Virginia Turfgrass Council / P.O. Box 5989 / Virginia Beach, VA 23471 / ADDRESS SERVICE REQUESTED
Journal of the Virginia Turfgrass Council | May/June 2012
Eighth ANNUAL DIGEST OF TURFGRASS RESEARCH IN VIRGINIA Research Articles 10 Water Quality Monitoring on Golf Courses 12 F all Fertilization, Traffic Tolerance and Recovery of Sprigged Bermudagrasses 14 Dormant Seeding of Zoysiagrass 15 P oa annua Suppression in Creeping Bentgrass Putting Greens 16 P reemergence and Postemergence Weed Control with Specticle 20 P reemergence Crabgrass Control with Split versus Single Applications 22 Sweet Vernalgrass Control 24 T esting of the Wisconsin GDD Model for Scheduling PGRs on Bermudagrass 26 E arly Detection of Stress on Annual Bluegrass on Putting Greens 27 Portable Turf Protection Panels 28 E fficacy of Selected Soil Insecticides Against White Grubs in Turf
Departments 6 President’s Message from Frank Flannagan 8 Director’s Corner from Tom Tracy, Ph.D. 29 Contact Information for VT Researchers 30 Calendar of Events 30 Index of Advertisers 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 ©2012 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.)
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 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 Steve Slominski 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
President’s Cover Message Story
Little Things Can Cost
— or Save — a Lot Frank Flannagan 2012–2013 VTC President
How
do we manage during these economic downturns? Do we continue to manage as we did before the economy went south? Do we hold the line and wait for better times? This is the perfect time to evaluate and increase the efficiency of your operation. Time spent accounting for the necessity of all expenditures can add up to significant cost savings. Whatever your decision, first and foremost make sure that your staff understands the plan and that your plan is flexible enough to withstand change as you go through the season. The following questions are what we used to eliminate wasteful spending in our operation. To date, several thousand dollars have been saved, and we are still digging. Some of the things we looked at in our operation were contracts. Are we being charged the price we agreed upon at the time we entered the contract? Are vendors adding surcharges for fuel, handling and even environmental fees? Do you have ongoing contracts that are not reviewed for long periods? How many times do you just sign the picking ticket and never see the actual bill before payment? Are you required to review invoices and sign the actual bill to verify to your general manager or accountant that you received the correct quantity ordered? As a manager, it is your responsibility to make sure that your employer (or you as a business owner) receives exactly what you are being asked to pay for. Do you allow employees to borrow equipment or take products for their personal use? Who is responsible for the repairs if the equipment breaks down before it is returned to your site? Do you allow employees to be paid extra time when they did not earn the time? What about those long lunch breaks or those extra stops between job sites? Do employees verify their overtime hours and document the reasons why they had overtime? What about equipment use? Does your staff allow equipment to sit idling for long periods, burning fuel that could be used cutting fairways or lawns? Everyone works under different circumstances, but during these tough times, we (as managers) should look at our operation and see how we can continue to provide the level of service that is expected in the most costefficient way possible. While these measures are necessary now to help make ends meet, when the economy improves, these savings can be used for upgrades, capital improvements or rewards for the employees who stuck with us during the lean times. c
6 | Virginia Turfgrass Journal May/June 2012 www.vaturf.org
Director’s Cover Corner Story
VTC Members Taking the Lead in Virginia’s Turfgrass Industry
A Tom Tracy, Ph.D. VTC Executive Director
recognized writer (whose books we all read in introductory literature classes) said of his works, “If I could fasten the mind of the reader… so firmly that he would forget words and be conscious only of his response, I felt that I would be in sight of knowing how to write… I strove to master words, to make them disappear.” This writer focused on the reaction of the reader, and he measured success by that reaction. The goal of an association’s executive director is similar to this writer’s goal. I am successful if I disappear into the background and turfgrass professionals across the state take ownership of our shared mission, which is to unify efforts to promote turfgrass improvement and to advance the turfgrass industry in the Commonwealth of Virginia. For any association to be successful, two critical roles must be filled. The director should work so as to appear only in the background, and members of the association should be in the forefront, setting policy, establishing direction and conducting key tasks. How is the VTC doing in fulfilling these two roles? I am not qualified to discuss my success in the former, but I can speak at length on the accomplishments of our members. Here is a snapshot of 4 meetings that happened in 26 hours during February. As you look at the meetings, you will see turfgrass industry professionals taking key leadership roles.
Meeting One
Time and Date: 11:00 a.m. on Thursday, February 16 Location: Laurel Hill Golf Course Purpose: Evaluate the 2012 Conference and make plans for the next one Meeting Host: superintendent Rick Owens
Meeting Two
Time and Date: 9:00 a.m. on Friday, February 17 Location: Spring Creek Golf Club Purpose: Plan the 2013 Virginia Turfgrass Foundation Golf Tournament Meeting Hosts: superintendent Brian Vincel and Marc Petrus
Meeting Three
Time and Date: 11:30 a.m. on Friday, February 17 Location: Virginia Green’s facility Purpose: Examine legislative issues that affect the turfgrass industry Meeting Host: Gil Grattan
Meeting Four
Time and Date: 1:00 p.m. on Friday, February 17 Location: Belmont Golf Course Purpose: Plan roles and responsibilities for the VTC’s board of directors Meeting Host: superintendent and VTC president Frank Flannagan
Virginia’s turfgrass industry — golf courses, sports fields, home and commercial turf, parks and recreation, sod producers and environmental areas — is strong and growing because professionals across the state are seeing themselves as part of its future. Instead of relying on one, or even a few, people to lead the proverbial charge, turfgrass professionals are meeting with legislators, speaking with local leaders, acquiring certifications that are above and beyond what is required, practicing scientific agronomic management and volunteering hours working on the nuts and bolts of the VTC. Our growth as an industry is assured because of the work of these professionals. c 8 | Virginia Turfgrass Journal May/June 2012 www.vaturf.org
Research Cover Articles Story
Water Quality Monitoring on Virginia Golf Courses
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 & Environmental Conservation; Chantel Wilson, Ph.D. Candidate, Crop & Soil Environmental Sciences Dept.; and Mike Goatley Jr., Ph.D., Extension Turfgrass Specialist and Professor, 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
With
the VGCSA’s recent publication of “Environmental Best Management Practices (BMPs) for Virginia’s Golf Courses,” we have begun the ground-truthing 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 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 groundtruthing through rigorous monitoring of water-quality parameters, both before and after implementation of BMPs. Six Virginia golf courses located within the watershed have been selected as test sites, with sample locations identified to monitor water quality (primarily nitrate and phosphate) flowing into and out of each golf course. One year (2011) of monitoring has been completed, and we have received national and state GCSA support to continue the project.
