5/13/2013

1

Current Turfgrass Research Update

J. Bryan Unruh, Ph.D.

University of Florida

Shade vs. Low Light ConditionsBMPs specifically address “shade” 

but not “low light.”

4

Low Light Conditions• Season fluctuation in solar radiation

• Low pressure systems ‐ tropical weather

• High pressure systems ‐ extended fog

5 6

Atmospheric Environment ‐ Light

Transmission

AbsorptionReflection

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2

Effects of Light on Turfgrass Growth

• Light intensity

• Light quality

• Light duration

7Absorbance peaks:  Chlorophyll a = 430 nm, 662 nm

Chlorophyll b = 454 nm, 643 nm 

Effect of Light Quality on Turfgrass Growth

Effect of Light Duration on Turfgrass Growth

• Light duration refers to the amount of time (hours) that the turf is exposed to sunlight.

– Influences plant growth and development.

• Physiological Responses

• Development Responses

9

Solar Radiation

• Energy (photons) delivered per unit of time over a specified area

– Watts per meter square per day (w m‐2 day‐1)

– Langley per day (cal cm‐2 min‐1)

– Micromoles per meter square per second                       (µmol m‐2 s‐1)

11

0

100

200

300

400

500

600

700

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Solar Rad

iation (Ly/D

ay)

Average Monthly Solar Radiation ‐ Ft. Pierce, FL

2008

2009

2010

201112 days = 8.72” rain

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3

Daily Light Integral

• Compilation of µmol m‐2 s‐1

• Measures total light absorbed in mol m‐2 d‐1

• Previous research focused on greenhouse bedding plant production

• DLI used for flower initiation and controlling plant growth and quality

DLI across the United States

Warm Season Turfgrasses ‐ Summer

• Maintain acceptable quality ‐

– ‘Tifeagle’ hybrid bermudagrass ‐ 32.6 mol m‐2 d‐1

– ‘Tifway’ hybrid bermudagrass ‐ 25.9 mol m‐2 d‐1

– ‘Celebration’ bermudagrass ‐ 18.4 mol m‐2 d‐1

– ‘Meyer’ Japanese zoysiagrass ‐ 12.7 mol m‐2 d‐1

Brian Glenn – Ph.D. Student1. Quantify the DLI 

requirement for most common warm‐season turfgrasses.

2. Identify parameters that contribute to shade tolerance.

3. Determine effect of light fluctuation on plant health.

• Hybrid bermudagrass

– ‘Tifway’ and ‘TifGrand’

• Common bermudagrass

– ‘Celebration’ 

• Zoysiagrass (Zoysia japonica) 

– ‘Palisades’ and ‘JaMur’

• Zoysiagrass (Zoysia matrella)

– ‘PristineFlora’ and ‘Diamond’

• St. Augustinegrass

– ‘Floratam’ and ‘Captiva’ 

• Centipedegrass

– ‘TifBlair’ 

• Bahiagrass

– ‘Argentine’

• Seashore paspalum

– ‘SeaDwarf’Minimum Acceptable Quality: 12.12 mol m‐2 d‐1

Minimum Acceptable Quality: 10.56 mol m‐2 d‐1 Minimum Acceptable Quality: 8.70 mol m‐2 d‐1

Jan – MarAverage temp: 73.84 °F

5/13/2013

4

‘Tifway’Bermudagrass

‘TifGrand’Bermudagrass

‘Celebration’Bermudagrass

0% 30% 60% 90%

0% 30% 60% 90%

0% 30% 60% 90%

Stanford et al., 2005Tifdwarf bermudagrass grown in growth chambers with  

14 hours light at 1/3 of full sunlight.

95/81 °F 81/66 °F

Influence of Temperature and Shade on Warm‐Season Turfgrasses

• Temperature regimes

– Summer (95, 70 °F)

– Spring/Fall (86, 61 °F)

– Winter (75, 50 °F)

• Shade Levels

– 0%

– 30%

– 60%

– 90%

Shade Avoidance vs. Shade Tolerance  

Henry and Aarssen 1997

Low Light Influences:

• Morphology 

– Elongation

– Decrease in weight per unit leaf area

– Increase in leaf area per unit shoot weight 

– Longer internodes

– Erect growth 

• Physiology

– Higher chlorophyll content

– Lower respiration

– Lower compensation point

– Reduced carbohydrate reserves

– Lower demand for water, nutrients

– Reduced heat, cold, drought, wear tolerance

– Increased production of gibberellic acid (GA)

