# Pale yellow st. aug blades w/thinning in patches



## Texastaug (May 23, 2019)

Can anyone identify the disease or fungus causing pale yellow on this st augustine? Some photos show the yellow areas and other photos show the healthier darker green area.

We have received too much rain for the past few months in Central Texas. So I haven't watered at all since the previous fall (5 months ago or so). Front lawn is mostly full sun. 
Back yard has 20 live Oaks so plenty of shade but does get moments of direct sun as seen in the photos.

I have pale yellow st augustine in both the front and back yards with maybe a bit more yellow in back compared to the front, but the back is twice as big so maybe they're roughly the same ratio of dark green to pale yellow. Front has a almost even 50/50 mix of I think Bermuda and st augustine with the Bermuda being nice green and some of the st augustine being the pale yellow. The back yard is almost 95+ percent st augustine and some occasional clover, dandelion, etc.

I have about 80 percent dark green to 20 percent pale yellow throughout both yards. I have 10,000 square feet of total lawn.

Lawn started to form pale yellow patches starting around early April, I think. Patches have spread a bit. This seems to happen every year. I recently did a lawn core aeration front and back.

I have applied disease ex and bio advanced fungus control for lawns about a week ago. I'm considering putting down another application in a week from now to try to get control of it. I am seeing mushrooms in my lawn usually in the areas where the blades are pale yellow but not always. I think the pale yellow is fungal but I have no idea which fungus causes this in st augustine. So I feel like I am potentially wasting my time and money.

On the "pest and lawn ginja" youtube channel he shows a lawn that has the similar pale yellow which he refers to as fluorescent yellow in his video title. This looks very much like what I have. He never mentions fungus in this video and he claims that it is salt in the soil due to the home being built on top of a lake bed or something, I can't remember what he said. He treats it with humic acid and maybe something else I can't remember.

Of course I've already bought but not yet applied some humates from Anderson but I don't expect it to be a short term fix. I also bought some azomite.

Maybe lack of nitrogen since I've only ferted with milorganite twice in the last 6 months with the most recent one being yesterday and the prior being 5 weeks ago? I know the slow release means the grass probably didn't get that fast jolt of nitrogen that it might need. But at this point I don't want to keep throwing down product without more direction on what I'm doing.

Any help would be greatly appreciated!


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## SCGrassMan (Dec 17, 2017)

Could be take all patch. Put down some appropriate fungicide and also some peat moss as top dressing and water in well.


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## Texastaug (May 23, 2019)

SCGrassMan said:


> Could be take all patch. Put down some appropriate fungicide and also some peat moss as top dressing and water in well.


Okay thanks for the reply, I will do that. I think you may be correct on the take all diagnosis. I've had someone tell me that before. I wasn't 100 percent on it though because I could never find any online info showing take all with the pale yellow.

I've already applied disease ex and also bio advanced fungus control for lawns 8 days ago. I think I'm going to order another round tonight so that I can apply it in about 6 more days from now.


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## SCGrassMan (Dec 17, 2017)

Make sure the products you mentioned are labeled for that.


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## TN Hawkeye (May 7, 2018)

Texastaug said:


> SCGrassMan said:
> 
> 
> > Could be take all patch. Put down some appropriate fungicide and also some peat moss as top dressing and water in well.
> ...


Could it be iron deficient? Google st Augustine chlorosis and the pics look pretty similar. Did you notice it bounce back a bit after the milorganite?


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## Texastaug (May 23, 2019)

I already spread liquid chelated iron recently with no results so far. I think grass has slightly worsened after my first milorganite app. My second milorganite app was yesterday so not enough time on that one. I think the fungus control products that I've already put down might have halted it for the past week. I'll likely put more fungus treatments in a week to further gain control of the fungus (assuming that's what it is based on the feedback here and the mushrooms growing every where)


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## Texastaug (May 23, 2019)

TN Hawkeye said:


> Texastaug said:
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> > SCGrassMan said:
> ...


I don't know how to reply directly. I wrote out a reply in the main thread I think.


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## Buffalolawny (Nov 24, 2018)

Could be a High PH level in the soil.
May need an added liquid iron feeding as well intergrated with your normal fertilising program.


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## CenlaLowell (Apr 21, 2017)

Would not surprise me if it some type of fungus. I'm beginning to hate St Augustine because how weak the grass is.


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## minifarmer (May 21, 2019)

It looks kind of like St Agustine Decline Disease or deficiency in a micronutrient.


