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2015 Sept/Oct Annual Bluegrass Seedhead Suppression Study
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Winter Applications of Ethephon and Mefluidide for Annual Bluegrass Seedhead Suppression
Submitted by Adam Van Dyke, M.S., Professional Turfgrass Solutions, LLC
Author email: adam@proturfgrasssolutions.com

Objectives
Determine if applications of Ethephon and Mefluidide applied Pre-snow/winter and Post-snow/winter, along with the combination, and including traditional spring applications will increase annual bluegrass seedhead suppression when compared to the traditional spring application program.

Materials and Methods
The study was condicted from November 2014 until June 2015 on a putting green at Mountain View Golf Course in Salt Lake City, UT. The turf was a mixture of 70% annual bluegrass (Poa annua) and 30% creeping bentgrass (Agrostis palustris). Ethephon 2SL (Control Solutions, Inc., Pasadena, TX), Embark 2S and Embark T&O (PBI Gordon Corp., Kansas City, MO) were applied in three winter programs and evaluated against a standard spring timing program for seedhead suppression of annual bluegrass. Winter programs included: 1) Pre-snow applications made on November 18, 2014; 2) Post-snow applications made on February 12, 2015; and 3) a combination of both Pre-snow and Post-snow timings. the standard spring program was initiated in March 17, 2015 at 350 growing degree day units using the base 32F model consisting of Ethephon 2SL with Primo Maxx (Syngenta Crop Protection, Inc., Greensboro, NC). A second spring application was made four weeks later on April 17, 2015. All winter treatments also received the spring program applications to compare the efficacy of the early timings on seedhead suppression to the spring program. Half the plots were aerified on March 30, 2015 with hollow-tines between the two spring applications to evaluate effects on spring quality during seedhead management. All treatments including products, rates, and timings are listed in Tabe 1. An untreated control was used for comparision. Treatments were applied to three replicate 4 foot by 6 foot completely randomized blocks with a CO2 sprayer operating at 40 psi, and fitted with a hand held boom with three TeeJet Al11002VS nozzles calibrated to deliver 2 gallons of water per 1000 sq. ft. A fungicide was applied to protect the turf from snow molds in December, but no other pesticides or plant growth regulators were applied during the study.

To access seedhead suppression, visual estimates of seedhead formation were made in spring, on a 0-100% scale, where 100= complete seedhead cover in the plots. Most seedheads began to emerge from untreated turf in mid-April, but were too small to effectively rate until May (Figure 1). Rouge seedheads were found as early as February. Seedhead estimates were made 4, 6, and 8 weeks after the second spring application. Turf quality and color were rated at each application, and about every 2-3 weeks in spring on a 1-9 scale, where 9= best quality and darkest green color. Turf injury following applications was rated on a 0-100% scale, where 20= highest acceptable discoloration. A chlorophyll meter was also used to measure plant injury and leaf chlorophyll content at each assessment on an index scale where higher numbers equal darker green plots. Three measurements were taken in each plot and averaged for the plot mean. All data was analyzed for differences using ARM with means compared using Fishers’ LSD. Data that was not homogeneous were subjected to transformations to normalize the data.

Summary of Seedhead Suppression
The treatments has a significant effect on the suppression of annual bluegrass seedheads as determined by visual estimates, and calculated control compared to untreated turf (Table 2). Specific effects include:

  • Seedheads began to emerge in late-April, and by early-May covered 29% of untreated plots. Seedheads peaked to 42% in late-May/early-June in untreated turf.
    • Turf receiving only spring timing applications did not have significantly fewer seedheads for 6-weeks and at best provided about 50% control.
    • Seedhead suppression was significantly enhanced when winter applications of Etgephon 2SL, Embark 2S and Embark TO were used prior to the normal spring program, as control was boosted to 70-98% for 8-weeks depending on the treatment and timing (Figure 2).
      • Ethephon 2SL performed the best with >90% suppression of seedheads. There were no statistical differences between pre-snow and post-snow timings - and the combination of both timings was not better, but did have the nighest numerical control of seedheads.
        • The addition of Embark TO at 10oz/A to Ethephon 2SL applied at both winter timings did not improve control but was still very good while not injuring the turf.
  • Embark TO seemed more consistent compared to Embark 2S for seedhead control in this experiment across seasonal timings. However, the post-snow applications of the Embark formulations seemed less effective compared to the other seasonal timings.
    • Embark 2S applied at just the post-snow timing did not improve seedhead control over the normal spring program by May, and the efficacy of Embark TO applied post-snow appeared to wear off in early June. It appears for Embark formulations to work in this scenario and at these rates they must be applied at the pre-snow timing.