• Leads to weakened structure

Decision Tools to aid the turf manager:

• Injury estimator for cultivation practices

• Scalping predictor

• Predictive pesticide applications

5/13/2013

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LightScout DLI 100 Light Meter• Compare light between 

locations• Displays light intensity 

levels every 4 seconds for 24 hours

• Measure PAR light (PhotosyntheticallyActive Radiation)

• Meter runs for 24 hours and calculates your Daily Light Integral (DLI)

• Packaged in sets of 3 light meters, or individually

www.specmeters.com

$59/each; $169/three

LightScout DLI 100 Meters

Without deflector shield leave 10’ ring

Leave at least 3’ untreated buffer

Use a deflector shield near water

27

Ring of Responsibility

27

Ordinances may vary; respect required fertilizer-free conservation easements and stormwater treatment buffers.

BMP

BMPs for the Enhancementof Environmental Quality on

Florida Golf Courses – pg. 13

29

Objective: To determine the effective size of an untreated buffer strip or “ring of responsibility” located adjacent to a body of water. 

30

5/13/2013

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Experimental Design

• Fertilizer Sources (1.0 lb N/1000 ft2)

– Ammonium Sulfate

– Polymer Coated Urea

– Nitroform

• Buffer Distances

– 0’, 3’, 6’ and 12’

• Rainfall Simulation

– 2” per hour

32

Distribution of TSN

Nitrogen SourceAS UF PCU UTC

TS

N L

oads

(g

)

0

2

4

6

8

10

33

Preliminary Observations• Ammonium Sulfate – treatments were comparable regardless of 

fertilizer upslope placement.– Between 21.4% and 24.5% of the applied N was recovered in the runoff.

• Urea‐formaldehyde – A 3.6 m unfertilized buffer distance reduced N losses to 3.9% of applied N, while all other distances were comparable and ranged from 6.9 – 7.7%.– The 3.6 m buffer provided 45% less N in comparison to placement closer to 

the source.– No prill movement was observed. 

• Polymer Coated Urea ‐ regardless of slope placement, N losses were negligible.– Only 0.41% of the applied N from PCU was recovered across all distances.– No prill movement was observed.

34

Statewide Fertilizer Rule

• Limits N to 1 lb per 1,000 ft2 maximum application rate or 0.7 lb per 1,000 ft2 for quick‐release N

• Limits P to 1/4 lb P2O5 per 1,000 ft2 per 

application and 1/2 lb P2O5 per 1,000 ft2 

annually

• Annual N rates follow UF recommendations

• Requires lawn care industry to follow Green Industries BMP manual

What Does the Rule Mean to Commercial Fertilizer Applicators?

• They are required to follow the Green Industry BMPs.– Must be certified by January 2014.

• Golf courses required to follow golf course BMPs.– Must of GIBMPs to apply fertilizer to “landscaped” areas of the golf course (i.e., club house).

• Athletic fields, park and recreation required to follow UF fact sheets.

• Sod growers follow sod BMPs

5/13/2013

7

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Per

cen

t Gro

wth

Po

ten

tial

0

20

40

60

80

100

Pensacola Tallahassee Jacksonville Gainesville Daytona Beach Orlando Tampa Ft. Pierce Naples Ft. Lauderdale Homestead Key West

2

sdoptTobsT

21

1

e

100GP

8/1/2008 2/1/2009 8/1/2009 2/1/2010 8/1/2010 2/1/2011 8/1/2011

Tot

al N

O3 Leac

hed

(kg

ha

-1)

0

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4

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16

Pre

cent G

row

th P

otentia

l

0

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SR Nitrogen Source Study – Jay, FL

2/1/2009 4/1/2009 6/1/2009 8/1/2009 10/1/2009 12/1/2009

Tot

al N

O3 Le

ach

ed (kg

ha-1

)

0

1

2

3

4

5

Per

cent

Gro

wth

Pot

entia

l

0

20

40

60

80

100

Arrows denote fertilizer application dates.

SR Nitrogen Source Study – Jay, FLEstimating Release Properties of Slow‐

Release Fertilizer MaterialsDr. Jerry Sartain

PERCENT N RELEASED OVER TIME FOR SELECTED CRN MATERIALS

7 14 28 42 56 84 112 140 1800

20

40

60

80

100

NITROFORM NUTRALENE MILORGANITE

POLYON SCU AN

5/13/2013

8

Getting a Response. . .

