Virginia Turfgrass Journal - May / June 2013

Journal of the Virginia Turfgrass Council

Ninth Annual Digest of Turfgrass Research in Virginia Science-Based Information for the Management of Golf Courses, Sports Fields, Lawns and Sod Farms

May/June 2013

Journal of the Virginia Turfgrass Council | May/June 2013

Ninth Annual

DIGEST OF TURFGRASS RESEARCH IN VIRGINIA Upcoming Events 10 H ampton Roads AREC Turfgrass Field Day, Pesticide Recertification and Certified Fertilizer Applicator — June 25, 2012

Summaries of More Research Projects 28 R apid Diagnostic Tool for Improved Spring Dead Spot Recommendations

Yellow Nutsedge Control with Combinations

Yellow Nutsedge and Southern Crabgrass

Research Articles 14 E ffect of Golf Turfgrass Management on the Water Quality of Streams in the Chesapeake Bay Watershed 16 Impact of Turf Fans on Creeping Bentgrass Putting Greens 18 A n Integrated Nutritional and Chemical Approach to Poa annua Suppression in Creeping Bentgrass Putting Greens 20 Dallisgrass Control in Bermudagrass

of Halosulfuron and Sulfentrazone

Control with Combinations of Halosulfuron with Quinclorac or Fenoxaprop

Departments 6 8 12 30 30 30

Director’s Corner from Tom Tracy, Ph.D. VTF Report from Betty Parker Industry News from Mike Goatley Jr., Ph.D. Calendar of Events Contact Information for VT Researchers Index of Advertisers

22 Acelepryn & HGW86 20SC White Grub Control in Turf (2012 DuPont Field Trials) 24 Weed Management in Pansy Beds

Virginia Turfgrass Council (VTC) serves its members in the industry through education, promotion and representation. The statements and opinions expressed herein are those of the individual authors and do not necessarily represent the views of the association, its staff, or its board of directors, Virginia Turfgrass Journal, or its editors. Likewise, the appearance of advertisers, or VTC members, does not constitute an endorsement of the products or services featured in this, past or subsequent issues of this bimonthly publication. Copyright ©2013 by the Virginia Turfgrass Council. Virginia Turfgrass Journal is published bimonthly.

Subscriptions are complimentary to members of VTC. POSTMASTER: Send change of address notification to VTC, P.O. Box 5989, Virginia Beach, VA 23471.

Postage guaranteed. Third-class postage is paid at Nashville, TN. Printed in the U.S.A. Reprints and Submissions: Virginia Turfgrass Journal allows reprinting of material published here. Permission requests should be directed to VTC. We are not responsible for unsolicited freelance manuscripts and photographs.

Contact the managing editor for contribution information. Advertising: For display and classified advertising rates and insertions, please contact Leading Edge Communications, LLC, 206 Bridge Street, Franklin, TN 37068-0142, (615) 790-3718, Fax (615) 794-4524. Deadlines are the first of the month prior to the following month’s publication. (Example: August 1 for the September issue.)

Director’s Corner

A Tip of the VTC Hat to Our

Tradeshow Tom Tracy, Ph.D. VTC Executive Director

I

Vendors

dedicate my column in this issue of the Virginia Turfgrass Journal to the vendors at our annual conference and tradeshow. This January event, held in Fredericksburg, is made possible by the companies and individuals who decide to invest their time and resources in setting up and manning a display. Over the years, I have come to realize four reasons why being a vendor at the January conference makes sense.

One, we make a tremendous effort to attract current and potential customers to booths. We know that vendors work hard during the show, making contacts and sales. When walking the floor of our annual conference, rarely will you see an unmanned display or, even worse, booths manned by people who are indifferent to conference attendees. One of the many ways we work to bring prospective buyers to the show is to ensure that education classes do not conflict with tradeshow hours. Our tradeshow hours are just that — tradeshow hours. Vendors need not be concerned that their efforts to promote products and services from their display are undermined by other conference programs.

Two, we provide a vendorneutral setting for each company to promote its products and services.

Each and every vendor is important to us. Newcomers and veteran vendors may take solace in our constant quest for fairness.

Three, we strive throughout the year to stimulate interest in the professional products and services provided by our vendors. The VTC, as a non-profit corporation, has certain IRS stated guidelines. One key guide is that our activities must enhance the entire industry (that is why we are called a “trade association”). We take the IRS mandate so seriously that it is incorporated into our Mission Statement. Every VTC activity — Journal articles, regional seminars, field days, visits to educate government bureaucrats and politicians — seeks to enhance the turfgrass industry. Vendors benefit when our industry grows (no pun intended).

Four, we use the conference to enlighten turf professionals about the latest in turfgrass research and issues affecting the industry. We bring in top-notch speakers, selected by industry leaders, to provide the information that our members want and need.

Here is a key point: an educated customer is the type of customer our vendors seek.

So, as you make plans for the January conference (scheduled for the week of January 27, 2014), please make sure that the VTC tradeshow and conference is part of those plans.

Whether you come as a vendor or as an attendee, you will find the tradeshow portion of the conference to be worth your time and money. Complete details are at www.turfconference.org,

6 | Virginia Turfgrass Journal May/June 2013 www.vaturf.org

the website we developed just for the January conference. c

VTF Report

Over $70,000

for Turfgrass Research!!

T

his year, the Virginia turfgrass Foundation funded or endorsed more than $70,000 of turfgrass research. We also added an additional $12,000 to the endowment fund, which stands at a whopping $464,184.24!

The measures put in place to establish a reserve fund in our seed-law balance that provides the lion’s share of our research dollars has proved effective, and we are excited to unveil this years’ list of projects endorsed for funding.

“Evaluation of Seashore Paspalum — a New Turfgrass Species for Virginia” Virginia Tech Researchers: Dr. Jeffrey Derr, Dr. Mike Goatley and David McCall Two-Year Project Investment Year 1: $15,469 + $7,000 for HRAREC turfgrass research program Year 2: $15,873 “New and Novel Chemistries and Timing Options for Managing Masked Chafers in Turfgrass” Virginia Tech Researcher: Dr. Roger R. Youngman One-Year Project Investment Year 1: $5,130

Virginia Turfgrass Journal is the official publication of The Virginia Turfgrass Council P.O. Box 5989 Virginia Beach, VA 23471 Office: (757) 464-1004 Fax: (757) 282-2693 vaturf@verizon.net

Betty Parker VTF Manager

“IPM for Putting Greens in Virginia: Using Iron Sulfate to Control Poa annua, Moss and Dollar Spot, while Reducing Nitrogen, Phosphorus and Pesticide Inputs” Virginia Tech Researchers: Dr. Erik Ervin and David McCall Two-Year Project Investment Year 1: $8,400 Year 2: $8,600 “Spatial Impact of Turf Fans on Creeping Bentgrass Putting Greens” Virginia Tech Researchers: David McCall and Dr. Erik Ervin Two-Year Project Investment Year 1: $19,070 Year 2: $17,770 “A Comparison of Turf Blankets for Winter Protection of Bermudagrass” Virginia Tech Researcher: Mike Goatley, Ph.D. Two-Year Project Investment Year 1: $5,000 Year 2: $5,000 “Investigation of a Suspected Oxadiazon-Resistant Goosegrass Population in Richmond, VA” Virginia Tech Researcher: Dr. Shawn Askew Year 1: 11,718 Total being funded for the year, beginning July 2013: $71,757

A big thank you to all who support the

efforts and goals of the Virginia Turfgrass Foundation! c 8 | Virginia Turfgrass Journal May/June 2013 www.vaturf.org

Published by Leading Edge Communications, LLC 206 Bridge Street Franklin, Tennessee 37064 (615) 790-3718 Fax: (615) 794-4524 Email: info@leadingedgecommunications.com Editor Mark Vaughn, CGCS VTC OFFICERS President Frank Flannagan Belmont Golf Course (804) 262-4939 Vice President Fredrick Biggers, CGCS Wintergreen Resort (434) 325-8252 Treasurer Brian Vincel, CGCS Spring Creek Golf Club (434) 566-2580 Past President Melissa Reynolds Dura Turf Service Corp.

