Journal of the Virginia Turfgrass Council
Eleventh Annual Digest of Turfgrass Research in Virginia Science-Based Information for the Management of Golf Courses, Sports Fields, Lawns and Sod Farms
May/June 2015
Virginia Turfgrass Council / P.O. Box 5989 / Virginia Beach, VA 23471 / ADDRESS SERVICE REQUESTED
Journal of the Virginia Turfgrass Council | May/June 2015
Eleventh Annual
DIGEST OF TURFGRASS RESEARCH IN VIRGINIA Upcoming Events 10 Mark Your Calendars Now for These Ever-Popular Get-Togethers
Research Reports 13 Traffic Tolerance and Spring Recovery of Multiple Bermudagrass Cultivars 16 Insecticide and Entomopathogenic Fungi Combos to Control Large White Grubs 18 Drought Resistance of Tall Fescue Established in Disturbed Urban Soils Utilizing Biosolids 20 Characterizing the Geographic Footprint of Spring Dead Spot of Bermudagrass in Virginia
Summaries of More Research Projects 27 Controlling Japanese Stiltgrass in Lawn Turf 28 Investigating the Mode of Action of Methiozolin 28 Roughstalk Bluegrass Control in Bentgrass and Kentucky Bluegrass Fairways
Departments 6 8 30 30 30
Director’s Corner from Tom Tracy, Ph.D. VTF Report from Betty Parker Calendar of Events Contact Information for VT Researchers Index of Advertisers
22 Using HPPD-Inhibiting Herbicides for Goosegrass Control in Bermudagrass 24 Pylex and Pylex plus Turflon Ester for Goosegrass Control in Bermudagrass 26 Tenacity + Princep + Pennant Magnum for Goosegrass Control in Bermudagrass
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 ©2015 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
Tom Tracy, Ph.D. VTC Executive Director
We
Come to the Bay Exceeded Expectations
did it! Come to the Bay, our endeavor to provide industry training in the Hampton Roads portion of the state, was a success. The event’s organizers and speakers received kudos from Chad Peevy, arborist and grounds manager at Old Dominion University. Chad sent more than twelve crew members to the con-
ference, most of them to our recertification programs. These attendees told Chad that the event was “exceptional, and they enjoyed it a great deal!” These are not the sort of comments we normally hear from attendees at pesticide and fertilizer certification classes! Several firsts happened at Come to the Bay. One, we incorporated a calibration segment in the pesticide
6 | Virginia Turfgrass Journal May/June 2015 www.vaturf.org
recertification classes. This addition was made because of the ongoing need of pesticide applicators to properly apply the right amount of product. Success or failure hinges on the applicator’s adherence to details, and reviewing them periodically never hurts. Two, we added a second day that we used to expand beyond pesticide and fertilizer certification. A general session offered in-depth classes for turfgrass professionals and arborists. Including arborist classes follows a trend set by industry leaders who see the value of uniting various segments of the industry. “Trees and Turfgrass: An Antagonistic Relationship?” by Joe Murray was one of the popular presentations. Attendees were shown the value of both trees and turfgrass and also the natural exclusivity of each in natural environments. Knowing the differences helps professionals better maintain both. Plans are underway for next year’s Come to the Bay. It is scheduled for February 23–24 (Tuesday and Wednesday). Initial discussion calls for us to structure the 2016 Come to the Bay around a transition-zone theme and will focus on the challenges and opportunities faced by turfgrass managers in this unique area. We are targeting industry professionals in eastern Virginia and northeastern North Carolina. Chad ended his praise of the event by saying, “Beginning a new industry conference is no simple task, and I look forward to supporting this in the future.” This year, we broke new ground with Come to the Bay, and with help from persons like Chad, the future is very bright c
VTF Report
Research abounds Betty Parker VTF Manager
for 2015
At
the January 26 meeting of the VTF, we endorsed a plethora of new research projects for the upcoming year. Our turfgrass research specialists will be busy at work this year at Virginia Tech. Much of the research that we have supported over the past couple of years can be reviewed in this edition of the Virginia Turfgrass Journal. We have a wonderful group of scientists at Virginia Tech working for the advancement of our industry. We should never take them for granted or fail to say thank you to all of them for the tireless work they do. Their research makes your job easier by finding ways to eradicate pests, prevent and treat disease, and develop quality turfgrass blends suited to your location that will be easier and less expensive to maintain. Four new proposals were reviewed and endorsed for funding. “Characterizing Herbicide-Resistant Annual Bluegrass” Virginia Tech Researcher: Shawn Askew, Ph.D., PPWS Department One-Year Project “The Heating Characteristics of Tall Fescue/Kentucky Bluegrass and Bermudagrass Sods As Affected by Harvest Season, Daily Time of Harvest, Turf Mowing Height and Soil Moisture at Harvest” Researchers: Mike Goatley, Ph.D., and Whitney Askew, CSES Department, Virginia Tech; with Jeff Everhart and Scott Woodward, Woodward Turf Farms, Remington, VA Two-Year Project “Selective Control of Perennial Grassy Weeds in Tall Fescue, Seashore Paspalum and Bermudagrass” Virginia Tech Researchers: Jeffrey Derr, Ph.D., and Adam Nichols Two-Year Project “Efficacy of Select Insecticides on White Grubs and Earthworms” Virginia Tech Researchers: Tom Kuhar, Ph.D., Curt Laub and Sudan Gyawaly, Department of Entomology One-Year Project In addition to the more than $45,000 committed to these projects, the Virginia Turfgrass Foundation has also pledged $40,000 over the next two years toward a muchneeded, industry-wide survey that will be executed through Virginia Tech. We ask that all of you help by responding to all inquires made to produce this survey. A survey is only as valid as the persons who participate! Thank you all who make the turfgrass industry a rewarding, if not challenging, place to work. c 8 | Virginia Turfgrass Journal May/June 2015 www.vaturf.org
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 Fredrick Biggers, CGCS Wintergreen Resort (434) 325-8252 Vice President Rick Owens, CGCS Laurel Hill Golf Club (703) 674-6934 Treasurer Scott Woodward Woodward Turf Farms (540) 727-0020 Past President Frank Flannagan msg1sg@verizon.net (804) 356-1535 VTC DIRECTORS Tony Montgomery Marc Petrus Jesse Pritchard Christian Sain Michael Skelton Rick Viancour, CGCS Jimmy Viars Brian Walker  VTC ADVISORY MEMBERS OF THE BOARD Mike Goatley, Ph.D. (Chair) Shawn Askew, Ph.D. Jeffrey Derr, Ph.D. Erik Ervin, Ph.D. David McCall Executive Director/ Director of PROGRAMS Tom Tracy, Ph.D. (757) 464-1004 Virginia Turfgrass Foundation Betty Parker (757) 574-9061
Journal of the Virginia Turfgrass Council
|9
Upcoming Events
Mark Your Calendars Now for These Ever-Popular Events!
June 23
Hampton Roads AREC Turfgrass Field Day, Pesticide Recertification and Exam for Virginia Certified Turfgrass Professional
August 25–26
September 14
Virginia Tech Turfgrass Research Field Days
Bob Ruff Jr. Memorial Research Golf Tournament
Virginia Tech
Wintergreen Resort — Devil’s Knob Course
Blacksburg, VA
Hampton Roads AREC Virginia Beach, VA
10 | Virginia Turfgrass Journal May/June 2015 www.vaturf.org
Wintergreen, VA
Research Report
Traffic Tolerance and Spring Recovery of Multiple Bermudagrass Cultivars Subjected to Simulated Fall Football Traffic Virginia Tech Researchers: Ben Kraemer, Graduate Student, Mike Goatley Jr., Ph.D., Professor and Turfgrass Extension Specialist, Jon Dickerson, Research Specialist, Whitnee Askew, Senior Technician, Shawn D. Askew, Ph.D., Associate Professor and Extension Turfgrass Weed Specialist, and David McCall, Turfgrass Pathologist and Research Associate Research Sponsor: Virginia Agricultural Experiment Station
As
the use of bermudagrass on athletic fields continues to expand north in the transition zone, it is important for turfgrass managers to understand how various cultivars perform in transitionzone climates. The primary objective of this study was to determine which bermudagrass cultivars best withstand and recover from fall traffic in Virginia.