• Research shows that you need 0.30 lbs / 1,000 ft2 of available nitrogen to see a response in turf.N Source 7 14 28 56 84 112 140 182

----------------------- % of Applied Nitrogen Released -----------------------

Nitroform 14 18 20 23 28 31 35 36

Nutralene 28 35 40 45 50 53 56 58

Polyon 12 23 49 75 86 90 93 94

SCU 30 50 70 84 92 95 98 99

IBDU 8 13 21 32 42 50 56 63

Osmocote 19 25 35 55 72 81 88 94

20-2-20 37 39 41 45 48 50 52 54

2/1/2009 4/1/2009 6/1/2009 8/1/2009 10/1/2009 12/1/2009

Tot

al N

O3 Le

ach

ed (kg

ha-1

)

0

1

2

3

4

5

Per

cent

Gro

wth

Pot

entia

l

0

20

40

60

80

100

Arrows denote fertilizer application dates.

SR Nitrogen Source Study – Jay, FL

Days30 60 90 1200

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Per

cen

t Gro

wth

Po

ten

tial

0

20

40

60

80

100

Pensacola Tallahassee Jacksonville Gainesville Daytona Beach Orlando Tampa Ft. Pierce Naples Ft. Lauderdale Homestead Key West

2

sdoptTobsT

21

1

e

100GP

Ocala Daytona Orlando TampaJAN 0.03 0.04 0.06 0.06FEB 0.05 0.05 0.08 0.08MAR 0.13 0.11 0.17 0.17APR 0.23 0.21 0.29 0.29MAY 0.44 0.41 0.50 0.52JUN 0.60 0.59 0.64 0.65JUL 0.65 0.65 0.67 0.68AUG 0.64 0.65 0.68 0.68SEP 0.57 0.60 0.64 0.65OCT 0.33 0.38 0.43 0.45NOV 0.13 0.16 0.21 0.22DEC 0.04 0.06 0.09 0.09

3.8 3.9 4.4 4.5

8/1/2008 2/1/2009 8/1/2009 2/1/2010 8/1/2010 2/1/2011 8/1/2011

Tot

al N

O3 Leac

hed

(kg

ha

-1)

0

2

4

6

8

10

12

14

16

Pre

cent G

row

th P

otentia

l

0

20

40

60

80

100

SR Nitrogen Source Study – Jay, FL

5/13/2013

9

Fertilizer BMPs

• Maintain a healthy, actively growing turfgrass to minimize the environmental impact of fertilizer and pesticide application, erosion, and stormwater runoff.

Fertilizer BMPs

1/1/2011 3/1/2011 5/1/2011 7/1/2011 9/1/2011

Tota

l NO

3 L

each

ed (kg

ha

-1)

0

2

4

6

8

10

12

14

16

Turf D

ensi

ty (1-9

; 6 m

inim

um

acc

epta

ble

)

0

2

4

6

8

Arrow denotes fertilizer application date.

SR Nitrogen Source Study – Jay, FL

1/1/2011 3/1/2011 5/1/2011 7/1/2011 9/1/2011

Tot

al N

O3 Le

ach

ed

(kg

ha

-1)

0

2

4

6

8

10

12

14

16

Rai

n (m

m)

0

10

20

30

40

50

60

Arrow denotes fertilizer application date.

SR Nitrogen Source Study – Jay, FL

Practical Considerations

• Nutrients must be applied based on the plant’s ability to assimilate them.

– This should supersede any calendar‐based regimen.

• Healthy, dense turf is the key to minimizing environmental impact of applied nutrients.

– As the health of the plant deteriorates – one can expect problems.

Practical Considerations

• Timing of application of enhanced efficiency (SR) nutrient sources should coincide with periods of active growth potential.

– The “release period” should not extend beyond periods of active growth.

5/13/2013

10

Nutrient Import from Sod

• Properly harvested sod comes with ~ ½” of soil.

– Nutrients applied at the farm are likely transported with the sod.

• Irrigation during sodestablishment can beexcessive if guidelinesare not followed properly.

Nutrient Import from Sod

Nitrate-N Leaching from Established Centipedegrass

01-May-05 01-Jun-05 01-Jul-05 01-Aug-05 01-Sep-05 01-Oct-05 01-Nov-05 01-Dec-05

To

tal N

O3 L

each

ed (

kg h

a-1)

0

1

2

3

4

5

Rai

nfa

ll (m

m)

0

20

40

60

80

100

120

140

6.13 kg/ha12.25 kg/ha24.50 kg/ha49.00 kg/ha

Arrows denote fertilizer application dates.