(804) 233-4972 VTC DIRECTORS Gil Grattan Rick Owens, CGCS Marc Petrus Mark Roberts Christian Sain Steve Smith Rick Viancour, CGCS Scott Woodward ­ VTC ADVISORY MEMBERS OF THE BOARD Mike Goatley, Ph.D. (Chair) Shawn Askew, Ph.D. Jeffrey Derr, Ph.D. Erik Ervin, Ph.D. Rajandra Waghray, Ph.D. Rod Youngman, Ph.D. Executive Director/ Director of PROGRAMS Tom Tracy, Ph.D. (757) 681-6065 Virginia Turfgrass Foundation Betty Parker (757) 574-9061

Upcoming Events

Tuesday, June 25 4th Annual Hampton Roads AREC Turfgrass Field Day, Pesticide Recertification and Certified Fertilizer Applicator Sponsored by

T

Virginia Tech and the Virginia Turfgrass Council

his year’s Turfgrass Field Day in Virginia Beach will be held on Tuesday, June 25, from 7:30 a.m. to 5:30 p.m. On this day, participants from all areas of the turfgrass industry will gather to see firsthand the research being conducted at Virginia Tech’s “east side” AREC. Attendees use this gathering to share ideas, discuss problems and their solutions and take advantage of the professional certification programs being offered, while vendors come in to display their latest equipment and services.

Members of the Virginia Tech turfgrass faculty, from both here and Blacksburg, will showcase well over 20 separate research trials. The tour of turf plots will show variety trials, weed and disease control, drought tolerance

and other studies in warm- and coolseason turf, including tall fescue, Kentucky bluegrass, hybrid bluegrass, perennial ryegrass, bermudagrass and zoysiagrass. c

Preregister for the event at the VTC website:

www.vaturf.org For more information, contact Dr. Jeffrey Derr at:

(757) 363-3912 or email JDerr@VT.edu

10 | Virginia Turfgrass Journal May/June 2013 www.vaturf.org

Schedule at a Glance 7:30 a.m. to 8:00 a.m.

Registration

8:00 a.m. to 12:00 p.m.

Tour of Turf Plots

12:00 p.m. to 1:00 p.m.

Lunch

12:30 p.m. to 2:30 p.m.

Pesticide Recertification

2:30 p.m. to 5:30 p.m.

Fertilizer Certification

Location Hampton Roads AREC 1444 Diamond Springs Road Virginia Beach, VA 23455

SAVE THE DATES! August 27–28 Turfgrass Field Days

Virginia Tech Blacksburg, VA

December 11–13 Virginia Tech’s Turfgrass Short Course

Fredericksburg, VA

January 27–30

VTC 54th Annual Turf & Landscape Conference and Trade Show

Fredericksburg Expo & Conference Center Fredericksburg, VA

Journal of the Virginia Turfgrass Council

| 11

Industry News

Virginia’s Fertilizer Applicator Certification Training (FACT) Program

By Mike Goatley Jr., Ph.D., Professor and Extension Turfgrass Specialist, Virginia Tech

S

everal private firms and individuals, as well as industry trade associations (such as the Virginia Turfgrass Council), began offering the first on-site Certified Fertilizer Applicator (CFA) training and testing programs in January 2013. These programs continue to be well received. As of April 15, I am pleased to announce another means of obtaining CFA status by way of a free online training and testing program — Fertilizer Applicator Certification Training (FACT).

Upon successful completion of the tests for each of ten subject areas in the online program, participants will meet the requirements of becoming a Virginia CFA as administered through the Virginia Department of Agriculture and Consumer Services (VDACS).

Certification is required of commercial fertilizer applicators and turfgrass managers fertilizing state or municipalowned sites. There are three catego-

ries of fertilizer applicators: (1) a VDACS-recognized CFA may apply fertilizer without on-site supervision, may provide individual applicator training and may provide on-site supervision of untrained applicators; (2) a trained applicator has completed an individual applicator training course, may apply fertilizer without a CFA being physically present on the land and shall not supervise application of fertilizer by an untrained applicator; and (3) an untrained applicator may apply fertilizer if under the direct, on-site supervision of a CFA. The deadline for affected parties to become certified is July 1, 2013.

Contractor-applicators and licensees who apply fertilizer to more than a total of 100 acres must report annually. Again, this part of the law applies primarily to “for hire” companies and/ or individuals. The law also applies to many of Virginia’s municipality-based

12 | Virginia Turfgrass Journal May/June 2013 www.vaturf.org

sports field managers and golf course superintendents; this part of the law states, “All state agencies, localities and other governmental entities, regardless of total annual application, must report annually. CFAs are required to report to VDACS, by zip code, the total acreage or square footage of land receiving lawn fertilizer and lawn maintenance fertilizer each year, and reports are due February 1 for the preceding calendar year.” Private facilities do not fall under this law at this time, but I encourage all turfgrass managers to participate in this program in order to account for more acres that are under some form of nutrient-management programming.

The information to be reported includes: (1) the name, mailing address, address of application site and telephone number of customer; (2) the name of person making or supervising the application; (3) the day,

month and year of application; (4) the weather conditions at start of application; (5) the acreage, area, square footage and plants treated; (6) the analysis of fertilizer applied; (7) the amount of fertilizer used, by weight or volume; and (8) the type of application equipment used.

The online FACT website can be found at www.ext.vt.edu/fact, and the site provides complete instructions on how to access the system, enroll in the training and complete the training and testing, as well as contact information for any questions. If you have specific questions regarding access to the online FACT program, the e-mail address is FACTAccess@vdacs.virginia. gov. If you have specific questions about the CFA program requirements, etc., contact Don Delorme at VDACS at donald.delorme@vdacs.virginia.gov.

The FACT program took a little more than eight months to develop, and it truly demonstrates a successful partnership between numerous individuals and state agencies. The FACT program is a collaborative effort between personnel in Virginia Cooperative Extension, Virginia Tech’s College of Agriculture and Life Sciences (CALS), VDACS and Virginia Department of Conservation and Recreation (VDCR). In particular, I offer my thanks to Mark Sumner, Information Technology Analyst for CALS, for being the driving force (from an IT perspective) to make this happen, Pat Hipkins of Pesticide Programs, Tim Sexton of VDCR and Andy Alvarez, Don Delorme, Larry Nichols and Erin Williams of VDACS, as well as a number of VCE agents and VDACS and VDCR employees who took the time to test the system.

