Virginia Turfgrass Council / P.O. Box 5989 / Virginia Beach, VA 23471 / ADDRESS SERVICE REQUESTED
Journal of the Virginia Turfgrass Council | May/June 2011
SEVENTH ANNUAL DIGEST OF TURFGRASS RESEARCH IN VIRGINIA RESEARCH ARTICLES 10 NTEP Trials for Creeping Bentgrass Putting Greens and Fairways 12 Identifying Candidate Herbicides for Moss Control 14 Considerations for Developing a Fungicide Program 18 Factors that Influence Brown Patch and Weeds in Tall Fescue 22 Effects of Tenacity and Drive on Tall Fescue and Bluegrass Establishment 24 New Chemistries and Timing Options for Managing Masked Chafers
SUMMARIES OF ADDITIONAL RESEARCH PROJECTS 26 Penthiopyrad Fungicide (Velista) New Fungicide Option for the Industry 26 Methiozolin, a New Herbicide for Poa Annua on Golf Putting Greens 27 Controlling Crabgrass with Corn Gluten Meal and Reduced Herbicide Rates 28 Sweet Vernalgrass Control with Mesotrione 28 DMI Influence on Suppression of Annual Bluegrass Seedheads
DEPARTMENTS 6 Director’s Corner
from Tom Tracy, Ph.D.
8 VTF Report
from Betty Parker
30 Contact Information for VT Researchers
30 Calendar of Events 30 Index of Advertisers
4 | VIRGINIA TURFGRASS JOURNAL May/June 2011 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 Melissa Reynolds Dura Turf Service Corp. (804) 233-4972 Vice President Frank Flannagan Belmont Golf Course (804) 501-5993 Treasurer Brian Vincel, CGCS Spring Creek Golf Club (434) 566-2580 Past President Rick Viancour, CGCS Golden Horseshoe Golf Club (757) 220-7489 VTC DIRECTORS Gil Grattan Vince Henderson Rick Owens, CGCS Marc Petrus Steve Slominski Steve Smith 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
Director’s Corner
WE’RE MAKING PROGRESS… Accomplishments and Ongoing Efforts Tom Tracy, Ph.D. VTC Executive Director
The
VTC takes a strong, proactive position of working with regulators, legislators and special-interest groups in our ongoing quest to fulfill our mission to unify efforts to promote turfgrass improvement and the advancement of the turfgrass industry in the Commonwealth of Virginia. Here are just a few of the many examples of our recent accomplishments. One, we worked closely with the Department of Conservation and Recreation to develop an urban component of its certified nutrient-management training program. Previously, the training focused on traditional agriculture, with attendees learning such things as how to calculate cubic feet of a hog-waste lagoon. Manure calculations are very important to farmers but have little bearing for urban areas. The new urban component was implemented in 2010, just in time to train planners who will be developing plans for a host of properties. For instance, by 2017, all golf courses in Virginia are required to have a nutrient management plan. Two, we worked with legislators and the Department of Agriculture and Consumer Services to develop the Certified Fertilizer Applicator Program (CFA). A result of legislation introduced in 2008, this program is the culmination of several years’ work. In a nutshell, the new program will require companies (and government agencies) that apply fertilizer to have, on staff, a certified fertilizer applicator to train all persons who apply fertilizer. The CFA program is still going through the regulatory process and may be tweaked a bit in the coming months, but it will become law sometime in the not-too-distant future. Three, many of us spent untold hours in Richmond during January and February working on reducing the myriad of fertilizer bills down to two that would be acceptable to the industry. The intensity of the effort was put into words by the President of the Virginia Senate who, when asked by one of the patrons to advance the bill that was the final result of all our efforts, said with a slight grin, “All in favor of approving this harmonious piece of legislation, please signify by saying ‘Aye.’” The bill passed. We will continue working for the industry, but we need your help! If you are not already a VTC member, please join. If you are a member, please consider upgrading your category (for instance, become a group member, if you’re currently joined as an individual). There is a whole lot more we want to do for you, but we are being held back by a lack of resources. Your membership is essential.
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VTF Report
Monitoring the
Seed Law Funds Betty Parker VTF Manager
R
ecently, the Virginia Department of Agriculture and the Virginia Turfgrass Foundation have discussed ways to monitor the fees that are collected in compliance with Virginia’s Seed Law established in 1994. There seems to be widespread confusion within the turf industry as to who is responsible for the license, registration and inspection fees that are being collected. In an effort to educate ourselves and protect this valuable fund that is used exclusively for turfgrass research, Dr. Jack Hall (who represents the turfgrass industry on the Virginia Agricultural Council) received the following explanation from Mr. Larry Nichols of the Virginia Department of Agriculture & Consumer Services (VDACS). “Virginia’s Seed Law and the Seed Fund can be found in Section 3.2–4000 et seq. of the Code of Virginia. Virginia’s Seed Law requires payment of license, registration and inspection fees to the Seed Fund.
License Fees Any person whose name appears on the label of seeds (grass, small grain, etc.) must obtain a license annually before distributing, selling or offering to sell such seed in the Commonwealth; this license fee is $50 per year.
Registration Fees Any person distributing lawn and turf seed mixtures in prepackaged containers of 100 lbs. or less must register the mixture annually. Typically, this registration fee is paid by the person whose name appears on the label (and is therefore licensed); this is an annual fee of $50 per lawn and turf seed mixture. (Note: this fee is only for lawn and turf seed mixtures. A ‘mixture’ is defined as ‘seeds consisting of more than one kind or variety, when claimed or present, in excess of five percent of the whole.’)
Inspection Fees Any person who introduces/distributes lawn and turf seed in Virginia must pay an annual inspection fee. Typically, this fee is paid by the person whose name appears on the label. (As a seed product is bought and sold, the last licensed person who sells the seed to an unlicensed person is responsible for paying the inspection fee. The last licensed person to sell the seed will be the person that has his or her name on the label.) This inspection fee is the greater of $35 per year or three-tenths of one percent of the gross sales receipts for lawn and turf seed sold during the year. In the Superstore A example below, the person who is required to pay the fees is determined by the name on the label of the seed: • If Superstore A is buying the seed mixture and repackaging it under the Superstore A label, then they (Superstore A) are required to obtain a license, register the seed products and remit the required inspection fees for those products. • If a person is selling to Superstore A, but retains their company name on the label, then the person/distributor who is selling to Superstore A must obtain a license, register their seed mixtures and remit the required inspection fees for those products. In this example, Superstore A is acting as a retailer for this product and is not required to meet licensing, registration and inspection fee requirements.” Jack Hall, Ph.D.
If you have any questions concerning Virginia’s Seed Law, please do not hesitate to call our office (757-574-9061), and if we can’t answer the question, we’ll direct you to someone who can.
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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 Š2011 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.)
Research Articles
NTEP TRIALS FOR CREEPING BENTGRASS Putting Greens and Fairways
Virginia Tech Researchers: Erik H. Ervin, Ph.D., Associate Professor, Turfgrass Physiology, with Dickie Shepherd (Senior Turf Technician, Dept. of Crop and Soil Environmental Sciences) and Mark Cote (Golf Course Superintendent, Pete Dye River Course of Virginia Tech) Sponsor: National Turfgrass Evaluation Program
Our
objective, over a 5-year-period, is to evaluate standard bentgrass cultivars against new lines of bentgrasses for adaptation to southwestern Virginia. As golf course budgets continue to tighten, cultivar selection can play a key long-term role in reducing maintenance costs in terms of fungicide, irrigation and thatch-control needs. These NTEP trials will provide critical selection information.
