San Antonio Express News
Sunday, September 18, 2005
By Dr. Jerry Parsons
If we would have wanted a brown lawn, we could have sodded a lawn with the dead blocks of grass we had brought to Milberger’s Nursery for analysis last weekend during the KLUP-930 AM radio program! Either aliens with small, round ships had landed in most folk’s lawns killing large spots of grass or most people have a serious problem. We decided that the two main culprits in this spontaneous ugliness were drought and diseases.
This is not the first week we have had this onslaught. We have been getting questions since the first of August. So many were received that Calvin Finch wrote an expose’ which appears at:
http://www.plantanswers.com/calvin finch_articles/brown_spots.htm. He writes: “Many lawns have brown dead looking areas. There are many causes of the brown areas, and in order to green the problem areas, you must diagnose the cause. The brown areas usually are caused by drought, brown patch, take-all-patch, chinch bugs or grubs. Drought is addressed with watering. Brown patch is a fungus disease caused by excessive water and cured by reducing the watering and applying a fungicide. Take-all-patch is a fungus disease that is controlled by acidification with sphagnum peat moss over a long treatment period. Both chinch bugs and grubs are killed by application of a soil insecticide.”
To further refine this analysis, I will state that most St. Augustine planted on shallow soil and watered less than once a week with an application of at least one inch of water WILL TURN BROWN. The exception is Floratam which is the most drought tolerant of all St. Augustinegrass. Also, brown spots near sidewalks or pavement is caused by drying-even if you have an automatic sprinkler system. The water from such systems are directed away from the sprinkler so the area immediately under and slightly behind the system dries and dies. Also, it is very difficult to apply enough water to the lawn in the hottest section of the lawn which has the shallowest soil when we have a spell of 100º F days with no rain. The dead areas are usually linear rather than round and almost always are in full sun. The areas can also be a spot in the lawn where the irrigation application of water is not even. What you “should have done” was to hand water the spots several times per week, but as Tanya Tucker sings: “It’s a little too late to do the right thing now!”
We used to think that brown patch disease (caused by Rhizoctonia solani fungus) was not too prevalent this time of year because the weather is dry and hot. It was thought to be a disease of the spring and autumn. Because some people water like maniacs (three times a week!!) during hot, dry weather, we have actually seen brownpatch in the summer. Labeled fungicides such as Turfcide 10G and Hi-Yield Lawn Fungicide Granules with terrachlor or PCNB; Greenlight Fung-Away Systemic Granules with thiophanate-methyl, Ortho Lawn Disease Control and Ferti-lome Systemic Fungicide with propiconazole and Sprectracide Immunox with myclobutanil will stop the brown patch fungus.
Take-all-patch is another fungus disease. It has an infection pattern similar to brown patch, but the symptom appears in the summer time. Take-all patch kills the entire grass plant and is very hard to control. Most fungicides do not work. Texas A&M has started recommending the system discovered by Dr.Phillip F. Colbaugh, Research scientist at the Dallas Texas A&M Research and Extension Center and outlined at: http://www.plantanswers.com/root_rot_fungus.htm. Basically, apply one-half
inch of sphagnum peat moss over the dead area to encourage recovery of the area. The sphagnum peat acidifies which eventually kills the disease.
It has been brought to my attention that there are effective chemicals which may work on Take-all patch. These include Spectracide Immunox, GreenLight Fung-Away Systemic Granules and Ferti-lome f-Stop with myclobutanil.
The major point of this article is on dead-spots-in-the-lawn. ALL OF THESE PROBLEMS could have been avoided if Floratam St. Augustine had been planted! See: http://www.plantanswers.com/ grass.htm It is the most drought tolerant of ALL the St. Augustines, it is chinch bug resistant and it is tolerant (does not show pronounced symptoms) of Brown Patch or Take-All Patch. With this said, those of you who have suffered the brown-spots-in-the-lawn phenomenon this summer should follow this advice. Rent a lawn de-thatching machine, cut and remove the dead grass areas, and re-sod with Floratam St. Augustinegrass. Problems solved!
One more point of interest, the ONLY organic solution which is effective on lawn diseases is the sphagnum peat for Take-All Patch. Sphagnum peat is not effective against Brown Patch. Lately there have been claims made that corn meal and a garlic extract is effective. This is absolutely false. Even if these purveyors claim that a University tested and/or recommended the product. Everyone trying to do the “environmentally friendly-to-a-fault” thing have been wasting their money. They would have been better off making corn bread and using their garlic for cooking purposes!
I will explain how these University tests and recommendations have been misrepresented in a desperate attempt to find an organic fungicide in the fourth column in September section entitled: Brown Spots in the Lawn and Effective Solutions at: http://www.plantanswers.com/garden_columns. htm. Also in that web-version I will write more about the importance of fungicides, chemical or not.
Dr. Jerry Parsons is a Professor for Texas A&M University and a Texas Cooperative Extension Horticulturist for over 30 years in South Central Texas. For more information on this or other horticulture topics, go to www.plantanswers.com and our County Extension website at http://bexar-tx.tamu.edu.