Even if you don’t need the CFA status, I hope you might find this information on fertilizer selection, use and programming of value as an educational tool. I would very much appreciate any constructive criticisms, comments, etc., regarding the FACT program, so please be sure to send your comments on the content and/or the testing to me at goatley@vt.edu. c Journal of the Virginia Turfgrass Council

| 13

Research Report

Effect of Golf Course Turfgrass Management on the Water Quality of Streams in the Chesapeake Bay Watershed Table 1. Mean nutrient levels in streams from eight seasonal sampling events on participating James River Watershed golf courses. “Ins” represent areas upstream of turf-management areas, and “outs” represent downstream areas.

Nitrate mg L-1 Mean

Standard Deviation

Course 1 IN

0.111

Course 1 OUT

0.086

Ammonium mg L-1

Phosphate mg L-1

Mean

Standard Deviation

Mean

Standard Deviation

0.093

0.115

0.109

0.016

0.030

0.109

0.078

0.097

0.000

0.000

Course 2 IN A

0.688

0.389

0.017

0.026

0.000

0.000

Course 2 OUT A

0.433

0.419

0.060

0.074

0.009

0.024

Course 2 IN B

0.404

0.310

0.085

0.075

0.000

0.000

Course 2 OUT B

0.209

0.159

0.046

0.054

0.000

0.000

Course 3 IN A

0.843

0.288

0.109

0.105

0.011

0.012

High: 0.183

High*: 1.046

High: 0.020

Course 3 OUT A

0.994

0.473

0.055

0.080

0.011

0.014

Washpad OUT

4.313

2.729

0.270

0.573

0.034

0.050

Course 3 IN B

1.530

0.887

0.063

0.044

0.051

0.071

High: 2.158

High: 0.102

High: 0.094

Course 3 OUT B

2.898

1.212

0.088

0.135

0.022

0.042

Course 4 IN A

2.726

1.919

0.059

0.063

0.001

0.002

High: 4.805

High: 0.004

High: 0.131

Course 4 OUT A

3.479

1.552

0.041

0.054

0.011

0.019

Course 4 IN B

1.014

0.568

0.086

0.169

0.010

0.013

Course 4 OUT B

3.309

1.469

0.246

0.582

0.006

0.012

1.457

0.043

0.027

0.015

0.008

0.003

Course 4 IN C

High: 1.488

High: 0.037

High: 0.010

Course 4 OUT C

2.618

1.171

0.025

0.039

0.003

0.008

Course 5 IN

0.217

0.309

0.046

0.061

0.007

0.020

Course 5 OUT

0.121

0.133

0.048

0.049

0.000

0.000

Course 6 IN A

0.216

0.220

0.033

0.036

0.000

0.000

Course 6 OUT A

0.124

0.113

0.037

0.056

0.000

0.000

Course 6 IN B

1.636

1.110

0.046

0.069

0.000

0.000

Course 6 OUT B

0.226

0.098

0.064

0.071

0.000

0.000

*High values represent the highest mean value of the corresponding “in.” aValues are the averaged means of two “in” sites. bValues are the averaged means of three “in” sites.

14 | Virginia Turfgrass Journal May/June 2013 www.vaturf.org

Virginia Tech Researchers: Erik Ervin, Ph.D., Professor of Turfgrass Culture & Physiology (Crop & Soil Environmental Sciences Dept.); Stephen Schoenholtz, Ph.D., Professor and Director of the Virginia Water Resources Research Center (Dept. of Forest Resources and Environmental Conservation); Chantel Wilson, Ph.D. Candidate (Crop & Soil Environmental Sciences Dept.); and Mike Goatley, Ph.D., Professor and Turfgrass Extension Specialist (Crop & Soil Environmental Sciences Dept.)

Research Sponsors: Virginia Golf Course Superintendents Association (VGCSA), GCSAA’s Environmental Institute for Golf, Virginia Turfgrass Foundation and Virginia Agricultural Council

W

ith the VGCSA’s recent publication of “Environmental Best Management Practices (BMPs) for Virginia’s Golf Courses,” we have begun the groundtruthing and implementation phases of this project. Widespread implementation of BMPs by golf courses is expected to conserve water and reduce environmental impacts, including lower nutrient loading to waterways from stormwater runoff, decreased pesticide usage and less potential for contamination of surface and groundwaters. Implementation of the published BMPs by Virginia golf courses will help achieve the total maximum daily load (TMDL) goals established by the EPA for protection of the Chesapeake Bay.

An important component of documenting the effectiveness of these guidelines will be ground-truthing through rigorous monitoring of water-quality parameters, both before and after BMP implementation. Six Virginia golf courses located within the watershed have been selected as test sites, with sample locations identified to monitor water quality (nitrate and phosphate, primarily) flowing into and out of each golf course.

Results to date

Data for eight quarterly sampling seasons (2011 and 2012) have been analyzed thus far for six golf courses in the James River Watershed. So far, we have not seen any significant trends of impairment with respect to dissolved xygen, specific conductance, temperature or pH on eight monitored stream sites.

As for nutrient levels, the averages for each of twelve monitored sites are presented in Table 1. Stream levels of nitrate-N were below the EPA established level of 10 mg/L for drinking water. No established guidelines for freshwater streams in VA are available, although < 1 mg/L is considered “good,” while 1 to 10 mg/L is considered “fair” water quality. Three of eleven sites (on three separate golf courses) had means of nitrate-N higher in the water as it left the course than the water entering the course, as well as concentrations > 1 mg/L. However, these differences do not appear to be significant.

Ammonium-N is also a source of N, allowing for algal growth and eutrophication. Ammonium-N increased at five of the sites (on four courses), but these increases were not significant.

As for phosphate-P, increases were observed at two downstream locations, with other courses showing downstream decreases or no detectable phosphate-P. Phosphate-P levels in waters leaving the course were below the EPA recommendation of 0.05 mg/L. Collection of total N, total P and benthic macroinvertebrates will begin in May 2013. We will also begin to determine stream flow values at this time. c

Journal of the Virginia Turfgrass Council

| 15

Research Report

The Impact of Turf Fans on Creeping Bentgrass Putting Greens Virginia Tech Researchers: David McCall, Turfgrass Pathologist and Research Associate; Chantel Wilson, Graduate Research Assistant; and Andrew Landreth, Undergraduate Research Assistant Research Sponsors: Toro, Virginia Ag Council, Virginia Turfgrass Foundation and SubAir Systems

B

ecause of its uniform appearance and ball roll, density and color, creeping bentgrass is considered the most desirable species for putting greens worldwide.

Unfortunately, stress to this cool-season species during summer months is one of the biggest limiting factors of its success in Virginia.

Numerous things happen to the physiology of creeping bentgrass during stressful conditions, preventing many important functions from occurring. When soil temperatures rise above 86°F, bentgrass has a net energy loss, resulting in a loss of functionality of both roots and leaves. Golf Figure 1. Rootzone and canopy temperatures at incremental distances from a stationary turf fan. Mean temperatures with the same letter are not significantly different.

course superintendents utilize various tactics to combat this.

Installing turf fans is one of the many strategies.

Turf fans are used on many golf courses in the Southeast and into the transition zone to provide much-needed airflow in areas with poor circulation. But what is the real benefit? Do fans really cool the turf surface? Do they affect the temperature of the rootzone, which is actually more important for plant survival? Does the added airflow dry out the turf to where more water is needed to keep it alive? How do turf fans impact stress-induced diseases, such as Pythium root rot?

Clearly, many questions need to be answered. We know that turf fans are valuable, but how much of the putting green is actually being impacted? These were some of the uncertainties that led us to our current research.

