Yellowish spots on St. Augustine Grass

16 years ago

Hello all. I have about 2-3 months old grass at home and lately I am seeing some yellowish spots on it, around the body of it not the top. I watered the lawn for the first month about 5 times a day, 1 hour each area (2 areas). Now I am watering it 2-3 times a week about 30 minutes each area and watering starts at 4 am. Now living in SFLA, we have been getting a lot of storms in the afternoon time in the last month or so. Am I overwatering, underwatering, or is it time for fertilizer? ANy info greatly appreciated.

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Comments (14)

Billl
16 years ago
If you haven't fertilized yet, it is time. Every 6 weeks or so would be common for St Aug.

For water, you really need to account for rain in your schedule. If you get a good soaking rain, you do more harm than good by watering more. Depending on your soil, a good rain means you don't have to water for several days and maybe even a week if it doesn't dry out quickly. If you are getting afternoon storms a couple of times a week, you may not need any extra water at all. A simple test is just to go out and stick your finger in the soil before you water. If it is still moist, give it another day and check again before watering.
hgiljr
Original Author
16 years ago
To be honest, this is my first home with my own lawn (past homes where maintained by the community). What fertilizer should be used? I usually mow the lawn once a week since if I wait two it is a killing due to the height. Common sense to me is that I should fertilize after mowing the lawn. I will do your simple test and see about the moist soil, only thing here in SFLA, we are under water restrictions and I can only water Wednesday and Saturday's so it is tricky... Thanks again
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I'm going to assume it is a fungal disease. Your watering is wrong enough to possibly get a root rot going. Would you mind posting a picture? The best garden pictures are taken on an overcast day to reduce the contrast between brights and shadows. For this the distance should be about 6 inches away. I have had a similar disease issue in my St Aug where it returned time after time, but mine was a surface disease and not affecting the roots. Mine did not go away until I treated it with corn meal - yes, the same stuff you eat. Apply at 20 pounds per 1,000 square feet over the entire yard. You can buy it in 50-pound bags at a feed store. Call first to see if they have it. Ask for the price. It should be well under $15 and more like $5. If the price is above $20 then it's not corn meal but corn gluten meal. That won't work. You want ordinary corn meal. Cracked corn will work, but don't use whole corn. Whole corn will turn your yard into a corn field (easily mowed down). Corn meal works biologically and not chemically. The corn decomposes with bacteria and fungi already living in the soil. One of the fungi that seems to accumulate especially well on corn is Trichoderma (try ko DER mah or trick oh DER ma). This is a predatory fungus that feeds on the disease causing fungus. Give it three full weeks to show improvement. If it seems like it is working, but you want to really hammer it home, reapply. If you have already used a chemical fungicide in the past few weeks, then corn meal won't work. Why? Because the Trichoderma has been killed off by the fungicide. In the future you should change your watering. I realize 99% of all Floridians water daily, but they are all wrong. All of them including the sprinkler guys who set everyone up. Here's more about watering. Watering: Deep and infrequent is the mantra for watering. This is for all turf grass all over the place. Deep means 1 inch all at one time. Put some cat food or tuna cans around the yard, and time how long it takes your sprinkler(s) to fill all the cans. Memorize that time. That will be the time you water from now on. My hose, sprinkler and water pressure takes 8 full hours to fill the cans. Your time will likely be less. I like gentle watering. As for watering frequency, that depends on the daytime air temperature. With temps in the 90s, deep water once per week. With temps in the 80s, deep water once every 2 weeks. With temps in the 70s, deep water once every 3 weeks. With temps below 70, deep water once a month. Note that you have to keep up with quickly changing temps in the spring and fall. This deep and infrequent schedule works in Phoenix and in Vermont, so it should work for you. The reason for deep and infrequent is to grow deeper, more drought resistant roots and to allow the soil to dry completely at the surface for several days before watering again. If it rains, reset your calendar to account for the rainfall.