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## Texastaug (May 23, 2019)

Do you know how to treat st augustine decline? I tried peat moss and two different fungicides, prodiamine (or was it propiconazole? I can't remember ) and one other with two treatments for each and the problem has only spread further. I'd say it's doubled in size and I'm seeing yellow everywhere in the backyard.


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## Texastaug (May 23, 2019)

SCGrassMan said:


> Could be take all patch. Put down some appropriate fungicide and also some peat moss as top dressing and water in well.


I put down two different fungicides, one liquid and one granular, Bayer was the liquid and scott's I think. I treated twice within a 3 week period. I also spread peat moss on all the yellow areas. Two weeks later and the yellowing is doubled in size and spread to areas that were previously green. What can I do?


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## Texastaug (May 23, 2019)

This is the newest photo of the yellowing. It looks worse in person compared to the picture. Lots of yellowing


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## SCGrassMan (Dec 17, 2017)

I'd do a soil test and also send in some plant tissue


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## pintail45 (Apr 26, 2018)

Texastaug said:


> Do you know how to treat st augustine decline? I tried peat moss and two different fungicides, prodiamine (or was it propiconazole? I can't remember ) and one other with two treatments for each and the problem has only spread further. I'd say it's doubled in size and I'm seeing yellow everywhere in the backyard.


SA Decline isn't curable. The good news is you don't have it. At least, I don't see it in the pictures. If you did, you'd notice a mosaic (mottled) pattern to the chlorosis, not parallel stripes.

I've seen several SA lawns do this, usually when it's hot and rainfall is abundant. I personally think it's new growth that's being pushed so fast by the hot weather/sunlight/rain that it doesn't have time to absorb nutrients from the soil.

In my experience it goes away by itself in a couple of weeks after the rains stop.


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## Texastaug (May 23, 2019)

I got the soil tested in front and the back and the only thing notable is that the nitrogen was slightly low. They recommended a nitrogen application. Ph was also high at around 7.7 with 6.2 being the cl.

Lawn got darker green in a few areas after applying scott's for southern lawns. I typically put down milorganite but I wanted to see what scott's could do.

However, there's still some new yellow spots popping up and other areas are growing in size with the yellowing. The Temps have been getting in the mid 90s during the day for the past few weeks but we're still seeing weekly rainfall that won't let the ground get really dry.

Any thoughts?


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## Greyleafspot (Oct 16, 2018)

What are you going to do for the ph. My guess is that's what's causing the yellowing.


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## Texastaug (May 23, 2019)

Greyleafspot said:


> What are you going to do for the ph. My guess is that's what's causing the yellowing.


They didn't make recommendations. I just bought some iron to eliminate that as a possibility for the yellow. For ph I don't know what to do. sulfur i think


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## LawnRat (Mar 22, 2019)

Texastaug said:


> Greyleafspot said:
> 
> 
> > What are you going to do for the ph. My guess is that's what's causing the yellowing.
> ...


Use an ammonium sulfate 21-0-0-0 fertilizer (24% sulfur) to gradually help lower ph. It's a long tough battle. 7.6 isn't too bad, I'd probably skip the elemental sulfur. I think with high calcium soils, changes to pH won't be permanent, but frequent apps with AS should help with iron uptake. Most iron supplements are ineffective with high pH, even most chelates. EDDHA chelated works best on high pH soils.


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## Cals Pajamas (Jul 17, 2019)

I just registered so i could chime in here. I was dealing with the same yellowing issue in my backyard as well as trying to battle dog urine spots. I have been using liquid Humic-12 of the N-Ext products at a rate of about 15 oz/1k every 3-4 weeks (so far I've only done 2 apps) and the yellowing is virtually all gone and while i still get die off from urine spots, they seem to be much quicker to fill back in.

I'm personally going to keep applying monthly in this one area (~1k sq ft) to stay on top of it. I have the opposite problem as you though with very low ph but i think when the ph is not optimal, the grass doesn't take up the nutrients like it should leading to these issues. I'm certainly no expert, just wanted to share my experience. Good luck


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## Texastaug (May 23, 2019)

LawnRat said:


> Texastaug said:
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> > Greyleafspot said:
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Okay thanks for the advice. I'm going to pick some up and give that a try. Three aps of AS a year a good rate? You think applying in late July would be fine considering the heat?


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## SmokerX (4 mo ago)

Please excuse me for necro mancing this thread. But, he has the soil tests. If you check the other areas where "yellow st augustine" pops up in the forums its all over Texas with posts from DFW also showing High Calcium Low Magnesium on their soil tests. The Original Poster is also closest to me in relation to distance. Like most I have tried Iron and Nitrogen and assuming its a fungus to no real results.