Research methods The fairway trial is being conducted on the beginning of the #6 fairway at the Pete Dye River Course (PDRC) of Virginia Tech. The area was treated with glyphosate twice in August 2008. The area was cored aggressively, and
plots were seeded on September 16. A starter fertilizer (20-27-10) was applied at 1.5 lbs. N/1,000 ft2. The putting green trial was seeded onto a fresh 90% sand/10% peat rootzone (meeting USGA specifications) on September 29, 2008, and fertilized with 9–20–98 to supply 1.0 lb. N/1,000 ft2/month. The maintenance personnel at PDRC maintained the fairway plots. The plots were mowed 3 times per week at 0.5", topdressed with sand in late fall 2009, fertilized the same as all other fairways and treated monthly with Trimitt (paclobutrazol), with diseases controlled curatively. The putting green trial there is mowed 5 times per week at 0.125", solid-tined and sandtopdressed in April and October and fertilized with approximately 4 lbs. N/1,000 ft2/year. Dollar spot is
Table 1. Bentgrass putting green, representative data for 2010 from the 2008 NTEP trial at the Turfgrass Research Center, Blacksburg. Entry
Declaration
Dollar Spot, 9 = none
Quality, 9 = best May
July
Oct
Oct
4.7
6.7
6.7
8.0
LTP-FEC
5.7
6.7
6.0
7.3
HTM
5.3
6.0
5.3
7.0
L-93
3.3
4.7
5.0
6.7
Penn A1
4.3
5.0
5.0
6.0
Penn A2
3.7
4.7
4.3
5.7
T1
4.3
3.3
3.7
5.0
Penncross
2.7
4.7
5.0
Villa*
3.3
3.3
LSD (0.10)
0.8
0.8
allowed to develop over the season, then rated and curatively controlled.
Research results (to date) In the putting green trial (see Table 1), some notable entries in terms of best overall quality are Declaration, LTP-FEC and HTM. Best entries in terms of dollar spot tolerance are Declaration and LTP-FEC. The velvet bentgrass entries in this trial quickly thinned and have become infested with creeping bentgrass. In the fairway trial (see Table 2), the entries with the best long-term quality are LTP-FEC, 007, HTM, Memorial, Authority and T-1. All of the colonial bentgrass entries (e.g., Greentime) have severely thinned from brown patch disease, while the creeping bentgrass entries have not.
Table 2. Bentgrass fairway, representative data for 2010 from the 2008 NTEP trial at the Pete Dye River Course of Virginia Tech. Entry
Brown patch, 9 = none
Quality, 9 = best May
July
Oct
July
007
7.3
7.3
8.0
8.7
Memorial
5.0
7.7
7.3
8.7
HTM
6.3
5.0
6.7
9.0
LTP-FEC
6.3
7.0
6.7
9.0
Authority
6.0
6.0
7.7
8.7
T-1
6.7
6.3
7.3
9.0
Declaration
5.7
5.7
6.3
9.0
L-93
6.3
6.0
7.0
8.7
6.3
Penncross
4.3
3.0
4.3
9.0
3.7
8.0
Greentime*
4.0
4.3
6.0
5.0
0.6
0.9
LSD (0.10)
1.1
1.0
0.7
0.8
*Villa is a velvet bentgrass; others are creeping. 10 | VIRGINIA TURFGRASS JOURNAL May/June 2011 www.vaturf.org
*Greentime is a colonial bentgrass; others are creeping.
Research Articles continued
Cover Story
IDENTIFYING CANDIDATE HERBICIDES FOR MOSS CONTROL Virginia Tech Researchers: Angela R. Post, Student; Shawn D. Askew, Ph.D., Associate Professor, Turfgrass Weed Science; and David McCall, Research Specialist, Plant Pathology, Dept. of Plant Pathology, Physiology and Weed Science Sponsors: The Virginia Turfgrass Foundation, The Virginia Turfgrass Council and The Virginia Agricultural Council
S
ince the loss of organometallic herbicides, we have seen an increase in the prevalence of silvery threadmoss (Bryum argenteum) as a weed in turf situations, especially on golf course putting greens. The loss of these herbicides, paired with golfer demand for faster playing surfaces, creates the perfect conditions on putting greens for moss establishment. Currently, only one professional herbicide, carfentrazone (Quicksilver), and three fungicides, chlorothalonil
(Daconil), mancozeb (Manzeb) and mancozeb + copper hydroxide (Junction) are labeled for moss control on putting greens. With this limited number of labeled products available, the golf industry has experimented with many off-label products with moderate success, including baking soda, lime, iron-containing fertilizers and Ultra Dawn dish detergent. Research to date has not provided a solid understanding of which chemistries work and which do not. The goal
of this research is to discover new options for silvery threadmoss control.
Our research A preliminary screening to evaluate herbicide effectiveness on silvery threadmoss was established to evaluate 49 herbicides at 1 and 2 times the labeled rate. Actively growing moss plugs approximately 1 cm in diameter were collected from a bentgrass putting green and separated into like groups for each of ten replicates. The
Photo 1. Procedure for high-throughput moss screen developed at Virginia Tech.
Ten replicate moss plugs were sprayed with herbicide for 99 unique treatments.
990 moss plugs were sorted to match a statistical randomization after being treated.
A device was built to take digital images of each 24-plug plate.
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Green cover of each moss plug was analyzed using computer software.
Research Cover Articles Stor y continued
replicate moss plugs were treated in a spray chamber calibrated to deliver 2 gal./1,000 ft2. They were then placed into 24-well cell-culture plates, where they remained for the duration of the study. Photos were taken at 0, 3, 7, 10, 14, 21 and 28 days after treatment (DAT). Data was captured in Sigma Scan Pro 5 and managed in ARM 8. Sigma Scan was set to count green pixels in a user-defined range, from hue = 40 to 100, and saturation = 0 to 100. When compared to the zeroday-after-treatment pixel counts, this provides a % reduction in green color for each moss plug, which we equate to a measure of control. Data were then statistically analyzed.
Research results At 3 DAT, carfentrazone reduced green color by 55%, and pelargonic acid reduced green color the most, by 89%. Other herbicides that significantly reduced green color included: flumioxazin, MSMA, glufosinate, sulfentrazone and an experimental herbicide that we are not yet at liberty to disclose. By 10 DAT, several herbicides reduced green color by above 90%, including flumioxazin, carfentrazone, fosamine, diquat and sulfentrazone. However, by this time,
algal growth over the moss plugs was significantly limiting our ability to attribute reduction in green color to herbicide activity versus algal growth. For example, the nontreated control plugs had 70% reduction in green color where no herbicide was applied. We completed the study despite the algal problem, and this preliminary screening supported previous literature reports that carfentrazone, flumioxazin and pelargonic acid effectively control silvery threadmoss. We were not able to support findings that oxadiazon and oxyfluorofen are effective. Several chemicals were added to the list of potential candidates for moss control, including an experimental product, MSMA, sulfentrazone and fosamine. Fungicide and surface sterilization screens were conducted and did not successfully solve the algal growth problem. Additional trials were conducted to adjust growing conditions of moss, and a protocol was developed where moss plugs are acclimated in growth chambers for one month prior to study initiation. Algal- or fungalinfected plugs are discarded prior to study initiation. Future work will use protocols that have been developed to grow moss
Photo 2. A sample plate showing herbicide treatment differences on moss plugs.
from vegetative fragments and other propagules to evaluate how various turf-protection products may influence moss colonization. Does a particular fungicide slow moss establishment? Do any plant growth regulators prevent moss colony expansion more than others? Culturing moss for experimental purposes is difficult, and these studies would be the first evaluation of how chemicals might influence moss colonization. Results of these studies may indicate that certain products, such as fungicides or PGRs, should be chosen over others because they help reduce the speed of moss colonization. We also have several biological organisms that selectively kill moss without harming creeping bentgrass, and studies are underway to evaluate their efficacy as biological moss control. We have identified the genus of one organism, and experienced plant pathologists at Virginia Tech indicate that our moss killer does not match any known species in that fungal genus. So, we will most likely be the first to characterize and describe this species for the scientific community. We will also hopefully kill more moss in the process!