Results for 2011
Two golf courses (D and F) had average NO3 levels greater than 1 ppm in exiting streams in 2011. However, these levels were far below the EPA drinking water quality standard of 10 ppm. Based on these slightly elevated levels, implementation of more rigorous BMP practices along these two streams will be considered for 2012. Only course A had PO4 levels above the EPA suggested limit of 0.05 ppm. Thus, our 2012 focus for course A will be on implementation of BMPs to achieve slight reductions in phosphorus runoff. c
Average (over four monitoring months) nitrate and phosphate concentrations found in streams flowing into and out of six bay watershed golf courses are listed in Table 1. Nitrate (NO3) and phosphate (PO4) are the nutrients of concern in terms of causing algal blooms, oxygen deprivation and subsequent health decline of aquatic organisms (i.e., eutrophication). NO3 levels of 1 ppm or greater are an indication of concern for increased algal growth, while PO4 levels above 0.05 ppm indicate greater overall potential for eutrophication.
Table 1. Pre-BMP implementation (2011) nitrate and soluble phosphorus (ppm) in streams coming into and going out of six Chesapeake Bay watershed golf courses. Data presented are averages over the whole monitoring year.
Stream In NO3#
Stream Out
PO4*
Golf Course
NO3
PO4
ppm or mg L-1
A
0.08
0.14
0.15
0.15
B
0.05
0.01
0.05
0.02
C
0.75
0.01
0.55
0.01
D
0.79
0.02
3.35
0.02
E
0.23
0.01
0.14
0.01
F
1.35
0.01
2.86
0.01
# EPA limit for safe drinking water is 10 ppm NO ; EPA water quality criterion for reducing 3
the risk of increased algal growth in water bodies is 1 ppm NO3. * EPA suggested water quality criterion to limit stream eutrophication is 0.05 ppm PO4.
10 | Virginia Turfgrass Journal May/June 2012 www.vaturf.org
Research Articles continued
Influence of Fall Fertilization Programs on the Traffic Tolerance and Recovery of Sprigged Bermudagrass Varieties
Virginia Tech Researchers: Eric Reasor, Undergraduate Student; Mike Goatley Jr., Ph.D., Extension Turfgrass Specialist and Professor; Whitnee Askew, Research Technician; Shawn D. Askew, Ph.D., Associate Professor, Turfgrass Weed Science; and David McCall, Research Specialist (Departments of Crop & Soil Environmental Sciences and Plant Pathology, Physiology & Weed Science)
Many
athletic fields in the transition zone are established with bermudagrass because of its ability to withstand heavy traffic, as well as its rapid growth rate and high density. However, the ability to withstand heavy traffic during the first year of establishment is challenging due to the onset of winter dormancy in mid-fall of a typical football season. Foot traffic from athletes, along with overseeding competition, can limit first-winter bermudagrass survival. This research evaluated how lateseason nitrogen applications affected fall traffic tolerance and the quality of newly established bermudagrass, as well as spring greening and recovery.
Our research
We began our research in June 2010 at Virginia Tech’s Turfgrass Research Center. On June 18, research plots were established by sprigging shredded sod of three bermudagrass cultivars: ‘Patriot’, ‘Riviera’ and ‘Wayland’. ‘Patriot’ and ‘Riviera’ are both commercially available cultivars, while ‘Wayland’ is an experimental ecotype selected at Virginia Tech for its rapid spring greening and spring dead spot tolerance. At the time of planting, nitrogen was applied at 1 lb. N/1,000
ft2. Irrigation was applied to promote active growth, and the plots were mowed three times weekly at 1-1/4". Additional nitrogen was applied to all plots at 1 lb. N/1,000 ft2 per month in July and August. The fall fertilization treatments extended nitrogen applications into September and October. September fertilization was 1 lb. N/1,000 ft2, totaling 4 lbs. of nitrogen for the growing entire season. The October 2010 treatment received only 1/2 lb. N/1,000 ft2 due to a dormancy-inducing frost in the middle of the month. The July, August, September and October nitrogen fertilization treatments were all made on the first day of each month. Beginning on August 30 and ending on November 7, simulated traffic
12 | Virginia Turfgrass Journal May/June 2012 www.vaturf.org
(using a Brinkman traffic simulator) was applied at six events per week, serving as a typical fall football schedule. Ratings of visual coverage, quality and density were taken on October 18 and November 1. Visual quality, percent green cover and percent bare-ground ratings were taken in spring 2011.
Results to date
On July 2, only two weeks after planting, ‘Patriot’ achieved 50% coverage, whereas ‘Riviera’ and ‘Wayland’ had 37.5% and 23.8% coverage respectively (data not shown). On July 22, ‘Patriot’ coverage was 97.5%, ‘Riviera’ increased to 85%, and ‘Wayland’ was 72.5%. All grasses reached 95% or greater coverage by August 6, with Patriot covering the quickest, followed by ‘Riviera’, then ‘Wayland’. The more rapid establishment rate of ‘Patriot’ gives it an advantage over the other two varieties because ‘Patriot’ has a thicker canopy by the time fall traffic begins. This was supported by visual percent coverage ratings taken on October 18 (six weeks after the initial traffic treat-
Research Articles continued
ment), where ‘Patriot’ had approximately 76% cover, ‘Riviera’ had 73% cover, and ‘Wayland’ had 67% (data not shown). The vegetative establishment with ‘Patriot’ tolerated more traffic in its first growing season, suggesting it would be an excellent choice for high-use fields during the fall football season. The greater traffic tolerance of ‘Patriot’ compared to the other grasses is further supported by visual percent bare-ground ratings prior to spring green-up. Data taken on April 12 (not shown) indicated that ‘Patriot’ had significantly less bare ground than ‘Riviera’ and ‘Wayland’, which both had greater than 30% bare ground. ‘Wayland’ and ‘Riviera’, however, demonstrated quicker spring greening than ‘Patriot’. The fall fertilization treatments of N applications ending in August, September or October provided similar visual coverage ratings across the three grasses; therefore, these data are averaged across the varieties in Table 1. On October 18 and November 1 (approximately six and eight weeks after traffic initiation), percent coverage ratings of trafficked plots receiving N through
either September or October were significantly greater than plots fertilized only through August. Extended fertilization provided benefits that persisted beyond the current season. Spring turf density was also increased from fall nitrogen applications due to the significantly lower bare-ground percentages in early spring (data not shown). Plots fertilized through September or October had approximately 27% bare ground, as compared to 34% bare-ground ratings for plots where N fertilization ended in August. The lower bare-ground ratings of fall fertilization will also lead to faster spring green-up and recovery, allowing for more time of lateral growth to increase traffic tolerance for the upcoming sports season.
coverage and improved quality in trafficked plots. • October fertility responses tended to be slightly higher than September but were not statistically different. The fall fertilization also decreased bareground ratings in early spring and accelerated spring green-up. • In general, varietal traffic tolerance ratings suggest that ‘Patriot’ > ‘Riviera’ > ‘Wayland’ for firstseason traffic tolerance. c
Conclusions
These trials are being repeated, but the following preliminary observations have been made. • Establishment is faster with ‘Patriot’ bermudagrass than with ‘Riviera’ or ‘Wayland’. • Extending nitrogen fertilization treatments into September and October increased grass
Above: ‘Patriot’ and ‘Riviera’ bermudagrass density in trafficked and non-trafficked plots that received monthly N fertilization treatments through August (A), September (S) or October (O).
