St. Augustine yellow-4th year in a row

St. Augustine yellow-4th year in a row

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SterlingBlue – posted 26 March 2007 19:06

I have lived in my house for 4 years and every year the yard has been yellow. Have consistently been told it is iron deficiency but Texas A&M soil test revealed iron levels to be perfect, in fact a little bit high. Nitrogen, however is very low. Read a post that said nitrogen can promote and often cause brown patch in St. Augustine. Even if nitrogen levels are low? I hired a professional lawn service last year and they made my yard worse so this year I’m going solo. Would appreciate any comments/suggestions. I live in N. Texas.


[This message has been edited by SterlingBlue (edited 26 March 2007).]

tommy – posted 28 March 2007 09:17

What else did the soil test say? Is the Ph too high……is there excessive salts? If the soil is alkaline, apply gypsum. Yes, too much nitrogen is not good when fighting brown patch, but low amounts of nitrogen will be neccesary for good plant growth. Try a low nitrogen organic such as ‘Milorganite’.

TexanOne – posted 30 March 2007 01:24

The St Augustine in the photos is chlorotic. The close-up photo that shows individual grass leafs with striped dark green and yellow bands running lengthwise along the leaf are classic symptoms. Chlorosis can be evident in any plant that is suffering from a lack of iron.

Since your soil test indicates you have plenty of iron, the most likely cause is high soil pH (>8.0) is “fixing” the iron so the plant cannot use it. Another cause of chlorosis can be excessive water or wet soil.

Your best bet to correct the problem is to lower the pH of the soil. Acidifying fertilizers include ammonium sulfate, diammonium phosphate, monoammonium phosphate, urea, and ammonium nitrate. You can also use sulfur, and natural organic mulches to do this, but these are slower acting.

SterlingBlue – posted 30 March 2007 15:23

Soil testing was done approx. 1 year ago, however, nothing has changed so I believe any treatment should be based on these results. I am attaching the 4-pages of results – samples from various parts of my nearly 6,000 sq.ft. yard. My front yard slopes down at about a 40-degree angle, therefore I took two samples from the front — top and bottom of yard.

Alkaline is mostly moderate, however, I note from the test results that sodium is very low. Does that mean apply salt? (Pardon my ignorance, but that’s why I’m here asking questions.) Thank you for all the assistance you can provide!

http://i172.photobucket.com/albums/w19/SterlingBlueEyes/Landscape/Soil_Test_fron t_yard_top.jpghttp://i172.photobucket.com/albums/w19/SterlingBlueEyes/Landscape/Soil_Test_f ront_yard_bottom.jpghttp://i172.photobucket.com/albums/w19/SterlingBlueEyes/Landscape/Soil_Test_side_yard .jpghttp://i172.photobucket.com/albums/w19/SterlingBlueEyes/Landscape/Soil_Test_back_yard .jpg

[This message has been edited by SterlingBlue (edited 30 March 2007).]

TexanOne – posted 31 March 2007 11:43

The soil profile looks very good. You don’t need more sodium. Low to very low amounts of sodium are good levels as sodium is toxic to most plants – the lower the sodium level, the better unless you are growing salt-cedar or paspalum turfgrass!

Based on the detailed information you have provided, I would recommend you apply 1 to 1.5 lbs of nitrogen / 1000 sq ft of turf area in the form of ammonium nitrate (21-0-0 fertilizer) every 60 days during the growing season. Another side benefit of the ammonium nitrate is it will lower the soil pH somewhat to a more neutral pH reaction. Around August or September, you may want to fertilize with a “complete” fertilizer with N-P-K ratios around 3 parts N, 1 part P, and 2 parts K. Again, you will want to apply about 1 to 1.5 lbs of total nitrogen with this complete fertilizer product. Here is a good website for understanding fertilizer labels:


Most nurseries and home improvement outlets have ammonium nitrate available, as it is a common fertilizer. In North Texas, it is commonly sold with additives such as 10% sulfur and/or zinc. Any of these blends are good.

The goal is to provide sufficient nitrogen to the St Augustine, and to also allow the soil to dry out a little between irrigation cycles. That may be difficult right now with all the recent rainfall in Texas, but by late May or early June, the excessive rainfall should be over. St Augustine will definitely get very chlorotic in excessively wet alkaline soils over time.

SterlingBlue – posted 01 April 2007 13:35

TexanOne: As my kids would say, “dude, you rock!” Thank you so much! This is exactly the kind of information I was looking for! I am looking forward to implementing this plan and hope I end up with greener pastures! Thank you again! Hopefully in a few months I can report back with favorable results!

TexanOne – posted 05 April 2007 16:41

Thank you Sterling. I hope the advice I gave you works out for you! I did neglect to mention one additional factor in my previous post:

About 1x or 2x during the summer and late fall, be sure to top-dress the St Augustine with organic decomposed compost, cow manure, corn meal, or a mixture of these about ¼” deep across the entire turf area. Although the chemical fertilizers will give you quick results, they are not a long-term solution to successful St Augustine culture.

In the past few years in Texas (and elsewhere I would imagine), there are major issues beginning to arise with fungal and disease problems with St Augustine. Although these problems have always existed in years past, the problems in recent years have become worse. There is a lot of debate why St Augustine is developing disease and fungal problems, but a major contributing factor does seem to be the overuse of chemical fertilizers and the under use of natural organic additives to sustain the natural microbial, fungal, and trace-element soil balance. Essentially, the soil under most turfgrass is becoming depleted and the results are showing up as diseased and dying turfgrass.

There are many articles available on St Augustine diseases, but here is one of the most common problems you may encounter during the hot summer months:


Another issue I would like to point out is that a healthy St Augustine lawn does not require any more water than the other “drought tolerant” turfgrasses being heavily marketed today. I am not sure about the irrigation requirements of the patented St Augustine varieties on the market today, but native Texas Common St Augustine is probably the toughest, most weed-free, and water-wise turf you can have in our state.

St Augustine has gotten a bad rap for being an excessive water user, which is simply not true. In fact, over-watering or excessive rainfall is one of the major players of St Augustine becoming diseased – so try to keep it just a shade on the dry side and you will find it will perform very well.

The only other issue to be concerned about is extreme cold (below zero temps), which will wholesale wipe out St Augustine during the winter. Irrigating St Augustine during the winter months, and allowing it to grow tall in late fall will greatly help in winter survival.

Good Luck!

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