Fall and/or Spring Applications of Granular Dithiopyr and Prodiamine for

Crabgrass (DIGSS) Control in Turfgrass

Michael W. Melichar, Daniel L. Loughner, Zachary J. Reicher, Daniel V.

Weisenberger, and Jeff A. Borger

Dow AgroSciences LLC, Purdue University, and The Pennsylvania State University

Fall and/or Spring Applications of Granular Dithiopyr and Prodiamine for Crabgrass (DIGSS)

Control in Turfgrass

• Research Justification

– Dithiopyr and prodiamine are labeled for pre-emergent crabgrass control in turfgrass

• Typical applications occur in spring prior to crabgrass emergence

• Little research has been conducted with fall application of granular dithiopyr and prodiamine

– Fall applications would benefit professional lawn care operators and golf course superintendents allowing time in the spring to complete other required turfgrass management operations

Fall and/or Spring Applications of Granular Dithiopyr and Prodiamine for Crabgrass

(DIGSS) Control in Turfgrass• Key Question: How do fall and/or spring applications of

dithiopyr granule and prodiamine granule compare for crabgrass (DIGSS) control?

• Trial Locations– IN (Fall 2006 – July 2007 / Fall 2007 – August 2008)– PA (Fall 2007 – August 2008)

• Methods– Plots; 1.5M X 1.5M– Replications; 3– Application Equipment; Shaker Bottle or Shaker Table

• Statistical Analysis– Combined data from three trials– ANOVA with Tukey means comparison test to determine

differences between treatment means (p < .05)

Fall and/or Spring Applications of Granular Dithiopyr and Prodiamine for Crabgrass (DIGSS)

Control in Turfgrass

• Key Findings

– Fall Applications• Dithiopyr

– A single fall application and a fall application followed by spring application provided acceptable crabgrass control at rates tested

– Fall application followed by spring application did not significantly improve crabgrass control over individual fall or spring applications at rates tested

• Prodiamine– Fall applications did not provide acceptable crabgrass control at

rates tested– Fall application followed by spring application provided

acceptable crabgrass control at rates tested

Fall and/or Spring Applications of Granular Dithiopyr and Prodiamine for Crabgrass (DIGSS)

Control in Turfgrass

• Key Findings

– Spring Applications• Dithiopyr

– March, April, and May applications of dithiopyr provided acceptable crabgrass control at rates tested

– June application of dithiopyr did not provide acceptable crabgrass control at rates tested

• Prodiamine– March and April applications of prodiamine provided acceptable

crabgrass control at rates tested– May and June applications of prodiamine did not provide

acceptable crabgrass control at rates tested

Fall and/or Spring Applications of Granular Dithiopyr and Prodiamine for Crabgrass (DIGSS)

Control in TurfgrassTreatment List (All treatments applied on 19-0-6 Fertilizer)

• October - Dithiopyr @ 560 g ai/ha• October - Prodiamine @ 730 g ai/ha• November - Dithiopyr @ 560 g ai/ha• November - Prodiamine @ 730 g ai/ha• November / May - Dithiopyr @ 560 fb 280 g ai/ha• November / May - Prodiamine @ 730 fb 280 g ai/ha• March – Dithiopyr @ 430 g ai/ha• March – Dithiopyr @ 560 g ai/ha• March – Prodiamine @ 730 g ai/ha• April – Dithiopyr @ 430 g ai/ha• April – Dithiopyr @ 560 g ai/ha• April – Prodiamine @ 730 g ai/ha• May – Dithiopyr @ 430 g ai/ha• May – Dithiopyr @ 560 g ai/ha• May – Prodiamine @ 730 g ai/ha• June (No Tillering) – Dithiopyr @ 430 g ai/ha• June (No Tillering) – Dithiopyr @ 560 g ai/ha• June (No Tillering) – Prodiamine @ 730 g ai/ha

Fall Applications

Spring Applications

Parts of a Box-Plot

Center 50%

0

20

40

60

80

100

120Response

+

Extreme Value

25th Percentile

MedianMean

75th PercentileUpper 25%

Lower 25%

*

*

*

*

0

10

20

30

40

50

60

70

80

90

100

9 9 9 9 9 9

+

+

+

+

+

+

78.4 54.2 87.4 51.5 99.1 82.8

Mean v alues below box, number of obs. abov e box

Treatment

% C

ontr

ol

Fall Applications (Crabgrass Control)