Our research
The conclusion of the 2007 NTEP Bermudagrass variety trial at the Turfgrass Research Center in Blacksburg offered a unique opportunity to traffic and observe 31 different bermudagrass cultivars growing in a relatively extreme transition-zone environment. Each cultivar was replicated three times, allowing for strong statistical conclusions to be obtained. Prior to fall 2013, all plots were maintained in the same manner and received no traffic other than that associated with regular mowing at a 1.5� cutting height. Traffic was applied in fall 2013 and 2014, and pertinent data on turfgrass density and recovery were collected in fall 2013, spring 2014 and fall 2014 (Photo1). Traffic was applied using a modified Brinkman Traffic Simulator (Photo 2), which features two studded, metal drums capable of applying both vert-
cal pressure and horizontal shearing. Resulting traffic patterns closely mimic those applied to sports fields used by athletes wearing studded cleats, with a single pass representing cleat traffic between the hashes and 30-yard lines on a football fields. The trafficking regimen was designed to mirror Virginia’s high school football season. On each trafficking date, three passes of the traffic simulator were made on each plot, which is equivalent to three football games. Following traffic simulation, data were collected in two forms for each date: subjective (visual ratings) and objective (Normalized Difference Vegetative Index [NDVI]) ratings (Photo 3). Visual ratings were recorded as percentage bare ground, with 0% being a full canopy and 100% being bare soil. Normalized Difference Vegetative Index ratings range from 0 to 1, with higher values equating to healthier turf. While NDVI technology is relatively new to the turfgrass industry, it shows promise as a way to objectively quantify overall turfgrass health. NDVI data points are created using LED technology capable of emitting both visible and near-red light, as well as specialized light-sensitive lenses capable of analyzing the levels of light forms being reflected off the turfgrass canopy. The
Photo 1. Trafficked and non-trafficked strips of bermudagrass (November 8, 2013).
ratios of visible and near-red light captured by the sensors are used to compute an overall NDVI value for each plot. To obtain NVDI data, the monitor is mounted on a wheeled transporter and manually walked across plots at a consistent pace. Journal of the Virginia Turfgrass Council
| 13
Research Report
Photo 2. The Brinkman Traffic Simulator features a slip clutch and studded cleats that represent the traffic from cleated sports shoes. Photo 3. The NDVI monitor provides an objective means of assessing plant health.
Research results
There were correlations between visual and NDVI data collected over the course of the study, with certain cultivars consistently placing in the top statistical category (Table 1). While NDVI and visual ratings did not perfectly align, general trends were similar for each data-collection method and allowed us to make some general observations about the grasses that had the best fall traffic-tolerance and spring-recovery characteristics. While these data may be a useful aid for bermudagrass cultivar selection in the state of Virginia, it is important to always consider relative details specific to each individual field. When making bermudagrass selection, con-
sider the intended season of use, the sport, the desired management level, etc. For example, Yukon performed exceptionally well in this study; however, it had more than five years to establish prior to being trafficked. Yukon is a seeded variety that is typically very slow to establish and, while it performed exceptionally in this trial, may not be the best selection if not given time to completely mature. Other cultivars may not appear in the top two statistical category rankings at all, but they still might be a viable option. For instance, Riviera is an example of a seeded variety that placed in middle statistical categories for fall traffic tolerance, but it fell in the third (NDVI) and seventh (visual) categories for spring recovery. These findings reinforce Riviera’s reputation as a relatively cold-tolerant and highgrowth-rate seeded bermudagrass variety. As a result, Riviera may be a low-risk choice for Virginia field managers seeking a seeded variety due to its documented ability to survive and recover from winter extremes. In terms of vegetative varieties, the same holds true for Patriot. While Patriot was an average performer in traffic tolerance in these trials, it placed in the second (NDVI) and third (visual) categories for spring recovery, supporting its use as a relatively predictable bermudagrass for survival and recovery from a Virginia winter. Conversely, other cultivars can perform exceptionally well in terms of fall traffic tolerance, but poor winter hardiness and spring recuperative abilities reduce their viability for year-
Table 1. Bermudagrass cultivar ranking in the top two statistical category rankings for fall 2013, spring 2014 and fall 2014.
Season
NDVI Ratings
Visual Ratings
Fall 2013
SWI-1113 (S), SWI-1057 (S), PSG 9Y2OK+ (S), RAD-CD1+ (S), Latitude 36 (V)
Ltitude 36 (V), Tifway (V), Northbridge (V)
Spring 2014
Yukon (S), Patriot (V)
Yukon (S), Northbridge (V), Latitude 36 (V)
Fall 2014
Hollywood (S), Yukon (S), RAD-CD1+ (S), Latitude 36 (V)
Northbridge (V), Latitude 36 (V), Premier (V), SWI-1057 (S), Tifway (V), Yukon (S), Patriot (V)
Cultivars are listed in order of statistical ranking and are comprised of the top two statistical categories. (V) = vegetative cultivar, (S) = seeded cultivar. + Experimental cultivar.
Bermudagrass Cultivars in Blacksburg’s 2007 NTEP Trial round use in some parts of Virginia. Tifway is an example of a cultivar that demonstrates strong fall traffic tolerance (average NDVI ranking = 5th, average visual ranking = 2nd) but has average to below-average spring recovery (NDVI ranking = 14th, visual ranking = 4th) in the Blacksburg climate. While Tifway may be an excellent performer for traffic tolerance, its lack of cold hardiness and propensity to winter damage in the coldest climates of Virginia makes it a significantly riskier choice in those locations as compared to other high-density, fine-bladed, cold-tolerant vegetative varieties like the newer Northbridge and Latitude 36 varieties. Overall, Latitude 36 and Northbridge have rapidly risen in prominence as desirable bermudagrass cultivars for use on athletic fields in the transition zone. Aside from possessing deep green color and a fine, soft texture, both are widely desired across the transition zone due to their unique ability to over-
come the three primary challenges facing transition-zone bermudagrasses: fall traffic tolerance, winter survival and spring recovery and green up. So far, Latitude 36 and Northbridge have met the standard challenges of a Virginia transition-zone climate and have done so at an above-average level. On the downside, these cultivars do require frequent verticutting, topdressing and mowing in order to prevent scalping and excessive thatch buildup. As a result, managers with limited labor, equipment or budget availability may be better suited using alternative varieties capable of meeting their requirements. Remember, cultivar selection should always be made based on your unique situation, and your decision must ultimately consider more than simply climate. Prior to making a final cultivar decision, it is wise to consult your Virginia Cooperative Extension turfgrass specialists and sports turf managers in your area to select varieties that will best serve your specific needs. c
Seeded
Vegetative
BAR 7CD5 Latitude 36 Gold Glove Midlawn Hollywood Northbridge IS-01-201 Patriot Numex-Sahara Royal Bengal OKS 2004-2 Premier Princess 77 Tifway PSG 91215 PSG 94524 PSG 9Y2OK PSG PROK Pyramid 2 RAD-CD1 Riviera Sunsport SWI-1057 SWI-1070 SWI 1081 SWI-1083 SWI-1113 SWI-1117 SWI-1122 Veracruz Yukon
Journal of the Virginia Turfgrass Council
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Research Report
Can Combinations of Insecticides and Entomopathogenic Fungi Do the Job on Hard-To-Kill Large White Grubs? Virginia Tech Researchers: Sudan Gyawaly, Graduate Student, Curt Laub, Research Associate, and Tom Kuhar, Ph.D., Professor, Department of Entomology Research Sponsors: Virginia Turfgrass Foundation (partial funding)
A
nnual white grubs remain the most important insect pests of turfgrass in Virginia. Among the handful of species of white grubs that may be encountered in Virginia turf, the most common are Japanese beetle (Popillia japonica Newman) and masked chafers (Cyclocephala spp). The life cycles of these species are similar in that adult beetles emerge about midJune and lay their eggs in the soil usually in July. The grubs that result from these hatched eggs feed on grass roots and can kill large patches of grass under heavy infestations (more than 10 per square foot) (Photo 1). Additional damage can occur when vertebrate animals dig up the turf in search of the grubs to eat. Insecticides such as the neonicotinoid Merit (imidacloprid) and the newer diamide insecticide Acelepryn (chlorantraniliprole) provide excellent control of young white grubs when these chemicals are applied during the summer months. However, these products, as well as most other registered turf insecticides, do not adequately control the larger, more mature white grubs that can be found feeding on turf during the fall and spring months.