Table 1: Visual percent coverage ratings of three bermudagrasses as influenced by traffic and fall N fertilization programs.
Bermudagrass Cover ------------Oct. 18, 2010------------
-------------Nov. 1, 2010--------------
A
S
O
LSD
A
S
O
LSD
Traffic
67.1% b *
73.0% a *
75.4% a *
2.9
70.8% b *
77.5% a *
77.5% a *
2.9
No Traffic
100
100
100
—
100
100
100
—
A = N fertilization ended in August, total of 3 lb. N/1,000 ft2 for the season. S = N fertilization ended in September, total of 4 lb. N/1,000 ft2 for the season. O = N fertilization ended in October, total of 4.5 lb. N/1,000 ft2 for the season. Means within the same row and measurement date followed by the same letter are not significantly different at p = 0.05. Means within the same column and measurement date separated by a * are significantly different at p = 0.05.
Journal of the Virginia Turfgrass Council
| 13
Research Articles continued
Dormant Seeding of Zoysiagrass Virginia Tech Researchers: Mike Goatley Jr., Ph.D., Extension Turfgrass Specialist and Professor; Whitnee Askew, Research Technician; and Eric Reasor, Undergraduate Student, Crop & Soil Environmental Sciences Dept. Research Sponsors: Patten Seed and Seed Research of Oregon
One
of the biggest challenges facing the use of seeded zoysiagrasses as a low-input, high-density turfgrass is its very slow establishment rate. Research at the University of Arkansas, published in 2006, demonstrated the potential for dormant seeding of bermudagrass. Could the same principle apply to seeded zoysiagrasses?
Our research
Each month from February 2011 through June 2011, we applied the seeds of two cultivars of zoysiagrass (‘Compadre’ and ‘Zenith’) at two seeding rates (1 and 2 lbs. of pure live seed per 1,000 ft2) on research plots at the Turfgrass Research Center. The existing stand of cool-season grass (perennial ryegrass) in the plots was treated 1 to 2 weeks prior to each monthly seeding date with glyphosate at 3 lbs. ai/A, and the plots were scarified with a power rake prior to seeding. Weed control treatments of 0.013 lb. ai/A foramsulfuron + 0.25 lb. ai/A quinclorac (primarily for intense pressure from crabgrass and goosegrass) were applied on June 24, July 9, July 20 and August 5. The plots received 1 lb. of N/1,000 ft2 (19-19-19) on July 1. Two times a week during periods of active growth, the plots were mowed to 1-1/2" with a rotary mower. No supplemental irrigation was applied. Germination (across all cultivars and seeding rates) was observed on April 26 for Feb. seeded plots, on May 30 for March seedings, on June 6 for April seedings, on June 16 for May seedings, and July 12 for June seedings.
Preliminary results
• There were no consistent statistical differences in germination or establishment rates between cultivars or seeding rates. Obvious differences in % zoysiagrass cover between seeding dates was observed (see photo and Table 1). Glyphosate control of existing coolseason grass was poor in March-treated plots and likely contributed to reduced stand establishment compared to February and April seedings. • “Dormant seedings” are demonstrating early establishment success compared to traditional timing approaches under minimal input (zero to low irrigation and fertility), but regularly scheduled weed control is critical for success. c
Zoysiagrass coverage on September 13, 2001, as indicated in plots marked by seeding month, variety (C = ‘Compadre’, Z = ‘Zenith’) and seeding rate (1 or 2 lbs. of pure live seed per 1,000 ft2).
Table 1. Visual estimations of % zoysiagrass in varying monthly seeding establishments of ‘Compadre’ and ‘Zenith’ cultivars of zoysiagrass.
Zoysiagrass Coverage Seeding Month
July 1
July 18
Aug. 2
Aug. 30
Sept. 13
Oct. 12
February
28.1% a
37.2% b
54.1% a
68.4% b
76.9% b
76.6% b
March
22.2% b
30.2% c
44.1% b
62.8% b
74.1% b
75.6% bc
April
30.6% a
47.2% a
61.3% a
83.1% a
91.6% a
91.0% a
May
9.4% c
21.7% d
33.1% c
57.5% b
67.2% b
67.2% c
June
0.0% d
1.5% e
4.2% d
12.6% c
17.3% c
16.6% d
Means followed by the same letter are not significantly different according to Student’s t-test at a p value of 0.05. 14 | Virginia Turfgrass Journal May/June 2012 www.vaturf.org
continued Research Articles
Poa annua Suppression in Creeping Bentgrass Putting Greens…
An Integrated Nutritional and Chemical Approach Virginia Tech Researchers: Nate Reams, M.S. Student, and Erik Ervin, Ph.D., Professor, Crop & Soil Environmental Sciences Dept. Sponsor: Virginia Agricultural Experiment Station
Poa
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. Acid pH (<5.5) is known to favor desirable Agrostis and Festuca species relative to Poa. Another component of this nutritional approach is to not apply P or K, as they are also 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 study their effects on Poa annua populations in a creeping bentgrass putting green over time.
Our research
The trial is on a mature (over 25 years old), sand-based putting green, originally seeded with ‘Penneagle’ creeping
bentgrass. The green was mowed five times per week at 0.125", with clippings collected. The Fe treatments were split with a generic seaweed extract (SWE) or paclobutrazol (PAC) to determine any additive effects on Poa suppression. FeSO4 rates were 0, 0.25 lb./M, 0.50 lb./M and 1.0 lb./M, applied to the foliage every two weeks from March through November 2011. Main FeSO4 plots were split by SWE (4 oz./M) or PAC (16 oz./A spring/ fall or 8 oz./A summer) on the same application schedule. Nitrogen was supplied to all plots uniformly via ammonium sulfate at 1.8 lbs. N/M/yr. No P or K was applied.