A

B

AB

A A

*

0

10

20

30

40

50

60

70

80

90

100

9 9 9 9

++ +

+

99.1 87.4 83.6 93

Mean v alues below box, number of obs. abov e box

Treatment

% C

ontr

ol

Fall/Spring Applications - Dithiopyr (Crabgrass Control)

A A A A

*

0

10

20

30

40

50

60

70

80

90

100

9 9 9

+

++

82.8 51.5 57.5

Mean v alues below box, number of obs. abov e box

Treatment

% C

ontr

ol

Fall/Spring Applications - Prodiamine (Crabgrass Control)

AA A

* *

*

0

10

20

30

40

50

60

70

80

90

100

9 9 9 9 9 9 9 9 9 9 9 9

+

+

++

+

++

+

++ +

+69.1 90.7 69.2 80.9 89 76.5 83.6 93 57.5 49.4 52.3 5.5

Mean v alues below box, number of obs. abov e box

Treatment

% C

ontr

ol

Spring Applications (Crabgrass Control)

B

ABAB

AB

A A A A A A A A

* *

*

0

10

20

30

40

50

60

70

80

90

100

9 9 9 9 9 9 9 9

+ ++ +

+

++

+69.1 69.2 80.9 76.5 83.6 57.5 49.4 5.5

Mean v alues below box, number of obs. abov e box

Treatment

% C

ontr

ol

Spring Applications - Dithiopyr vs Prodiamine (Crabgrass Control)

B

ABAB

AAAAA

Dimension & Barricade Granule Fall/Spring Timing Study

Untreated – Indiana (2006 – 2007)

Dimension & Barricade Granule Fall/Spring Timing Study

October 15 Application – Indiana (2006 – 2007)

(88%)Dimension @ 0.5 lb

a.i./A

(81%)Barricade @ 0.65 lb a.i./A

Dimension & Barricade Granule Fall/Spring Timing Study

November 15 Application – Indiana (2006 – 2007)

(89%)Dimension @ 0.5 lb a.i./A

(82%)Barricade @ 0.65 lb a.i./A

Dimension & Barricade Granule Fall/Spring Timing Study

November 15 fb May 15 Application – Indiana (2006 – 2007)

(91%)Dimension @ 0.5 + 0.25 lb a.i./A

(86%)Barricade @ 0.65 + 0.25 lb a.i./A

Dimension & Barricade Granule Fall/Spring Timing Study

March 15 Application – Indiana (2006 – 2007)

(65%)Dimension @ 0.38 lb a.i./A

(94%)Dimension @ 0.5 lb a.i./A

(85%)Barricade @ 0.65 lb a.i./A

Dimension & Barricade Granule Fall/Spring Timing Study

April 15 Application – Indiana (2006 – 2007)

(86%)Dimension @ 0.38 lb a.i./A

(93%)Dimension @ 0.5 lb a.i./A

(57%)Barricade @ 0.65 lb a.i./A

Dimension & Barricade Granule Fall/Spring Timing Study

May 15 Application – Indiana (2006 – 2007)

(90%)Dimension @ 0.38 lb a.i./A

(96%)Dimension @ 0.5 lb a.i./A

(9%)Barricade @ 0.65 lb a.i./A

Dimension & Barricade Granule Fall/Spring Timing Study

June 15 Application – Indiana (2006 – 2007)

(56%)Dimension @ 0.38 lb a.i./A

(47%)Dimension @ 0.5 lb a.i./A

(75%)Barricade @ 0.65 lb a.i./A

Fall and/or Spring Applications of Granular Dithiopyr and Prodiamine for Crabgrass (DIGSS)

Control in Turfgrass

• Conclusions

– Dithiopyr– Fall applications and fall application followed by spring

application provided comparable crabgrass control to spring applications at rates tested

– Prodiamine– Fall applications did not provide comparable crabgrass

control to spring applications at rate tested– Fall application followed by spring application provided

better crabgrass control than spring applications at rates tested