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For those of you who are unfamiliar, Neil Sperry is a Texas based garden guru. He has a radio show and is syndicated in many of the big news papers in Texas. Neil Sperry is the bane of my existence. Whatever he says, I do the opposite. I followed him from about 1992 to 2002 and realized my grass looked worse every year. Then I switched to organic and learned a lot about lawn care on this and other forums. He, apparently gets all his information from sponsors selling products. I could make a living following him around to fix the mistakes he has people making. Sunlight - Neil says, St. Augustine needs 4 hours of sunlight daily just to survive, and 6 hours of hot, direct sunlight if you hope for it to grow vigorously. Again, my front lawn in SA had zero hours of sunlight per day for the duration of 25 years. It was under the canopy of several very large live oak trees. For 10 years it deteriorated, and for 15 years under organic fertilizer, it looked great. Here is a picture of my grass grown in the most dense shade in that yard. Looking straight down reveals all the flaws in the turf. What you can see is the grass was growing outward and not upright. When it is in full sun, it grows more upright driven that way by the sheer amount of grass. Here is the same yard from an angle. The house faced north and this is the front yard. There is a huge tree to the left of the walkway and two large trees in the bed to the right. This yard got no direct sunlight at all. You can see grass invading between the bricks and over the concrete. It is not doing poorly. Neil Sperry would say this is impossible. Here is a picture of my current house - back yard, south facing slope in full sun. The grass is dense. You can see the grass needed fertilizer, but besides that...in the foreground is weeds mowed at the mower's lowest setting. You can see the St Augustine runners expanding their territory into the weeds at a rate of about 15 feet per year. You can see the hose and a long handled yard tool sort of buried in the grass. The only reason you can see them is the grass is too dense for the hose and tool to sink farther down. You can tell the depth of the grass on my dog's legs. They are buried to the hock. Drought - Neil says, St. Augustine needs more water than most of our other lawngrasses (fescue excepted). If you let it get too dry, and especially if you do so repeatedly, St. Augustine will be weak, and it may even die away. This is about the worst thing you can say about St Augustine. The main reason is it is bordering on untrue. It "may" die away. St Augustine is not bermuda. Bermuda will come back from no water for a year. Here in Bandera I had a side yard where the St Aug was golden brown. It had been that way for months before I bought the house. I figured it was dead and neglected it for another year, which was a drought year. But when I watered it, the golden runners came to life. It was solid St Augustine. Had this grass been in full sun, it "may" have died away, but for whatever reasons, it came back after getting no irrigation from June to March. Here is a picture from my previous house in George West, TX. The grass is 32 inches high and had not been watered for many months. You can see the top of my dog's tail and her ears (different dog). When you mow St Augustine high, it needs less water. If you don't mow it at all, it needs no water to thrive. Please do not let the so called drought intolerance deter you from St Augustine. Fertilizer - Neil says, in part, ... Most clay soils have excessive amounts of phosphorus (middle number of the analysis), so soil tests usually suggest a high-quality, all-nitrogen fertilizer be added. What the hell? Who has clay in Texas??? Okay, now the OP describes his location as between San Antonio and Del Rio. As it turns out, there is a pocket of clay soil in D'Hanis, TX, along that route, so this might actually pertain, TO HIM, but almost noplace else. Clay soil is a red herring. Get the soil tested if you absolutely cannot grow anything. Otherwise, go with organic fertilizer and see the miracle unfold. Disease - Neil says, Gray leaf spot is a fungal disease that shows up in mid-summer into early fall. You’ll see diamond-shaped, gray-brown lesions on the midribs of the blades and occasionally on the runners themselves. This disease is most prevalent following applications of nitrogen. In fact, the additional symptoms of gray leaf spot are yellowed leaves that look like they need more nitrogen. I get gray leaf spot any time of year. My lawn woke up with it this year in early spring. Caused by too much nitrogen? I get it after months and months of no nitrogen at all. Like now, for instance. The lawns on his St Augustine Diagnostics page are all mowed way too short. Between that and his comments on drought scaring people into watering too much, it's no wonder people have problems with St Aug.
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Billl
16 years ago
You can use pretty much any fertilizer you want on St Aug. What you don't want to use are "weed-n-feed" products. St Aug is very sensitive to many of the common herbicides, so read all the labels VERY carefully before you put anything like that on your lawn. As for mowing timing, it doesn't matter. Since you are under water restrictions though, you will probably want to fertilize on Wed or Sat so you can water it in.
skoot_cat
16 years ago
I agree with bill about the watering.

