Folks are always wanting to do the impossible. "Impossible" in this
area consists of trying to change the alkaline soils in this area to
acidic or even neutral. Novices always try to change or modify the
local soil pH in an effort to grow their favorite gardenia or azalea.
The results are always the same -- failure.

The alkalinity problem can be treated or temporarily altered.
The temporary alteration involves elimination of the culprit causing the
problem - the soil. If extremely acid-loving plants such as azaleas or
gardenias are to be grown, an artificial growing media should be used.
Standard potting soil is not acid enough and will not maintain an acid
condition over a long period of time with the alkalinity bombardment of
water and soil leachings. To insure an acid-enduring growing media,
mix two-thirds sphagnum peat and one-third WASHED sand (not regular sand
since it contains lime and weed seed). Excavate a suitable (large
enough to contain the root system of the mature-size plant which you are
planting) size hole, and fill with the sphagnum-peat-sand mix. DO NOT
INCORPORATE ANY OF THE NATIVE SOIL WITH THE MIX! This may sound like
a lot of trouble but it prevents a lot of ugliness later. Many rose
growers follow a similar plan of action to insure vigorous plant growth.
And, if you don't make this "modification BEFORE you plant, don't
expect to correct the problems later!

Of course, the choice of peat moss may make the difference between
success or failure. One has to be careful of the kind of peat moss he
or she uses to alter the soil horror with which we must contend.
There are three major types of peat moss in the trade. They are
moss-peat (peat moss), reed-sedge peat, and peat humus. Peat is the
organic remains of plants accumulating in swamp areas where ordinary
decay has been retarded by immersion in water. It may require from 100
to over 500 years to produce a layer of peat a foot thick. The rate
depends on the type of plant and its environment. Moss-peat (peat
moss) is formed chiefly from the sphagnum type mosses. Nearly all peat
imported from Canada or Europe is derived from sphagnum moss. It is
very acidic with a pH of 3.6 to 4.2. The color is tan to brown. Moss
peat is light weight, porous, high in moisture-holding capacity but low
in nitrogen (0.6 to 1.4 percent). It is an excellent soil conditioner
but will require some lime when used to grow anything other than
acid-loving plants in containerized or container-like (such as the
excavated hole) situations.

This is what we need in South central Texas --- something
that is inherently acid and will release acid gradually as it
decomposes. Because sphagnum peat moss is so extremely acid, it cannot
be neutralized by the constant bombardment of alkalinity which is
experienced in local soils. The pH of most landscapes ranges from 7.8
to 8.2. Organic material (leaves, grass clippings, tree trimmings)
produced locally, grown in alkaline soil, will produce a more basic or
alkaline decomposed product. So to "fight off" the onslaught of
alkalinity, an organic material produced in an area which has acid soils
MUST be used.

So why is pH so important? When the pH of a soil is too
high (alkaline) or too low (acidic), most of the minor fertilizer
elements (iron, manganese, molybdenum) become unavailable for plant
uptake. Plants must have the minor elements, especially iron,
Iron deficiency in plants is a problem common to many landscapes due to
our very alkaline soil. For further information about lawn
fertilization, see:

http://aggie-horticulture.tamu.edu/plantanswers/turf/publications/fertiliz.html

Iron is essential for the formation of chlorophyll (the green
pigment in plants). Therefore, when iron is unavailable to the plant,
iron deficiency (sometimes referred to as iron chlorosis) results.
Prolonged iron deficiency can result in decreased shoot and root growth
because of a lack of chlorophyll to maintain photosynthesis. Iron
deficiencies do not usually result from a lack of iron but rather
because the iron is tied up or "fixed" in insoluble compounds. Iron is
most commonly deficient in alkaline soils although excessive levels of
phosphate, manganese, zinc and copper can produce iron deficiency.
Waterlogged soils can also reduce the availability of iron.

Identification of the problem is not difficult. Look for two
things:

1) Progressive yellowing of the newest leaves occurring first. If
lower, older leaves turn yellow first, then the problem is something
other than iron deficiency.

2) Leaves with darker green veins and the tissues between the
veins turning yellowish green. When iron deficiency is severe the
entire leaf may become white and finally brown.

Iron chlorosis is most prevalent on members of the grass family
(such as St. Augustine even though some varieties such as Floratam are
more resistant), certain fruit trees (citrus and peaches), many
vegetables (particularly beans), many flowers and ornamentals, and some
shade trees. Plants that thrive in acid soil, such as azaleas or
gardenias, can likewise be severely affected. Since iron deficiency is
often the result of alkaline soil reactions, acidifying soils would
appear to be a practical solution. Calcareous soils, however, may have
large reserves of calcium to buffer attempts to lower the pH,
particularly if the soil is fine textured.

