Michigan State University

Not Rolled Rolled 3X / Week

Why does frequent lightweight rolling decrease dollar spot?

Why rolling may decrease dollar spot activity

• Removes dew – (Williams and Powell, 1996; Ellram et al., 2007; Walsh et al., 1999)

• Removes leaf litter – (Williams et al., 1996)

• Decrease concentration of guttation – (Vargas, 2005; Williams et al., 1996)

• Increases soil moisture holding capacity (altered microbial populations?)

– Couch and Bloom, 1960; Liu et al., 1995; Nikolai, 2005)

• Induced plant defense responses – Nikolai, 2005; Hammerschmidt, (unpublished)

Treatments

• Control (not rolled) • Rolled once in the A.M.* • Rolled once in the P.M.* • Rolled twice in the A.M.*

• *5 days/wk for duration of study • Randomized block design - 3 replications

12’

7’

2x a.m. 1x a.m.

1x a.m.

1x a.m. 2x a.m. 1x p.m.

2x a.m. 1x p.m.

1x p.m.

Materials and Methods • USGA green mix soil

– Topdressed bi-weekly

• Mixed stand Agrostis stolonifera cv. ‘Independence’ and Poa annua

• Tru-Turf R52-11T greens roller

• Rolled June-October • Hand mowed 6 days/wk

– @ 0.156” (3.96mm)

• NO FUNGICIDES

Hypothesis I

• Rolling (typically in the morning), removes excess dew and plant guttation fluid

• Removal/dispersal limits

pathogen proliferation • Moisture • Food source • Inoculum

Why rolling may decrease dollar spot activity

• Removes dew – (Williams and Powell, 1996; Ellram et al., 2007; Walsh et al., 1999)

• Removes leaf litter – (Williams et al., 1996)

• Decrease concentration of guttation – (Vargas, 2005; Williams et al., 1996)

• Increases soil moisture holding capacity (altered microbial populations?)

– Couch and Bloom, 1960; Liu et al., 1995; Nikolai, 2005)

• Induced plant defense responses – Nikolai, 2005; Hammerschmidt, (unpublished)

35.7 a

26.4 ab

17.7 b

3.5 c

0

5

10

15

20

25

30

35

40

Control 1x a.m. 1x p.m. 2x a.m.

Dol

lar s

pots

plo

t-1

Rolling treatment

2008

P ≤ 0.05

146.6 a

70.6 b 72.0 b

20.2 c

0

20

40

60

80

100

120

140

160

control 1x a.m. 1x p.m. 2x a.m.

2009

Rolling treatment P ≤ 0.05

296.5 a

83.6 bc 96.8 b

27.7 c

0

50

100

150

200

250

300

Control 1x a.m. 1x p.m 2x a.m.

Rolling Treatment

2010

P ≤ 0.05

Dollar spot by season (AUDPC)

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

0

5000

10000

15000

20000

25000

30000

2008 2009 2010

a ab

abc

c

a

b b

c

a

b b

c

AUDPC

(P < 0.05).

1x p.m. Control Aug. 19, 2010

1x a.m. Control

Aug. 19, 2010

Control 2x a.m.

Aug. 19, 2010

Control

Control

2x a.m.

1x p.m.

Aug. 19, 2010

Why rolling may decrease dollar spot activity

• Removes dew – (Williams and Powell, 1996; Ellram et al., 2007; Walsh et al., 1999)

• Removes leaf litter – (Williams et al., 1996)

• Decrease concentration of guttation – (Vargas, 2005; Williams et al., 1996)

• Increases soil moisture holding capacity (altered microbial populations?)

– Couch and Bloom, 1960; Liu et al., 1995; Nikolai, 2005)

• Induced plant defense responses – Nikolai, 2005; Hammerschmidt, (unpublished)

Soil Moisture

0

5

10

15

20

25

2008 2009 2010

%VW

C (3

.8 c

m so

il de

pth)

Control

1x a.m.

1x p.m.

2x a.m.

* * *

Year * Significant (P ≤ 0.05)

Hypothesis II

• Rolling suppresses dollar spot by promoting microbial mediated inhibition (i.e. antagonism, competition etc.)

http://www.endure-network.eu/about_endure/all_the_news/in_depth_biological_controls

Bacterial Biological Control

Pseudomas spp. -P. aerofaciens -P. aeruginosa -P. fluorescens -P. lambergii -P. putida-fluorescens -Other Pseudomonas spp.