Thus, summertime application timing is very important for insecticide efficacy. However, this is not always practical. Mixtures of insecticides with different modes of action may have a synergistic effect and provide a much higher level of efficacy than either product used alone. Here, we evaluated if large (late instar) white grubs could be controlled effectively with reduced rates of Merit or Acelepryn if each was mixed with an entomopathogenic fungus (EPF) product such as Botanigard (Beauveria bassiana) or Met F52 (Metarhizium anisopliae). Three experiments were conducted at Virginia Tech from 2012 to 2013 to investigate this question.
Our research: Experiment 1
Can EPF products enhance the activity of low application rates of Acelepryn on mature white grubs in the lab? Third-instar masked chafer grubs were collected from untreated turf at the Virginia Tech Turfgrass Research Center in fall 2012. Experiments were carried out at 25°C (77°F) and 90% relative humidity in a temperature chamber in 30-ml plastic cups filled with sandyloam soil and perennial ryegrass as food. One grub was placed in each cup.
Photo 1. White grub damage to turf in southwest Virginia (left) and masked chafer grub.
16 | Virginia Turfgrass Journal May/June 2015 www.vaturf.org
Treatments are listed in Table 1 and included reduced rates of Acelepryn, full recommended rates of Botanigard and Met F52, and each combination of Acelepryn plus fungi. For each treatment, a total of 2 ml of insecticide solution was applied to each container. For the control treatment, 2 ml water was applied. The cups were sampled each week for number of live grubs, and percentage mortality was ultimately assessed after four weeks.
Research results to date
There was a significant effect of treatments on grub mortality (Table 1). The combined application of half the recommended rate of Acelepryn plus Botanigard resulted in the highest grub mortality among the treatments. However, even this treatment resulted in only about 50% mortality of the grubs. None of the combined treatments resulted in a synergistic interaction, only additive effects on efficacy. Nonetheless, with the exception of a half rate of Acelepryn mixed with Met F52, combinations of EPFs with Acelepryn increased the overall grub mortality compared with either used alone.
Our research: Experiment 2 Do EPF products or combinations of EPFs with insecticides affect egg-laying by Japanese beetles? Research has shown that adult female scarab beetles may be able to detect whether soil is infested with entomopathogenic fungi or treated with insecticides, and choose to not deposit their eggs in that soil. In summer 2013, more than 1,000 adult Japanese beetles were collected from Kentland Research
Table 1. Mortality of third-instar masked chafer grubs exposed to insecticide treated perennial ryegrass in containers in the laboratory. Treatment Rates (amount of product/1,000/ft2)
% Mortality (mean ± SE) of White Grubs
Acelepryn (1/2 rate)
0.184 fl. oz.
35.0 ± 11.9 ab
Acelepryn (1/4 rate)
0.091 fl. oz.
12.5 ± 4.8 b
3 oz.
17.5 ± 6.3 ab
Treatment
Photo 2. Containers with treated soil and caged Japanese beetle females, to determine the effect of entomopathogenic fungi and insecticides on ovipostion.
Farm near Blacksburg and kept at room temperature for 3 to 5 days prior to experiments. Experiments were carried out in the Virginia Tech greenhouse in 8-cm diameter PVC tubes filled with sandy loam soil (Photo 2). Perennial ryegrass was provided as food. Five female beetles were released in each experiment arena and covered with fine mesh. The treatments used in this experiment are shown in Table 2. The tubes were sampled 10 days after treatment, and the numbers of eggs laid at different soil depth were recorded. The effect of treatment on number of eggs laid was analyzed.
Research results
There was a significant effect of treatments on number of eggs laid (Table 2). There was no difference in numbers of eggs laid between EPF treatment and untreated control. All insecticide treatments except Acelepryn at the onefourth rate had fewer eggs than the control. The effect of combined treatments on egg number was highly variable.
Our research: Experiment 3 To evaluate the field efficacy of EPF products and combinations of EPFs with insecticides on control of white grubs. To evaluate the effect of combined applications of entomopathogenic fungi and insecticides in the field, treatments were applied in (spring) April, (summer) July and (fall) November 2013 at Blacksburg and Tazewell County. Grubs were sampled approximately one month after treatment for spring and fall treatments, and four months after treatment for summer treatments, using a sod cutter to examine the density of grubs in the soil and thatch region.
M. anisopliae (Met F52)
8 oz.
27.5 ± 6.3 ab
Acelepryn (1/2 rate) + Met F52
B. bassiana (Botanigard)
0.184 fl. oz. + 3 oz.
27.5 ± 8.5 ab
Acelepryn (1/4 rate) + Met F52
0.091 fl. oz. + 3 oz.
30.0 ± 5.8 ab
Acelepryn (1/2 rate) + Botanigard
0.184 fl. oz. + 8 oz.
55.0 ± 15.2 a
Acelepryn (1/4 rate) + Botanigard
0.091 fl. oz. + 8 oz.
32.5 ± 11.1 ab
—
5.0 ± 2.9 b
Untreated control
Means with same letter are not significantly different. Tukey’s test (P < 0.05). Table 2. Effect of entomopathogenic fungi and insecticide treatments on the number of eggs laid by Japanese beetles on perennial ryegrass. Treatment Rates (amount of product/1,000/ft2)
Eggs Laid per Container (mean ± SE)
Acelepryn (1/2 rate)
0.184 fl. oz.
7.8 ± 3.26 ab
Acelepryn (1/4 rate)
Treatment
0.091 fl. oz.
12.4 ± 4.03 b
Merit (1/2 rate)
0.098 oz.
1.4 ± 0.97 a
Merit (1/4 rate)
0.049 oz.
2.0 ± 0.83 a
M. anisopliae (Met F52)
3 oz.
8.2 ± 4.83 ab
B. bassiana (Botanigard)
8 oz.
7.6 ± 2.11 ab
Acelepryn (1/2 rate) + Met F52
0.184 fl. oz. + 3 oz.
11.2 ± 3.02 b
Acelepryn (1/4 rate) + Met F52
0.091 fl. oz. + 3 oz.
9.6 ± 1.83 ab
Merit (1/2 rate) + Met F52
0.098 oz. + 3 oz.
0.8 ± 0.59 a
Merit (1/4 rate) + Met F52
0.049 oz. + 3 oz.
2.0 ± 1.54 a
Acelepryn (1/2 rate) + Botanigard
0.184 fl. oz. + 8 oz.
4.0 ± 0.89 a
Acelepryn (1/4 rate) + Botanigard
0.091 fl. oz. + 8 oz.
19.2 ± 1.15 b
Merit (1/2 rate) + Botanigard
0.098 oz. + 8 oz.
0.8 ± 0.80 a
Merit (1/4 rate) + Botanigard
0.049 oz. + 8 oz.
0.2 ± 0.20 a
—
16.6 ± 3.47 b
Untreated control Means with same letter are not significantly different.
Research results
For the Blacksburg site, we found that there was no significant difference among the treatments for both the April and November trials. The location ended up having only a moderate density of white grubs, which made assessments of efficacy difficult. However, there was significant difference among the treatments for the July applications of the insecticides. Significant reductions in numbers of white grubs
occurred with half rates of Acelepryn or Merit, one-fourth rates of Acelepryn, a half rate of Acelepryn + Met F52 and a half rate of Merit + Botanigard.