To prevent a plant's suffering the fate of "iron poor blood", use
the following techniques:

1) Totally avoid the perpetual problems with yellowing foliage of
plants by planting only Extension recommended, tried-and-proven plant
types. Lists of recommended ornamentals are available at:

http://aggie-horticulture.tamu.edu/plantanswers/publications/southcnt.html

2) Add iron. The best approach to correct the yellowing
condition of existing plants is to use either chelated iron or iron
sulfate (Copperas) as both a soil treatment and as a foliar spray.
Spray applications of sulfates and chelates often are more effective and
give quicker results than soil applications. However, the effect will
normally not be as long-lasting and repeat applications may be
necessary. Be certain to keep any iron products off walks, driveways,
brick or masonry surfaces, since they will cause staining. MALCOLM
BECK OF GARDENVILLE ADDS: "Fresh iron stains on a sidewalk or anywhere
can easily be cleaned up with oxalic acid. Gardenville sells it or it
can be purchased at some True Value stores. It is normally used to
bleach wood. It will not hurt plants and works really good on FRESH
iron stains." Soil applications of iron sulfate to green a lawn
that is yellow and suffering from iron chlorosis MUST be made
uniformly and concisely to avoid foliage burn and stripping. When using
a drop-type spreader, be sure to overlap wheel paths on passes through
the area being treated, walk at a rapid, steady rate (to avoid overdoses
of the free-flowing, granular iron sulfate). Water the iron
sulfate-treated area after the application has been made.

The good news is that there is now a granulated, i.e., doesn't
pour through the spreader as Copperas does, product which contains the
same percent iron as Copperas and has the nitrogen fertilizer to
provide a quick green-up. It is sold as Ironate (NOT Ironite which has
not been effective in my tests! and is said to contain arsenate since it
is a mined product.)

Iron chelates are expensive and some commercially formulated
types don't perform well in alkaline soils. Malcolm Beck and I
discovered a way for homeowners to make their own iron chelate. An iron
chelate is an piece of organic material with the iron molecule tightly
attached. As the organic material decomposes, the iron molecule is
released into the soil for use by the plants. So, basically, an iron
chelate is a slow-release iron source. If you can imagine how easily
and completely iron products will stain walks, driveways, brick or
masonry surfaces, you can readily see how those iron molecules can
quickly attach to an organic product (carrier) such as leaves, grass
clippings, mulch, lawn dressings, etc. From this notion years ago we
began to recommend that gardeners make their own iron chelate product.
This can be simply done by spreading iron sulfate, in the form of
Copperas or the new improved version with nitrogen named Ironate, onto
and into organic mulches. This should be done in layers and every time
organic material is added. How much to add? Add it until the top of
each layer of the organic material is darkened -- it would be difficult
to add too much since the soil deactivates the iron molecule so rapidly.
If you need a measurement, mix one cup of iron sulfate (copperas or
Ironate) to each bushel of mulch applied.

A COMMENT FROM MALCOLM BECK: "The best product I have discovered to
grow plants and keep them green is Green Sand. I introduced Green Sand
to this area and it contains from 10 to 20 percent iron. It is a
naturally occurring mineral found in Texas. The Green Sand should be
applied to a garden area at the rate of two pounds per 100 square feet
and to lawn areas at the rate of 15 pounds per 1000 square feet. It
will not burn so additional amounts can be added to severely chlorotic
areas.
Gardenville is selling SAWS compost mixed with Greensand and being
sold as Sports Turf Plus."

If you have the concept of how to cure yellowing, chlorotic
lawns by the addition of iron and nitrogen, how would you like to cure
certain fungus diseases as well? Dr. Phil Colbaugh and
Research-Extension colleagues at the Texas A&M Research Center at Dallas
have discovered that using a top-dressing or lawn dressing with the acid
peat moss (Michigan Peat or Peat Compost) results in control of TAKE-ALL
ROOT ROT
on St. Augustine grass on Dallas area home lawns. In comparison
studies, peat moss topdressing reduced symptoms of TAKE-ALL ROOT ROT
for longer periods than cow manure compost and is thus considered the
more effective disease control product.

INTRODUCTION
In recent years we have discovered that underground organs of turf
grasses are commonly attacked by ectotrophic fungi that cause
destructive patch diseases. Ectotrophic fungi grow over living turf
grass roots and underground stems as runner hyphae (dark fungal
threads). There are several ectotrophic fungi that cause turf grass
diseases and their appearance is similar on the different turf grass
hosts they attack. For convenience, all of these fungi are referred to
as ETRIF (ectotrophic root infecting fungi) to simplify their diagnosis
and associations with the similar turf diseases they cause.

Take-all root rot (TARR) of St Augustine grass has emerged as a
major problem on landscapes in Texas as well as other states along the
Gulf Coast including Florida. The disease is caused by Gaeumannomyces
graminis var. graminis, which belongs to the ETRIF pathogen group. The
brown-black mycelial growth of the fungus (Fig.1) colonizes roots,
stolons and shoots but it is primarily a root destroying pathogen.
Damaging effects of this disease on St. Augustine grass were first
observed and described in Texas by Dr. Joseph Krausz (plant pathologist
at Texas A&M University) and in Florida by Dr. Monica Elliott
(University of Florida). In a 1999 survey of St. Augustine grass lawns
in north Dallas, we observed yellow patch symptoms (Fig. 3) of the
disease on 61% of 70 lawns during the month of September. If this
disease progresses it kills the stolons and produces patches of dead
grass during summer ranging from 3-10 ft in diameter. Because of the
widespread nature of this disease, our research investigations sought to
develop a practical control measure for landscapes with St. Augustine
grass lawns.