-Dollar spot -Take all patch -Pythium spp. -Summer patch -Brown patch -Fusarium spp. -Leaf spot

-Enterobacter cloacae

-Dollar spot -Pythium blight -Summer patch

-Xanthamonas maltophilia -X. campesris

-Summer patch -Leaf blight

-Serratia marcescens -Serratia spp. -Streptomyces spp. -Bacillus spp. -Various PGPR’s

-Dollar spot -Spring leaf spot -Brown patch -Pythium -Summer patch

Microbial Analysis

• 20 soil cores taken from each plot

• Homogenized to get a

representative root zone sample

• Prepped and analyzed for

phospholipid fatty acids (PLFA)

• Measurements recorded and compared

min5 10 15 20 25 30 35

pA

10

20

30

40

50

60

70

FID1 B, (E09A11.426\A0020001.D)

1.5

72

1.6

09

1.7

23

2.5

84

3.0

76

3.7

55

3.8

96

4.1

35

4.6

56

5.7

88

7.1

41

8.6

67

9.0

03

9.4

73

10.3

24

12.0

47

12.4

57

13.8

07

15.5

55

17.2

88

18.9

72

20.6

22

22.2

16

23.7

68

25.2

63

30.3

26

35.2

34

PLFA Analysis

• Extracts fatty acids from soil samples and detects them via gas chromatography

• Different microbial groups can be distinguished

by exclusive or shared PLFAs • By measuring the relative abundance in soil

samples, a general “fingerprint” of microbial activity can be obtained

Lipid biomarker

0.0000.2000.4000.6000.8001.0001.2001.4001.6001.800

Rel

ativ

e abu

ndan

ce (m

ol %

)

PLFA

Individual PLFAs

Control

1x a.m.

1x p.m.

2x a.m.

**

*

**

* * **

*

**

*

*

** * * *

*

* = 0.10

** = 0.05

PLFA Grouping • Care should be taken in connecting individual PLFAs to

specific microbial groups; it is perhaps better to look at the trends in groups of fatty acids.

Taxonomic group PLFA biomarkers

PLFA group Specific PLFA markers Reference

Gram-positive bacteria

Branched PLFAs

i15:0, a15:0, 15:0, i16:0, 17:0, i17:0, a17:0

Ratledge and Wilkinson, 1988 and Zogg et al., 1997, Liang et al.

2008.

Gram-negative bacteria

Cyclopropyl and mono

PLFAs

16:1ω7c, cy17:0, cy19:0 and 18:1ω9t

Ratledge and Wilkinson, 1988 and Zogg et al., 1997, Liang et al.

2008.

Fungi Polyunsaturated PLFAs

18:1ω9c, 18:2ω6c and 18:3ω6c Myers et al., 2001; Vestal and White, 1989, Liang et al. 2008.

Total Bacteria Multiple groups i15:0, a15:0, 15:0, i16:0, 17:0, i17:0, a17:0, 16:1ω7c, cy17:0,

cy19:0, 18:1ω9t, 18:1ω7c, cy19:0ω8c

Bossio et al., 1998, Ratledge and Wilkinson, 1988 and Zogg et al.,

1997, Frostegård and Bååth, 1996, Liang et al. 2008.

Gram negative bacteria

Control 1x a.m. 1x p.m. 2x a.m.6

7

8

9

10

11

12

Rolling treatment

PLFA

rel

ativ

e ab

unda

nce

(mol

%) Gram positive bacteria

Control 1x a.m. 1x p.m. 2x a.m.4

5

6

7

8

Rolling treatment

PLFA

rel

ativ

e ab

unda

nce

(mol

%)

Total Bacteria

Control 1x a.m. 1x p.m. 2x a.m.10

12

14

16

18

20

Rolling treatment

PLFA

rel

ativ

e ab

unda

nce

(mol

%)

PLFA Groupings

02468

101214161820

Totalbacteria

Gram-negbact

Gram-posbact

Fungi

PLFA

rela

tive

abun

danc

e (m

ol %

)

Control

1x a.m.

1x p.m.

2x a.m.

Microbial Abundance in Upper (1.5 in) Root Zone

1x – 8x/day Rolling Study MSU (2009)

Total bacteria

1x 2x 4x 8x15

16

17

18

19

20

21

Rolling treatment

PLFA

rel

ativ

e ab

unda

nce

(mol

%)

1x 2x 4x 8x0

10

20

30

40

50

60

*

Dollar Spot

Rolling treatment

Dol

lar

spot

infe

ctio

n ce

nter

s pl

ot-1

Results and Conclusions • A.M. and P.M. rolling resulted in significant

dollar spot reductions Suggests dew/guttation removal is not the underlying

mechanism • Rolling 2x day-1 consistently resulted in the

lowest seasonal dollar spot incidence Cumulative effects

• Increases in %VWC in the upper root zone in rolled plots. Potential ecological effects Trends toward higher bacterial proportions Possibly contributing to dollar spot reduction

Photo courtesy of the O.J. Noer Foundation

Questions?