Seeded
Bermudagrass Establishment:
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Renovation
and Damage Repair
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| Seeded bermudagrass
varieties offer turf managers the unique ability to cost effectively
repair or replace turf. Determining what type of renovation you want/need
to perform will dictate the approach you need to take. This Agronomic Information Sheet discusses three
types of renovation projects, |
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I.
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Repairing
damaged turf, |
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II.
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Replacing
undesirable turf, and |
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III.
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Improving poor performing turf |
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| Each of these
three types of renovation projects requires specific agronomic practices
to ensure their success. |
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| Deep
tilling and root zone preparation allows the turf manager to: |
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Correct
pH in the root zone |
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Incorporate
immobile nutrients into the root zone |
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Eliminate
compaction |
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Remove
existing weeds or undesired turf |
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Eliminate
the thatch layer |
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Establish
good seed to soil contact |
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| However, some
renovation situations don’t allow for thorough soil preparation. The
following information will guide you through the renovation process
and describe how many of these obstacles can be overcome. |
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This seedbed was worked to a fine consistency
that will provide uniform seed to soil contact,
germination, and emergence.
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Renovations
often don't allow for extensive
soil preparation, creating uneven conditions
for germination & lengthening the
establishment period.
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| I. Repairing Damaged Turf |
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| The turf on the
crown of this soccer field has been damaged over the course of the
season. Renovation with seeded
bermudagrass is a cost-effective solution to this common problem. |
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1.
Select a
variety possessing similar color, density, and
texture as the existing turf.
Some seeded varieties now offer improved tolerance
to drought, excessive wear or winter injury and may be better
suited for your situation.
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2.
Remove thatch that may
interfere with seed to soil contact by using a reel mower, flail
mower, or verti-cutter to scalp and prepare a seedbed. By observing a soil profile (as shown left)
the turf manager can determine how much thatch should be removed. Seed caught in a thatch layer of dead turf and
organic matter will not establish as well as seed placed in
the actual soil. |
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3.
Aerification of
the existing turf with a deep-tine aerifier
will help remove thatch, reduce compaction, increase drainage
and water infiltration, and improve the ability to move nutrients
into the root zone during the grow-in. Several passes may be
necessary to achieve the desired results. Hollow-tine aeration will require the use of
a drag or steel netting to thoroughly break apart the cores
before seeding. |
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This solid-tine aerifier
can create holes 10-12” deep, increasing the water infiltration
of the seedbed.
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This “spiker” aerifier has shorter tines
spaced closer together and is used to
break up the soil surface.
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Disrupt the soil surface by cutting shallow grooves
using a verti-cutter or flail mower, or by lightly aerating
with ¼" to ½" deep aeration holes. These
depressions in the soil improve seed to soil contact, remain
moist longer, and provide protection to young seedlings from
traffic, mower tires, and wind. |
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An
aerifier was used to create ¼” -
½” deep
wells in this badly worn, high traffic area.
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A
verticutter is being used to cut through
thatch, creating shallow grooves in the soil.
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These
seedlings have established in the
aeration holes shown above.
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These
seedlings are emerging from the
shallow grooves formed by the verticutter.
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Broadcast, drill, or drop spread seed uniformly over
the soil surface. A drag or steel net may be used to lightly
work seed into the soil. For a more uniform seeding pattern,
use a half rate of seed on the first pass and then seed again
at a right angle to the direction of the first pass. |
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Drop
spreaders are an easy, cost effective
way to seed bermudagrass.
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Brillion
seeders can be used for
large, level areas.
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| Slit
seeders can be used effectively to place the seed in contact
with the soil without having to remove excessive amounts of
thatch from the seedbed. Place the seed as close to 1/8” depth as possible. |
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| Bermudagrass
seed should not be planted deeper than ¼”. This only allows for an
1/8” margin for error when attempting to seed at a 1/8” depth
using a slit seeder or brillion.
Uneven ground or improperly adjusted equipment can cause
the seed to be placed deeper than is desired.
Carefully monitor seeding equipment and seeding depth
when planting to assure proper placement of the seed in the
seedbed. |
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| II. Replacing Undesirable Turf |
| At times, it
may be desirable to convert an established bermudagrass turf or another
turfgrass species to an improved bermudagrass variety.
The following information will provide suggestions for successfully
performing this renovation. |
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| 1.
Killing the existing turf effectively
is an important first step towards achieving a pure stand of the desired
turf variety. Methods for doing this vary depending on the species
of the existing turf. |
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Converting
Cool Season Grasses to Warm Season Grasses
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A.