Results to date
One year of frequently applied high rates of FeSO4 have resulted in considerable reductions in Poa annua, dollar spot pressure and moss invasion (Table 1). These reductions do not appear to be related to reductions in soil pH or P-availability (data not shown). Perhaps the reductions are due to the desiccating effects of the treatments, 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
Table 1. Percent Poa annua, visual color ratings, dollar spot and moss counts within a creeping bentgrass putting green as affected by FeSO4 and PGR treatments.
FeSO4 (lb./M)
PGR
Poa % May 2011
Poa % Nov 2011
Color 2011 Av. 9 = best
Dollar spot infection centers
Moss colony centers
0
PAC
13.8% def
0.0% cd
6.5 e
28.3bcde
34.3a
0
SWE
36.3% ab
36.3% ab
6.0 f
45.3bcd
6.3cd
0
Control
42.5% a
46.3% a
5.9 f
89.0a
8.0cd
0.25
PAC
8.0% f
16.3% cde
7.4 b
21.0cde
32.5a
0.25
SWE
31.3% abc
25.0% bcd
6.7 cde
60.3ab
10.3bc
0.25
Control
26.3% bcd
28.8% bc
6.6 de
55.0abc
8.8cd
0.50
PAC
10.0% bcde
3.5% e
7.9 a
6.5e
19.0b
2.44
SWE
28.8% abc
20.0% cd
7.0 c
34.0bcde
0.8cd
2.44
Control
27.5% bcd
22.5% bcd
6.9 cd
31.8bcde
0.8cd
4.88
PAC
7.3% f
4.3% e
8.0 a
2.5e
4.5cd
4.88
SWE
17.5% cdef
11.3% de
7.4 b
16.0de
0.1d
Control
23.8% bcde
18.8% cd
7.5 b
15.3de
0.5cd
LSD 0.05
14.9
14.1
0.3
38.0
10.1
4.88
Journal of the Virginia Turfgrass Council
| 15
Research Articles continued
Cover Story
Preemergence and Postemergence Weed Control with Specticle Virginia Tech Researchers: Jeffrey F. Derr, Ph.D., Professor of Weed Science, and Adam E. Nichols, Research Assistant, Hampton Roads Agricultural Research and Extension Center, Virginia Beach Sponsors: The Virginia Turfgrass Foundation, The Virginia Agriculture Council and Bayer
S
pecticle is the newest preemergence herbicide developed for use in bermudagrass turf. It contains the active ingredient indaziflam, which has a different mode of action — inhibition of cellulose biosynthesis — compared to other preemergence herbicides used for crabgrass control. Therefore, in addition to being an effective crabgrass preventer, Specticle also has a place in herbicide rotation programs to limit the development of resistance.
Our research
Over the past two years, we have evaluated single applications, as well as split applications, of Specticle in established stands of ‘Tifsport’, ‘Savannah’ and ‘Yukon’ bermudagrass. In our single-application trials, we covered the rate range for Specticle, from 2.5 ounces product per acre (0.031 lb. active ingredient/acre) to
5 ounces product (0.0062 lb. ai/A). We made our applications in early March for both years. In 2010 and 2011, we also compared a single application of Specticle in March at 4.4 ounces product per acre (0.05 lb. ai/A) to two applications of 2.2 ounces product per acre (0.025. lb ai/A) applied 2 months apart (March and May). Finally, we wanted to evaluate postemergence control of annual bluegrass (Poa annua), since there had been reports that Specticle could control this weed after emergence. We conducted this trial in March 2011 with well-established annual bluegrass.
Research results
In 2010, we observed excellent control with all single-applications rates in June (Table 1). When we evaluated the plots in July and September, crabgrass cover had decreased as the Specticle rate
increased. Crabgrass cover with the middle rate of Specticle was similar to that seen with Ronstar 2G, while the highest rate gave similar control as Barricade. In 2011, we observed excellent postemergence control of both Persian and corn speedwell with all singleapplication rates of Specticle (Table 2). Speedwells can be difficult to control. Even in September, preemergence crabgrass control with Specticle was excellent with all three rates in 2011. When comparing single applications to split applications, the two programs gave similar crabgrass control in 2010, while the split application tended to give better control in 2011. In our annual bluegrass trial, Specticle reduced the stand and flower production of this weed, although acceptable control was observed only at the highest rate (5 oz. product per acre), and it took over a month to
Table 1. Preemergence crabgrass control with Specticle in 2010.
SOUTHERN CRABGRASS Rate lb. ai./A
6/17/2010 % Control 84 DAT*
7/20/2010 % Cover 117 DAT *
9/2/2010 % Cover 161 DAT*
0%
51%
83%
Specticle 20WP
0.031
92%
19%
39%
Specticle 20WP
0.047
96%
12%
23%
Treatment Untreated
Specticle 20WP
0.062
98%
5%
11%
Barricade 65 WDG
0.75
99%
6%
9%
Ronstar 2G
3.0
97%
10%
19%
6
17
23
LSD (P=.05) * DAT = Days After Treatment
16 | Virginia Turfgrass Journal May/June 2012 www.vaturf.org
Research Articles continued
achieve that level of control (Table 3, next page). Monument was the most effective herbicide in this trial. We made only a single application of each herbicide. Making a second application would probably have improved the control seen with Velocity or the other treatments. Specticle gave partial control of henbit at all rates tested.
Summary
Specticle provides long-term preemergence control of crabgrass, similar to that seen with Barricade and Ronstar. It will also control emerged speedwell, as well as suppress other emerged weeds, such as henbit and annual bluegrass. It is therefore best used as a preemergence herbicide, but it could be used with postemergence products for broader-spectrum control of emerged weeds. c
Table 2. Postemergence control of Persian and corn speedwell, and preemergence control of crabgrass with Specticle in 2011.
Corn Persian Speedwell Speedwell
Treatment Rate lb. ai./A Untreated
Southern Crabgrass
4/26/11 % Cover 40 DAT*
4/26/11 % Cover 40 DAT*
6/20/11 % Cover 95 DAT*
7/15/11 % Cover 120 DAT*
9/5/11 % Cover 172DAT*
43%
9%
23%
53%
86%
Specticle
0.031
0%
0%
1%
3%
8%
Specticle
0.047
0%
0%
1%
2%
4%
Specticle
0.062
0%
0%
1%
4%
9%
Barricade
0.75
26%
6%
0%
2%
4%
Ronstar
3.0
19%
6%
0%
2%
6%
15
4
4
7
11
LSD (P=.05)
* DAT = Days After Treatment
Journal of the Virginia Turfgrass Council
| 17
Research Articles continued
Cover Story
Table 3. Postemergence annual bluegrass (Poa annua) control with Specticle.
