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dfedele84

Please Help - Gray Leaf Spot on St. Augustine

11 years ago

Hi - I'm a relatively new homeowner trying to take control over a neglected St. Augustine lawn in north central FL. Since moving in I've applied some weed and feed in early June which did seem to green the lawn some. I started noticing some weeds and sprayed some Ortho Weed B Gone Max on parts of the lawn in July. About a week later, I noticed some yellowing of areas. I took a sample into the local IFAS office here and got a diagnosis of gray leaf spot and rhizoctonia leaf and sheath blight (rhizoctonia zeae). All the while, we've been getting a lot of rain here and the temps are well above 90 with high humidity. I'm assuming my application of weed killer really stressed the lawn and encouraged fungal growth.


My big question is where to go from here? I've read on here that the fungus sort of recedes in the cooler months. Should I just wait it out? Is there anything else I can do?

Comments (13)

  • 11 years ago

    Thanks for the help. I don't have any experience with those products. Can you purchase them at most garden centers? Also, how do you go about making sure you use the 5lb to 1,000 sq ft rate?

  • 11 years ago
    last modified: 11 years ago

    my 2 cents, I will put some composted cow manure from Walmart about 1.53 per bag in those spots, weeds killer will weaken the grass too, be careful. For the Crabgrass weed, you have to hand pick the roots now before it spreads over the lawn. You can put coffee ground to the lawn too. Mow higher about 4 inches.

    dfedele84 thanked jctsai8b
  • 11 years ago
    last modified: 11 years ago

    I'm not sure what's in weed be gone max, if I ever use have to herbicides this time of year it's in very small areas. As far as weed and feed goes, I steer clear once the temps hit 85. Otherwise you run the risk of burning the grass. For my lawncare regimen, I typically do 4 applications of 16-4-8, one in April, June, August and sometimes October.

    I recently had pretty bad fungus on my lawn, brown patch. Treated with an application of Bayer fungicide at the curative rate, watered it in then another application of f-stop 2 weeks later. On top of the 2nd application, I used milorganite, you could also use some other sort of organic fertilizer, and that should help choke out the fungus.. Some people have also used corn meal if you don't want to go the fungicide route, I don't have any experience with that.

    I can tell you that my grass has already started to recover over the last week and a half. Given another week it should be back in great condition.

    Here a link to my blog and post particularly about taking care of St. Augustine grass. I even have a lawn care schedule on there that tells you when to apply fertilizer and pesticides.

    Trust me I know where you're coming from, I struggled early on with my lawn but after some time got the hang of it. You will to.

    dfedele84 thanked Jeremy Millrood
  • 11 years ago

    St Augustine is very sensitive to "normal" herbicides. The Floritam variety is even more sensitive. If you don't know which you have that would be important to find out before you use any herbicides or fungicides.

    If you have not yet used any fungicide, you can try corn meal at a rate of 20 pounds per 1,000 square feet. I've used it every year for the past 14 and it works well for me. You can apply it any time, even when the temps are above 85 degrees. Give it 3 weeks to work and new grass should come in healthy. Repeat any time if you want to. Corn meal is also an organic fertilizer so if you don't use it on the entire lawn, you'll have dark green spots where you did use it. Besides diseases often jump around the yard, so just to the entire yard.

    You can't control Mother Nature, but you can control your own watering. Mature St Aug should only be watered once a week during the hottest part of summer. Then as it cools off you can back off to once every 2, 3, and 4 weeks. When you water it give it a full inch. Time how long it takes your sprinkler to deliver an inch by setting out some cat food or tuna cans. Then water for that time every time you water.

    dfedele84 thanked dchall_san_antonio
  • 11 years ago

    Thank you all for the feedback. I've got a few questions about corn meal. Can corn meal ever damage St. Augustine? Is there a certain number of times you should use corn meal throughout the year? Is it a replacement for Milorganite or other fertilizers?

  • 11 years ago

    Corn can't damage St. Aug or any other grass under normal usage rates. If you were, for instance, to drop a quarter inch of corn meal across the lawn, that could do some damage, though, by smothering the crowns, and also from the rampant bacterial decay that would be going on.

    If you're applying the standard 10 to 20 pounds per thousand, though, it's perfectly safe.

    Once--twice at most--per year is all that's required for fungal defenses. More, however, is also just fine and corn works as a great soil conditioner. My top flight year was several hundred pounds per thousand of corn to condition my soil.

    Milorganite is 5-2-0, corn is closer to 1.6-0.6-0.4. It's a pretty poor replacement for Milo or other fertilizers unless used at pretty high amounts (60 pounds per thousand). Soybean meal (7-1-2) or cottonseed meal (also 7-1-2) are superior for feeding the lawn and require far smaller amounts (15 pounds per thousand) to deliver a full pound of nitrogen.