Research conclusions
• Combinations of entomopathogenic fungi with insecticides such as Merit and Acelepryn may increase efficacy against hard-to-kill, large white grubs. • The presence of certain EPFs or insecticides in the soil may reduce egg-laying by Japanese beetles. c Journal of the Virginia Turfgrass Council
| 17
Research Report
Drought Resistance Response of Tall Fescue Established in Disturbed Urban Soils Utilizing Biosolids Virginia Tech Researchers: Adam Boyd, Graduate Student; Erik H. Ervin, Ph.D., Professor of Turfgrass Culture & Physiology; Gregory Evanylo, Ph.D., Professor and Extension Specialist, Jonathan Dickerson, Research Specialist Sr., and Xunzhong Zhang, Ph.D., Advanced Research Scientist Research Sponsor: Metropolitan Washington Council of Governments Material Suppliers: D.C. Water Authority, Alexandria Sanitation Authority and Spotsylvania Sanitation Authority
U
rban development is a primary cause of soil degradation. As populations continue to swell, development extends further from city centers and encroaches into surrounding rural and forested areas. A result of population growth is increased biosolids production. Increasing regulations on agricultural biosolids land application have resulted in wastewater-treatment plants seeking alternative means of land application. Contractor use of biosolids to improve disturbed urban soils following construction offers a beneficial use and alternative means of disposal for wastewater-treatment plants, while also possibly reducing fertilizer and irrigation requirements. The objective of this experiment is to evaluate different biosolids mixes that are applied at estimated agronomic N and P rates and compare their effects on the persistence of tall fescue (Festuca arundinacea) with a synthetic fertilizer when subjected to drought or non-drought conditions.
Our research
In fall 2013, a research plot measuring
110' x 68' was prepared by stripping the O, E, and A horizons leaving the subsoil (B horizon) exposed. The trial was then divided into 40 plots measuring 12' x 12', with a 2' buffer strip separating each. A subterranean irrigation system was installed to allow for uniform irrigation during establishment. Two biosolids products from the Alexandria Sanitation Authority (ASA) and the Spotsylvania Sanitation Authority (SSA) were used. The ASA product is an exceptional quality (EQ) Class A dewatered biosolids and was used unmixed, as well as mixed with sand and sawdust at a ratio of 50% biosolids/25% sand/25% sawdust. The SSA product is an EQ Class A dewatered biosolids that was composted with wood fines. Rates used were based on an annual agronomic tall fescue N requirement of 4.6 lbs./1,000 ft2 and P rate of 1.3 lbs./ 1,000 ft2. Synthetic fertilizers were used to supplement the P-rate-amended biosolids plots and for the comparison control plots. Following incorporation of the amendments, tall fescue was seeded at a rate of 8 lbs./1,000 ft2 and established over the fall 2013 to spring 2014 season.
18 | Virginia Turfgrass Journal May/June 2015 www.vaturf.org
Loading rates for each of the amendments are listed below. 1. Synthetic fertilizer (control) — urea (46-0-0) 4.6 lbs. N/1,000 ft2/year (split applications in August and October 2013) 2. Alexandria dewatered biosolids mix (Alex-N) — agronomic N rate: 4.6 lbs. plant available nitrogen (PAN)/1,000 ft2/year (estimated) 3. Alexandria dewatered biosolids mix (Alex-P) — agronomic P rate: 1.3 lbs. PAN/M/year (estimated), supplemented with synthetic fertilizer to apply the other 3.3 lbs. N/1,000 ft2 4. Alexandria dewatered biosolids (Alex-DW) — 4.6 lbs. PAN/1,000 ft2/year (estimated) 5. Spotsylvania biosolids compost (Spots) — 4.6 lbs. PAN/1,000 ft2/year (estimated) In May 2014, supplemental irrigation during establishment was discontinued. The plots were split into their respective irrigation regimens, and evapotranspiration (ET) replenishment cycles commenced. The two different irrigation regimes are 0% and 80% ET replenishment, respectively. The ET rate was estimated using on-site
Table 1. Irrigated = 80% ET Replacement Every Three Days. Parameters Clipping Yield Treatment
Turfgrass Quality
NDVI
37 WAT
45 WAT
49 WAT
37 WAT
45 WAT
49 WAT
37 WAT
45 WAT
49 WAT
Control
86.5 a
23.6 a
59.5 a
7.4 a
7.8 a
7.5 a
0.84 a
0.87 a
0.83 a
Alex-N
21.4 b
3.1 b
25.5 b
6.7 a
5.3 c
6.0 b
0.74 c
0.76 c
0.74 b
Alex-P
20.5 b
3.8 b
36.1 b
5.9 b
5.5 bc
5.8 b
0.77 bc
0.80 b
0.74 b
Alex-DW
32.1 b
3.9 b
25.5 b
6.9 a
6.1 b
6.1 b
0.79 b
0.80 b
0.75 b
Spots
32.3 b
3.7 b
33.2 b
6.7 a
5.8 bc
6.6 b
0.76 bc
0.78 bc
0.75 b
Means followed by the same letter are not significantly different (P ≤ 0.05). Weeks after treatment – WAT
Table 2. Non-Irrigated = 0% ET Replacement. Parameters Clipping Yield Treatment
Turfgrass Quality
NDVI
37 WAT
45 WAT
49 WAT
37 WAT
45 WAT
49 WAT
37 WAT
45 WAT
49 WAT
Control
86.5 a
14.7 a
59.5 a
7.4 a
4.8 a
7.5 a
0.84 a
0.76 a
0.83 a
Alex-N
21.4 b
2.5 bc
25.5 b
6.7 a
3.4 b
6.0 b
0.74 c
0.70 bc
0.74 b
Alex-P
20.5 b
5.0 b
36.1 b
5.9 b
3.8 b
5.8 b
0.77 bc
0.72 b
0.75 b
Alex-DW
32.1 b
1.1 c
25.5 b
6.9 a
3.9 b
6.1 b
0.79 b
0.68 c
0.75 b
Spots
32.3 b
1.7 c
33.2 b
6.7 a
3.5 b
6.6 b
0.76 bc
0.71 bc
0.75 b
Means followed by the same letter are not significantly different (P ≤ 0.05). Weeks after treatment – WAT
atmometers every three days, and irrigation was supplemented to replenish the moisture loss. Turfgrass color and quality, volumetric soil moisture percentage to a 2" depth, Normalized Difference Vegetative Index (NDVI) and clipping yield were measured bi-weekly throughout the growing season. (NDVI can be defined as a quantitative ratio of reflected red wavelengths of light relative to near infrared wavelengths and corresponds closely to leaf density and chlorophyll content.) Lack of irrigation was also used to compare the plots for drought-stress responses.
Research results
During the first May through July 2014 irrigation season, results show that the control plots treated with inorganic fertilizers consistently had improved responses relative to the biosolids-amended plots (Tables 1 and 2). Clipping yield, quality and NDVI were all significantly greater in the control plots, while volumetric soil moisture percentage readings (data not shown) were consistently lower. Results seem to be heavily dependent on nitrogen availability, which indicates that our original loading
rate estimates for all of the biosolids treatments were too low. Mineralization rates of nitrogen in organic amendments are highly variable based on environmental conditions such as soil type, available moisture and temperature fluctuations, making estimation of nitrogen availability difficult. Loading rates for future field trials will need to be adjusted upward to attempt to narrow the N-availability gap between the inorganic and organic amendments. The research with the current biosolids mixes and loading rates will continue through 2015. c Journal of the Virginia Turfgrass Council
| 19
Research Report
Characterizing the Geographic Footprint of Ophiosphaerella Species Causing Spring Dead Spot of Bermudagrass in Virginia Virginia Tech Researchers: David McCall, Turfgrass Pathologist and Research Associate, Elizabeth Bush, Senior Research Associate, and Scott Johnson and Katie Dougherty, Undergraduate Students Research Sponsors: USDA-NIFA, Extension IPM Program
S
pring dead spot (SDS) is the most common and destructive disease of bermudagrass turf in marginal regions of adaptation, including throughout the Mid-Atlantic. In addition to being unsightly, the depressed voids left behind can potentially be an injury hazard on athletic playing surfaces. While documentation of the disease dates back over four decades, its epidemiology is still largely a mystery. Chemical and control strategies often produce inconsistent results. When various tactics are successful, it is typically a gradual improvement over several seasons. Our research in Virginia has shown that even with well-timed fungicide applications in the fall, a minimum of two years is needed for substantial suppression of the disease. The same mantra has proven true in other states, both with chemical and cultural strategies. Expected responses by managing with fertility have proven even slower. Research from Maryland in the late 1980s indicated that SDS may be effectively managed over time with the use of ammonium sulfate as a primary nitrogen source. This became the industry go-to for turf managers who chronically struggled with the disease. However, results have been highly
variable with stories of success, failure and everything in between. More recently, the pathology team at NC State determined that management with fertility was highly dependent on the causal agent species under artificially induced conditions. The researchers from NC State concluded that Ophiosphaerella herpotricha (Oh) is best managed with ammonium sulfate, whereas O. korrae (Ok) is unaffected. Conversely, calcium nitrate appears to be much more effective at suppressing Ok, with little to no effect on Oh. While this finding appears to be a breakthrough in our understanding of SDS epidemiology, field studies in Virginia under natural populations were highly inconsistent. One reason appears to be related to the speciation of the causal agent. Our current understanding of SDS is that the disease is caused by three species of Ophiosphaerella. Historically, species distribution is separated into geographies. O. narmari is known to incite disease in Australia and New Zealand, with a few isolated pockets in the U.S. Oh is typically considered the dominant species in the Midwest and more northern portions of the transition zone. Ok dominates in Southeastern states where SDS is a problem. To muddy waters even more, there have been confirmed
20 | Virginia Turfgrass Journal May/June 2015 www.vaturf.org
cases where multiple species are present in the same field. The geography of Virginia places our turf managers right in the battleground over which species to manage against.