Summary of Turf Quality and Color
The treatments had significant effects on turf quality and color on 3 of 7 dates as determined by visual ratings (Tables 3, 4). Specific effects include:

  • Pre-snow applications of Ethephon 2SL and Embark formulations in late-fall did not negatively impact turf quality in winter. No visible injury or crown rising occurred in weeks following the November applications. Similiar leaf chlorophyll measurements between treated and untreated turf in December support the safety of these winter applications on turf entering dormancy (Table 5). The post-snow applications in late-winter were also safe and did not cause injury or crown rising of putting green turf.
    • Difference in leaf chlorophyll were not measured in weeks following the February application as turf broke dormancy, but slight visual differences in color were observed from select winter treatments before the normal spring applications were made in March.
      • Ethephon 2SL applied at the pre-snow or post-snow timings significantly increased turf color and improved turf quality in March. The combination of Ethephon 2SL and Embark TO applied at both timings was the best treatment. Embark formulations did not have the same effect on color and quality when applied at similar timings as Ethephon 2SL but may be influenced by the rates used.
  • After normal spring applications began in mid-March, visual color was better in most treated turf over untreated turf in April and turf quality was better in May. However, ratings were likely influenced by Primo being included in the mix. Fertilization began at this time that further confounded things. Although leaf chlorophyll was not significantly different throughout the trial, levels were higher late summer in turf that received the winter Ethephon 2SL applications (Table 5). This suggests there are plant health benefits to making these winter applications as part of a seedhead management program.

Conclusion
Applying Ethephon 2SL and Embark formulations in seasonal winter timings improved annual bluegrass seedhead suppression over normal spring timings. The normal spring program provided 50% suppression of seedheads, but early applications of Ethephon 2SL at pre-snow and/or post-snow timings (then followed by the spring program) - suppressed >90% of seedheads for 8-weeks. Embark 2S and Embark TO were not as effective as Ethephon 2SL in this experiment, but did improve control over normal spring timing. However, the post-snow timing was not as effective at suppressing seedheads compared to applications made at the pre-snow timing. Embark materials were applied at lower than label rates in this experiment. The winter applications of Ethephon 2SL and Embark formulations were safe to putting green turf and did not cause crown rising. Turf quality, visual color and leaf chlorophyll enhancements in spring were observed from making winter applications of Ethephon 2SL but not from Embark 2S or Embark TO.

Table 1. Seasonal program treatment of Ethephon and Mefluidide products for seedhead suppression.

Program
Product/Rate (oz/1000)
Application Dates
Pre-Snow+Spring
Ethephon 2SL/5
Ethephon 2SL/5+Primo/0.125
Ethephon 2SL/5+Primo/0.125
Nov. 18, 2014
Mar. 17, 2015
Apr. 13, 2015
Pre-Snow+Spring
Embark 2S/1 oz per ac.
Ethephon 2SL/5+Primo/0.125
Ethephon 2SL/5+Primo/0.125
Nov. 18, 2014
Mar. 17, 2015
Apr. 13, 2015
Pre-Snow+Spring
Embark TO/10 oz per ac.
Ethephon 2SL/5+Primo/0.125
Ethephon 2SL/5+Primo/0.125
Nov. 18, 2014
Mar. 17, 2015
Apr. 13, 2015
Post-Snow+Spring
Ethephon 2SL/5
Ethephon 2SL/5+Primo/0.125
Ethephon 2SL/5+Primo/0.125
Feb. 12,2015
Mar. 17, 2015
Apr. 13, 2015
Post-Snow+Spring
Embark 2S/1 oz per ac.
Ethephon 2SL/5+Primo/0.125
Ethephon 2SL/5+Primo/0.125
Feb. 12,2015
Mar. 17, 2015
Apr. 13, 2015
Post-Snow+Spring
Embark TO/10 oz per ac.
Ethephon 2SL/5+Primo/0.125
Ethephon 2SL/5+Primo/0.125
Feb. 12,2015
Mar. 17, 2015
Apr. 13, 2015
Pre-&Post-Snow+Spring
Ethephon 2SL/5
Ethephon 2SL/5
Ethephon 2SL/5+Primo/0.125
Ethephon 2SL/5+Primo/0.125
Nov. 18, 2014
Feb. 12,2015
Mar. 17, 2015
Apr. 13, 2015
Pre-&Post-Snow+Spring  Embark 2S/1 oz per ac.
Embark 2S/1 oz per ac.
Ethephon 2SL/5+Primo/0.125
Ethephon 2SL/5+Primo/0.125
Nov. 18, 2014
Feb. 12,2015
Mar. 17, 2015
Apr. 13, 2015
Pre-&Post-Snow+Spring
Embark TO/10 oz per ac.
Embark TO/10 oz per ac.
Ethephon 2SL/5+Primo/0.125
Ethephon 2SL/5+Primo/0.125
Nov. 18, 2014
Feb. 12,2015
Mar. 17, 2015
Apr. 13, 2015
Pre-&Post-Snow+Spring
Ethephon 2SL/5+Embark TO/10 oz per ac.
Ethephon 2SL/5+Embark TO/10 ox per ac.
Ethephon 2SL/5+Primo/0.125
Ethephon 2SL/5+Primo/0.125
Nov. 18, 2014
Feb. 12,2015
Mar. 17, 2015
Apr. 13, 2015
Spring Check
Ethephon 2SL/5+Primo/0.125
Ethephon 2SL/5+Primo/0.125
Mar. 17, 2015
Apr. 13, 2015
Untreated
---
---