Photo 3. A “top secret" biological organism that selectively kills moss has been discovered and is being evaluated by Dr. Askew's group and David McCall's lab at Virginia Tech.
Journal of the Virginia Turfgrass Council
| 13
Research Articles continued
CONSIDERATIONS FOR DEVELOPING A FUNGICIDE PROGRAM Virginia Tech Researchers: David McCall, Research Associate, Turfgrass Pathology, Dept. of Plant Pathology, Physiology and Weed Science Sponsors: 3Tier Technologies, BASF, Bayer Environmental Science, Floratine Products Group, QualiPro, Syngenta Crop Protection and Valent Professional Products
Many
good fungicide programs are the same, but they’re different. While that sounds like an oxymoron, it is actually a true description. Like opinions on the economy, different people have different views on what’s best. Life would be pretty boring if it were so simple that one spray program would be ideal for everyone. The reason this will never happen is because situations vary greatly from location to location,
budget to budget, season to season. Also, what passes the “eye test” for one individual may not for another. The turf pathology unit at Virginia Tech has been evaluating various season-long disease and stress management programs since 2006. Over time, programs have been tweaked, removed, added and completely revamped. This topic is generally one of the most common discussions I have with golf course superintendents throughout the off-season and leading into spring. Developing a spray program can go in many
Side-by-side comparison of some common fungicide programs. Each is disease free, but offers subtle differences that reflect personal preference. From left: Plots with (a) regular pigment incorporation typically appear greener, (b) growth regulation with DMI fungicides and trinexapac-ethyl have a “faster” bluish appearance and (c) non-pigmented, non-regulating fungicides are also healthy.
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directions. The programs we have evaluated over the years have been developed both in-house and by various manufacturers and distributors. Each program has its own strengths and weaknesses. Some of the factors that should be considered are discussed below.
Pigments The use of pigments to aid in stress and disease management is becoming much more common. Bayer Environmental Science has been the industry leader in this movement with their StressGard product line, though several manufacturers now offer their own options. As several physiological studies have demonstrated, there is undoubtedly more product involvement than simply coloring the turf. One of the best analogies for describing the effects of pigments on turfgrass is the use of sunscreen. Like with sunscreen, these pigments coat (and absorb into) leaf tissue and protect the plant from stress, such as UV degradation. Pigments available as pre-mixtures that have been tested at VT include: fosetyl-Al (Signature), triticonazole (Triton Flo), triticonazole + chlorothalonil (Reserve), iprodione + trifloxystrobin (Interface) and triadimefon + trifloxystrobin (Tartan). Some pigments are purchased independent of fungicides and are tank-mixed by the end user. Generally speaking, most benefits are seen when applied prior to stress and after multiple applications.
Cover Stor y continued
DMI fungicides The DMI fungicides have been around for decades now, yet they still remain a major weapon for controlling turf diseases. Some of the older active ingredients are used less today, but they still have an important place in the industry. Several new fungicides in this class are now available and include metconazole (Tourney), tebuconazole (Torque) and triticonazole (Trinity and Triton Flo). As with any product, each of these newer fungicides has its own set of pros and cons. In my experiences, I have seen less growth regulation, and improved brown patch and anthracnose activity, compared with propiconazole. However, propiconazole typically has superior dollar spot control over these new products. There is no lack of evidence on the abilities of propiconazole as a strong fungicide. The primary side effect of propiconazole applications during the summer time is growth regulation. The decision on whether or not to make this a routine tool is a matter of personal preference. I talk with some superintendents who love the regulation, stating that they feel it increases uniformity and ball roll. Others are scared to death of it when temperatures rise into the mid-80s and above. I don’t recall any situation where turf actually died from labeled rate applications, but clearly notice the growth regulation.
Early season fungicides Many superintendents are making early season applications with DMI fungicides or boscalid to control dollar spot. There is a growing pool of evidence at VT and other universities that this early application can delay the onset of disease and reduce the rate of disease development throughout the season. One of the concerns with an early
Journal of the Virginia Turfgrass Council
| 15
Research Articles continued
season dollar spot application, however, is the interaction with plant growth regulators (PGR) used for seedhead suppression. Several researchers at Virginia Tech have ongoing projects looking to address this concern. Some preliminary results are presented in this research edition (see page 28), although more thorough descriptions should be available in the future.
Resistance management The best strategies for reducing the likelihood of resistance have been discussed for years. The most common approaches are (a) rotating with different chemical classes, (b) tank-mixing with contact fungicides or (c) a combination of both. I recommend a combination of both alternating chemistries and tankmixing with contact fungicides, like
chlorothalonil. The reason for tankmixing with a contact fungicide is that most of these attack fungi at multiple sites, resulting in a greatly reduced likelihood of developing resistance. Contact fungicides also typically have a rapid knockdown of fungi on the leaf surfaces.
Cultural practices While cultural practices are their own set of variables, there is great interaction in the overall management against diseases. This past summer, many of the golf courses that experienced severe turf loss were those where the superintendent was unable to practice sound cultural strategies. In most cases, this was no fault of his or her own; budgets were cut, aerification was skipped for various reasons, fertility
was decreased, and key preventive fungicide applications were bypassed. In our evaluations, nutrition played an important role in the plants’ abilities to withstand biotic and abiotic stresses. In nearly all cases, plots receiving adequate nutrition have had less dollar spot and anthracnose. This is not new information. Some of the more common diseases today include dollar spot, anthracnose and brown ring patch. With each of these diseases, the common factor is that severity is increased when nutrition is limited. As with fungicides, there is no magic number or product. Needs vary from situation to situation. However, if these diseases continue to be problematic, it may be a good natural indicator for what needs to be addressed.
Conclusion Heading into battle against summer, developing a good spray program can be very beneficial, but it is important to understand that what is written on that paper or computer screen is far from the be-all and end-all for the season. One of the best quotes I heard while working with Dr. Brandon Horvath (formerly at Virginia Tech) was a lesson he learned during his time in the turf disease lab at Michigan State: IPM plans are great in January, not July. This was especially true last season, when most of the Commonwealth experienced a historically brutal summer. The plans were in place heading into the season, but it all went out the window once the heat settled in. There is no way of predicting weather conditions months in advance, but history can at least point us in the right direction. Both chemical and cultural strategies are like football; you go into the game with a specific game plan, but you almost always need to make some in-game adjustments to counteract what the opposing team does.