I believe it is competitive nutrient lock out between High levels of Calcium and low levels of magnesium and have applied epsom salt to increase competitive magnesium levels. I believe heat and drought play a role in this by causing stress, increasing watering with city water that is hard water and contains calcium and no rain means no rain water to wash the excesses of calcium away.

I notice that certain species of bermuda grass are less prone to this yellowing compared to SA, although hybrid species, such as Mohawk, Sultan or Sydney seems more fragile and prone to chlorosis. At least for what ive seen in its nursery stages of development. I believe left untreated, it can cause massive die back that invites in opportunistic fungus to feast on the decay, but SA will usually bounce back during spring, when heavy rain water comes in to flush out calcium. Whereas this seems to be a problem most experienced toward the end of summer and into fall. Fall being where it is blamed on fungus as rains come in to water your dead thatch and promote a composting environment.

Please note that A&M makes no mention of this on their soil report and most will declare it fungus or iron deficiency, while PH plays a role as calcium hard water is highly alkaline. Again I have tried this angle with little results and only began to experience this when I forgot I was supposed to be broadcasting epsom salts, because WHY? my lawn looks great so why worry about it?... Until it doesnt.

I believe potential solutions are broadcasting epsom salts and possibly collecting rain water to become less dependent on hard well and tap waters, but this option is costly and may not be feasible for the amount of water required for SA.

As far as what species of Bermuda, I have noticed, seems most resistant to the chlorosis of the "Texas effect" I cant make an accurate ID. Its definitely not a hybrid type dwarf type. Possibly Common? the one Pennington developed for Texas lawns? Or a type of sod for contractors? Or some random box store bag seed? Its not Princess 77. I think you'll know it when you see it, if you look closely toward the end of summer. It's the ones staying dark green that likes to grow into a heavy lawn sod, overgrow, with prolific runners. Prolific runners are probably an opportunity to take a sample.

Also, it sounds not kosher, but by keeping both species of bermuda and St. augustine in the same lawn. St. Augustine tends to fill up shaded areas, while Bermuda fills up sunny areas and, to me, that mixture seems preferable to weeds or bald patches. Then in "good years" where the "Texas effect" is not as pronounced St. augustine will out perform Bermuda and fill my lawn. And in bad years the Bermuda out competes, as its the sole survivor and almost demands I fill in the aggro'd regions of decay with bermuda overseed. Then once the surviving Rhizomes and runners of St. augustine bounce back its almost game over for Bermuda, and in this way I selectively breed a more survivable lawn in the field. It's not as preferable aesthetically as, lets say, a monoculture of princess 77. But more preferable to the inevitable bald patches and opportunistic weeds taking hold.


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## ionicatoms (Mar 8, 2020)

SmokerX said:


> If you check the other areas where "yellow st augustine" pops up in the forums its all over Texas with posts from DFW also showing High Calcium Low Magnesium on their soil tests.


You seem to have over-generalized from a small sample. I'm afraid the Dunning-Kruger effect has more to do with your beliefs than plant/soil science. This forum includes numerous reports of yellowing from across the South and several directly contradict an allegation of low magnesium in the soil or inadequate rain fall. To the best of my knowledge, @UltimateLawn is one such case.

St. Aug can yellow due to a variety of reasons, but in general I agree that a micronutrient application should be one of the first things somebody with this symptom tries. I've had good luck with both Southern Ag Palm Nutritional and GCF MicroGreene.


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## SmokerX (4 mo ago)

Florida is much different than This specific region of Texas so I pulled up some data specific to this region: Texas is hard mode. Florida is easy street for growing St. Aug.

ThreeWiggle
Houston
376 Ca
20 Mg
ratio: 18 to 1
ImrockDee
NorthDFW
Ca 4616
Mg 185
ratio: 25 to 1
Texasstaug
Cedar Park
Ca 14973
Mg 582
ratio: 25 to 1

As you can see by the diagram. The ideal ratio is 2 to 1. With Ca inducing a Mg deficiency. I believe the dunning kruger to exist with Texas A and M not telling you youre running a 25 to 1 ratio on cal mag. People seeing that soil test and suggesting or spraying iron then pretending there was some significant result. Your neighbor when youre dabbing on his property line with epsom salts and people using a cal mag combined product when youre running a 25 to 1 ratio.

I had a sneaking suspicion this might be the case when applications of iron and nitrogen had little effect and I said hey wait a minute didnt I used to broadcast epsom salt when I didnt have this problem? Didnt I stop doing that for at least the last few years? Then checked this guys soil samples to confirm it should be around a 25 to 1 ratio for this region, without amendment.