 

Table 2. Effect of seedhead suppressors on seedhead production of annual bluegrass, UT, 2014-15.


Product/Rate (oz/1000)
TimingX
SeedheadsY

  May 11
June 1
June 12
     (% of plot)
Untreated
---
28.9 az
41.6 a
33.3 a
Ethephon 2SL/5+Primo/0.125
Spring
12.8 ab
20.9 ab
16.4 b
Embark 2S/0.02
Post-snow fb spring timing
10.1 b
20.2 ab
8.2 bc
Embark TO/0.2
Post-snow fb spring timing
6.3 b
12.6 b
6.5 c
Embark 2S/0.02
Pre-snow fb spring timing
8.0 b
12.6 b
4.6 c
Embark 2S/0.02
Pre- & Post-snow fb spring timing
4.8 b
15.9 ab
3.3 cd
Embark TO/0.2
Pre- & Post-snow fb spring timing
8.0 b
3.8 c
8.2 bc
Embark TO/0.2  Pre-snow fb spring timing
5.2 b
4.1 c
4.6 c
Ethephon 2Sl/5
Pre-snow fb spring timing
1.3 c
3.8 c
0.6 de
Ethephon 2SL/5
Post-snow fb spring timing
1.3 c
2.3 c
0.6 de
Ethephon 2SL/5
Pre- & Post-snow fb spring timing
0.6 c
1.6 c
0.4 de
Ethephon 2SL/5+Embark T&O/0.2
Pre- & Post-snow fb spring timing
0.6 c
1.6 c
0.1 e

ANOVA
df
     
Treatment
11 ***
***
***


X Timings receiving winter applications (Pre-/Post-snow) also received the standard spring timing that included Primo.
Y Annual bluegrass seedhead production.
Z Means within same column with the same letter are not different significantly (P=0.05)
*, **, ***, ns, significant at P<0.05, 0.01, 0.001, or not significant respectively.


 

Table 3. Effect of Ethephon and Mefluidide seasonal timings on putting green quality, UT, 2014-15