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Research Articles continued
MAINTENANCE PRACTICES that Influence BROWN PATCH and WEED ENCROACHMENT IN TALL FESCUE Virginia Tech Researchers: Matthew Cutulle, Graduate Research Assistant; Jeffrey F. Derr, Ph.D., Professor of Weed Science; and Adam E. Nichols, Research Assistant (all at Virginia Tech’s Hampton Roads Agricultural Research and Extension Center, Virginia Beach); David McCall, Turfgrass Pathologist (Virginia Tech, Blacksburg); with Brandon Horvath, Ph.D., Assistant Professor of Plant Pathology (University of Tennessee, Knoxville) Sponsors: The Virginia Turfgrass Foundation and The Virginia Agricultural Council
Tall
fescue is one of the most commonly grown turfgrasses for home lawns and other lowermaintenance turf areas in the United States. Tall fescue’s popularity is attributed to a deep root system (drought tolerance), relatively low nitrogen requirements and a resistance to most diseases. However, one pest in tall fescue is the fungal pathogen Rhizoctonia solani, which infects tall fescue stands during hot, humid conditions when tall fescue is already under summer stress. The subsequent disease, brown patch, is aesthetically unpleasing and can thin out the turfgrass stand, leading to the germination and encroachment of winter annual weeds such as annual bluegrass and summer weeds such as crabgrass. We have been investigating the impact of maintenance practices on brown patch and subsequent weed infestations. Typically, tall fescue is overseeded in the fall, so applying preemergence herbicides to control annual bluegrass is not an option. Currently, there is no postemergence herbicide option for controlling emerged annual bluegrass in tall fescue in the spring. One potential postemergence herbicide for control of annual bluegrass in tall fescue, however, is bispyribac-sodium (Velocity). Unfortunately, preliminary reports indicate that applications of
bispyribac-sodium to cool-season grasses increase susceptibility to brown patch, thus promoting the consequential increase of summer disease and fall weed encroachment. Chitinase activity is positively correlated with resistance to R. solani in rice; thus, if applications of bispyribacsodium reduce chitinase activity in tall fescue, it may be responsible for increased brown patch. Hybrid bluegrass may be an alternative grass to grow in the transition zone. Hybrid bluegrass cultivars have been developed from crosses between Kentucky bluegrass (Poa pratensis) and Texas bluegrass (Poa arachnifera). Hybrid bluegrass has the desirable qualities of Kentucky bluegrass (i.e., color, quality and brown patch resistance), but it was bred to have increased heat and drought tolerance. However, hybrid bluegrass requires more fertility and may not establish as quickly as tall fescue. Our hypothesis is that combining hybrid bluegrass (which is resistant to brown patch) with tall fescue (which establishes quickly) will reduce overall disease severity and weed encroachment, thus leading to reduced fungicide and herbicide inputs while maintaining turf quality.
Impact of mowing and fertilization scheduling In ‘RTF’ tall fescue, we evaluated 2
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mowing heights (2.5" and 4"), 3 levels of fertility (1, 3.5 and 4.5 lbs. of nitrogen per 1,000 ft2 annually) and Ronstar G (oxadiazon) application versus no preemergence crabgrass herbicide. Three common bermudagrass plugs (4" in diameter) were transplanted to each plot. We measured bermudagrass diameter, brown patch disease severity and turf quality over time. The experiment was conducted twice in Virginia Beach, once in Blacksburg and once in Knoxville.
Results Plots that did not receive Ronstar had significantly more southern crabgrass than the plots that were treated. Crabgrass became so severe in the plots mowed at 2.5" with no Ronstar that it outcompeted both tall fescue and common bermudagrass. When plots were treated with Ronstar, mowing at 2.5" resulted in greater bermudagrass spread compared to plots mowed at 4" when averaged across all levels of fertility (see Table 1). There seemed to be a trend for increased bermudagrass growth with increased fertility in the 2.5" mowing height. For the 4" mowing height, the reverse was true — increased fertility lead to decreased bermudagrass encroachment. Mowing at 2.5" with high fertility resulted in significantly more brown
Research Articles continued
patch than any other treatment combination (see Table 2). Overall, mowing at 4" resulted in better visual quality, and we would recommend this mowing height with the use of a preemergence herbicide in tall fescue turf. Mowing at 2.5" and not applying a crabgrass preventer resulted in almost total loss of tall fescue within one growing season. Applying some nitrogen fertilizer to tall fescue in late summer may aid in its recovery from brown patch.
Table 1. Impact of mowing height and fertility on bermudagrass diameter in August 2009.
Mowing Height
Fertility
Bermudagrass Diameter
Letter Group
2.5 inch
low
52.55 cm
B
2.5 inch
med
53.66 cm
B
2.5 inch
high
66.60 cm
A
4 inch
low
32.8 cm
C
4 inch
med
30.7 cm
C
4 inch
high
30.3 cm
C
Impact of Velocity Research was conducted at Virginia Tech’s Hampton Roads AREC in Virginia Beach to evaluate the impact of Velocity rate and timing on annual bluegrass control and brown patch severity in tall fescue. The study was established in the spring of 2009 and repeated in 2010. Tall fescue plots were treated with bispyribac-sodium (Velocity) applied at 15 or 30 grams per acre on April 22 or May 22, with a repeat application two weeks later. Plots were mowed at 4" and received 3 lbs. N/1,000 ft2. Annual bluegrass, turf quality and brown patch cover ratings were taken.
Results – impact on annual bluegrass control In the 2009 study, annual bluegrass cover was 18% on June 19 in the untreated control plots. Applying bispyribac-sodium at 30 grams active ingredient/acre in April dramatically reduced annual bluegrass cover to only 1%. Decreasing the application rate to 15 g/acre in April resulted in 4% annual bluegrass cover. Applications in May resulted in 15% annual bluegrass cover when 15 g/acre of bispyribac-sodium was applied and 11% annual bluegrass cover when 30 g/acre was applied. In 2010, bispyribac-sodium applications did not effectively control annual bluegrass. Untreated check plots contained 40% annual bluegrass on
Table 2. Impact of mowing height and fertility on percent brown patch in August 2009.
MOWING HEIGHT
FERTILITY
% BROWN PATCH
LETTER GROUP
2.5 inch
low
22%
B
2.5 inch
med
20%
B
2.5 inch
high
28%
A
4 inch
low
12%
C
4 inch
med
13%
C
4 inch
high
15%
C
June 22. Applying bispyribac-sodium in April resulted in 31% and 26% annual bluegrass cover when treated with 15 g/acre and 30 g/acre, respectively. Plots treated in May with 15 g/acre had 35% annual bluegrass cover. Increasing the herbicide rate to 30 g/acre resulted in 23% annual bluegrass cover in June. The lack of effective annual bluegrass control in the spring of 2010 compared to the spring of 2009 may be
attributed to more rain in the fall of 2009 versus 2008 and a cooler spring in 2010 compared to 2009. Thus, annual bluegrass growth was more robust in 2010 compared to 2009, making this weed harder to control in 2010.
Results – impact on brown patch Applying bispyribac-sodium in May resulted in increased brown patch in both studies, while April applications did not increase disease severity.
Journal of the Virginia Turfgrass Council
| 19
Percent brown patch in the untreated check in 2009 was 40%, and 41% in plots treated in April. However, applying bispyribac-sodium in May increased brown patch to 63% when 15 g/acre was applied and 60% brown patch when 30 g/acre was applied. Less brown patch was observed in 2010 than 2009. On June 22, 2010, 10% brown patch was recorded in the untreated plots. Application of bispyribac-sodium in April increased brown patch severity to 15%, regardless of rate. Applications of bispyribacsodium in May resulted in 23% brown patch when treated with 15 g/acre. When the herbicide rate was increased to 30 g/acre in May, brown patch severity increased slightly to 24%. In our greenhouse study, all tall fescue plants treated with bispyribacsodium had more brown patch when compared to the untreated plants. Also, treated plants treated exhibited more shoot growth six weeks after application compared to the untreated check. Tall fescue treated with bispyribac-sodium had less chitinase activity than the untreated check. Tall fescue’s increased susceptibility to brown patch when treated with bispyribac-sodium may be attributed to two things: • Increased shoot growth three to six weeks after the herbicide is applied. This creates succulent young growth during warm, humid conditions, which are conducive to brown patch infection. • Application of bispyribac-sodium results in a small reduction in chitinase activity and increases general stress to tall fescue, making it more susceptible to disease infection.