Our research is designed to answer some of the questions that remain regarding potential benefits of turf fans on golf putting greens â&#x20AC;&#x201D; specifically, the spatial component associated with fan placement and the impact on the ability of secondary pathogens to further impede creeping bentgrass growth and development. The objectives of the research are to (a) determine distal benefits of turf fans on in-play golf putting greens and (b) evaluate the impact of fans on reducing Pythium root rot and other secondary disorders by improving the microenvironment. Research in 2012 looked to address some of the key response variables associated with distal benefits.

Our research

During the summer of 2012, we began studying the spatial impacts of turf fans in Richmond. An oscillating 5hp Electric Turf Breeze 50" (TB-50-Premium, by SubAir Systems, LLC) fan was installed on an in-play putting green in May, and it ran continuously throughout the summer until after all data

Figure 2. Soil moisture at incremental distances from a stationary turf fan. Mean temperatures with the same letter are not significantly different.

16 | Virginia Turfgrass Journal May/June 2013

Figure 3. Mapped reflectance data to show the spatial impact of turf fans on golf putting greens. Relative turf quality is highest in dark green areas, followed by light green, blue, yellow and orange.

collections. Measurements of soil and canopy temperatures, soil moisture and maximum and average wind speeds were collected on three dates in July and August. These measurements were compared with mapped geo-referenced reflectance data using an online data-processing service.

As an objective measurement of turf quality, this type of data is often more sensitive at detecting stress than the naked eye.

Results to date

Air movement from the fan exceeded four miles per hour across the green, but the benefits were less apparent at greater distances from the fan. Analyzed data showed that temperatures and soil moisture increased at increasing distances from the fan base. Cooling effects were more dramatic on rootzone temperatures than on canopy temperatures (Figure 1). Soil moisture was reduced by approximately ten percent at distances closest to the fan (Figure 2). This is important because certain diseases are more severe in wetter soils. Reflectance generated and mapped showed a distinct region closest to the fan with highest turf quality values (green), with most other areas having reduced quality (Figure 3).

Conclusions

To date, our data shows a spatial impact on optimal benefits of turf fans. With one season of data, turf fans (when installed properly) appear to be a useful tool for cooling the rootzones and managing moisture content. Reflectance mapping is strongly correlated with soil measurements and can be a rapid tool for assessing how well fans are performing. Even a few degrees can make a difference in the physiological response of creeping bentgrass and annual bluegrass. Not only will the turf be able to function more properly, fungicide performance should also be maximized. This ultimately should result in fewer applications needed throughout the summertime.

Research efforts in 2013 will focus on fan initiation timing and ultimate impact on Pythium root rot, a difficultto-control disease during peak summer stress. c

Journal of the Virginia Turfgrass Council

| 17

Research Report

An Integrated Nutritional and Chemical Approach to Poa annua Suppression in Creeping Bentgrass Putting Greens Our research

Virginia Tech Researchers: Nate Reams, M.S. Student, and Erik Ervin, Ph.D., Professor of Turfgrass Culture & Physiology (Crop & Soil Environmental Sciences Dept.)

Research Sponsors: Virginia Agricultural Experiment Station, Virginia Turfgrass Foundation and Virginia Agricultural Council

P

oa annua suppression in cool-season putting greens is a perennial challenge in many temperate climates around the world. A nutritional approach, common in the U.K. and becoming more popular in the U.S., is frequent use of sulfates of iron (Fe) and ammonium to provide plant nutrition plus gradual rootzone acidification. Acidic soil (pH <5.5) is known to favor desirable Agrostis (bentgrass) and Festuca (fescue) species relative to Poa. Another component of this nutritional approach is to not apply P or K, since they are thought to favor Poa. In the U.S., it is also very common to use repeated applications of Class B plant growth regulators (PGRs), paclobutrazol or flurprimidol, to selectively injure Poa throughout the growing season.

Such practices may be safe and successful in mild maritime climates, but what are the effects in the humid subtropical climate of Virginia? Our objective was to apply very high foliar rates of FeSO4 and determine their effects on Poa annua populations in a creeping bentgrass putting green over time.

Table 1. Percent Poa annua, dollar spot infections and moss counts within a creeping bentgrass putting green as affected

by FeSO4 and PGR treatments over three years.

The trial is on a mature (more than 25 years old), sandbased putting green, originally seeded with â&#x20AC;&#x2DC;Penneagleâ&#x20AC;&#x2122; creeping bentgrass. We mowed the green five times per week at 0.125", with clippings collected. The Fe treatments were split between a generic seaweed extract (SWE) or paclobutrazol (PAC) to determine any additive effects on Poa suppression. FeSO4 rates were 0, 0.25 lb./1,000 ft2, 0.50 lb./1,000 ft2 and 1.0 lb./1,000 ft2, applied to the foliage every two weeks from March through November in both 2011 and 2012. Main FeSO4 plots were split by SWE (4 oz./1,000 ft2) or PAC (22 oz./A in spring/fall or 11 oz./ A in summer) on the same application schedule. Nitrogen was supplied to all plots uniformly via ammonium sulfate at 1.8 lbs. N/1,000 ft2/yr. No P or K was applied.

Our results to date

Three years of frequently applied high rates of FeSO4 have resulted in considerable reductions in Poa annua (especially in combination with paclobutrazol), dollar spot pressure and moss invasion within a creeping bentgrass putting green (Table 1) that do not appear to be related to reductions in soil pH or P-availability (data not shown). Perhaps the Poa reductions are due to differential desiccation and direct toxicity, but we have no data at this time to support this statement. This research will continue for a number of years as we attempt to understand this phenomenon. c

PGR

Poa % May 2011

0

PAC

13.8 def

20.0 cd

1.4 fg

28.3 bcde

34.3 a

0

SWE

36.3 ab

36.3 ab

17.8 cde

45.3 bcd

6.3 cd

0

Control

42.5 a

46.3 a

29.4 abc

89.0 a

8.0 cd

0.25

PAC

8.0 f

16.3 cde

0.1 g

21.0 cde

32.5 a 10.3 bc

FeSO4 (lb./1,000 ft2)

Poa % May 2012

Poa % Dollar Spot Infection # May 2013 Sept. 2011

Moss Colony Centers Sept. 2011

0.25

SWE

31.3 abc

25.0 bcd

12.2 defg

60.3 ab

0.25

Control

26.3 bcd

28.8 bc

13.1 def

55.0 abc

8.8 cd

0.50

PAC

10.0 bcde

3.5 e

1.3 fg

6.5 e

19.0 b

0.50

SWE

28.8 abc

20.0 cd

21.5 bc

34.0 bcde

0.8 cd

0.50

Control

27.5 bcd

22.5 bcd

35.3 a

31.8 bcde

0.8 cd

1.00

PAC

7.3 f

4.3 e

6.7 efg

2.5 e

4.5 cd

1.00

SWE

17.5 cdef

11.3 de

21.8 bcd

16.0 de

0.1 d

Control

23.8 bcde

18.8 cd

30.3 ab

15.3 de

0.5 cd

LSD0.05

14.9

14.1

12.2

38.0

10.1

1.00

18 | Virginia Turfgrass Journal May/June 2013 www.vaturf.org

Journal of the Virginia Turfgrass Council

| 19

Research Report

Dallisgrass Control in Bermudagrass Table 1. Percent dallisgrass control in June (23 days after the second spring application) and in November (22 days after the second fall application).