Sod installation

Nitrate-N Leaching from Established St. Augustinegrass

01-May-05 01-Jun-05 01-Jul-05 01-Aug-05 01-Sep-05 01-Oct-05 01-Nov-05 01-Dec-05

To

tal N

O3 L

each

ed (

kg h

a-1)

0

1

2

3

4

5

Rai

nfal

l (m

m)

0

20

40

60

80

100

120

140

16.17 kg/ha32.83 kg/ha65.17 kg/ha98.00 kg/ha

Arrows denote fertilizer application dates.

Sod installation

Impact of Fertilizer Applications to Semi-Dormant andDormant Lawn Grasses on Environmental Quality

01-Oct-06 01-Nov-06 01-Dec-06 01-Jan-07 01-Feb-07 01-Mar-07 01-Apr-07 01-May-07

Tot

al N

O3 L

each

ed (

kg h

a-1

)

0

5

10

15

20

25

0.0 kg N ha-1

6.13 kg N ha-1

12.25 kg N ha-1

24.50 kg N ha-1

49.00 kg N ha-1 Rai

n (m

m)

0

10

20

30

40

50

60

Arrows denote fertilizer application dates.

Sod installed 25-Sep-06

Nutrient Import from Sod Practical Considerations• Avoid fertilization of newly laid sod for 30 – 60 days.– Sufficient nutrients likely exist.

• Encourage sod installers/landscapers to inquire about the timing of the last farm‐applied nutrients.– Use ranges rather than specific dates

• < 2 weeks = no fertilizer for 60 days• 2 – 4 weeks = no fertilizer for 30 – 60 days• > 4 weeks = no fertilizer for 30 days

– This could prove burdensome for less “tech‐savvy” producers.

59 60

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Nitrogen Sources at High Rates Under High Rainfall/Irrigation Conditions

61

0

0.5

1

1.5

2

2.5

http://training.ifas.ufl.edu/research/turfgrass_nutrient_symp2013/index.html

Multi‐State, Collaborative Warm‐Season TurfgrassBreeding Project

USDA-SCRI Funded, 5 years, 3.9 million

Research Objectives• Turfgrass scientists from five institutions will exchange germplasm to capitalize on the genetic diversity of turfgrass species using classical and modern methods of plant breeding.– Bermudagrass, zoysiagrass, St. Augustinegrass, seashore paspalum, and ryegrass. 

• Genetic enhancement to improve drought and salinity tolerance following traditional methods of plant breeding, embryo rescue, and mutagenesis. 

• Genetic enhancement using Marker Assisted Selection in order to tag and track native genes controlling drought and salinity tolerance.

Turfgrass Canopy – Research Objectives

• To determine differences of 16 genotypes warm season turfgrasses for canopy reflectance and WUE under well watered condition and dry down.

• To determine species or genotype differences in canopy characteristics including leaf area and leaf angle under well watered condition and dry down.

• To establish correlation between canopy characteristics and WUE of 16 genotypes.

5/13/2013

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Turfgrass Root – Research Objectives

• An in situ study on sod based rooting dynamics of St. Augustine and Bermudagrass. 

• A greenhouse study on root architecture and water absorption patterns of different warm season turfgrass species.

• A study on root morphological characteristics of warm season turfgrass species for their field drought performance.

Images of root growth, trend throughout the season (Tube 5, 4” mw ht )

4/08/2011 4/22/2011 5/6/2011

5/20/2011 6/03/2011 6/17/2011

Well watered tubes vs Dry down tubes

Well watered tubes

Dry down tubes

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Discoloration & Decreased:GrowthTranspirationPhotosynthesisRecoveryPest ResistanceStress Resistance

Maximum:Growth/RootingTranspirationPhotosynthesisRecuperationDensityUniformityCH2O BalanceStress TolerancePest Resistance

Discoloration &Decreased:GrowthRootingTranspirationPhotosynthesisRecoveryPest ResistanceStress Resistance