Results – impact on quality On June 19, 2009, plots treated with bispyribac-sodium in April had higher quality ratings than the untreated check because they were darker green. May applications of bispyribac-sodium resulted in lower quality ratings than the untreated
20 | VIRGINIA TURFGRASS JOURNAL May/June 2011 www.vaturf.org
Research Articles continued
check. A flush of green growth was exhibited about 6 weeks after bispyribac-sodium application. The green flush of growth was not observed at any time during the 2010 study. Bispyribac-sodium can cause temporary injury and growth suppression in tall fescue, but as the turf outgrows the injury, it may have a higher quality than untreated turf. If temporary injury can be tolerated, tall fescue appears to have acceptable tolerance to Velocity. Since May applications may increase brown patch severity, earlier applications would be preferable.
Combinations of tall fescue and hybrid bluegrass for reduced pesticide inputs
cultures of tall fescue. Brown patch infestations were highest in the monoculture of tall fescue. The high brown patch severity observed in the summer of 2009 thinned out the monoculture of tall fescue, leading to weed encroachment in November 2009. Tiller counts taken in February 2008 indicated an approximate 1 to 1 ratio of the two turf species when tall fescue was seeded at 3 lbs./1,000 ft2 with 1.13 lbs./1,000 ft2 of hybrid bluegrass. At the higher seeding rate of tall fescue with the lower seeding rate of hybrid bluegrass, the ratio was approximately 4 tillers of tall fescue to 1 tiller of hybrid bluegrass. Biannual tillers taken in 2009 and 2010 showed a species shift favoring hybrid bluegrass. By five years after seeding, very little tall fescue remained,
probably due to both drought and brown patch infections, and hybrid bluegrass dominated the combination plots. Without additional inputs, monocultures of hybrid bluegrass cannot outcompete annual and perennial weeds, while monocultures of tall fescue are susceptible to summer drought and disease. Combinations of hybrid bluegrass with tall fescue result in lower weed density compared to monocultures of hybrid bluegrass, as well as lower brown patch incidence compared to monocultures of tall fescue. Thus, there are advantages to combining these two species. Over time, however, overseeding with tall fescue may be necessary if one wishes to maintain a blend of tall fescue and hybrid bluegrass, since hybrid bluegrass will become dominant.
Our research utilized the cultivars ‘Greenkeeper’ tall fescue and ‘Thermal Blue Blaze’ hybrid bluegrass. Plots were seeded with four treatments: • 6 lbs./1,000 ft2 Greenkeeper alone • 2.25 lbs./1,000 ft2 Thermal Blue Blaze alone • 5.4 lbs./1,000 ft2 Greenkeeper with 0.6 lbs./1,000 ft2 Thermal Blue Blaze • 3 lbs./1,000 ft2 Greenkeeper with 1.13 lbs./1,000 ft2 Thermal Blue Blaze These plots were established in fall 2006 and fall 2008 at Virginia Tech’s Hampton Roads AREC. All plots were mowed at 4" and received 3 lbs. N/1,000 ft2/year. Percent turfgrass cover, weed cover, brown patch severity and tiller counts were taken from the plots throughout the year. No preemergence herbicides were applied to this trial.
Results Tall fescue germinated more quickly than hybrid bluegrass, resulting in greater weed density in hybrid bluegrass monocultures. Weed cover in the combination seeding treatments was similar to that seen in mono-
Journal of the Virginia Turfgrass Council
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Research Articles continued
EFFECTS OF TENACITY AND DRIVE on Tall Fescue and Bluegrass Establishment Virginia Tech Researchers: Jeffrey E. Derr, Ph.D., Professor of Weed Science, and Adam E. Nichols, Research Assistant, Virginia Tech’s Hampton Roads Agricultural Research and Extension Center, Virginia Beach Sponsors: The Virginia Turfgrass Foundation and The Virginia Agricultural Council
G
rowing cool-season turfgrasses in the transition-zone climate of southeast Virginia in the summer is a challenge. While tall fescue (Festuca arundinacea) establishes fairly quickly and has both the heat and drought tolerances to survive these summers, its susceptibility to brown patch (Rhizoctonia solani) presents a major problem in home lawns or other turf areas. Kentucky bluegrass (Poa pratensis) has very desirable characteristics and is not susceptible to brown patch, but it has poor heat and drought tolerance. Kentucky bluegrass is also slow to establish, resulting in weed encroachment that leads to density and uniformity problems. With the release of the new hybrid bluegrasses (Poa pratensis x arachnifera), the desirable characteristics of Kentucky bluegrass have been matched with the heat tolerance of Texas bluegrass. However, the hybrid bluegrasses establish slowly, leaving new plantings susceptible to weed encroachment. Until the introduction of Drive (quinclorac), the only preemergence herbicide option at the time of seeding cool-season turf was Tupersan (siduron). Drive (quinclorac), however, cannot be used at seeding time of Kentucky bluegrass. Tenacity (mesotrione) has recently been introduced for use in seeded and established Kentucky bluegrass and certain other cool-season grasses. Tenacity controls a range of annual broadleaf weeds and, thus, will be of benefit when seeding slowestablishing turf species such as Kentucky bluegrass. Tenacity may also have utility in hybrid bluegrass.
This study examined the effects of Drive, Tenacity and the combination of the two herbicides on the establishment of tall fescue, Kentucky bluegrass and four hybrid bluegrasses.
Our research ‘Greenkeeper’ tall fescue, ‘Midnight’ Kentucky bluegrass and ‘Solar Green’, ‘Dura Blue’, ‘Thermal Blue’ and ‘Thermal Blue Blaze’ hybrid bluegrasses were seeded on October 14, 2008. The tall fescue was seeded at 6 lbs./1,000 ft2, while all of the bluegrasses were seeded at 2.25 lbs./1,000 ft2. Fertility was applied at the time of seeding at a rate of 0.75 lbs. N/1,000 ft2 from an 18–24–12 fertilizer. Fertilizer applications were repeated three more times in November, March and May. Trimec Classic was also applied in May to remove uncontrolled broadleaf weeds. Treatments were applied the day after seeding. Tenacity was applied at a rate of 0.25 lb. active ingredient/ acre. Drive was applied at a rate of 0.75 lb. ai/acre. The combination was applied at the individual rates. Percent turf cover and percent weed cover were rated periodically from December through May. We have continued to maintain these plots, allowing us to determine long-term persistence of these cultivars. We repeated the entire trial in the fall of 2009.