Percent Dallisgrass Control Treatment, Rate and Timing 1

Untreated

2

Celsius

3.7

oz./a

3

4

5

6

7

Spring

+ Revolver

26.2

fl. oz./a

Spring

+ Celsius

3.7

oz./a

Spring 2

+ Revolver

26.2

fl. oz./a

Spring 2

Celsius

3.7

oz./a

Spring

+ Revolver

26.2

fl. oz./a

Spring

+ Celsius

3.7

oz./a

Fall

+ Revolver

26.2

fl. oz./a

Fall

Celsius

3.7

oz./a

Fall

+ Revolver

26.2

fl. oz./a

Fall

+ Celsius

3.7

oz./a

Fall 2

+ Revolver

26.2

fl. oz./a

Fall 2

Celsius

3.7

oz./a

Spring

+ Revolver

26.2

fl. oz./a

Spring

+ Celsius

3.7

oz./a

Spring 2

+ Revolver

26.2

fl. oz./a

Spring 2

+ Monument

0.53

oz./a

Fall

+ Monument

0.53

oz./a

Fall 2

Monument

0.53

oz./a

Spring

+ Monument

0.53

oz./a

Spring 2

Celsius

3.7

oz./a

Fall

+ Revolver

26.2

fl. oz./a

Fall

Celsius

3.7

oz./a

Fall 2

+ Revolver

26.2

fl. oz./a

Fall 2

MSMA

2.0

lb. ai/a

Spring

+ MSMA

2.0

lb. ai/a

Spring 2

+ MSMA

2.0

lb. ai/a

Fall 2

+ MSMA

2.0

lb. ai/a

Fall 2

LSD (P = .05)

June 29

November 30

23 DAT-B

22 DAT-D

0%

1%

45%

3%

0%

9%

0%

83%

45%

86%

44%

84%

53%

89%

27

5

Virginia Tech Researchers: Jeffrey F. Derr, Ph.D., Professor of Weed Science, and Adam Nichols, Research Assistant, Hampton Roads Agricultural Research and Extension Center, Virginia Beach Sponsors: Bayer Environmental Science, Virginia Turfgrass Council and Virginia Turfgrass Foundation

D

allisgrass (Paspalum dilatatum) is a troublesome weed in both cool- and warm-season turf. Its wide blades and tall seedheads make the weed especially conspicuous in bermudagrass turf.

Dallisgrass is a warm-season perennial that goes dormant in the fall and resumes growth in the spring.

This weed spreads by short rhizomes as well as by seed. Over time, dallisgrass clumps expand due to rhizome growth.

MSMA, the most commonly used herbicide for dallisgrass control, currently can be used only in sod production and on golf courses and rights-ofway areas. Current MSMA labels do not allow applications to home lawns or commercial settings. It is unclear what products will be available to replace MSMA in the future, although it appears that uses for MSMA in golf, sod and rights of way will continue for three years. Additional control options are therefore needed for this weed in turf.

Our research

20 | Virginia Turfgrass Journal May/June 2013 www.vaturf.org

We have been investigating herbicides, herbicide combinations and

herbicide application timing for dallisgrass control in bermudagrass. The herbicides tested include Revolver (foramsulfuron), Celsius (a threeway combination of iodosulfuron, thiencarbazone and dicamba), Tribute Total (a three-way combination of foramsulfuron, thiencarbazone and halosulfuron) and Monument (trifloxysulfuron). We included MSMA for comparison.

All of these herbicides will injure dallisgrass, although this weed will recover from single applications. For some of these products, label restrictions prevent making more than two applications per season, so in our repeat applications, we have rotated herbicides to stay within label restrictions. We have tested multiple spring, multiple fall and spring-followed-byfall applications. We compared broadcast applications to spot treatments.

For certain herbicides, a higher dose can be applied using a spot treatment, although only about one quarter of the total turf area could be treated using these doses. For the broadcast treatments, we applied Celsius at 3.7 ounces per acre, Revolver at 26 fluid ounces per acre and Monument at 0.5 ounces per acre.

Research results to date

Two applications of Celsius plus Revolver or two applications of Monument in spring provided 45% dallisgrass control by the end of June, slightly lower than that seen with two applications of MSMA (53% control), but dallisgrass completely recovered from these applications by fall. Applying a single Celsius plus Revolver treatment in spring followed by a single Celsius plus Revolver treatment in the fall also did not provide acceptable control of this weed.

Two applications of Celsius plus Revolver in fall, two applications of Celsius plus Revolver in spring followed by two applications of Monument in the fall, or two applications of Monument in spring followed by two applications of Celsius plus Revolver in fall all provided 80% or greater dallisgrass control at the end

Dallisgrass, with its wide leaf blades and tall seedheads, is quite conspicuous when growing in bermudagrass.

of November, which was comparable to that seen with multiple applications of MSMA. When evaluated the following spring, however, none of the spring, fall or spring plus fall programs utilizing Revolver, Celsius or Monument provided acceptable control of dallisgrass. Multiple fall applications of Tribute Total also have injured dallisgrass, but have not provided acceptable long-term control. It appears that eradicating dallisgrass will involve repeat treatments over multiple years if MSMA is not available.

As to bermudagrass tolerance, we saw unacceptable but temporary injury following either two spring or two fall applications of Celsius plus Revolver in our 2011 trial. The injury, which was most likely due to the Celsius component, decreased significantly a week later. In the 2012 trial, the injury from these treatments was noticeable but

not unacceptable. No injury was seen following the Monument applications.

We have not observed injury to established bermudagrass from Revolver or Monument applications in other studies, but we have observed temporary injury following Celsius applications.

With the products available for dallisgrass suppression in bermudagrass, it appears that multiple spring and fall applications will be needed for acceptable dallisgrass control.

Of the two timings, fall seems to be the more effective application timing.

Applications may need to be timed to spring when dallisgrass greens up and resumes growth, as well as treatments in the fall to weaken the plant going into winter. Adjuvant addition, including ammonium sulfate and methylated seed oil, may also be beneficial in these spray programs. More research is needed on alternatives to MSMA for dallisgrass control. c Journal of the Virginia Turfgrass Council

| 21

Research Report

Acelepryn & HGW86 20SC White Grub Control in Turfgrass (2012 DuPont Field Trials) Virginia Tech Researchers: Rod Youngman, Ph.D., Professor; Curt Laub, Research Associate; Shaohui Wu and Sudan Gyawaly, Graduate Students, Department of Entomology Sponsors: DuPont Professional Products, Virginia Agriculture Council and Virginia Turfgrass Foundation

To

evaluate the efficacy of various soil insecticides against white grubs on golf course turf, we conducted research at two locations in southwest Virginia in 2012: (1) Tazewell Country Club, where the turf is an 80% fescue/20% bluegrass mixture, and (2) the Virginia Tech Turfgrass Research Center in Montgomery County on 100% ‘Penncross’ bentgrass.

Table 1. Treatment list for 2012 Dupont Acelepryn & HGW86 20SC white grub efficacy trials in Tazewell and Montgomery Counties, Virginia.

Trt. No.

Application Timing1

Treatment/ Formulation

Application Rate (amt. product/acre)

1

Early

DPX-HGW86 20SC

4.0 fl. oz.

2

Early

DPX-HGW86 20SC

6.0 fl. oz.

3

Early

DPX-HGW86 20SC

8.0 fl. oz.