Treatment
Rate lb. ai./A
Untreated
Henbit
Annual bluegrass
Annual bluegrass
Annual bluegrass
4/12/11 % Control 26 DAT*
4/12/11 % Control 26 DAT*
4/12/11 Seedhead 26 DAT*
4/28/11 % Cover 42 DAT*
15%
0%
8.5
63%
Specticle
0.031
33%
18%
8.0
39%
Specticle
0.047
53%
18%
6.8
35%
Specticle
0.063
50%
18%
6.8
35%
Celsius
0.106
75%
33%
4.0
24%
Celsius
0.208
73%
50%
2.5
17%
Velocity
0.033
53%
8%
8.0
43%
Velocity
0.066
65%
15%
7.0
40%
Monument
0.025
75%
50%
2.0
1%
18
11
1.2
13
LSD (P=.05)
Seedhead ratings: 1 = no seedheads; 10 = plot covered in seedheads. * DAT = Days After Treatment
18 | Virginia Turfgrass Journal May/June 2012 www.vaturf.org
Research Articles continued
Cover Story
Preemergence Crabgrass Control
with Split versus Single Applications in Tall Fescue Virginia Tech Researchers: Jeffrey F. Derr, Ph.D., Professor of Weed Science, and Adam E. Nichols, Research Assistant, Hampton Roads Agricultural Research and Extension Center, Virginia Beach Sponsors: The Virginia Turfgrass Foundation and The Virginia Agriculture Council
T
hree species of crabgrass can infest turfgrass in Virginia: smooth, large and southern. All three species are summer annuals, starting to germinate generally in mid-March to early April in southeastern Virginia. Although we tend to focus on the onset of crabgrass germination, we must also consider the long germination period for this group of weeds. Our long growing
season in Virginia is beneficial for crop production, but it also allows for extended crabgrass germination. In southeastern Virginia, crabgrass may germinate over a five-month period, from March into August. Most of our crabgrass preventers, however, provide only about three months of control, with late-season germination resulting in crabgrass infestations in July and August. The
use of split herbicide applications may address the mid- to late-germination period.
Our research
Our trials compared Tenacity (mesotrione), Barricade (prodiamine), Pendulum AquaCap (pendimethalin) and Dimension (dithiopyr) applied in single versus split applications. We applied each product at what we
Table 1. Preemergence crabgrass control in tall fescue with single and split applications in 2011.
SOUTHERN CRABGRASS COVER Treatment
Rate in lb. ai/A
Untreated
6/20/11 103 DAT 40 DAT2
7/19/11 132 DAT 69 DAT2
9/8/11 183 DAT 120 DAT2
2%
21%
84%
Tenacity
0.125
5%
33%
77%
Tenacity
0.25
5%
40%
91%
Tenacity + Tenacity
0.125 0.125
3%
35%
75%
Barricade 65 WDG
0.75
0%
1%
2%
Barricade + Barricade 65 WDG
0.38 0.38
0%
0%
2%
Pendulum AquaCap
3.0
0%
3%
29%
Pendulum AquaCap + Pendulum AquaCap
1.5 1.5
0%
0%
7%
Dimension 2EW
0.5
1%
9%
35%
Dimension 2EW + Dimension 2EW
0.25 0.25
0%
1%
23%
1
16
21
LSD (P=.05)
DAT = days after the first application DAT2 = days after the second application (for the split application treatments) 20 | Virginia Turfgrass Journal May/June 2012 www.vaturf.org
considered a standard single rate and compared that to splitting that rate into two applications spaced two months apart. Our single rates, in early March, in pounds active ingredient per acre (lb. ai/A), were: • Barricade 65 WDG 0.75 • Dimension 2EW 0.5 • Pendulum AquaCap 3.0 • Tenacity 0.25 Our split applications were applied at the same time in early March, with a second application in May: • Barricade 0.38 + 0.38 • Dimension 0.25 + 0.25 • Pendulum AquaCap 1.5 + 1.5 • Tenacity 0.125 + 0.125
Research results
Table 1 shows the results from the 2011 trial. None of the single or split applications of Tenacity provided acceptable preemergence crabgrass control in July. Tenacity probably has a better fit as a postemergence product or a short-term residual material similar to the uses for Drive. Barricade gave similar crabgrass control in July and September from both single and split applications in both 2010 and 2011. Pendulum AquaCap and Dimension 2EW tended to give better crabgrass control late in the season from split applications, compared to single applications. The benefits of split applications of crabgrass herbicides may depend on the specific herbicide being used. The peak for crabgrass germination may vary from year to year, depending on temperature and rainfall patterns. In 2011, dense crabgrass populations were not observed until July and August, explaining why a split application resulted in better control for certain herbicides. Environmental conditions, especially rainfall amounts, may also affect the benefits seen with split applications, since herbicide longevity is directly impacted by rainfall amounts. c
Research Articles continued
Cover Story
Sweet Vernalgrass Control in Cool-Season Turf
Virginia Tech Researchers: Adam Smith, Graduate Student, and Shawn D. Askew, Ph.D., Associate Professor, Turfgrass Weed Science, Plant Pathology, Physiology & Weed Science Dept. Research Cooperators: Brookmeade Sod Farm, Inc.
S
weet vernalgrass (Anthoxanthum odoratum) is a new weed concern in Virginia for cool-season turfgrass. A perennial grass weed that can easily adapt to new environments, it is highly competitive in the spring due to its rapid growth, early flowering and potential allelopathic suppression (of desirable turf). Its light green color also decreases turf aesthetics. In recent years, sod producers, homeowners and golf course superintendents have seen an influx in sweet vernalgrass. Additionally, the Virginia Tech Weed Clinic, which identifies and provides control recommendations to individuals who send in weed samples, has documented a drastic increase in the number of sweet vernalgrass samples being submitted. Herbicides are typically the most realistic option for controlling perennial weeds in established turf. Unfortunately,
Photo 1: Mature sweet vernalgrass with seedhead.
control options for sweet vernalgrass in turfgrass are unknown due to a lack of research studies. The objectives of this research are to determine sweet vernalgrass control options with herbicides in cool-season turf with minimal turf injury. Experiments explored herbicide efficacy, rate and timing recommendations for sweet vernalgrass control for the purposes of maximizing herbicide sustainability and turf health.