Very rarely will you see someone suggest epsom salts, or break it down as scientifically or eloquently as I just did. Its not rock science. As far as over generalizing from a small sample its 2 cases of 25 to 1 ratio in a known lime stone outcropping. I think its safe to say Im not running a 2 to 1 ratio and my lawn looks like its got take all or root rot (opportunistic composters)

Like you want to get rid of your root rot? Provide more oxygen to your roots. Not bug killer. Youre not even addressing the problem. The root rot is just taking an opportunity to address your already dead roots. Again, not rock science.

Florida? Yeah thats a completely different scenario that is probably easily picked up on your soil samples, known and addressed.

"microgreene" 134 dollar??!! Ok lets say you go with that. That's 2.5 gallons of microgreen for $67 OR you get 4 pounds ferrous sulfate $21 and 18 lbs epsom salt $28. Thats $49. Thats enough epsom salt for 7,500 sq ft. of lawn for the epsom and 35,000 sq ft for the iron, according the Louisiana State University Agg center and the back of the box of epsom salt brand epsom salt. Also epsom salt is 13% combined sulfur. Vs the microgreen will get you 2,500 sq ft + shipping the water weight. Also you have the ferrous sulfate laying around to do cool stuff with it like use it as a mordant or use the epsom salt to relieve occasional constipation. Im not seeing much in there besides that Besides traces of manganese zinc and copper. Copper I got some as root killer and Ive never felt the need to spray it on my lawn except as bourdeoux mixture and ok, maybe just a little sprinkling in with a iron foliar spray a few times.

To Me the Iron and Magnesium are the heavy hitters in that package. Mg being the central figure in a chlorophyll molecule, having a 4 to 1 ratio with Nitrogen for every chlorophyll molecule, whereas I cant find the ratio for adding to a lawn on a bag of pure zinc sulfate...20-70 parts per million of zinc are good levels for corn since corn is a big grass. On that A&M soil test theyre not even testing for those...But testing for Magnesium..The micro micros cost more on the soil test. Magnesium at 4 to 1 for every nitrogen in a chlorophyl, it should be considered more than just a micro. Its like having an iron deficiency in your hemoglobins.

thats 4 molecules N for 1 Magnesium molecule for every chlorophyl molecule. (the rest is carbon and hydrogen chains around are 4N 1Mg star of the show.)

Also notice the difference pound for pound of Iron and Magnesium. its 8,750 sq ft for iron but only 416 sq. ft. for Magnesium pound for pound. Where Iron is proclaimed as the deficient macronutrient. Zinc isnt even on the radar. Iron sulfate pulls down PH.

_____

All right, this is the bonus round: As Ive showed above magnesium is the important micro here 4 to 1 N etc. My guess is its an imperfect system, like Around 25 percent of the time RuBisCO incorrectly collects oxygen molecules instead of CO
2, creating CO2 and ammonia that disrupt the photosynthesis process. Plants remove these byproducts via photorespiration. photorespiration decreases the efficiency of CO2 assimilation by 40%. The plant cant figure out which one is a CO2 and which one is an 02. So 25% of the time its eating an 02 then having to puke back up the carbon it collected as co2 reducing it another 40%. Thats all, also being effected by temperature.

So what if Calcium and Magnesium are similar? Both of them are an oxidized metal you always find in their metal oxide form. Maybe it cant tell the difference and keeps grabbing calcium and examining it after uptake hoping its magnesium and at a 25 to 1 ratio its like oh no, not again. And this is the way calcium effect magnesium lock out. Because the other one in that chart is Potassium. Which is the same. Its a metal commonly found as an oxide. Important for plant growth.


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## ionicatoms (Mar 8, 2020)

A Mehlich III Mg value > 20 ppm indicates that a turfgrass response to Mg is unlikely (Sartain 1993).

The whole ratio approach to fertilization lends itself to abuse. The bottom line on magnesium is as follows:



Furthermore, you missed my point which is that you made a sweeping generalization which is directly contradicted by readily available evidence. You recommend epsom salt for one lawn, fine, whatever. Yet if you go look at many test results for lawns without this problem, you'll see the exact same ratios and if you bother to look at lawns having this problem across the nation, they don't have the same ratios you seem to think are a concern.

As it turns out, yellowing is caused by more than one thing and a high calcium to magnesium ratio probably isn't even one of them if extractable Mg levels are above 20 ppm.


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