4

Early

Acelepryn 1.67SC

8.0 fl. oz.

5

Early

Merit 75WP

6.4 oz.

Meridian 25 WG +

8.58 oz.

DPX-HGW86 20SC

10.3 oz.

6

Early

7

Late

DPX-HGW86 20SC

4.0 fl. oz.

8

Late

DPX-HGW86 20SC

6.0 fl. oz.

9

Late

DPX-HGW86 20SC

8.0 fl. oz.

10

Late

Acelepryn 1.67SC

8.0 fl. oz.

11

Late

Merit 75WP

6.4 oz.

Meridian 25 WG +

8.58 oz.

DPX-HGW86 20SC

10.3 oz.

12

Late

13

--

Untreated check

1 Early Application: June 7 at Site 1 (Tazewell); June 13 at Site 2 (Montgomery).

Late Application: July 11 at Site 1 (Tazewell); July 12 at Site 2 (Montgomery).

Our research

The treatments used in these trials are shown in Table 1.

Plot size was 5 ft. by 5 ft. Application timings were either early (June) or late (July). Early applications were applied on June 7 at Site 1 and on June 13 at Site 2, and late applications were applied on July 12 at Site 1 and on July 11 at Site 2. Liquid insecticide treatments were applied as foliar sprays using a CO2 backpack sprayer equipped with four 8008VS stainless steel spray tips and calibrated to deliver 80 gpa at 40 psi.

Approximately 1/2" of overhead irrigation water was applied immediately after treatments were applied. No fungicides were applied at either site.

White grub counts were taken on September 14 at Site 1 and on September 13 at Site 2. A sod-cutting machine was used to cut a 12" wide by 1" deep strip the length of each plot: in each untreated check plot, a 2' section of turf was

Table 2. White grub counts in Tazewell County, Virginia (Site 1).

Application Rate (amt. product/acre)

White grubs per sq. ft. (+ SEM)

--

9.50 (1.17) a

DPXHGW86 / June / Low

4.0 fl. oz.

9.00 (1.08) a

DPXHGW86 / June / Med.

6.0 fl. oz.

3.00 (0.41) b

Meridian+DPXHGW86 / June

8.58 + 10.3 oz.

3.00 (0.71) b

Meridian+DPXHGW86 / July

8.58 + 10.3 oz.

1.50 (1.50) bc

DPXHGW86 July / High

8.0 fl. oz.

1.25 (0.75) bc

DPXHGW86 June / High

8.0 fl. oz.

1.00 (0.71) bc

6.4 oz.

0.75 (0.48) bc

Acelepryn / June

8.0 fl. oz.

0.50 (0.50) bc

DPXHGW86 / July / Low

4.0 fl. oz.

0.50 (0.29) bc

DPXHGW86 / July / Med.

6.0 fl. oz.

0.00 (0.00) c

Acelepryn / July

8.0 fl. oz.

0.00 (0.00) c

6.4 oz.

0.00 (0.00) c

Treatment/Timing1/ Formulation Untreated check

Merit / June

Merit / July

1 Early Application: June 7. Late Application: July 11.

The treatment source of variation for white grubs was highly significant (P < 0.0001) according to ANOVA. Statistical analysis including Tukey’s HSD was performed on square root transformed data (x + 0.5)1/2. Actual treatment means are shown in table. Means within a column by site followed by the same letter are not significantly different (P > 0.05; LSD).

22 | Virginia Turfgrass Journal May/June 2013 www.vaturf.org

examined (= 2 sq. ft. per plot); in each treatment plot, one 12" section of turf was examined (= 1 sq. ft. per plot). Prior to analysis, all data were corrected to 1 sq. ft. per plot.

Results to date

A total of 217 white grubs were collected from the two sites. Although species counts were not recorded in 2012, most of the white grubs collected were masked chafers (Cyclocephala spp.).

At Site 1, the treatment source of variation for white grubs was highly significant. The density of white grubs in the untreated check and in the early (June) application of the low rate of DPX-HGW86 20SC was significantly higher than in all the other treatments (see Table 2). Also, the density of white grubs in the early (June) applications of Meridian 25WG + DPXHGW86 20SC and the medium rate of DPX-HGW86 20SC were significantly higher than in the late (July) applications of Acelepryn 1.67 SC, Merit 75WP and the medium rate of DPX-HGW86 20SC (Table 2).

At Site 2, the treatment source of variation for white grubs was not significant (Table 3).

Phytotoxicity was not observed in any plot over the course of the experiment. c

Table 3. White grub counts in Montgomery County, Virginia (Site 2).

Application Rate (amt. product/acre)

White grubs per sq. ft. (+ SEM)

DPXHGW86 / July / Low

4.0 fl. oz.

3.75 (2.17)

DPXHGW86 / July / Med.

6.0 fl. oz.

2.50 (1.89)

Treatment/Timing1/ Formulation

Untreated check

2.38 (0.90)

DPXHGW86 / June / Low

4.0 fl. oz.

2.25 (1.31)

DPXHGW86 / June / Med

6.0 fl. oz.

0.50 (0.50)

DPXHGW86 / June / High

8.0 fl. oz.

0.50 (0.29)

DPXHGW86 / July / High

8.0 fl. oz.

0.25 (0.25)

Acelepryn / July

8.0 fl. oz.

0.25 (0.25)

Acelepryn / June

8.0 fl. oz.

0.00 (0.00)

Merit / June

6.4 fl. oz.

0.00 (0.00)

8.58 + 10.3 oz.

0.00 (0.00)

6.4 fl. oz.

0.00 (0.00)

8.58 + 10.3 oz.

0.00 (0.00)

Meridian+DPXHGW86 / June Merit /July Meridian+DPXHGW86 / July

1 Early Application: June 7. Late Application: July 11.

The treatment source of variation for white grubs was not significant (P > 0.05), according to ANOVA. Statistical analysis was performed on square root transformed data (x + 0.5)1/2. Actual treatment means are shown in table.

Journal of the Virginia Turfgrass Council

| 23

Research Report

Weed Management in Pansy Beds Virginia Tech Researcher: Jeffrey F. Derr, Ph.D., Professor of Weed Science, Hampton Roads Agricultural Research and Extension Center, Virginia Beach Sponsors: BASF and Virginia Nursery & Landscape Association

P

ansy is an important species for winter and spring color in commercial plantings and home landscapes.

Pansies offer a wide choice of flower colors, and the plants can persist into early summer. Control of winter weeds, though, is a management concern for landscapers who maintain pansy beds.

Over the years, I have conducted trials to determine which preemergence herbicides can be applied after transplanting pansy. We have collected data on pansy injury, pansy flowering and control of weeds such as common chickweed and annual bluegrass. Pansy tolerance has varied somewhat from year to year, either due to the cultivars I evaluated, the plant size at treatment, weather conditions or the herbicide application rate. I often use different cultivars each year based on availability. Some conclusions, however, can be reached from these trials.

The chemicals I have evaluated include Snapshot, a granular combination of isoxaben and trifluralin, and FreeHand, a granular combination of dimethenamid and pendimethalin. Single active-ingredient products that I have evaluated include BroadStar (flumioxazin), Gallery (isoxaben), Dimension (dithiopyr), Pennant (metolachlor), Surflan (oryzalin), Tower (dimethenamid) and Specticle (indaziflam). I have placed special emphasis on comparing the different formulations of pendimethalin, including the emulsifiable concentrate (Pendulum EC), microencapsulated (Pendulum AquaCap), water-dispersible granule (Pendulum WDG) and granular (Pendulum 2G) forms.