Our research
As reported in the November/ December 2013 issue of the Virginia Turfgrass Journal, localized sampling confirmed that both Oh and Ok species are present in Virginia, but that one species tends to dominate a site-specific population. In order to make the greatest strides in disease suppression, geography-based control recommendations are needed to minimize the severity of SDS. Using a rapid diagnostic method, the Virginia Tech Turfgrass Pathology and Plant Disease Clinic labs have been working in collaboration to more clearly define the distribution of the two primary pathogens responsible for SDS in Virginia. Symptomatic plant tissue was collected from roughly 50 locations in Virginia and surrounding states. The presence or absence of each species was determined using published primer sets specific to internal transcribed spacer regions of each species using real-time polymerase chain reaction (qPCR). Each location
was determined to be dominant for Oh or Ok or to have a mixed population. Location-specific speciation results were geo-referenced with GIS software to create map layers of the causal agents (see map). This mapping system is now being used to develop geography-specific SDS suppression recommendations for turf managers in Virginia and beyond.
Research results
While there are regions within the Commonwealth where we are confident in predicting populations, there are overlapping areas and sites with mixed populations. Most sampling locations across western and northern Virginia tested positively for Ohdominant populations. Areas closest to the Chesapeake Bay tended to have Ok populations. Three sites situated close to the James River, from the Bay
to Richmond, had mixed populations. Results from our 2014 sampling have helped create a baseline for future exploration. We will continue to strategically sample around the Commonwealth for further delineation. More exciting, our future objectives
are to explore relationships between geographies and physical and/or environmental parameters so that these correlations can be expanded to assist turf managers throughout the transition zone and other regions where SDS is problematic. c
Journal of the Virginia Turfgrass Council
| 21
Research Report
Using HPPD-Inhibiting Herbicides for Goosegrass Control in Bermudagrass Virginia Tech Researchers: John R. Brewer, M.S. Student, Michael C. Cox, Graduate Research Assistant, Sandeep S. Rana, Doctoral Student, and Shawn D. Askew, Ph.D., Associate Professor and Extension Turfgrass Weed Specialist
F
ew postemergence herbicide options exist for goosegrass (Eleusine indica) control on bermudagrass turf. Recent restrictions on MSMA have rendered the longstanding combination of MSMA plus metribuzin ineffective since turf managers can no longer treat enough area or enough times to effectively address goosegrass infestations. Now, the loss of diclofop has further limited postemergence control options in bermudagrass. Most turf managers are using multiple treatments of foramsulfuron and sulfentrazone, but these herbicides are expensive and effective only on seedling goosegrass. Recent turfgrass registration of the HPPD-inhibiting herbicides mesotrione (Tenacity) and topramezone (Pylex) has led to attempts to achieve selective goosegrass control in bermudagrass with these new herbicides. Topramezone, in particular, effectively controls large goosegrass plants at half the maximum use rate in cool-season turf. At rates as low as 7% of the maximum labeled rate, topramezone can control seedling goosegrass. Unfortunately, bermudagrass turf is typically injured by topramezone.
Our Research
At Virginia Tech, we have been evaluating potential topramezone programs for goosegrass control in bermudagrass since 2012. Two green-house trials were conducted in 2012 and 2013 to evaluate various rates of topramezone in combination with several rates of triclopyr (Turflon Ester) for goosegrass control and bermudagrass response. In 2013 and 2014, topramezone at 0.25 and 0.5 oz./A was applied alone or in mixture with triclopyr at 4 oz./A on 31 cultivars of bermudagrass maintained at a 1.25" mowing height. In 2014, two trials were conducted to evaluate goosegrass control and bermudagrass response to topramezone at 0.1 and 0.2 oz./A applied weekly with and without triclopyr at 1 oz./A.
Research Results
Greenhouse studies in 2012 and 2013 suggested that topramezone at 0.25 and 0.5 oz./A and triclopyr at 4 oz./A represented the best balance between bermudagrass safety and goosegrass control. These rates were used in subsequent field trials in 2013 and 2014 to evaluate bermudagrass
Response of 31 bermudagrass cultivars to topramezone (Pylex) applied at 0.25 or 0.5 oz./A alone or mixed with triclopyr (Turflon Ester) at 4 oz./A. Bronze plots contained Turflon, and white plots are only Pylex. Photo taken 21 days after treatment.
cultivar response and goosegrass control. At three trial sites, goosegrass cover ranged from 19% to 37 %. By 10 weeks after initial treatment (WAIT), topramezone at either rate alone or with triclopyr reduced goosegrass cover to between 0% and 7%. All bermudagrass cultivars were injured 30% to 70%. White symptoms from topramezone alone persisted for at least two weeks. Necrotic symptoms from triclopyr combinations ranged between 20% and 40% but persisted for as long as 5 weeks. Despite the initial greenhouse results, field studies suggest that lower rates of triclopyr may be more effective. The treatments of topramezone alone at 0.1 and 0.2 oz./A injured bermudagrass 41% and 16%, respectively at 7 WAIT. These studies suggest that HPPDinhibiting herbicides may be more injurious to bermudagrass in Virginia than has been reported from states further south. In addition, low use rates of topramezone can effectively control goosegrass in bermudagrass, but severe bermudagrass injury may persist for two weeks or more. c
At 28 days after treatment, almost all Pylex plots have recovered, but the bronze color and stunting of plots treated with the Turflon + Pylex mixture is still persisting. Future work will use lower rates of Turflon.