Our research
We established our field studies on a commercial sod farm in Richmond, Virginia, in mature tall fescue turfgrass infested with sweet vernalgrass. Eight herbicide treatments were applied two different sweet vernalgrass growth stages: at plant emergence and at 2to 3-tiller growth stages. Treatments included mesotrione, fenoxaprop, ambicarbazone, quinclorac, MSMA, methiozolin and sulfentrazone. These herbicides reflect multiple herbicide modes of action, including ACCase
inhibitors, PPO inhibitors, HPPD inhibitors, synthetic auxins and photosystem II inhibitors.
Preliminary results
Preliminary results suggest that mesotrione may be the only option for sweet vernalgrass control (Photo 2 and Figures 1 and 2), since the EPA has cancelled all agricultural uses of MSMA (including turfgrass). Results also suggest that there may be a differential rate need for mesotrione based on application timing. Sequential applications of mesotrione may be required if control regimens are initiated at plant emergence, and a single application may be needed if control regimes are initiated at the 2to 3-tiller growth stage (Photos 1 and 2). Research currently underway will confirm this differential rate need. Understanding how mesotrione application timing and plant growth stages may affect herbicide rate need will provide important information that will lead to sustainable and economical use of mesotrione. c
Photo 2: Mesotrione (right) control at 71 DAT, compared to a non-treated check (left).
22 | Virginia Turfgrass Journal May/June 2012 www.vaturf.org
Research Articles continued
Figure 1: Sweet vernalgrass control in 2010 at 34 and 71 days after treatment (DAT).
NTC = non-treated control MSMA = MSMA Meso1 = mesotrione (single application at 2- to 3-tiller growth stage) Meso2 = mesotrione (sequential application at weed emergence)
Fen = fenaprop Quin = quincloraq Ami = ambicarbazone Meth = methiozolin Sulf = sulfentrazone
Figure 2: Sweet vernalgrass control in 2011 at 36 and 71 DAT.
NTC = non-treated control MSMA = MSMA Meso1 = mesotrione (single application at 2- to 3-tiller growth stage) Meso2 = mesotrione (sequential application at weed emergence)
Fen = fenaprop Quin = quincloraq Ami = ambicarbazone Meth = methiozolin Sulf = sulfentrazone
Journal of the Virginia Turfgrass Council
| 23
Research Articles continued
Cover Story
Testing of the Wisconsin GDD Model for Scheduling Plant Growth Regulator Applications on Bermudagrass in Virginia
Virginia Tech Researchers: Erik Ervin, Ph.D., Professor of Turfgrass Culture & Physiology; Xunzhong Zhang, Research Assistant Professor; Frederick Shepherd, Research Technician; Derek Cataldi and John Royse, Graduate Research Assistants; and Allan Zhang, Undergraduate Research Assistant, Crop & Soil Environmental Sciences Dept Sponsors: Virginia Agricultural Research Station
C
ommonly used plant growth regulators (PGRs) for reducing clipping yields — such as Primo Maxx (trinexapac-ethyl), Cutless (flurprimidol) or their combination, Legacy — often do not last the full four weeks when the label rate is applied. As temperatures increase, plant metabolism (or breakdown) of these PGRs occurs faster, often resulting in less than two weeks of suppression and more clippings than from untreated areas (the “rebound” effect). This phenomenon has been documented to occur to a greater extent on coolseason grasses maintained at low mowing heights (e.g., putting greens). To confront this issue, researchers at the University of Wisconsin developed
and tested a growing degree day (GDD) base 0˚C model for PGR applications on putting greens and fairways. Their results indicated that PGR re-applications every 200 GDDs are required to provide consistent clipping yield suppression throughout the growing season. Use of this 200 GDDs base 0˚C spray trigger resulted in the need to apply the four-week label rates of Primo (0.125 oz./M) every 5 to 12 days in Wisconsin. Our objective was to determine the applicability of their model on low-cut bermudagrass cultivars in Virginia.
Our research
Mature stands of ‘Patriot’ and ‘Tifway419’ hybrid bermudagrasses maintained
at a 1/2" cutting height and fertilized with 0.5 lb. N/M (May through September) were used in this 2011 study. Irrigation was applied as needed to prevent wilt. PGRs tested were: • Primo Maxx (at 2 rates: 0.125 oz./M and 0.25 oz./M) • Cutless MEC (0.25 oz./M) • Legacy (0.25 oz./M) Each PGR was applied based on the following triggers: 200, 400, or 600 GDDs. A GDD was defined as the daily high temperature + the daily low temperature in ˚C, divided by 2 (or average daily temperature), minus a base temperature of 0˚C. The values were taken from the weather.com site (under Farming) for the Blacksburg area code (24060). Based on the
Figure 2. Clipping reduction (%) as influenced by Legacy and Cutless MEC at 200, 400 and 600 GDDs in ‘Tifway’ bermudagrass.
Figure 1. Example of GDD calculator from weather.com.
24 | Virginia Turfgrass Journal May/June 2012 www.vaturf.org
continued Research Articles
example from the website for June 1 to 9, 2011 (Figure 1), if the last application of the 200 GDDs treatment was on June 1, then the next should be on June 10. This model does not work if you try to use a base of 32Ë&#x161;F instead of 0Ë&#x161;C, since the GDD units accumulate too quickly. PGR applications were made from May 15 to September 15, with clippings collected and dried every Monday, Wednesday and Friday to closely document yield differences. Visual turf quality ratings (1 = dead, 9 = best) were taken bi-weekly.
suppression consistently. Hybrid bermudagrass is not as strongly regulated, however, by Cutless MEC (flurprimidol), which should be applied every 200 to 400 GDDs or every 7 to 14 days. We are repeating the trial in 2012 with the following changes based on
2011 results: dropping the high rate of Primo and the use of 200 GDDs as a spray trigger for Primo and Legacy (harmful and unrealistic), and adding in an 800 GDDs spray treatment and a treatment where PGRs are applied every 28 days. c
Research results
Re-application of PGRs based on 200 GDDs resulted in 24 applications over 20 weeks (on average, an application every 5 days). The 400 and 600 GDD spray triggers resulted in an average application interval of 9 or 14 days, respectively. Obviously, all of these triggers were much more frequent than the 28-day label interval! Frequent application of all three PGRs at 200 GDDs resulted in a loss of bermudagrass quality compared to the untreated control (data not shown). PGR application at the 400 or 600 GDDs intervals did not reduce bermudagrass quality. Bermudagrass maintained at 1/2" was very responsive to the frequent PGR applications made in this study. Primo at both rates and at all three GDD intervals resulted in 60% to 80% clipping suppression throughout the summer (data not shown). The same was true for Legacy. However, only Cutless MEC (0.25 oz./M) applied every 200 GDDs provided consistent season-long clipping yield suppression of 50% to 60%; the less frequent application triggers of 400 and 600 GDDs provided inconsistent 10% to 20% suppression and periods of rebound (Figure 2).