Research results By the beginning of December in the first trial, the faster-establishing tall fescue had 86% cover in the control and Tenacity plots (Table 1). All of the
22 | VIRGINIA TURFGRASS JOURNAL May/June 2011 www.vaturf.org
bluegrasses were at half of the cover of the tall fescue in the untreated and Tenacity plots. All plots receiving Drive and the combination of Drive plus Tenacity had far less turf cover, especially in the bluegrass plots. The lower turf cover was due to noticeable stunting of growth by the Drive component. Due to the lack of parsely-piert (Alchemilla microcarpa) control, potentially combined with increased weed encroachment due to lower turf cover, plots treated with Drive alone had as much weed cover as the untreated plots in February (Table 2). At this same time, the Tenacity and Tenacity plus Drive treated plots were nearly weed-free. We observed excellent preemergence control of hairy bittercress, henbit, common chickweed, cudweed and parsley-piert with Tenacity at three months after treatment. By April, turf cover in all species, for both untreated and Drive plots, were lower than the December ratings due to high weed cover. The Tenacity plots had greater turf cover than the Drive and untreated plots, but they did have a large amount of white clover (Trifolium repens), while the Tenacity plus Drive plots remained nearly weed-free. At this time, the hybrid bluegrasses had less turf cover than tall fescue in the Tenacity plots. Following a Trimec Classic application in early May to remove broadleaf weeds, another turf cover rating showed how much turf was underneath the weed cover. The untreated and Tenacity plots in all the species had greater than 90% cover. The Drive
Research Cover Articles Stor y continued
and combination plots without weed competition had less turf cover, again due to stunting caused by Drive. When evaluated one-and-a-half to two-and-a-half years after seeding, we observed that three of the hybrid bluegrass cultivars (Solar Green, Thermal Blue and Thermal Blue Blaze) all had similar cover to Greenkeeper tall fescue. Midnight Kentucky bluegrass was at less than 25% cover, indicating that this species is not suited for southeastern Virginia. Dura Blue’s cover was intermediate between the Kentucky bluegrass and the other three hybrid bluegrasses. Although having lower cover than the other hybrid bluegrasses in the trial, Dura Blue has a darker green color and a more compact growth habit than the other hybrid bluegrasses tested.
Conclusions Hybrid bluegrass has acceptable tolerance to Tenacity at seeding time, while Drive causes noticeable stunting of growth. The response of hybrid bluegrass is thus similar to that for Kentucky bluegrass. Tenacity provides excellent control of winter annual broadleaf weeds, allowing for quicker turf establishment. While adding Drive to Tenacity at seeding broadens the weed-control spectrum (including control of white clover), this combination also stunts hybrid bluegrass growth. A better approach would be to apply Tenacity alone at seeding, followed by an application of a postemergence broadleaf herbicide for clover in the spring. A crabgrass treatment would also be needed in spring or summer. Currently, Tenacity is registered for use in most cool-season turf situations. The hybrid bluegrasses tested have greater adaptability in Tidewater Virginia than Kentucky bluegrass does. They tolerate the environmental conditions in a similar fashion as tall fescue. In another longer-term trial, we have seen ‘Thermal Blue Blaze’ hybrid bluegrass persist longer than Greenkeeper tall fescue, probably due to brown patch reducing the stand of tall fescue.
Table 1. Turf Cover Ratings for all Treatments and Varieties COVER (%) TREATMENT
VARIETY
December
April
May
Untreated
‘Greenskeeper’ TF
86
60
99
Drive
‘Greenskeeper’ TF
63
22
95
Tenacity
‘Greenskeeper’ TF
86
93
99
Tenacity+Drive
‘Greenskeeper’ TF
53
88
94
Untreated
‘Midnight’ KB
35
14
94
Drive
‘Midnight’ KB
27
27
73
Tenacity
‘Midnight’ KB
40
80
95
Tenacity+Drive
‘Midnight’ KB
21
80
74
Untreated
‘Solar Green’ HB
39
23
96
Drive
‘Solar Green’ HB
24
26
77
Tenacity
‘Solar Green’ HB
46
81
96
Tenacity+Drive
‘Solar Green’ HB
22
88
86
Untreated
‘Thermal Blue’ HB
41
24
97
Drive
‘Thermal Blue’ HB
28
33
82
Tenacity
‘Thermal Blue’ HB
43
84
97
Tenacity+Drive
‘Thermal Blue’ HB
26
93
88
Untreated
‘Dura Blue’ HB
31
4
96
Drive
‘Dura Blue’ HB
21
10
70
Tenacity
‘Dura Blue’ HB
34
73
96
Tenacity+Drive
‘Dura Blue’ HB
18
70
76
Untreated
‘Thermal Blue Blaze’ HB
45
7
98
Drive
‘Thermal Blue Blaze’ HB
28
23
82
Tenacity
‘Thermal Blue Blaze’ HB
44
72
99
Tenacity+Drive
‘Thermal Blue Blaze’ HB
24
90
88
Table 2. Weed Cover Ratings COVER (%) TREATMENTS
FEBRUARY WEED
APRIL CLOVER
APRIL PARSLEY-PIERT
Untreated
27 a
28 a
32 b
Drive
28 a
0c
67 a
Tenacity
1b
19 a
0c
Tenacity+Drive
0b
0c
0c
LSD (p=0.05)
3
7
9
Journal of the Virginia Turfgrass Council
| 23
Research Articles continued
NEW CHEMISTRIES and TIMING OPTIONS for MANAGING MASKED CHAFERS Virginia Tech Researchers: Rod Youngman, Ph.D., Professor; Curt Laub, Research Associate; and Shaohui Wu and W. R. Kuhn, Dept. of Entomology Sponsors: Virginia Turfgrass Foundation
Table 1. Site data, VAC/VTF soil insecticide efficacy trial, 2010. SITE NO. AND LOCATION
COUNTY
TURFGRASS VARIETY/MIXTURE
1. Tazewell Country Club
Tazewell
Fescue 80%, bluegrass 20%
2. Auburn Hills Golf Club
Montgomery
Fescue 80%, bluegrass 20%
3. Virginia Tech Turfgrass Research Center
Montgomery
100% Penncross bentgrass
M
asked chafers seem to be more prevalent than other common white grub species in turfgrass lately. From our efficacy trials conducted over the past several years, we know that masked chafers have mostly been the dominant species. This trend continued in 2010. Of the three sites in which we placed our white grub efficacy trial (Table 1), white grub pressure was high enough in one of the sites to make a meaningful analysis of the data.
Our research The treatments used in these trials are listed in Table 2. Early applications were applied on April 16 at site one, April 23 at site two and April 15 at site three. Late applications were applied on July 19 at site one and on July 20 at sites two and three. Liquid insecticide treatments were applied as foliar sprays. At sites one and three, approximately 1/2" of overhead irrigation water was applied immediately after treatments were applied. At site two, no irrigation was applied. White grub counts (per square foot) were taken on September 17 (site one), September 29 (site two) and October 1 (site three). In each treatment plot, one 1 square foot section of turf (1" deep) was examined.
Research results At site 1 (Tazewell), 116 identifiable white grubs were collected, and they were identified as follows: 83 (71.6%) masked chafers (Cyclocephala spp.), 22 (19%) Japanese beetles (Popillia japonica), 8 (6.9%) May or June beetles (Phyllophaga spp.), 2 (1.7%) Asiatic garden beetles (Maladera castanea) 24 | VIRGINIA TURFGRASS JOURNAL May/June 2011 www.vaturf.org
Research Articles continued
and 1 (0.9%) green June beetle (Cotinis nitida). The treatment source of variation for white grubs was highly significant (P = 0.0040). The density of white grubs in the untreated check was significantly higher than in the early Acelepryn 1.67 SC treatment and both early and late Aloft treatments (Table 3). At site two, because zero white grubs were detected in the untreated check plots, the treated plots were not sampled. At site three, all plots were sampled, but zero white grubs were detected experiment-wide. Phytotoxicity was not observed in any plot over the course of the experiment. DuPont Product Development representative Dr. Chuck Silcox recommends applying Acelepryn 1.67SC at the low white grub rate of 8 oz./acre early in the season, rather than later, to take advantage of the moist conditions that spring typically provides. The idea is to move the active ingredient in Acelepryn down into the thatch and soil layers. A DuPont dissipation study (Figure 1) shows that the active ingredient remains active at 0.1 lb./acre or higher for five months. Our findings (Table 3) tend to confirm this for the early application of Acelepryn 1.67SC. Both timing options for Aloft GCSC also gave superior control of white grubs.