Conclusion #1.

Herbicide choice is important!

Although they provide exceptional weed control, BroadStar and Specticle cause severe damage to pansy and thus cannot be used. Dimension also has caused significant injury and reduction in flowering in pansy and therefore also should be avoided. The injury from Dimension was slow to appear, with the damage sometimes not apparent until seven or eight weeks after treatment.

It is harder to make conclusions concerning the isoxabencontaining products Gallery and Snapshot. In some trials, I saw little to no injury, with significant injury in others, which may have been due to differences in cultivar sensitivity to this herbicide. In one trial, the maximum use rate of Snapshot (200 lbs. product per acre or 5 lbs. active ingredient per acre) reduced the stands of most pansy cultivars, but it appeared to reduce the stands of Colossus and Delta Fire more so than Dynamite or the Viola cultivar, as shown in Table 1 (page 26). As you can see in Table 2 (page 26), this rate of Snapshot caused significant injury to all five pansy cultivars. For the dimethenamid-containing products Tower and FreeHand, I generally saw good tolerance at the use rates for these products. Pansy also tolerated Surflan and Pennant in my trials.

Conclusion #2.

Formulation is very important!

Do not use an emulsifiable concentrate (EC) form of pendimethalin, since it can cause significant injury and flower reduction in pansy. My impression is that the injury is primarily due to foliar uptake and not due to root uptake/stunting, even though this is a root-inhibiting herbicide. Granular forms of pendimethalin have generally caused no injury and no flower reduction, so that would be the preferred formulation. If you prefer a sprayable

24 | Virginia Turfgrass Journal May/June 2013 www.vaturf.org

Research Report continued

product, Pendulum AquaCap is much safer on pansy than the EC form.

is calibrated so that you do not inadvertently apply two or three times what you intend to apply.

Conclusion #3. Rate is important!

Summary

I generally evaluate rates above the maximum use rate in order to determine the extent of tolerance. Ideally, we would like to see the crop (in this case, pansy) tolerate four times the use rate. As you can see in Table 2, when we went to twice and four times the common use rate of FreeHand (150 lbs. per acre or 2.62 lb. ai/A), we started to see injury in the pansy cultivars. We also observed reductions in flower counts per plant when we exceeded the typical use rate of FreeHand (data not shown). So, stay at the lower end of the rate range, and make sure your equipment

Herbicide choice, rate and formulation are all important factors when choosing a preemergence product in pansy beds. Certain herbicides that can be applied to woody nursery plants, such as BroadStar, are too injurious to pansy.

Consider using a granular formulation, such as Pendulum 2G, as it probably will be the safest type to apply to pansy.

Avoid the maximum labeled rates, since higher rates have greater potential to cause injury. Apply the product after transplanting and after an irrigation to settle the soil. Apply any desired mulch after herbicide application. c

Table 1. Number of living pansy plants three months after preemergence herbicide application for the following cultivars: Matrix Morpheus, Colossus Yellow Blotch, Viola Penny Mickey, Dynamite Wine Flash and Delta Fire.

Rate Treatment

lb. ai/A

Untreated Tower

1.0

Number of Living Pansy Plants per Plot 106 DAT Matrix

Colossus

Viola

Dynamite

Delta Fire

5.0

4.5

5.0

4.8

4.8

5.0

4.5

4.3

5.0

4.3

Tower

2.0

4.8

3.5

4.0

3.3

4.8

Tower

4.0

4.5

5.0

4.8

5.0

4.0

Snapshot

5.0

2.8

1.5

4.5

3.8

1.8

FreeHand

2.62

5.0

4.3

5.0

5.0

4.8

FreeHand

5.25

4.8

4.5

4.5

4.0

4.5

FreeHand

10.5

4.3

3.3

4.8

4.3

4.3

Pendulum 2G

4.0

4.5

4.8

5.0

5.0

5.0

Specticle

0.045

0.5

0.0

2.8

0.0

0.3

1.2

1.0

1.3

1.1

1.4

LSD (P=.05)

Table 2. Percent injury four months after preemergence herbicide application to the following pansy cultivars: Matrix Morpheus, Colossus Yellow Blotch, Viola Penny Mickey, Dynamite Wine Flash and Delta Fire.

Rate Treatment

lb. ai/A

Untreated

Percent Injury 126 DAT Matrix

Colossus

Viola

Dynamite

Delta Fire

0%

1%

0%

0%

1%

Tower

1.0

0%

0%

0%

0%

3%

Tower

2.0

5%

7%

1%

3%

3%

Tower

4.0

4%

3%

3%

0%

3%

Snapshot

5.0

75%

85%

53%

58%

78%

FreeHand

2.62

1%

4%

1%

3%

3%

FreeHand

5.25

13%

14%

7%

19%

15%

FreeHand

10.5

30%

43%

26%

35%

36%

Pendulum 2G

4.0

3%

6%

1%

2%

6%

Specticle

0.045

93%

100%

80%

98%

95%

14

12

17

20

15

LSD (P=.05)

26 | Virginia Turfgrass Journal May/June 2013 www.vaturf.org

Cover Story continued

Journal of the Virginia Turfgrass Council

| 27

Research Summaries Rapid Diagnostic Tool for Improved Spring Dead Spot Recommendations

Yellow Nutsedge Control with Combinations of Halosulfuron and Sulfentrazone

Virginia Tech Researcher: David McCall, Turfgrass Pathologist, and Elizabeth Bush, Plant Diagnostician

Virginia Tech Researchers: Jeffrey Derr, Ph.D., and Adam Nichols, Virginia Tech

Research Sponsors: USDA-NIFA Extension IPM Program

S

pring dead spot is easily the most common and destructive disease of bermudagrass turf. The depressed voids left behind are not only unsightly, but also they can potentially be an injury hazard on athletic playing surfaces.

Two species of Ophiosphaerella are known to incite disease in our region. O. korrae is the dominant species in the Carolinas and other southeastern states, while O. herpotrica is more prevalent in Maryland, Kentucky and throughout the Midwest.

Previous research has documented that each species can be successfully managed with different nitrogen sources.

After three years of field testing in Virginia, our results have not been as clearly defined. With Virginia being in the transitional area of predominant species, we hypothesize that populations are mixed in most locations, preventing us from being able to develop sound recommendations.

In collaboration with the Plant Diseases Clinic at Virginia Tech, we are working to develop a rapid diagnostic procedure for identifying the pathogen to species. In 2013, intensive sampling of our four test sites around the state will provide insight into variability within a site. Future samples will be submitted from across Virginia and surrounding states to develop a geographic distribution of species for more precise recommendations.

Spring dead spot on Tifway 419 bermudagrass.

Research Sponsors: Gowan Company, the Virginia Turfgrass Council and the Virginia Turfgrass Foundation

S

edgeHammer, which contains the active ingredient halosulfuron, provides effective postemergence control of yellow nutsedge, but it is slow acting. Dismiss, which contains sulfentrazone, works much faster than SedgeHammer, but it often does not provide as effective long-term control as SedgeHammer. We wondered if a combination of the two herbicides might result in both rapid and effective long-term control of yellow nutsedge.