Conclusions
Primo (trinexapac-ethyl) at 0.125 oz./M strongly regulates hybrid bermudagrass and does not need to be applied any more frequently than every 600 GDDs or 14 days to achieve greater than 50% Journal of the Virginia Turfgrass Council
| 25
Research Articles continued
Early Detection of Stress on Annual Bluegrass on Putting Greens Virginia Tech Researchers: David S McCall, Dept. of Plant Pathology, Physiology, and Weed Science; and Valerie A. Thomas and Laura Lorentz, Dept. of Forest Resources and Environmental Conservation
A
nnual bluegrass is considered both a desirable turfgrass species and problematic weed on golf putting greens in our region. Its growth attributes make it desirable because of its density and ability to withstand close mowing, although management requirements are much greater than with creeping bentgrass. Both annual and perennial biotypes are found on golf putting greens. Despite its perennial nature, however, the latter often suffers from numerous stresses during the summer months, frequently resulting in widespread plant death. Advanced stress detection of annual bluegrass could be highly beneficial for timing key management events, such as fungicide applications or irrigation.
Our research
We are currently exploring a unique method — hyperspectral radiometry — for early stress detection of annual bluegrass. Since herbicide injury typically produces expected (predictable)
results, this approach was used as an initial screen for stress detection. Two herbicides known to injure annual bluegrass — bispyribac-sodium and amicarbazone — were chosen for this initial experiment. We conducted our trials on a research golf putting green at the Virginia Tech Golf Course in October 2011. The site consisted of a mixed stand of annual bluegrass and creeping bentgrass. Bispyribac-sodium and amicarbazone were applied at 30 grams ai/A and 100 grams ai/A, respectively, on October 3, 2011. For each plot, ten distinct colonies of annual bluegrass were selected for daily data collection before and after herbicide application. Reflectance data were collected and analyzed from each subsample. Three hundred spectrum data were pooled and analyzed to provide one spectral signature for each treatment per day. Plots were also monitored daily for injury that was visible to the human eye alone.
26 | Virginia Turfgrass Journal May/June 2012 www.vaturf.org
Research results
In bispyribac sodium-treated plots, a mild chlorosis was first visually noticed five days after application and remained through the duration of data collection. Injury from amicarbazone was less pronounced. Using spectral analysis software, reflectance data were graphed for each day. Temporal effects were evident with each herbicide throughout the study at 715nm using second derivative analysis. Days zero and one, days two and three, and days four and five, were clustered together, respectively. Amicarbazonetreated plots were analyzed similarly. While visible symptom development was not as obvious, the analysis also detected change two days after application.
Conclusion
Results from this experiment provide evidence that physiological changes may be detected with spectral analysis as early as two days after application with two herbicides, before damage symptoms can be seen visually. It is not known at this time whether the same spectral features used for this analysis will be present when exposed to other biotic or abiotic stresses. For outbreaks of many diseases to occur, annual bluegrass and other species must be predisposed to abiotic stresses, such as heat or drought. If the spectral feature described in this report is consistent for all stresses of annual bluegrass, this information could prove highly beneficial for turf managers attempting to control diseases preventatively with adequate application timing. Additional research is ongoing. c
continued Research Articles
Portable Turf Protection Panels Virginia Tech Researchers: John Royse, Graduate Student; Erik Ervin, Ph.D., Professor of Turfgrass Physiology; Mike Goatley Jr., Ph.D., Extension Turfgrass Specialist/Professor, Crop & Soil Environmental Sciences Dept. Sponsor: U.S. National Park Service. Donation of Panels: Colbond (Arnhem, The Netherlands), Matrax Inc. (Newfoundland, NJ) and Terraplas USA (Kilgore, TX)
P
ublic events, such as concerts, rallies and festivals, impact turf health when held on natural turfgrass surfaces. In addition to pedestrian and vehicular traffic, the impact associated with these events is due to the placement of physical structures on the turf surface, including tents, stages and seating areas. To abate the damage to the turf surface, portable turf protection panels can be used. Scientific data associated with these panels, however, are lacking for facility managers and owners.
Our research
We used four panel treatments — plywood, plywood + Enkamat Plus™ and white high-density polypropylene [single sided (Terratile™) or double sided (Matrax™)], see Photo 1 — to cover tall fescue (Festuca arundinacea). The effects of light availability, duration of covering (2, 4, 6, 8, 10, 12, 14, 16, 18 or 20 days), season (spring, summer and fall) and soil moisture were evaluated in field and growth chamber trials.
Research results
The panels that allowed light transmission to the canopy provided the best visual turf quality, greater
maintenance of total chlorophyll content and longest tolerance to days of cover (Table 1 and Photo 2). However, when treatments were put under conditions that simulated low light (such as under a concert stage), there were no differences between panel types (data not shown). Moderate soil moisture availability during covering resulted in greater maintenance of chlorophyll content when compared to low soil moisture in full sunlight (data not shown). Also, due to greater overall temperatures in summer, coverage periods needed to be decreased in order to maintain high-quality turf (Table 1).
Photo 1: Portable turf protection panels as laid out on tall fescue in our field experiments.
Research conclusions
Plywood and plywood + Enkamat are not good options when covering turfgrass in any season. Matrax performed the best overall in high temperatures (Picture 2) and did not sink into the turf during saturated soil conditions. Based on these results, it is our recommendation to the U.S. National Park Service and those hosting large staged concerts in their stadiums or fields to require the use of Matrax-type panels for maximum turf protection and recovery. c
Photo 2: High temperatures stress on tall fescue eight days under Terratile panel (top) compared to Matrax (bottom) in summer 2011.
Table 1. Light transmission, summer temperatures under panels and predicted days that panels can be left on tall fescue in spring, summer and fall. Average Summer Panel Type
Days of cover before turf recovery becomes unacceptable
Light Transmission
Temperature under Panel
Spring
Summer
Fall
Matrax
5%
85°F
20
12
20
Terratile
25%
90°F
20
10
20
Plywood
0%
87°F
6
1
4
Plywood + Enkamat
0%
86°F
6
1
4
Journal of the Virginia Turfgrass Council
| 27
Research Articles continued
Efficacy of selected soil insecticides against white grubs in turf Virginia Tech Researchers: Rod Youngman, Ph.D., Professor; Curt Laub, Research Associate; and Shaohii Wu, Dept. of Entomology Research Sponsors: Virginia Turfgrass Foundation and Virginia Agriculture Council
In
Table 1. Treatment list for 2011 VAC/VTF turfgrass soil insecticide efficacy trials at Tazewell Country Club, Virginia. Trt. No.
