knot nematodes here, too.

    Bookmark   February 1, 2008 at 3:32AM
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lou_midlothian_tx(z8 DFW, Tx)


Any explanation why GS worked better? Specific type of sugar that help control RK? How does that work?

    Bookmark   February 1, 2008 at 2:08PM
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Lou...Any brand of granulated sugar seems to work. For molasses to be effective you really have to saturate the grass deeply which takes a lot of molasses so that the application does not just 'float' on the grass blades. This takes time and can be more costly than sugar. I have no idea why sugar works. Hopefully there is a grad student out there reading this who will undertake a controlled experiment in laboratory conditions. This is a common method used by home tomato growers to reduce RK damage. Handfuls of sugar placed in the planting hole and replenished at soil surface around tomato plants monthly. I knew of this and decided to try it on lawns infected with RK. Much to my surprise it is very effective.

    Bookmark   February 1, 2008 at 3:22PM
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lou_midlothian_tx(z8 DFW, Tx)


Are we talking about liquid molasses or dry molasses? What is the application rate for granulated sugar?

    Bookmark   February 1, 2008 at 4:28PM
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nandina, brown (cane)-sugar is sucrose crystals with a coating of molasses from the crystallisation process. Further processing removes the molasses and white sugar is the end product. (We do this when we make lemonade with brown sugar and lime juice; any undissolved sugsr crystals are colorless). Molasses is the liquid which is removed by centrifuging massecuite to obtain the sucrose. This liquid fraction has a very little sucrose and small quantities of many of the elements originally in the sugar cane crop. It can contain significant amounts of phosphates because triple superphosphate is often added to the expressed cane juice to help in its clarification process. The sugar in molasses can be converted into alcohol by fermentation action in which specific strains of yeast are used.
So I imagine that many of the beneficial bacteria in soils will thrive on sucrose (raw or brown or Demerara sugar). In using liquid molasses one is trading away some sucrose for other products like phosphates, calcium magnesium etc.
(A tablespoon of molasses was my organic supplement for as long as my grandmother lived). So called 'dry molasses' is the product obtained when molasses is sprayed on a grain residue. The resultant product must be more conducive to bacterial growth than either alone. But its greatest benefit would have to be its ease of application. Molasses is difficult to apply on a field scale.
For the information of one or two of you guys out there I am old enough to have seen that tried.

    Bookmark   February 2, 2008 at 7:23AM
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lou_midlothian_tx(z8 DFW, Tx)


There's an organic cotton farm in West Texas that sprays molasses on the land few times a year. That's it. No supplemental water irrigation. No fertilization. Rainfall is all they get and apparently, they do significantly better than conventional cotton farms nearby at larger profit margin and less labor...

    Bookmark   February 3, 2008 at 12:12PM
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ronalon...thanks for your post. When I first began doing my experimenting lady luck provided me with an inexpensive source of sugar and molasses products. One of those situations of being in the right place...etc. and meeting the right person. So, I played with many ideas related to root knot nematodes infesting southern lawn grasses. My conclusion was that granulated sugar was the most effective control. Remember...based on skoot cat's post I am suggesting that RK may be a contributing factor to his lawn problem. Until he tests for RK we will not know if my supposition is correct. But, southeners should be very alert to possible RK when lawns/annuals/veggies show weakened growth and send soil off for RK testing.

I agree that dry molasses is conducive to bacterial growth. My tests with it for RK did not seem to control it as well as granulated sugar. I welcome any additional testing by others.

    Bookmark   February 3, 2008 at 1:30PM
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dchall_san_antonio(8 San Antonio)

I've seen pictures of that cotton field Lou mentioned. I will try to get the owner of those pictures to post them on his website. Unfortunately he's not computer savvy, but his kids or grand kids should be able to do it, if granddad will allow it. The magic of that molasses treatment is that he's also a no-till guy. His roots stay in the soil all winter so the beneficial fungi in the soil do not need to restart every year. The beneficial fungi provide "roots" to the deeper moisture in the soil. In a good year for rain this farmer has as good a crop as his neighbors, but he did not have to pay for his water or maintenance on the watering equipment. Thus his expenses are much lower than his neighbors and profits better. In a bad year for rain, his production is much lower, but the extra cost for water for the neighbors sucks away all their profit. He still beats them to the bank. The molasses (a well known bacterial food) seems to keep the soil fungi healthy. The soil food web is a complicated thing.

    Bookmark   February 3, 2008 at 1:44PM
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So let me get this straight.

Are you speculating I have root knot nematode and not brown patch? Or the RK is contributing or causing the brown patch?

The reason I ask is because 2 years ago I took a 1x1' sample of the affected BP area (w/soil and roots) to my local extension office and they determined it was in fact brown patch.

    Bookmark   February 4, 2008 at 10:07AM
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lou_midlothian_tx(z8 DFW, Tx)

RK might be contributing to BP problem by making your grass weak and more prone to getting BP.

At least, that's my understanding. one way to find out is to send the soil sample somewhere for RK testing.

    Bookmark   February 4, 2008 at 1:55PM
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skoot cat, you may have a (root knot) nematode problem and here is why I think so.
You have been on an organic lawn care program for three years. Nematode populations have been reduced significantly by the application of OM, but not eliminated. There is enough testimonial evidence that your organic treatments significantly reduce fungi diseases.
The symptoms of root knot infestation are typical of moisture/nutrient deprivation because the roots are damaged. The symptoms you describe are more consistent with this condition as opposed to brown patch disease in which case the color of the turf goes from green through yellow to brown, in widening circles and the growing centers of the grass pull away easily and sloppily from the stem.
Brown patch is comparatively easy to identify from sod samples; nematodes are a slightly different matter. Root galls may betray their activity but their presence and intensity are determined by specialised examination of soil samples. Such samples are collected and specially packaged and require a pre-payment. The sod sample you took into the Extension Office may have shown the symptoms of brown patch but that did not exclude nematodes. Additionally, I do not recall that in November the temperature and humidity conditions were conducive to fungi proliferation, but I may be mistaken.
Brown patch is more likely to occur in moist locations rather than in shady areas; I am not sure what nematodes do.
Because of the cost and time involved I always try to eliminate the other pests, diseases, cultural and environmental factors that can cause the signs and symptoms. Then, only nematodes remain. Finally, this can be confirmed by soil analysis.

    Bookmark   February 9, 2008 at 6:11AM
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