The best option for removing cool season grasses is to apply a non-selective
herbicide when turf is actively growing. Planting can be done as soon as the next day
with no harm to the germinating seed or developing seedling. Check the herbicide label for details.
B.
Some herbicides will gradually and safely remove cool season grasses
from a stand of warm season grass. However, many of these products persist in the
soil and may have detrimental effects on seedling bermudagrass. Always wait the amount of time specified on
the herbicide label before planting bermudagrass.
C.
Finally, cultural practices can be used to remove the cool season
grasses. Performing the renovation
when air temperatures, soil moisture, and humidity are unfavorable
for cool season grasses can cause them to be removed naturally,
creating an environment that favors warm season grasses like bermuda. Other cultural
practices that can be used are imposing low mowing heights (scalping)
or applying 1-2 lbs. of Nitrogen in the form of Ammonium Nitrate
while dew is present and high temperatures are expected.
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Converting
from one warm season turf to another
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A. Several
applications of a non-selective herbicide spaced 3-4 weeks apart
may be necessary to completely kill the existing turf.
Ideally, tillage would be performed to break apart roots
and underground rhizomes that may still persist.
B. Fumigation
of the area to be renovated will eliminate all grass and weed species
present in the soil. However fumigation is expensive and should only
be done by a licensed professional.
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2.
Remove the dead turf using a reel mower, flail mower,
verticutter, sod cutter, or similar piece of equipment.
This will provide a better opportunity for seed to soil contact. Ideally, thatch would be uniformly tilled into
the root zone of the seedbed.
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Too
much dead turf and thatch on the soil
surface interferes with seed to soil contact.
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Here
the dead turf has been removed,
exposing the soil surface.
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| 3.
Aerification (See
step three in “Repairing Damaged Turf Areas”) |
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| 4.
Disrupt the soil surface using a verticutter or flail mower
to cut shallow grooves into the soil surface.
This step is critical to the germination and survival of the
young seedling as illustrated by the picture below. |
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Wayne
Philley of Mississippi State University
kneels before plots of common bermudagrass
turf that are being converted to an improved variety (Princess 77). Plots
were sprayed with
RoundUp at a 4qts/acre rate. The plot on Wayne’s left was Verticut
in three directions before
seeding, the one on his right was not.
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| 5.
Seed (See step five in “Repairing Damaged Turf Areas”) |
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| III.
Improving Poor Performing Turf |
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| In situations
where the existing turf is performing poorly, changing the variety
may appear to be a logical means of improvement. However, changing grass varieties or species
may or may not improve the performance of the turf if the underlying
problem is not corrected. |
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| Causes
for poor performance in turf may include: |
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Poor
drainage may be corrected by aggressively aerating
the soil. Severe cases may require |
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breaking
up compacted soil, installation of drainage tile, or re-grading
of the soil surface. |
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Poorly
designed irrigation systems often are the cause behind
dry areas where turf is |
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performing
poorly. Make sure heads
have 100% overlap and periodically check to insure |
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all heads are functioning correctly. |
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Poor
fertility or pH levels can
be determined by testing the soil. Soil test results will |
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provide
recommendations for the amount of fertilizer or soil amendments
required to correct |
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the problem. A listing
of soil labs in the United States and Canada can be found here. |
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Dense
Shade may require the
removal of trees, pruning, or planting of an adapted |
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turfgrass
species. |
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High
salt concentrations in irrigation water and/or soils
can cause turf to perform poorly.
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Leaching
of the soils with high volumes of water can help prevent salts
from building up in |
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the root zone. |
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Thatch
buildup decreases the vigor of turfgrass by restricting movement
of water, |
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fertilizers,
and pesticides into the soil. Thatch
must be periodically removed in |
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order
to maintain a healthy root zone and to prevent scalping of the
top-growth |
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during
mowing. |
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Pests
such as insects or nematodes that cause serious damage
to turfgrass need to |
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be
identified and controlled. |
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Turfgrass
disease could be the cause of poor performing turf. Your local Turfgrass |
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Extension
Agent can assist you in diagnosing a particular turfgrass disease
and |
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make
recommendations for treatment. |
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Improper
mowing with equipment that is not sharpened or adjusted
correctly can |
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damage
turf. It is generallyrecommended
to use a reel mower for mowing heights |
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of
less than 1” and a rotary mower for heights above 1”.
Never remove more than 1/3rd of |
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the total leaf surface in one mowing |
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