  • 11 years ago

    based on dchall's previous post it would seem that you could put corn meal down at any time without risk of damaging the lawn. Seems like you could substitute in place of regular fertilizers, but you may have to apply more frequently. My experience is in using fertilizers like green edge which is 100% organic slow release and that is what I've had success with when looking to green up my lawn during the growing season, or between feedings with 16-4-8.

  • 11 years ago

    dchall_san_antonio is way more positive on cottonseed meal than the UF Ext. Ofc. You mention "if you haven't used fungicide" you can use cottonseed meal. I plugged Floratam about three weeks ago with a little potting soil and heaping teaspoon Milorganite in each hole. Took off really well and then the constant rain and humidity has almost taken out about a third of the plugs and it appears to be gray leaf spot. Sprayed Bayer Fungus Control for Lawn and wondered if I can still use the cottonseed meal and how you spread it. FL ext guy says I'll probably lose it all but it was a lot of work and it's still got a lot of green with some dead thatch in many plugs. What do you think?

  • 11 years ago

    Forgot to mention I'm in 9B about thirty miles north of Tampa FL

  • 11 years ago

    Lyn you're talking about corn meal, not cottonseed meal. I almost never mention cottonseed meal. But if I do a search/replace in your post and sub in corn meal, then I would agree. I'm extremely supportive of using corn meal to control fungus. In fact the performance of corn meal in treating fungal disease in turf is the main reason I converted from chemicals to organics. That was in 2002. I've been using it successfully every year since. And yet Texas A&M University is publishing everything they can to squash the idea that corn meal has any effectiveness. To me that's simple misdirection of education. If they can't make it work, they need to come look at my lawn and figure out what they're doing wrong. I have some ideas about what they're doing wrong, but haven't seen their research. The silly thing is that it was TAMU who first published the idea that corn meal was an effective tool against disease (in peanuts). That was back in the 90s and they've been fighting against themselves ever since.

    Anyway you can't use corn meal once you've used a chemical fungicide. Corn depends on the growth of a predatory fungus for its effectiveness. If you have a fungicide down then that beneficial fungus will not thrive in sufficient populations to do anything. If it has been several weeks since you used the fungicide you could try applying a very light dusting of compost to restore the beneficial microbes and then the corn meal.


    >>green edge which is 100% organic slow release

    I just want to comment on the idea that organic fertilizer is slow release. Chemical fertilizers work on several principles but generally those are chemical imbalances forcing the fertilizer into the roots as quickly as the roots will take them in. Organic fertilizer is made from food materials like corn, wheat, soybean, cottonseed, alfalfa, etc. That food becomes food for the living microbes (bacteria, fungi, microarthropods, and others) at the surface of the soil. As the original food/fertilizer decomposes from the microbes, then subsurface microbes decompose the byproducts from the first level decomposers. The process of a succession of microbes decomposing previous decomposers is so complicated it is referred to as the soil food web. At about 3 weeks after the original application of food/fertilizer to the surface, the resulting byproduct of decomposition is actual NPK type of plant food in a form akin to what comes in a bag of chemical fertilizer. So it is not that organic fertilizer is "slow release" so much as it just takes a really long time for the biology of the soil to convert the original mammal food to plant food. But this is the way Mother Nature has designed the process. It has worked for a really long time. On the other hand, chemical fertilizers that call themselves 'slow release' are caused to be that way by coating them in a slow dissolving chemicals.

  • 11 years ago

    Thanks for the really great reply. I had put cottonseed in search but good to know its corn meal. I have a small track tilled for more sod plugs that has nothing in it. Think I'll try the corn meal and wait a few weeks for it to breakdown and to get out of this constant evening rain pattern. I had been researching cottonseed meal for the camellias - oops. Vegetable garden only has sand and pigeon manure with grass clippings. Good results except for the incessant stink bugs. Don't know much about other additives but always prefer organic. Thanks again

  • 11 years ago

    The more organic you can get, the fewer pest bugs you should find. You might spray the plants with a mix of molasses (3 ounces per gallon), milk (3 ounces per gallon), a couple aspirin, and water (1 gallon per gallon). Spray every surface of the plants every 2 weeks. The idea is to improve the health of the microbes that live on the outside of the plants. There are about 20 layers of microbes living there. When they are healthy they seem to make the plants "invisible" to predators and diseases. My science on this topic comes from 20 years of judging regional high school science fairs. Every year someone did an experiment using various concoctions vaporized over plants in an enclosed cabinet. The ones that worked best were salycilates (aspirin is one of those). Molasses and milk are foods and have been shown to improve microbe health.

    You might also put in a bird bath and a bird feeder. Birds will quickly rid your yard of pest bugs. They will also rid your garden of many veggies and fruits, so careful what you do with this information.