The objective of our research was to determine the efficacy of combinations of halosulfuron and sulfentrazone on the control of yellow nutsedge (Cyperus esculentus). The efficacies of these treatments were rated for control of yellow nutsedge versus SedgeHammer and Dismiss applied alone, and an untreated control.

Treatments containing sulfentrazone caused more injury to yellow nutsedge at 2 days after treatment (DAT) than those lacking sulfentrazone. At 15 DAT, however, adding halosulfuron at 1 oz. product per acre to sulfentrazone at 8 fl. oz. product per acre reduced yellow nutsedge control compared to Dismiss at 8 fl. oz. per acre applied alone. By 23 and 65 DAT, though, no significant differences were observed among the herbicide treatments. Long-term control was similar among the treatments.

Adding halosulfuron to sulfentrazone appeared to reduce the rapid action of sulfentrazone, although long-term sedge control was unaffected. So, there may not be any benefit to combining these two herbicides. Additional trials are needed to verify this conclusion.

Yellow Nutsedge and Southern Crabgrass Control with Combinations of Halosulfuron with Quinclorac or Fenoxaprop Virginia Tech Researchers: Jeffrey Derr, Ph.D., and Adam Nichols, Virginia Tech Research Sponsors: Gowan Company, the Virginia Turfgrass Council and the Virginia Turfgrass Foundation

U

sed for control of yellow nutsedge, dallisgrass, crabgrass and other turf weeds, MSMA is currently being phased out for turf use, with current products labeled only for golf, sod production and highway rights of way. With the future uses of MSMA in turf unclear, alterna-

28 | Virginia Turfgrass Journal May/June 2013 www.vaturf.org

tives are needed to address control of those weed species.

Our objective with this research was to determine the efficacy of combinations of halosulfuron (the active ingredient in SedgeHammer) with either fenoxaprop (the active ingredient in Acclaim Extra) or with quinclorac (the active ingredient in Drive) for the control of yellow nutsedge and smooth crabgrass. The efficacies of these treatments were rated for control of yellow nutsedge and smooth crabgrass in open-field situations and in a mowedturf situation. All treatments were tested against an untreated control.

Treatments containing quinclorac injured southern crabgrass by 4 days after treatment (DAT). Crabgrass control decreased over time in all quinclorac-treatment plots due to regrowth of injured plants. A second application was needed to improve control, but only single applications were tested in this study. Adding halosulfuron to quinclorac had no additional effect on smooth crabgrass.

Fenoxaprop gave good (75%) crabgrass control at 67 DAT, but adding halosulfuron to fenoxaprop reduced crabgrass control to only 28%.

This was not surprising, as we have observed antagonism of grass control when Acclaim Extra is combined with certain other herbicides.

All treatments containing halosulfuron, including combinations with Acclaim Extra, gave excellent yellow nutsedge control at 67 DAT. Sulfentrazone plus quinclorac caused significant injury to crabgrass and yellow nutsedge at 1, 4 and 8 DAT, but control of both weeds decreased over time.

In conclusion, halosulfuron (SedgeHammer) and fenoxaprop (Acclaim Extra) should be applied separately, since combinations result in antagonism of crabgrass control.

Combining these two herbicides, though, does not result in any antagonism of yellow nutsedge control.

Halosulfuron can be combined with quinclorac, but additional applications of quinclorac made be needed for acceptable crabgrass control.

Combinations of halosulfuron with quinclorac provide similar yellow nutsedge control to that seen with halosulfuron applied alone. c

Journal of the Virginia Turfgrass Council

| 29

Turfgrass Calendar June 25

Hampton Roads AREC Turfgrass Field Day, Pesticide Recertification and Certified Fertilizer Applicator

Hampton Roads AREC Virginia Beach, VA

July 21–23

PLANET Legislative Day on the Hill

Washington, D.C.

July 23–25

TPI Summer Convention & Field Days

(Turfgrass Producers International) Chicago, IL

August 18–22

StormCon — 2013 Conference The Stormwater Pollution Prevention Conference

Sheraton Myrtle Beach Convention Center Myrtle Beach, NC

August 27–28 Turfgrass Field Days

Virginia Tech Blacksburg, VA

Virginia Tech’s Turfgrass Researchers October 23–26

Shawn D. Askew, Ph.D.

Mike Goatley Jr., Ph.D.

School of Grounds Management and Green Industry Expo

Virginia Tech Box 0330 Glade Rd. Facility Blacksburg, VA 24061 (540) 231-5807 Email: saskew@vt.edu

Virginia Tech 424 Smyth Hall, CSES Dept.

Blacksburg, VA 24061 (540) 231-2951 Email: goatley@vt.edu

November 15–18

Jeffrey F. Derr, Ph.D.

David S. McCall

(American Society of Landscape Architects) Boston Convention & Expo. Center Boston, MA

Virginia Tech Hampton Roads Agricultural Research Center 1444 Diamond Springs Rd. Virginia Beach, VA 23455 (757) 363-3912 Email: jderr@vt.edu

Virginia Tech 435 Old Glade Rd. Blacksburg, VA 24061 (540) 231-9598 Email: dsmccall@vt.edu

December 11–13

Erik H. Ervin, Ph.D.

Fredericksburg, VA

Virginia Tech 335 Smyth Hall, CSES Dept.

Blacksburg, VA 24061 (540) 231-5208 Email: ervin@vt.edu

Galt House Hotel and Kentucky Expo Center Louisville, KY ASLA – Annual Meeting & Expo

Virginia Tech’s Turfgrass Short Course

January 27–30, 2014

Roger R. Youngman, Ph.D.

Virginia Tech 216A Price Hall, MC 0319 Blacksburg, VA 24061 (540) 231-9118 Email: youngman@vt.edu

VTC 54th Annual Turf & Landscape Conference and Trade Show

Fredericksburg Expo & Conference Center Fredericksburg, VA

October 23–25

PLANET Green Industry Conference

Louisville, KY

Index of Advertisers Agriguard . ................................................. 15 Alliance Material Handling, INC.............. 19 www.alliancemat.com Aqua-Aid, Inc.............................................. 17 www.aquaaid.com BASF............................................................. 3 www.basf.com Bayer............................................................. 5 www.bayerprocentral.com Buy Sod.............................Inside Back Cover www.buysod.com Collins Wharf Sod Farm............................ 29 www.collinswharfsod.com Colonial Farm Credit................................. 30 www.colonialfarmcredit.com

Egypt Farms Inc......................................... 13 www.egyptfarms.com Gowan Company.................................. 19, 27 www.gowanco.com Kesmac Inc.................................. Back Cover www.kesmac.com Landmark Turf & Native Seed................... 3 Leading Edge Communications................ 11 www.LeadingEdgeCommunications.com Luck Stone Corporation............................ 13 www.luckstone.com Mid Atlantic Sports Turf........................... 17 Modern Turf, Inc....................................... 29 www.modernturf.com

30 | Virginia Turfgrass Journal May/June 2013 www.vaturf.org

Oakwood Sod Farm, Inc........................... 11 www.oakwoodsod.com RBB Sales & Consulting, Inc.................... 27 www.rbbturflandscapeconsultants.com Riverside Turf........................... Inside Front www.riversideturf.com Southern States Cooperative....................... 9 www.southernstates.com The Turfgrass Group............................ 7, 25 www.theturfgrassgroup.com Virginia Valley Water Systems................... 23 Winfield Solutions, LLC............................ 29 Woodward Turf Farms Inc........................ 19 www.woodwardturf.com