More Discoloration•Leaf Firing•Dormancy•Decreased PS•Increased RS•CH2O Reduction

DehydrationCH2O DepletionMeristem Death

Credit: Drs. Richard White and David Chalmers- Texas A&M University

Dormant, Quiescent, Severely

Damaged or Dead

RecoveryPossible

ModeratelyDry

Optimum

Excessive

Low <<<<<<<<<<<<<<<<<<<<<<<<< Soil Moisture >>>>>>>>>>>>>>>>>>>>>> High

Turfgrass Water Stress Continuum

Rel

ativ

e P

lant

Hea

lth

Low

High

Plant Health

Drought Tolerance vs Drought Resistance:Understanding How Turf is Affected by Drought

Zoysiagrass

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10 20 30 40 50 60 70 80

Turf Quality (1‐9; 9=B

est)

June 23, 2009Empire

Ultimate

JaMur

El Toro

Cavalier

Palisades

Zorro

Emerald

Zeon

Pristine

Empire Ultimate

JaMur El Toro Cavalier Palisades Zorro

Zoysiagrass

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10 20 30 40 50 60 70 80

Turf Quality (1‐9; 9=B

est)

June 23, 2009 Empire

UltimateJaMur

El Toro

Cavalier

PalisadesZorro

Emerald

Emerald Zeon Pristine

5/13/2013

14

Severely Damaged,

slow recovery

or Dead

RecoveryPossible

ModeratelyDry

Optimum

Excessive

Low <<<<<<<<<<<<<<<<<<<<<<<<< Soil Moisture >>>>>>>>>>>>>>>>>>>>>> High

Floratam St. Augustinegrass Water Stress Continuum

Rel

ativ

e P

lant

Hea

lth

Low

High

Plant Health

Severely Damaged,

slow recovery

or Dead

RecoveryPossible

ModeratelyDry

Optimum

Excessive

Low <<<<<<<<<<<<<<<<<<<<<<<<< Soil Moisture >>>>>>>>>>>>>>>>>>>>>> High

Zoysiagrass Water Stress Continuum

Rel

ativ

e P

lant

Hea

lth

Low

High

Plant Health

Dormant or

Quiescent, slow

recovery

May 2, 2011 – Acceptable Turf Color Preliminary Observations• All grasses respond to drought – they just do it differently.– Zoysigrasses wilt and fire very quickly and very uniformly (green  brown).

– St. Augustinegrass fades over time with some green foliage lingering for weeks (green  yellow‐green  yellow brown).

– Centipedegrass wilts quickly but also recovers (turns green again) very quickly.

– Seashore paspalum can be very slow to recover due to the plant’s priority on producing below‐ground plant parts.

– Bermudagrass and bahiagrass are very drought responsive but may not provide the desired turf quality.

5/13/2013

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aab

abc abcabcd abcde

abcdebcde

cdef cdefdef

ef

f f

0

5

10

15

20

25

root

bio

mas

s (g

)

0

5

10

15

20

25

30

0% 30% 60% 90%

Captiva

Cavalier

EIToro-Z

Emerald-

Empire-Z

Floratam

Geo-ZM

JaMur-ZJ

Palisade

Palmetto

Pristine

Ultimate

Zeon-ZM

Zorro-ZM

root

bio

mas

s (g

)

aa

a

a

0

2

4

6

8

10

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14

16

0% 30% 60% 90%

root

bio

mas

s (g

)

a

ab

abc abc abcabc

abcbc

bc bcbc c c

c

48

50

52

54

56

58

60

62

64

Wat

er u

se (

ml/d

ay)

0.165

0.160

0.155

0.145

0.140

0.134

0.129

0.124

Wat

er u

se (

inch

es/d

ay)

~ 15% difference in water use.

a

b

c

d

0

10

20

30

40

50

60

70

80

90

0% 30% 60% 90%

Wat

er u

se (

ml/d

ay)

0.233

0.207

0.181

0.155

0.129

0.103

0.078

0.052

0.026

Wat

er u

se (

inch

es/d

ay)

• 30% Shade  19.8% reduction in water use

• 60% Shade  35.8% reduction in water use

• 90% Shade  60.5% reduction in water use

Bottom line:

• Advancing the science of warm‐season turf management – moving beyond anecdotal information and supposition.

• Complex interactions exist among environmental and soil factors – greatly complicates the research.

• Science must produce usable information –the “so what” of our work.

Questions? www.gatorturf.comhttp://edis.ifas.ufl.edu

www.facebook.com/gatorturf

www.facebook.com/UFTurf

J. Bryan Unruh, Ph.D.West Florida Research and Education Center

University of Florida/IFASjbu@ufl.edu