Application Timing
Treatment/ Formulation
Application Rate (amt. product/acre)
1
April 20
Acelepryn 1.67SC
8.0 fl. oz.
2
April 20
DPX-HGW86 20SC
8.0 fl. oz.
3
April 20
Allectus GCSC
4.5 pt.
4
April 20
Merit 75WP
6.4 oz.
5
July 19
Zylam 20SG
32.0 oz.
6
July 19
Acelepryn 1.67SC
8.0 fl. oz.
7
July 19
DPX-HGW86 20SC
8.0 fl. oz.
8
July 19
Merit 75WP
6.4 oz.
9
—
Untreated check
—
Table 2. Site 1 white grub counts for 2011 VAC/VTF turfgrass soil insecticide efficacy trials at Tazewell Country Club.
2011, we conducted white grub efficacy trials at the Tazewell Country Club (in Tazewell County, Virginia) to evaluate the efficacy of various soil insecticides against white grubs on golf course turf. Both sites contained a mixture of 80% fescue and 20% bluegrass.
Our research
Table 1 lists the treatments and rates that were included in this study. Application timings were either early (April 20) or late (July 19). Liquid insecticide treatments were applied as foliar sprays, using a CO2 backpack sprayer equipped with 4, 8008VS stainless steel spray tips and calibrated to deliver 80 gpa at 40 psi. Table 3. Site 2 white grub counts; 2011 VAC/VTF turfgrass soil insecticide efficacy trials at Tazewell Country Club, Virginia.
Treatment/ Formulation/ Timing
White grubs per sq. ft. (± SEM)
Treatment/ Formulation/ Timing
White grubs per sq. ft. (± SEM)
Untreated check
24.13 (3.48) a
Untreated check
19.13 (2.45) a
DPX-HGW86 20SC April
23.25 (5.22) a
DPX-HGW86 20SC April
14.25 (3.82) ab
Merit 75WP April
22.00 (4.26) a
Allectus GCSC April
11.50 (2.90) ab
Zylam 20SG July
19.00 (3.42) ab
Merit 75WP April
8.25 (2.46) ab
Allectus GCSC April
9.00 (1.63) b
Zylam 20SG July
5.50 (2.1) bc
Acelepryn 1.67SC July
2.00 (1.08) c
Acelepryn 1.67SC July
0.25 (0.25) c
DPX-HGW86 20SC July
0.75 (0.48) c
DPX-HGW86 20SC July
0.25 (0.25) c
Acelepryn 1.67SC April
0.00 (0.00) c
Merit 75WP July
0.25 (0.25) c
Merit 75WP July
0.00 (0.00) c
Acelepryn 1.67SC April
0.00 (0.00) c
Means within a column by site followed by the same letter are not significantly different (P > 0.05; LSD). 28 | Virginia Turfgrass Journal May/June 2012 www.vaturf.org
Contact Information
Virginia Tech’s Turfgrass Researchers
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 subsequently taken on September 9.
Research results
A total of 811 white grubs were collected from the two sites. Of these, 198 of the identifiable white grubs were identified as follows: • 127 masked chafer (Cyclocephala spp.), 64.1% • 62 Japanese beetle (Popillia japonica), 31.3% • 8 Asiatic garden beetle (Maladera castanea), 4.0% • 1 May or June beetle (Phyllophaga spp.), 0.5% At both sites, the treatment source for white grubs was highly significant. At both sites, the density of white grubs in the untreated check and in the early (April) applications of DPX-HGW86 20SC, Merit 75WP and Allectus GCSC were significantly higher than in the early and late (July) applications of Acelepryn 1.67SC and in the late applications of DPX-HGW86 20SC and Merit 75WP (Tables 2 and 3). Also, at Site 1, the density of white grubs in the early application of Zylam 20SG was significantly higher than in the early and late applications of Acelepryn 1.67SC and in the late applications of DPX-HGW86 20SC and Merit 75WP (Table 2). At Site 2, the density of white grubs in the untreated check was significantly higher than in the late application of Zylam 20SG (Table 3). Phytotoxicity was not observed in any plot over the course of the experiment. c
Shawn D. Askew, Ph.D. Virginia Tech Box 0330 Glade Rd. Facility Blacksburg, VA 24061 (540) 231-5807 Email: saskew@vt.edu
Mike Goatley Jr., Ph.D. Virginia Tech 424 Smyth Hall, CSES Dept. Blacksburg, VA 24061 (540) 231-2951 Email: goatley@vt.edu
Jeffrey F. Derr, Ph.D. Virginia Tech Hampton Roads Agricultural Research Center 1444 Diamond Springs Rd. Virginia Beach, VA 23455 (757) 363-3912 Email: jderr@vt.edu
David S. McCall Virginia Tech 435 Old Glade Rd. Blacksburg, VA 24061 (540) 231-9598 Email: dsmccall@vt.edu
Erik H. Ervin, Ph.D. Virginia Tech 335 Smyth Hall, CSES Dept. Blacksburg, VA 24061 (540) 231-5208 Email: ervin@vt.edu
Roger R. Youngman, Ph.D. Virginia Tech 216A Price Hall, MC 0319 Blacksburg, VA 24061 (540) 231-9118 Email: youngman@vt.edu
Journal of the Virginia Turfgrass Council
| 29
Index of Advertisers
Turf Industry Events May 22
Pesticide Recertification Gypsy Hill Park’s Gymnasium Staunton, VA
June 4
Bob Ruff Jr. Memorial Research Golf Tournament Spring Creek Golf Course Gordonsville, VA
June 12
Pesticide Recertification Hampton, VA
June 19
SVTA Research Golf Tournament (Shenandoah Valley Turfgrass Assn.) Rock Harbor Golf Course Winchester, VA
June 26
Hampton Roads AREC Turfgrass Field Day & Pesticide Recertification Virginia Beach, VA
June 26–27
STMA Mid-American Regional Conference & Trade Show Cincinnati, OH
July 8–10
PLANET Legislative Day Washington, DC
July 30 – August 3
TPI Summer Convention & Field Days (Turfgrass Producers Intl.) Asheville, NC
August 28–29
Virginia Tech Turfgrass Field Days Blacksburg, VA
October 6
VA Sod Growers Field Day Woodward Turf Farms Remington, VA
December 11–13
Virginia Tech’s Turfgrass Short Course Fredericksburg, VA
January 28–31
VTC’s 53rd Annual Turf & Landscape Conference and Trade Show Fredericksburg Expo & Convention Center Fredericksburg, VA
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