Apply only enough water to wet the soil in the rootzone. For Florida's sandy soils, 3/4 inch of water is generally sufficient. Do not water the lawn again until signs of wilt occur. As the soil begins to dry out, the lawn will show a lack of available moisture by wilted leaf blades. This condition is evidenced by a lengthwise folding or rolling of the blades, caused by a loss of turgor or water pressure within the plant. Wilting is best seen on the older leaves of the grass plant because the youngest leaf is not fully expanded and will appear as if it is wilted. Lawns under drought stress curl up their leaves. Unless rain is forecast in the next 24 hours, lawns should be irrigated when 30 to 50 percent of the lawn shows signs of wilt.

To determine how much water your sprinklers are applying you can do a simple test. Randomly place 6-10 tuna cans in each zone the night before you sprinklers are set to run. Measure the amount of water in each can to determine if you applied 3/4". If not, water longer next time. Be sure to check your irrigation system for uniform coverage at the same time. I have to water my zones with rotor head for 70mins each to get 3/4in.

About fertilizing S.A. in SF: Low Maintenance 4x per year/growing season. High Maintenance 6x per year/growing season. Read link below for important info about fertilizing. If you are interested in an Organic approach, let me know. I have maintained my S.A. in Central FL for 3 years with excellent results. I will be glad to help.

A few other things that are a must for S.A.
1. Mow at the Highest setting and Frequently, never remove more than 1/3 of the leaf blade.
2. Keep your blade sharp
3. Recycle your clipping back to the lawn
3. Irrigate Uniformly, early A.M., Infrequent

The link below will tell you everything and more that you want to know about maintaining healthy S.A. in SF. be sure to Bookmark it, its a great reference tool.

Here is a link that might be useful: UF-IFAS website
hgiljr
Original Author
16 years ago
Thanks for all the info. Skoot Cat you are right, that link is more than what I might need but VERY helpful. Now as for fertilizer, right now I am just looking for a basic one I can get at a nursery or local improvement store (home depot). Is there any particular number I should just target? Thanks again
skoot_cat
16 years ago
Look for a fertilizer with slow-release N. Low P and high K.

The 3 numbers on the bag are in this order, NPK: N = Nitrogen, P = Phosphorus, K = Potassium
lou_spicewood_tx
16 years ago
Lesco fertilizer is good enough. I've seen numbers like 24-2-11 so look for that at home depot.
ronalawn82
16 years ago
hgiljr, I have a contact in Margate and I am told that the rainfall alone is quite sufficient to keep the grass growing well there; your comment about mowing reinforces this and I would not worry too much about watering. As for inorganic feritilizing, I think that the timing is too late; there is too much rain. Apply 'Milorganite' or similar product. The temperature is right and these products will not leach away. And lest I forget, the yellow spots might be the beginning of a fungus infection. If the spots become outlined by a brown margin in the shape of an hourglass, that will confirm it. Again the temperature and (over?)watering can contribute to fungi growth at this time. Keep a close watch on the area. If it spreads wider or gets more intense in the same area, you might want to treat it. Accurate diagnosis is ESSENTIAL.
hgiljr
Original Author
16 years ago
OK here is a macro picture of what I am seeing on certain area of my lawn. Thanks Ronalawn for your info but it was a bit too late since I had already completed my fertilization. Now if what is happening is fungus, what are the steps to treat it and what should and should not do? Thanks again
http://s195.photobucket.com/albums/z18/hgiljr/?action=view&current=P1010005.jpg

Here is a link that might be useful:
skoot_cat
16 years ago
It appears to be Gray leaf spot, which is from overwatering/prolonged periods of rainfall. Once S.A. is established, the disease is chronic but not severe.

Avoid excess nitrogen such as liquids or quick-release
Water Early A.M. @ 1/2 to 3/4" only when needed/wilting occurs.
hgiljr
Original Author
16 years ago
GREAT... I already spread the fertilizer this past weekend. I went with the Lesco fertilizer 24-2-11 which has a high N level from my rookie knowledge. What should be done now? THanks again for everyone's help on this matter.
Billl
16 years ago
Ya gotta relax man! You are killing the lawn with kindness. As long as you do the "Basics" right, your lawn should bounce back fine.

Keep it mowed - at least weekly - on the highest setting. Since you have a fungal problem going, bag the clippings until you can get that under control. After that, mulch mowing is best.

Water only as needed. Extra water feeds fungal problems, so only water when the lawn needs it.

Fertilizer - you are fine here. Just get on a plan of fertilizing once every 6 weeks or so. The lesco is fine. You might consider getting a soil test sometime to make sure your other nutrients are in line. Without that, the general rule is to use a "balanced" fertilizer (one with some of all the nutrients) about once a year and any regular lawn fertilizer the rest of the time.
skoot_cat
16 years ago
I agree with billl, RELAX!

Your lawn needed to be fertilized anyway. Im sure the fertilizer was in a slow release form.

Just stick to billl's suggestions above, you'll be fine.
lou_spicewood_tx
16 years ago
24-2-11 is SLOW release fertilizer! Don't worry too much about it. I've used it before.

Watering is the biggest key. Don't water TOO OFTEN! In a perfect world, it'd rain once a week about an inch of slow soaking rain over night. Over in Texas, it plainly SUCKS to deal with FREQUENT rains that make grass yellow out.

Yellowish spots on St. Augustine Grass

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