Table 2. Treatment list for 2010 turfgrass soil insecticide efficacy trials, Tazewell and Montgomery Counties, Virginia. TRT. NO.
APPLICATION TIMING1
APPLICATION RATE (AMT. PRODUCT/ACRE)
1
Early
Acelepryn 1.67 SC
8.0 fl. oz.
2
Early
DPX-HGW86 20SC
8.0 fl. oz.
3
Early
Aloft GCSC
11.65 fl. oz.
4
Early
Merit 75 WP
6.4 oz.
5
Early
Safari 20SG
32.0 oz.
6
Late
Acelepryn 1.67 SC
8.0 fl. oz.
7
Late
DPX-HGW86 20SC
8.0 fl. oz.
8
Late
Aloft GCSC
11.65 fl. oz.
9
Late
Merit 75WP
6.4 oz.
10
Late
Safari 20SG
3.2 oz.
Untreated Check
—
11 1
TREATMENT/FORMULATION
Early Application — Site 1: April 16; Site 2: April 23; Site 3: April 15. Late Application — Site 1: July 19; Sites 2 and 3: July 20.
Table 3. White grub counts, 2010 turfgrass soil insecticide efficacy trials, Tazewell and Montgomery Counties, Virginia.
Figure 1. DuPont Acelepryn turfgrass dissipation results.
1 2
SITE NUMBER AND LOCATION1
TREATMENT/FORMULATION/TIMING2
WHITE GRUBS PER SQ. FT. (± SEM)
1: Tazewell Country
Untreated check
8.13 (2.38) a
Safari 20SG Early
6.00 (2.27)
Safari 20SG Late
5.00 (2.65)
DPX-HGW86 20SC
2.75 (1.89)
DPX-HGW86 20SC Late
2.00 (2.00)
Merit 75WP Early
1.25 (0.75)
Merit 75WP Late
1.00 (0.71)
Acelepryn 1.67SC Early
0.25 (0.25) b
Acelepryn 1.67SC Late
0.75 (0.75)
Aloft GCSC Early
0.00 b
Aloft GCSC Late
0.00 b
Zero white grubs were detected at sites two and three; therefore data are not presented here. Early Application — Site one: April 16; Site two: April 23; Site three: April 15. Late Application — Site one: July 19; Sites two and three: July 20.
Journal of the Virginia Turfgrass Council
| 25
Additional Research Summaries
PENTHIOPYRAD FUNGICIDE (VELISTA) New Fungicide Option for the Industry Virginia Tech Researcher: David McCall, Research Associate, Turfgrass Pathology, Dept. of Plant Pathology, Physiology and Weed Science Sponsor: DuPont Professional Products
Control of anthracnose basal rot with Velista.
The
turfgrass industry should have a new fungicide product available sometime in the coming year. DuPont is expected to release penthiopyrad (DPX LEM 17) under the trade name Velista. This fungicide belongs in the same class as flutolanil (Prostar) and boscalid (Emerald). Penthiopyrad’s unique feature is that it has activity against a wider range of turf pathogens than either flutolanil or boscalid. Flutolanil is highly effective for management of basidiomycete fungi (brown patch, fairy ring and red thread). Boscalid is used primarily for controlling dollar spot, and it has virtually no activity against basidiomycetes. Penthiopyrad,
on the other hand, has activity against both of these groups and more. This product has been tested extensively at Virginia Tech for several years. Activity against three of the most common turf diseases (dollar spot, brown patch and anthracnose) compares favorably with common standards, with no reported phytotoxicity. Control of summer patch looks promising, although little data is available at this time. Since this is a single-site mode of action, resistance will almost assuredly arise in the future. The most effective way to address this is rotation with different classes of fungicides, such as the DMI or strobilurins (QoI), and/or tank mixture with a contact fungicide.
METHIOZOLIN, A NEW HERBICIDE FOR Poa Annua CONTROL ON GOLF PUTTING GREENS Virginia Tech Researchers: Shawn D. Askew, Ph.D., Associate Professor, and Brendan McNulty, Graduate Student, Turfgrass Weed Science, Dept. of Plant Pathology, Physiology and Weed Science Sponsors: The Virginia Turfgrass Foundation and The Virginia Agricultural Council
M
ethiozolin (MRC-01) is a new herbicide that was recently registered for use on golf putting greens in South Korea. This herbicide was first sprayed in the U.S. by Dr. Shawn Askew at Spotswood Country Club near Harrisonburg, VA. For the past two years, only Virginia Tech and Auburn University have evaluated methiozolin, and results have been astounding. Last fall, researchers at other universities began evaluating
this herbicide, and it has performed well across the U.S. Methiozolin kills annual bluegrass (Poa annua), crabgrass, goosegrass and roughstalk bluegrass, and it is safe for use on creeping bentgrass putting greens and all other species of cool- and warm-season turf. Dr. Askew was invited to a pre-submission meeting with the U.S. EPA last June, and methiozolin will probably be available for U.S. markets as early as 2013 or 2014. It will be primarily
26 | VIRGINIA TURFGRASS JOURNAL May/June 2011 www.vaturf.org
used on golf putting greens. In the future, the herbicide may be used on fairways or lawns for control of annual bluegrass or roughstalk bluegrass. Moghu Research Center, the Korean company that is developing this herbicide, has agreed to send $98,000 in research funding to Dr. Askew to partially support a Ph.D. student that will work on understanding the mode of action and mechanism of selectivity of methiozolin starting in spring 2011.
Additional Research Summaries continued
CONTROLLING CRABGRASS IN COOL-SEASON TURF with Corn Gluten Meal and Reduced Herbicide Rates Virginia Tech Researcher: Adam Smith, Graduate Student, and Shawn D. Askew, Ph.D., Associate Professor, Turfgrass Weed Science, Dept. of Plant Pathology, Physiology and Weed Science
For
homeowners, lawncare operators and publicrecreation field managers desiring and/or needing to reduce the amount of pesticides they use, corn gluten meal (CGM) has become a popular herbicide alternative. A byproduct of corn processing, CGM is sold as a granular-applied organic preemergent herbicide. Research has shown that CGM, applied at 975 kg/ha, can achieve partial weed control. For some, partial
weed control is not sufficient, so subsequent CGM applications are made. CGM is 9% nitrogen, and in coolseason turf, one application of CGM exceeds the VA spring nitrogen application recommendation. To minimize the risk of nitrogen over-fertilization while improving weed control, CGM was impregnated with the label rates of prodiamine, pendimethalin, oxadiazon and dithiopyr, and applied as a granular product on cool-season turf. Treatments were applied once or as a split application.
Nontreated plots had, on average, 40% smooth crabgrass cover. Several herbicide/CGM combos reduced crabgrass cover. Prodiamine/CGM applied once provided the best control (7.5% cover). Only prodiamine combinations resulted in smooth crabgrass cover under 10%. The results suggest that some herbicides can be mixed with CGM to improve crabgrass control. Experiments will continue this coming summer.