Research Report
Pylex and Pylex plus Turflon Ester for Goosegrass Control in Bermudagrass Virginia Tech Researchers: Jeffrey Derr, Ph.D., Professor of Weed Science, and Adam Nichols, Research Assistant, Hampton Roads Ag. Research and Extension Center, Virginia Beach Research Sponsors: BASF, The Virginia Turfgrass Council and The Virginia Turfgrass Foundation Table 1. Bermudagrass tolerance to the applied treatments. Bermudagrass Tolerance (1–9 scale) (1 = no injury, 4 = unacceptable injury, 9 = complete death)
3 DAT 10 DAT 16 DAT 22 DAT 30 DAT 38 DAT 45 DAT 7/13/14 3 DAT (2) 9 DAT (2) 6 DAT (3) 8 DAT (4) 16 DAT (4) 23 DAT (4) 7/20/14 7/26/14 8/2/14 8/10/14 8/18/14 8/25/14 1 Untreated Check
8 DAT 7/10/14
16 DAT 1 DAT (2) 7/18/14
23 DAT 8 DAT (2) 7/25/14
29 DAT 6 DAT (3) 7/31/14
36 DAT 13 DAT (3) 8/7/14
44 DAT 21 DAT (4) 8/15/14
0%
0%
0%
0%
0%
0%
Research results
1.0
1.0
1.0
1.0
1.0
1.0
0.1 fl. oz./a 0.5% v/v
2.3
4.3
5.3
4.8
2.6
1.5
1.0
3 Pylex, plus 0.1 fl. oz./a Turflon Ester, 1 fl. oz./a plus MSO 0.5% v/v
3.3
4.9
6.5
7.0
5.6
4.5
3.3
4 Pylex, plus MSO
0.2 fl. oz./a 0.5% v/v
3.0
4.8
5.8
5.8
4.0
3.3
2.3
5 Pylex, plus 0.2 fl. oz/a Turflon Ester, 1 fl. oz./a plus MSO 0.5% v/v
4.8
6.4
7.4
8.1
7.1
5.1
4.0
6 Revolver
1.0
1.0
1.0
1.0
1.0
1.0
1.0
0.5
0.6
0.5
0.5
0.6
0.6
0.7
17.4 fl. oz./a
LSD (P= .05)
Table 2. Goosegrass control when treatments were applied to 2-to-3-leaf goosegrass. % Control at 2-to-3-Leaf Goosegrass
1 Untreated Check 2 Pylex, plus MSO
0.1 fl. oz./a 0.5% v/v
34%
55%
44%
67%
66%
65%
3 Pylex, plus Turflon Ester, plus MSO
0.1 fl. oz./a 1 fl. oz./a 0.5% v/v
48%
64%
63%
87%
89%
87%
4 Pylex, plus MSO
0.2 fl. oz./a 0.5% v/v
58%
96%
98%
100%
100%
100%
5 Pylex, plus Turflon Ester, plus MSO
0.2 fl. oz/a 1 fl. oz./a 0.5% v/v
93%
99%
99%
100%
98%
98%
6 Revolver
17.4 fl. oz./a
56%
84%
97%
100%
99%
97%
20
25
36
24
28
28
LSD (P= .05)
Our research
This trial was conducted on an established stand of Tifway 419 bermudagrass. Four applications of Pylex treatments, spaced one week apart, or two applications of Revolver, two weeks apart, were made. For turf tolerance, the treatments were made on: • June 10, 2014, under 81˚F air temperature, 65% relative humidity and 30% cloud cover • June 17, 2014, under 84˚F air temperature, 65% relative humidity and 10% cloud cover • June 26, 2014, under 84˚F air temperature, and 20% cloud cover • July 2, 2014, under 88˚F air temperature and 20% cloud cover Goosegrass was grown in pots and treated at either the 2-to-3-leaf or 2-to3-tiller growth stage. In both situations, 4 applications of Pylex treatments or 2 applications of Revolver were made. Goosegrass was treated at a different time than bermudagrass.
1.0
2 Pylex, plus MSO
G
oosegrass is a troublesome weed in turfgrass, as it generally is more difficult to control than crabgrass species. We evaluated the potential for Pylex (topramezone) applied along or in combination with Turflon Ester (triclopyr) for goosegrass control and bermudagrass tolerance. We compared these treatments to Revolver.
24 | Virginia Turfgrass Journal May/June 2015 www.vaturf.org
Bermudagrass injury increased when the Pylex rate was increased or when Turflon Ester was added to Pylex (Table 1). Unacceptable injury to bermudagrass was noted at 3 days after the second application (3 DAT2), at 9 DAT2 and at 6 DAT3 from all treatments containing Pylex. At 16 days after 4 applications (16 DAT4), bermudagrass injury was at acceptable levels when Pylex was applied
alone but was unacceptable when Turflon Ester at 1 fl. oz./A was added to Pylex at either 0.1 or 0.2 fl. oz./A. Revolver did not cause any bermudagrass injury in this trial. Three applications of Pylex at 0.2 fl. oz./a with or without Turflon Ester gave essentially complete control of goosegrass when applied at the 2-to-3-leaf stage (Table 2). After 4 applications, Pylex applied alone at 0.1 fl. oz./A gave unacceptable control, but control was acceptable when Turflon Ester was added to that rate. Four applications of Pylex applied alone at either rate gave excellent control of 2-to-3-tiller goosegrass (Table 3). Adding Turflon Ester to Pylex at either rate resulted in poor control of tillered goosegrass. Additional research is needed to reduce bermudagrass injury while maintaining goosegrass control when
Table 3. Goosegrass control when treatments were applied to 2-to-3-tiller goosegrass. % Control at 2-to-3-Tiller Goosegrass
1 Untreated Check
8 DAT 1 DAT (2) 7/18/14
15 DAT 8 DAT (2) 7/25/14
21 DAT 6 DAT (3) 7/31/14
28 DAT 7 DAT (4) 8/7/14
36 DAT 15 DAT (4) 8/15/14
43 DAT 22 DAT (4) 8/15/14
0%
0%
0%
0%
0%
0%
2 Pylex, plus MSO
0.1 fl. oz./a 0.5% v/v
16%
51%
63%
86%
94%
93%
3 Pylex, plus Turflon Ester, plus MSO
0.1 fl. oz./a 1 fl. oz./a 0.5% v/v
14%
36%
33%
25%
29%
26%
4 Pylex, plus MSO
0.2 fl. oz./a 0.5% v/v
30%
65%
75%
99%
100%
100%
5 Pylex, plus Turflon Ester, plus MSO
0.2 fl. oz/a 1 fl. oz./a 0.5% v/v
16%
48%
64%
87%
94%
90%
6 Revolver
17.4 fl. oz./a
8%
43%
55%
55%
64%
53%
10
17
23
18
23
26
LSD (P= .05)
applying Pylex. Adding Turflon Ester to Pylex increases bermudagrass injury
and may antagonize the goosegrass control provided by Pylex. c
Journal of the Virginia Turfgrass Council
| 25
Research Report
Tenacity + Princep + Pennant Magnum for Goosegrass Control in Bermudagrass Table 1. Injury to Tifway 419 bermudagrass from the applied treatments. Tifway 419 Bermudagrass Injury (1–9 scale) (1 = no injury, 4 = unacceptable injury, 9 = complete death)
1 Untreated Check
3 DAT 7/25/14
9 DAT 7/31/14
16 DAT 3 DAT (2) 8/7/14
24 DAT 11 DAT (2) 8/22/14
31 DAT 18 DAT (2) 8/22/14
37 DAT 24 DAT (2) 8/28/14
45 DAT 32 DAT (2) 9/5/14
1.0
1.0
1.0
1.0
1.0
1.0
1.0
2 Tenacity, plus Princep, plus Capsil
5 fl. oz./a 8 fl. oz./a 0.25% v/v
AB AB
2.8
5.9
4.3
6.5
6.4
6.6
3.5
3 Tenacity, plus Princep, plus Pennant Magnum, plus Capsil
5 fl. oz./a 8 fl. oz./a 21 fl. oz./a 0.25% v/v
AB AB AB AB
2.8
6.6
4.5
6.6
6.4
6.6
3.1
4 Tenacity, plus Princep, plus Capsil
5 fl. oz./a 16 fl. oz./a 0.25% v/v
AB AB
2.8
5.4
4.0
6.6
6.0
6.3
2.9
5 Tenacity, plus Princep, plus Pennant Magnum, plus Capsil
5 fl. oz./a 16 fl. oz./a 21 fl. oz./a 0.25% v/v
AB AB AB AB
3.0
6.6
5.0
7.5
7.1
7.4
4.3
6 MSMA, plus Sencor
2 lb. ai/a 5.3 oz. wt./a
AB AB
4.0
2.5
2.8
2.8
4.9
5.3
2.6
0.6
1.1
0.6
0.9
0.8
0.6
0.7
LSD (P = .05)
Table 2. Injury to TifSport bermudagrass from the applied treatments. TifSport Bermudagrass Injury (1–9 scale) (1 = no injury, 4 = unacceptable injury, 9 = complete death)
1 Untreated Check
3 DAT 7/25/14
9 DAT 7/31/14
16 DAT 3 DAT (2) 8/7/14
24 DAT 11 DAT (2) 8/22/14
31 DAT 18 DAT (2) 8/22/14
37 DAT 24 DAT (2) 8/28/14
45 DAT 32 DAT (2) 9/5/14
1.0
1.0
1.0
1.0
1.0
1.0
1.0
2 Tenacity, plus Princep, plus Capsil
5 fl. oz./a 8 fl. oz./a 0.25% v/v
AB AB
2.0
3.4
2.3
4.4
2.4
1.5
1.0
3 Tenacity, plus Princep, plus Pennant Magnum, plus Capsil
5 fl. oz./a 8 fl. oz./a 21 fl. oz./a 0.25% v/v
AB AB AB AB
2.0
3.5
2.8
5.1
2.5
1.5
1.0
4 Tenacity, plus Princep, plus Capsil
5 fl. oz./a 16 fl. oz./a 0.25% v/v
AB AB
2.3
3.4
2.8
4.3
2.6
1.6
1.0
5 Tenacity, plus Princep, plus Pennant Magnum, plus Capsil
5 fl. oz./a 16 fl. oz./a 21 fl. oz./a 0.25% v/v
AB AB AB AB
2.3
3.4
2.8
5.3
2.9
2.0
1.1
6 MSMA, plus Sencor
2 lb. ai/a 5.3 oz. wt./a
AB AB
4.0
1.9
3.0
2.0
3.6
2.4
1.4
0.4
0.6
0.7
0.7
0.8
0.7
0.4
LSD (P = .05)
26 | Virginia Turfgrass Journal May/June 2015 www.vaturf.org
Research Summaries Virginia Tech Researchers: Jeffrey Derr, Ph.D., Professor of Weed Science, and Adam Nichols, Research Assistant, Hampton Roads Ag. Research and Extension Center, Virginia Beach Research Sponsors: Syngenta, The Virginia Turfgrass Council and The Virginia Turfgrass Foundation
G
oosegrass is a troublesome weed in turfgrass, as it generally is more difficult to control than crabgrass species. We evaluated the potential for combinations of (1) Tenacity (mesotrione) plus Princep (simazine) and (2) Tenacity plus Princep plus Pennant Magnum (metolachlor) for postemergence control of goosegrass and safety in bermudagrass. We compared these treatments to a combination of MSMA plus Sencor.