Product/Rate (oz/1000)
Timing
QualityY

  Nov. 18
Dec. 4
Feb. 12
Mar. 17
Apr. 13
Apr. 27
May 11
June 1

 
    (#)
Ethephon 2SL/5+Embark TO/0.2
Pre- & Post-snow fb spring timing
7.0 aZ
5.0 a
5.0 a
5.3 a
5.7 a
5.0 a
 6.7 a
 6.7 a
Ethephon 2SL/5
Pre-snow fb spring timing
7.0 a
5.0 a
5.0 a
4.9 ab
5.7 a
 5.7 a
 6.3 ab
 6.7 a
Ethephon 2SL/5  Post-snow fb spring timing
 --- ---
4.7 a
4.6 ab
5.7 a
 6.0 a
 6.7 a
 6.3 ab
 Ethephon 2SL/5 Pre- & Post-snow fb spring timing
7.0 a
5.0 a
5.0 a
5.0 ab
5.7 a
 5.3 a
 6.3 ab
 6.7 a
Embark TO/0.2
Pre- & Post-snow fb spring timing
7.0 a
5.0 a
4.7 a
4.3 bc
5.3 a
 5.3 a
 6.0 abc
Embark 2S/0.02
Pre-snow fb spring timing
7.0 a
5.0 a
5.0 a
4.3 bc
5.3 a
 5.7 a
 5.7 bcd
 5.7 abc
Embark TO/0.2
Pre-snow fb spring timing
7.0 a
5.0 a
5.0 a
4.0 c
5.3 a
 5.0 a
 6.0 abc
 6.3 ab
Ethephon 2SL/5+Primo/0.125
Spring
 --- ---
5.0 a
4.0 c
5.7 a
 5.7 a
 5.3 cd
 5.7 abc
Embark 2S/0.02  Pre- & Post-snow fb spring timing
7.0 a
5.0 a
5.0 a
4.0 c
5.3 a
 5.3 a
 6.0 abc
 5.7 abc
Embark TO/0.2
Post-snow fb spring timing
---
--- 5.0 a
4.0 c
5.0 a
 5.0 a
 5.7 bcd
 5.3 bc
Embark 2S/0.02
Post-snow fb spring timing
---
---
4.3 a
4.0 c
5.0 a
 5.0 a
 5.3 cd
 5.7 abc
Untreated
  7.0 a
5.0 a
5.0 a
4.0 c
5.0 a
 5.3 a
 5.0 d
 5.0 c

ANOVA
 df                
Treatment
 11  ns ns
ns
 **  ns ns * *

XPre-snow = Nov. 18, 2014; Post-snow = Feb. 12, 2015; Spring timings = March 17 & April 13, 2015
**NOTE**Timings receiving winter applications also received the standard spring timing that included Primo.
YTurf quality rating scale: 1-9; 9=best, 6=acceptable, 1=worst.
ZMeans within same column with the same letter are not different significantly (P=0.05)
*, **, ***, ns, significant at P<0.05, 0.01, 0.001, or not significantly respectively.

Table 4. Effect of Ethephon and Mefluidide seasonal timings on putting green color, UT, 2014-15.


Product/Rate (oz/1000)
TimingX
 ColorY
    Nov. 18
Dec. 4
Feb. 12
Mar. 17
Apr. 13
Apr. 27
May 11
June 1
   
(#)
 Ethephon 2SL/5
 Pre-snow fb spring timing
 7.0 az
 5.0 a
 4.7 a
 4.7 a
 6.7 a
 7.0 a
 6.3 a
 6.7 a
 Ethephon 2SL/5  Post-snow fb spring timing
 ---  ---  4.0 b
 4.7 a
 6.3 ab
 6.3 a
 6.7 a
 6.3 a
 Ethephon 2SL/5  Pre- & Post-snow fb spring timing
 7.0 a
 5.0 a
 4.7 a
 5.0 a
 5.7 bcd
 5.7 a
 6.3 a
 6.7 a
 Ethephon 2SL/5+Embark TO/0.2  Pre- & Post-snow fb spring timing  7.0 a
 5.0 a
 4.7 a
 5.3 a
 5.7 bcd
 5.3 a
 6.7 a
 6.3 a
 Ethephon 2SL/5+Primo/0.125  Spring  ---  ---  4.0 b
 3.3 b
 6.0 abc
 6.0 a
 6.0 a
 6.3 a
 Embark 2S/0.02
 Pre-snow fb spring timing  7.0 a
 5.0 a
 4.0 b
 3.7 b
 6.0 abc
 6.0 a
 6.0 a
 5.7 a
 Embark TO/0.2
 Pre-snow fb spring timing  7.0 a
 5.0 a
 4.0 b
 3.7 b
 5.3 cd
 5.7 a
 6.3 a
 6.0 a
 Embark TO/0.2  Pre- & Post-snow fb spring timing  7.0 a
 5.0 a
 4.0 b
 3.3 b
 5.3 cd
 5.7 a
 6.0 a
 6.3 a
 Embark 2S/0.02  Post-snow fb spring timing  ---  ---  4.0 b
 3.0 b
 5.0 d
 6.0 a
 6.0 a
 6.3 a
 Embark TO/0.2  Post-snow fb spring timing  ---  ---  4.0 b
 3.0 b
 5.7 bcd
 5.7 a
 6.0 a
 5.7 a
 Embark 2S/0.02  Pre- & Post-snow fb spring timing  7.0 a
 5.0 a
 4.0 b
 3.0 b
 5.7 bcd
 5.7 a
 6.0 a
 5.3 a
 Untreated  ---  7.0 a
 5.0 a
 4.0 b
 3.3 b
 5.0 d
 6.0 a
 5.7 a
 5.3 a