Journal of the Virginia Turfgrass Council
| 27
Additional Research Summaries continued
SWEET VERNALGRASS CONTROL with Mesotrione Virginia Tech Researcher: Adam Smith, Graduate Student, and Shawn D. Askew, Ph.D., Associate Professor, Turfgrass Weed Science, Dept. of Plant Pathology, Physiology and Weed Science
S
weet vernalgrass is a perennial grass common in unmanaged pastures and meadows. Previously, it has not been a weed problem in managed turf systems except in lawns and athletic fields with a high cutting height. However, it easily adapts to new environments and is highly competitive in the spring with a rapid growth rate, early flowering and allelopathic suppressive ability. This year, the Virginia Weed Clinic saw an increase in the number of sweet vernal-
grass samples in lawn-height turf, from both homeowners and sod growers across the state. It was also a problem reported across the Northeast. Sweet vernalgrass is difficult to control in cool-season turf, where we are seeing it as an emerging weed problem. We conducted an experiment to evaluate herbicide options for sweet vernalgrass control in lawn-height tall fescue. We applied seven herbicide treatments at a sod farm near Richmond, Virginia. At 34 days after treatment
(DAT), MSMA at 2.1 kg ai/ha, mesotrione applied once at 0.28 kg ai/ha and mesotrione applied twice at 0.14 kg ai/ha were the best treatments controlling sweet vernalgrass by 73%, 63% and 57%, respectively. (Other treatments included fenoxaprop, quinclorac, amicarbazone, methiozolin and sulfentrazone, but none provided adequate control of sweet vernalgrass.) By 71 DAT, control from MSMA declined to 40%, whereas mesotrione applied twice gave 67% control. A single application at the full labeled rate of mesotrione provided the best control at 100%. No treatment significantly injured or reduced the density of tall fescue. The rapid growth of sweet vernalgrass in spring may explain why a single application of mesotrione performed best. The timing of applications during the most rapid phase of growth will likely pay an important role in the level of control.
DMI Influence on Suppression of ANNUAL BLUEGRASS SEEDHEADS Virginia Tech Researchers: David McCall, Research Associate, Turfgrass Pathology, Dept. of Plant Pathology, Physiology and Weed Science, and Shawn D. Askew, Ph.D., Associate Professor, Turfgrass Weed Science, Dept. of Plant Pathology, Physiology and Weed Science
To
reduce the impact of annual bluegrass seedheads on golf putting greens, many superintendents apply plant growth regulators (PGRs) to suppress their development. Timing is critical for successful suppression. Common indicators for proper timing are growing degree day models (GDD50) and the blooming of forsythias. These indicators are also useful for timing early season dollar spot applications, which delay the epidemic and slow the rate of development. Demethylation inhibiting fungicides (DMI) are among the most commonly used for this purpose. Several within this group have growthregulating properties, however, which concerns some turf managers about their interaction with PGRs used for seedhead suppression.
We developed a study at the Virginia Tech Golf Course in 2010 to test these interactions. Fungicides included fenerimol (Rubigan), metconazole (Tourney), myclobutanil (Eagle), propiconazole (Banner Maxx), triadimefon (Bayleton) and triticonazole (Trinity). Growth regulators included mefluidide (Embark, Em) and a tank mixture of ethephon (Proxy) + trinexapac-ethyl (Primo Maxx). The timing of application for each was based on GDD50 models, with initial PRGs applied on April 1 and DMIs applied on April 14. In addition to seedhead suppression and dollar spot development, health measurements were collected by visual estimation of turf quality (1–9 scale) and spectral analysis with normalized difference vegetation index (NDVI), and relative vegetative index (RVI).
28 | VIRGINIA TURFGRASS JOURNAL May/June 2011 www.vaturf.org
As expected, Em was the most efficient at seedhead suppression, but it also resulted in the poorest quality turf for nearly six weeks. Although the Proxy/Primo Maxx tank mixture reduced seedhead development to a lesser extent than Em, it had the highest plant health measurements of all treatments. Though insignificant, there was a consistent trend across five ratings that most DMIs had fewer seedheads than untreated plots. Propiconazole and triadimefon had the greatest reductions. Both NDVI and RVI spectral analysis indicated that of all treatments, those containing Proxy/Primo Maxx had the highest quality, and those containing Em had the lowest quality. Health of all DMIs alone were comparable to untreated plots, with propiconazole and triadimefon trending to the least quality. This study will be repeated in 2011.
Photo 1. Lawn-height tall fescue infested with sweet vernalgrass.
Photo 2. Lawn-height tall fescue previously infested with sweet vernalgrass, 71 days after treatment with mesotrione at 0.28 kg ai/ha.
Index of Advertisers
Calendar of Events
Turf Industry Events
Basf . . . . . . . . . . . Inside Front Cover www.basf.com
May 24
July 17–18
August 30–31
Pesticide Recertification Gypsy Hill Park Gymnasium Staunton, VA
ANLA Annual Meeting (American Nursery & Landscape Assn.) Liaison Capital Hill Washington, DC
Turfgrass Field Day Blacksburg, VA
June 7 Bob Ruff Jr. Memorial Golf Tournament Wintergreen Lower Course Wintergreen, VA
June 14 Pesticide Recertification Bruton Heights Bldg. Williamsburg, VA
June 28 Turfgrass Field Day and Pesticide Recertification Hampton Roads AREC Virginia Beach, VA
July 18–22 TPI Summer Convention & Field Days (Turfgrass Producers International) Grand Sierra Resort Reno, NV
January 16–19, 2012 VTC 52nd Annual Turf & Landscape Conference and Trade Show Fredericksburg Expo & Conference Center Fredericksburg, VA
July 19 Pesticide Recertification Expo and Conference Center Fredericksburg, VA
Buy Sod, Inc. . . . . . . . . . . . . . . . . . . 5 www.buysod.com Collins Wharf Sod Farm . . . . . . . 15 www.collinswharfsod.com E & S Soil and Peat . . . . . . . . . . . 20 www.eandssoil.com East Coast Sod & Seed . . . . . . . . . 11 www.eastcoastsod.com Egypt Farms, Inc. . . . . . . . . . . . . . . . . 29 www.egyptfarms.com FMC Professional Solutions . . . . . . . 17 www.fmcprosolutions.com Growth Products, Ltd. . . . . . . . . . . . . 21 www.growthproducts.com Luck Stone Corporation . . . . . . . . 9 www.luckstone.com Mid-Atlantic Sports Turf . . . . . . . 16 Modern Turf, Inc. . . . . . . . . . . . . 24 www.modernturf.com Oakwood Sod Farm, Inc. . . . . . . . 15 www.oakwoodsod.com
Contact Information
Quali-Pro . . . . . . . . . . . . . . . . . . . . . 3 www.quali-pro.com
Virginia Tech’s Turfgrass Researchers 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 Station 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
30 | VIRGINIA TURFGRASS JOURNAL May/June 2011 www.vaturf.org
RBB Sales & Consulting, Inc./ Turf Landscape Consultants . . . . 15 www.rbbturflandscapeconsultants.com Roxbury Farm & Garden Center . . . . . . . . . . . . . . . 20 www.roxburyfarmgarden.com Southern States Cooperative . . . . 29 www.southernstates.com Texas Sod Leasing . . . . . . . . . . . . 27 www.texassod.com The Turfgrass Group . . .7, Back Cover www.theturfgrassgroup.com Winfield Solutions, LLC . . . . . . . . . . .5 Wood Bay Turf Technologies . . . . . . .9 www.woodbayturftech.com Woodward Turf Farm Inc. . . . . . .20, Inside Back Cover www.woodwardturf.com