Our research
We evaluated these treatments in both Tifway 419 and TifSport bermudagrass. We made two applications of each treatment: • July 2, 2014, under 80˚F air temperature, 81% relative humidity and 0% cloud cover • August 4, 2014, under 77˚F air temperature, 89% relative humidity and 45% cloud cover
Research results
Applying Tenacity plus Princep or Tenacity plus Princep plus Pennant Magnum caused unacceptable injury to Tifway 419 bermudagrass (Table 1). Significant injury was still apparent 32 days after the second application. Adding Pennant Magnum to Tenacity plus Princep at 16 fl. oz./A increased the injury to Tifway 419. Less injury from these treatments was seen in TifSport bermudagrass. Unacceptable injury seen in this cultivar was diminished by 18 days after the second application, with no injury apparent at 32 days after the second application (Table 2). Bermudagrass cultivar has a significant impact on the tolerance of this species to Tenacity plus Princep. All treatments gave 95% or greater control of 2- to 3-leaf goosegrass after one application, and all treatments gave 100% goosegrass control after two applications. c
Controlling Japanese Stiltgrass in Lawn Turf Virginia Tech Researcher: John R. Brewer, Graduate Research Assistant, Shawn D. Askew, Ph.D., Associate Professor and Extension Turfgrass Weed Specialist, and Sandeep S. Rana, Doctoral Student
J
apanese stiltgrass (Microstegium vimineum) is a nonnative, grassy weed that has become a severe problem in the eastern United States. Native to Asia, Japanese stiltgrass was introduced to the U.S. in 1919 and can thrive in various types of environments from New York to Florida, including wetlands, woodlands, lawns, landscape beds and mountainous regions. Due to its flexible habitat tolerance and ability to grow under both shade and full sunlight, Japanese stiltgrass (JSG) is threatening native understory species. Research has been conducted to determine the most efficient and economical chemical or mechanical methods to control this weed. Studies in the past have used selective herbicides and mechanical controls, including fenoxaprop, imazapic, sethoxydim, mowing, hand-pulling and others, to evaluate Japanese stiltgrass control in natural areas such as wetlands and forest but not in a lawn or turf setting. Our study in Newport, VA, was conducted on a residential lawn to determine the most effective chemical means to control Japanese stiltgrass without injuring the desired turfgrass. The trial was initiated on August 15, 2014, on a mixed Kentucky bluegrass and tall fescue lawn. Initial Japanese stiltgrass cover in the lawn plots ranged from 30% to 80%. Treatments included: • Tenacity (mesotrione) at 8 oz./A once • Tenacity at 4 oz./A twice • Pylex (topramezone) at 1 oz./A once • Pylex 0.5 oz./A twice • Drive (quinclorac) at 1.33 lb./A once • Drive at 0.78 lb./A twice
• Acclaim Extra (fenoxaprop) at 28 oz./A once • Acclaim Extra at 14 oz./A once • Acclaim Extra at 7 oz./A once • Turflon (triclopyr) at 32 oz./A once • Tenacity at 8 oz./A plus Turflon at 32 oz./A once • Pylex at 1 oz./A plus Turflon once All treatments included an adjuvant (NIS or MSO) except Acclaim and Turflon. These treatments were applied with a hooded sprayer at 30 GPA and 3 mph. At 3 weeks after initial treatment (WAIT), Tenacity, Drive and Turflon controlled JSG less than 40%. Pylex at the low rate, combinations of Pylex or Tenacity with Turflon, and Acclaim at 14 or 28 oz./A controlled JSG at least 67%. At 6 WAIT, JSG had recovered from most treatments. Acclaim Extra at any rate completely controlled JSG. Pylex plus Turflon controlled JSG 75%, and all other treatments controlled JSG less than 50%. These data suggest that Acclaim Extra is the only herbicide that can completely control JSG with single applications. Interestingly, Acclaim Extra can completely control JSG regardless if the use rate is 7 oz./A or 28 oz./A. This discovery should help practitioners control JSG more economically than previously thought. c
Native to Asia, Japanese stiltgrass (Microstegium vimineum) has become a severe problem in the eastern United States. Journal of the Virginia Turfgrass Council
| 27
Research Summaries
Investigating the Mode of Action of Methiozolin: Cell Wall Biosynthesis Inhibition Versus Tyrosine Aminotransferase Inhibition
M
ethiozolin is a new herbicide developed by Moghu Research Center for the safe and selective removal of annual bluegrass (Poa annua) from creeping bentgrass putting greens. Although this herbicide has proven very effective at controlling annual bluegrass, there is some dispute as to the mode of action of this chemical. Previous research has presented evidence that methiozolin inhibits cell wall biosynthesis and that it may be an inhibitor of tyrosine
Demonstration of how 4-HPP feeding improves duckweed growth in presence of methiozolin but has no affect on Poa annua (annual bluegrass) response to methiozolin.