DESCRIPTION OF FIELD SYMPTOMS
Symptoms of take-all root rot disease (TARR) typically appear on
St Augustine grass as diseased patches of turf during late spring and
throughout the summer months. Pathogen activity causes a severe root rot
that completely destroys tap roots which anchor St. Augustine grass
stolons to the ground. Visual symptoms of the disease on lawns are
initially small yellow patches of turf with leaf blades that appear
chlorotic while the healthy leaves remain a typical green color (Fig.
3). The yellow patches are thought to be associated with the production
of a toxin by the ETRIF fungus when the turf is growing under stressful
conditions. Yellows symptoms of the disease can persist on lawns
throughout the summer growing season. Dark brown or black mycelial
threads of this fungus (Fig. 1) are distinctive and produce scattered
black dots (hyphopodia) that anchor the fungus to the plant. Roots of
affected plants become shortened, discolored, and often have dark
colored lesions that are visible upon inspection with a hand lens.
Eventually the roots become completely rotted and shriveled to form a
non-functional root system (Fig 2). In the final stages of decline,
diseased stolons gradually succumb to hot summer temperatures or cold
winter weather and produce large patches of dead grass that do not
recover from injury.

Affected patches of turf can at first be quite small ranging from
1-2 feet in diameter; however, they also appear as larger areas that can
range from 5-10 feet in diameter. Diseased areas are not always circular
but often appear as roughly circular patterns in the lawn. In our 2002
TARR survey on North Dallas lawns, we observed a higher number of
take-all symptoms in heavily shaded areas compared to areas receiving
direct sunlight or partial shade for most of the day (Fig. 5). TARR
disease should not be confused with white grub damage which can also
appear at the same time of the year. The best clue is to look for the
yellow or chlorotic leaf extensions (fig. 3) on St. Augustine grass turf
that has not received mowing for several days. Symptoms of TARR disease
also include the appearance of brown shriveled roots that are killed by
the fungus as opposed to white grub damage where the roots are actually
removed by insect feeding.

SEARCH FOR A PRACTICAL DISEASE CONTROL ON DALLAS HOMELAWNS
We used two approaches to control the TARR disease in field
investigations on area lawns during the past three years.

One approach utilized conventional fungicide sprays with
Terraguard or Bayleton, Heritage, and Banner Maxx using 2.9L of spray
per 10 m2. A second approach utilized topdressing lawn care products
including (1) manure compost and (2) sphagnum peat moss. Manure products
can enrich the microbial number and diversity for variable lengths of
time and low pH products like peat moss had been shown to suppress the
Gaeumannomyces fungus in previous research. While some of the manure
based topdressing regimens demonstrated improved turf grass growth,
effects on disease control were only partial and limited in duration.
Research field plots with the fungicides Terraguard (4 - 8 oz) or
Bayleton (2 oz) treatments gave good results for controlling the
take-all root rot symptoms. Success with fungicide treatments was better
on a lawns maintained under shaded conditions compared to lawns in full
sunlight.

A second approach with topdressings used low pH topdressing with
sphagnum peat moss. This topdressing approach has consistently
demonstrated TARR disease suppression in field studies during the past
two years. Our field comparisons of manure compost vs. peat moss
topdressings indicate the peat moss to be a more effective long-term
approach for reducing symptoms of the TARR disease. Some of the older
research literature on the fungus causing TAP indicates its aversion to
low pH. This might explain how the peat moss (pH = 4.4) controls the
fungus on exposed stolons and roots where the disease is active.

CONCLUSIONS
There is no indication of varietal resistance to take-all root rot
since the disease has been noted on all of the commercial St. Augustine
grass varieties. The use of fungicide applications is also limited with
only a few fungicides that are approved for use on this disease.
Although there is good evidence that fungicides are capable of
controlling the disease, environmental conditions and vigor of the turf
may pose some limitations on the effectiveness of fungicide treatments.
At this time we have no explanation as to why we observed a lack of
uniformity in fungicide effectiveness on different lawns.

The use of organic topdressing to control turf grass disease is a
relatively new approach to controlling turf grass diseases. Because of
the complexity of microbial antagonism, fertility values of topdressing
materials, different types of diseases and susceptibility of pathogens
to pH, most of this type of research is directed by trial and error
experimentation. We do have good evidence that the acid peat moss
topdressings result in control of TARR on St. Augustine grass on Dallas
area home lawns. In comparison studies, peat moss topdressing reduced
symptoms of TARR for longer periods than cow manure compost and is thus
considered the more effective disease control product. Additional
research will address the best time to apply peat moss topdressing
products as well as possible effects on other turf grass pathogens and
diseases.