 ANOVA  df                
 Treatment  11
 ns  ns  *  ***  *  ns  ns  ns

XPre-snow = Nov. 18, 2014; Post-snow = Feb. 12, 2015; Spring timings = March 17 & April 13, 2015
**NOTE**Timings receiving winter applications also received the standard spring timing that included Primo.
YTurf quality rating scale: 1-9; 9=best, 6=acceptable, 1=worst.
ZMeans within same column with the same letter are not different significantly (P=0.05)
*, **, ***, ns, significant at P<0.05, 0.01, 0.001, or not significantly respectively.

Table 5. Effect of Ethephon and Mefluidide seasonal timings on putting green chlorophyll content, UT, 2014-15


Product/Rate (oz/1000)
TimingX
 Chlorophyll ContentY
    Nov. 18
Dec. 4
Feb. 12
Mar. 17
Apr. 13
May 11
Jun. 1
   
     (index)
 Ethephon 2SL/5
 Post-snow fb spring timing
 ---  ---  124 a
 144 a
 207 a
 233 a
 243 a
 Ethephon 2SL/5  Pre-snow fb spring timing
 166 az
 141 a
 128 a
 146 a
 207 a
 220 a
 232 a
 Ethephon 2SL/5+Embark TO/0.2  Pre- & Post-snow fb spring timing
 172 a
 139 a
 128 a
 143 a
 201 a
 214 a
 243 a
 Embark 2S/0.02
 Pre- & Post-snow fb spring timing  165 a
 133 a
 120 a
 136 a
 213 a
 221 a
 230 a
 Ethephon 2SL/5+Primo/0.125  Spring  ---  ---  125 a
 138 a
 202 a
 215 a
 240 a
 Untreated  ---  166 a
 136 a
 122 a
 138 a
 220 a
 214 a
 224 a
 Ethephon 2SL/5  Pre- & Post-snow fb spring timing  166 a
 137 a
 121 a
 137 a
 201 a
 222 a
 237 a
 Embark 2S/0.02  Pre-snow fb spring timing  164 a
 135 a
 123 a
 142 a
 199 a
 217 a
 236 a
 Embark TO/0.2
 Pre- & Post-snow fb spring timing  165 a
 137 a
 123 a
 138 a
 201 a
 220 a
 234 a
 Embark TO/0.2  Pre-snow fb spring timing  164 a
 137 a
 120 a
 135 a
 189 a
 216 a
 233 a
 Embark TO/0.2  Post-snow fb spring timing  ---  ---  119 a
 129 a
 194 a
 208 a
 223 a
 Embark 2S/0.02  Post-snow fb spring timing  ---  ---  117 a
 132 a
 183 a
 212 a
 224 a

 ANOVA  df              
 Treatment  11  ns  ns  ns  ns  ns  ns  ns

XPre-snow = Nov. 18, 2014; Post-snow = Feb. 12, 2015; Spring timings = March 17 & April 13, 2015
**NOTE**Timings receiving winter applications also received the standard spring timing that included Primo.
YChlorophyll index measured with a CM-1000 chlorophyll meter on a 0-999 scale, where higher numbers equal darker green turf.
ZMeans within same column with the same letter are not different significantly (P=0.05)
*, **, ***, ns, significant at P<0.05, 0.01, 0.001, or not significantly respectively.

 

Figure 1. Seedheads of annual bluegrass began to emerge in mid-April and were assessed every 2 weeks beginning in May when they matured and were easier to see in the canopy. Photo taken April 27, 2015

 

Figure 2. Winter applications of Ethephon 2SL (top photo) to putting green turf significantly reduced annual bluegrass seedheads in spring over normal spring programs (bottom photo) without causing injury. Photos taken May 11, 2015.

Contact Gary Leeper at RMGCSA
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