aminotransferase (TAT). TAT is an important enzyme in the pathway that creates tocopherols (Vitamin E compounds) and plastoquinones (molecules involved in photosynthesis). Since all previous research on methiozolin mode of action was conducted on model species, our goal was to test for proposed mode of action affects on annual bluegrass, the primary targeted weed of methiozolin. As reported in the literature, methiozolin inhibits the incorporation of 14C-labeled glucose into the cellulose and hemicelluloses fractions of the cell wall. To further investigate this effect, we utilized 13Cglucose, a different, stable isotope of carbon, to trace the incorporation of labeled glucose into the sugar constituents of the cell wall of annual bluegrass, creeping bentgrass, perennial ryegrass and tall fescue. Methiozolin inhibited 13 C- glucose incorporation into rhamnose, arabinose and galactose approximately 30%, regardless of species and equivalent to the known CBI, indaziflam. In addition, overcoming potential TAT inhibition
Roughstalk Bluegrass Control in Creeping Bentgrass and Kentucky Bluegrass Fairways Virginia Tech Researchers: Sandeep S. Rana, Doctorate Student, and Shawn D. Askew, Ph.D., Associate Professor and Extension Turfgrass Weed Specialist Researcher Cooperator: Suk J. Koo, Ph.D., Moghu Research Center, Daejeon, South Korea Research Sponsor: Moghu Research Center, Daejeon, South Korea
28 | Virginia Turfgrass Journal May/June 2015 www.vaturf.org
Virginia Tech Researcher: Kate Venner, Graduate Research Assistant, Shawn D. Askew, Ph.D., Associate Professor and Extension Turfgrass Weed Specialist, and Eva Colla’kova’, Assistant Professor Research Cooperator: Suk J. Koo, Ph.D., Moghu Research Center, Daejeon, South Korea Research Sponsor: Moghu Research Center, Daejeon, South Korea with 4-hydroxyphenylpyruvate (4-HPP) feeding had no influence on cell wall inhibition. Further research is warranted to determine if cellulose or hemicellulose sugars are affected differently, or if reduced incorporation is simply indicative of reduced growth via a different pathway. Several studies have been initiated investigating TAT inhibition as a potential mode of action of methiozolin. Previous research using a species of duckweed implicated TAT inhibition by feeding plants with exogenous 4-HPP, a downstream product of this pathway. As a result of this feeding, duckweed recovered from methiozolin treatment. In studies at Virginia Tech, we have been able to reduce methiozolin impacts on duckweed through 4-HPP feeding, but such feeding has had no influence on annual bluegrass or other turfgrass species response to methiozolin. Although these studies are not yet concluded, current data suggest that methiozolin may not affect TAT in turfgrasses like it does in duckweed, or 4-HPP can’t efficiently alleviate such effects. c
R
oughstalk bluegrass (Poa trivialis) is one of the most troublesome weeds of creeping bentgrass and Kentucky bluegrass fairways. Chemical control options for roughstalk bluegrass are limited in cool-season turf. Under development by Moghu Research Center, methiozolin (Poa Cure) is a new isoxazoline herbicide that has been reported in Virginia and Korea to control roughstalk bluegrass with safety to creeping bentgrass, perennial ryegrass, Kentucky bluegrass and tall fescue. Our objectives were to compare various application timings and
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tank mixtures of PoaCure for roughstalk bluegrass control in creeping bentgrass and Kentucky bluegrass fairways. Trials were initiated on October 22, 2013, on a creeping bentgrass fairway at the Pete Dye River Course of Virginia Tech (Radford, VA) and Highland Golf Course at Primland Resort (Meadows of Dan, VA), and on a Kentucky bluegrass fairway at the Glade Road Research Facility (Blacksburg, VA). Treatments included: • PoaCure at 52 or 78 fl. oz./A applied 4 times in fall or spring or 2 times in fall and spring • PoaCure at 52 fl. oz./A applied twice in fall followed by PoaCure plus primisulfuron at 0.5 oz./A or amicarbazone (Xonerate) at 2 oz./A applied in spring • primisulfuron or amicarbazone applied twice in spring • bispyribac-sodium (Velocity) at 2 oz./A (only at creeping bentgrass sites) applied twice in fall and spring
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All treatments were sprayed at twoweek intervals. Treatments also included a non-treated check for comparison. The interaction of location by treatment was insignificant for both roughstalk bluegrass control and turf cover, so data were pooled over locations for mean separation. One year after initial treatment (YAIT), fall and fall-followed-by-spring applications of PoaCure at 78 fl. oz./A controlled roughstalk bluegrass 90% and higher than PoaCure at 52 fl. oz./A at all applications timings, except fall applications of PoaCure at 52 fl. oz./A followed by PoaCure plus primisulfuron in spring (Figure 1). When tank-mixed with primisulfuron, PoaCure at 52 fl. oz./A controlled roughstalk bluegrass 88% and equivalent to fall or fall-followedby-spring applications of PoaCure at 78 fl. oz./A (Figure 1). The high rate of PoaCure controlled roughstalk bluegrass higher than PoaCure at the lower rate, regardless of application
Figure 1. Roughstalk bluegrass response to PoaCure at different application timings compared to Velocity, Xonerate and primisulfuron at one year after the initial treatment. Means with same uppercase letters are not significantly different according to Fisher’s Protected LSD at the 5% level of significance.
timing (data not shown). PoaCure did not injure the desired turf regardless of application rate and timing. Fall only and fall-followed-byspring applications of PoaCure had a turf cover of 80% to 90% and higher than primisulfuron or amicarbazone alone, 1 YAIT (data not shown). c Journal of the Virginia Turfgrass Council
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Turfgrass Calendar June 16
Pesticide Recertification (Regional Seminar)
Hampton, VA
June 23
Hampton Roads AREC Turfgrass Field Day, Pesticide Recertification and VCTP Exam
Hampton Roads AREC Virginia Beach, VA
July 15
UMD Turfgrass Field Day
University Turf Farm at the University of Maryland College Park, MD
July 19–21
PLANET Legislative Day on the Hill
Washington, D.C.
July 27 – August 1 Perennial Plant Symposium
Hilton Baltimore Baltimore, MD
August 2–6
StormCon — 2015 Conference
The Stormwater Pollution Prevention Conference JW Marriott Austin Austin, TX
August 25–26
VT / Blacksburg Turfgrass Field Days and VCTP Exam
Virginia Tech Blacksburg, VA
September 14
Bob Ruff Jr. Memorial Research Golf Tournament
Wintergreen Resort — Devils Knob Course Wintergreen, VA
Virginia Tech’s Turfgrass Researchers Shawn D. Askew, Ph.D.
Virginia Tech 435 Old Glade Road Blacksburg, VA 24061 (540) 231-5807 saskew@vt.edu Jeffrey F. Derr, Ph.D.
Virginia Tech Hampton Roads Agricultural Research Station 1444 Diamond Springs Rd. Virginia Beach, VA 23455 (757) 363-3912 jderr@vt.edu Erik H. Ervin, Ph.D.
Virginia Tech 339 Smyth Hall, CSES Dept. Blacksburg, VA 24061 (540) 231-5208 ervin@vt.edu Mike Goatley Jr., Ph.D.
Virginia Tech 420 Smyth Hall, CSES Dept. Blacksburg, VA 24061 (540) 231-2951 goatley@vt.edu David McCall
Index of Advertisers Agronomic Lawn Management..............29 www.fertilizewithalm.com Alliance Material Handling, Inc...............9 www.alliancemat.com BASF........................................................25 www.basf.com Bayer..........................................................5 www.bayerprocentral.com Brouwer Kesmac.....................................12 www.kesmac.com Buy Sod......................... Inside Back Cover www.buysod.com Collins Wharf Sod Farm.........................10 www.collinswharfsod.com Colonial Farm Credit..............................29 www.colonialfarmcredit.com Daniel Sod Farms....................................29 www.danielsodfarms.com Landmark Turf & Native Seed..............21 www.turfandnativeseed.com Leading Edge Communications.............11 www.LeadingEdgeCommunications.com Lebanon Turf...........................Back Cover www.countryclubmd.com Luck Stone Corporation...........................9 www.luckstone.com
Virginia Tech 435 Old Glade Road Blacksburg, VA 24061 (540) 231-9598 dsmccall@vt.edu
Modern Turf, Inc......................................6 www.modernturf.com
With Suppport from:
Smith Seed Services................................29 www.smithseed.com
Thomas P. Kuhar, Ph.D.
Virginia Tech Dept. of Entomology 216 Price Hall 170 Drillfield Drive Blacksburg, VA 24061 (540) 231-6129 tkuhar@vt.edu
January 25–28
Mid-Atlantic Turfgrass Expo
Fredericksburg Expo & Conference Center Fredericksburg, VA
30 | Virginia Turfgrass Journal May/June 2015 www.vaturf.org
Pennington Seed......... Inside Front Cover www.penningtonseed.com Progressive Turf Equipment, Inc..........15 www.progressiveturfequip.com
Southern States Cooperative....................3 www.southernstates.com The Turfgrass Group.........................7, 23 www.theturfgrassgroup.com
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