The Official Publication of the Tennessee Turfgrass Association and the Tennessee Valley Sports Turf Managers Association
The Official Publication of the Tennessee Turfgrass Association and the Tennessee Valley Sports Turf Managers Association
TA B L E O F C O N T E N T S AUGUST/SEPTEMBER 2007
F E AT U R E D A RT I C L E S
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12 Cover Story
Overseeding for Success on Bermudagrass Sports Fields Turf Basics — Value-Based Assessment of Turfgrass Fertilizers Applied Research — The Facts on HerbicideResistant Weeds Turf Tips — Crumb-Rubber Topdressing for Athletic Fields
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Turf Basics
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Turf Tips
Turf Talk — The Rules, Your Golf Course and Your Staff
D E PA RT M E N T S
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From the TTA President, Bill Francis
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From the TVSTMA, Al Ray
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News from the TTA
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TTA Scholarship Information
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Calendar of Events
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Index of Advertisers
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TENNESSEE TURFGRASS
AUGUST/SEPTEMBER 2007
Email TTA at: tnturfgrassassn@aol.com
FROM THE PRESIDENT BILL FRANCIS
reetings from Upper East Tennessee! Hopefully, conditions are much improved as we enter the downhill run of the season. At the time I wrote this, rain was pouring down on the Midwest, but we could not get more than a drop in East Tennessee. As a matter of fact, the measly .75" we did manage to receive during the month of May broke the all-time record at the Tri Cities Regional Airport. Is it just me, or is there really no such thing as a normal year? The TTA Marketing Committee, led by Shelia Finney, has been working hard to put together a TTA website. I am happy to announce that, with a tremendous amount of help from Rodney Tocco of The University of Tennessee, we now have an official TTA website at www.ttaonline.org. Within the site, you will find useful information such as membership and scholarship applications, a schedule of statewide events and many other useful links. In addition, there is an area for sales and trades where members can list — free of charge — equipment for sale or purchase. Similarly, there is an additional link for job postings, which members may post at no charge. We hope that you will take advantage of these options by simply contacting the
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webmaster with your listings. Although the website is up and running, it is not necessarily complete, so it will be an ongoing project. We will try to keep the information timely and fresh. Therefore, be sure and check it out the next time you are online. For those of you who were unable to attend the Field Day and Education Conference at the University of Tennessee back in May, you certainly missed a good one. I think I can speak for many others who were there when I say that this was the best one yet. The research facility is ever improving, and the education portion the second day was tremendous. Dr. Sorochan, Dr. McElroy, Dr. Samples and the other fine individuals affiliated with the turfgrass program at UT are causing people to take notice of the program there. The energy and ideas that these individuals bring forth is exciting, and the progress that has been made over the last five years definitely deserves our continued support. In closing, please don’t forget to check out the website. We feel this can be a valuable aspect of your membership. As with anything new, though, it will take some time to “get it right.” Therefore, as always, we welcome your feedback and comments.
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The Official Publication of the Tennessee Turfgrass Association and the Tennessee Valley Sports Turf Managers Association
Tennessee Turfgrass is the official publication of The Tennessee Turfgrass Association 400 Franklin Road Franklin, Tennessee 37069 (615) 591-8286 tnturfgrassassn@aol.com Published by Leading Edge Communications, LLC 206 Bridge Street Franklin, Tennessee 37064 (615) 790-3718 Fax (615) 794-4524 Email:info@leadingedgecommunications.com Editor Mr. Bobby Stringer Scientific Editor Dr. J. Scott McElroy TTA OFFICERS President Mr. Bill Francis The Ridges Golf & CC (423) 913-2276 Vice President Mr. Bob Hogan The Hogan Company (888) 224-6426 Secretary/Treasurer Mr. Bobby Stringer Germantown Country Club (901) 754-7755 Past President Mr. Jeff Case (901) 373-4344 Executive Secretary Mr. Jim Uden (615) 591-8286 TTA 2007 BOARD OF DIRECTORS Mr. Cory Blair Ms. Shelia Finney Mr. Roger Frazier Mr. Mickey Lovett Mr. Bill Marbet Mr. Bob McCurdy Mr. Scott McNeer Mr. Tommy Mittlesteadt Mr. Scott Morgan Mr. Mitch Parker Mr. Robert Stroud Mr. Frank Turner TTA ADVISORY MEMBERS OF THE BOARD Mr. Bill Blackburn Dr. J. Scott McElroy Mr. Lynn Ray Dr. Tom Samples Dr. Dennis Shepard Dr. John Sorochan
FROM THE TVSTMA
I
hope everyone enjoyed a successful spring and summer sports season. It was a busy and exciting one in Middle Tennessee, with the high school baseball state championships and Vanderbilt University hosting regional baseball action the following weekend. Congratulations to all the host sites. The facilities were in terrific shape, and I heard many compliments from competitors, fans and administrators from all areas of the state and the country. The mark of TVSTMA members was evident at every venue, and it was a showcase of their talents. Speaking of Middle Tennessee, thanks to area Program Chair Marty Kaufman, CSFM, for arranging our mid-state area Field Day on June 7. Marty and Ensworth School were gracious hosts, and we appreciate the opportunity to visit their fine facilities. A lot of work goes into organizing these events. Doing so around a busy schedule, in a professional manner, and pulling together such a special group of speakers and presenters is quite a feat. Such efforts continue to increase awareness of the value of trained professionals in the appearance, safety and playability of our athletic surfaces. Field quality is the first impression made upon visitors, and often, it is a big part of the memories they take with them when they leave. A well-maintained and well-groomed athletic field is a reflection on your organization and your community. Pride is contagious. Make your fields something to be proud of, and that pride will perpetuate itself. Keep up the good work, continue to communicate with your administrators, share with others and always encourage TVSTMA membership. It is showing on our fields, and it substantiates the importance of what we do. As we ready ourselves for fall sports, remember our active members when making your plans. There are a lot of good products, services and advice available and offered by professional and commercial members who put a lot of effort into our organization. If you believe in TVSTMA, take advantage of these resources that we are so fortunate to have at our fingertips. I look forward to seeing everyone in Greenville for our Upper East Tennessee Field Day on August 10 as arranged by Tom Garner. Until then, good luck to all! Al Ray TVSTMA President
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TENNESSEE TURFGRASS
AUGUST/SEPTEMBER 2007
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The Tennessee Turfgrass Association 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, Tennessee Turfgrass Magazine, or its editors. Likewise, the appearance of advertisers, or Turfgrass Association members, does not constitute an endorsement of the products or services featured in this, past or subsequent issues of this quarterly publication. Copyright Š2007 by the Tennessee Turfgrass Association. Tennessee Turfgrass is published bi-monthly. Subscriptions are complimentary to members of the Tennessee Turfgrass Association. POSTMASTER: Send change of address notification to Tennessee Turfgrass Association, 400 Franklin Road, Franklin, TN 37069. Postage guaranteed. Presorted standard postage is paid at Franklin, TN. Printed in the U.S.A. Reprints and Submissions: Tennessee Turfgrass allows reprinting of material. Permission requests should be directed to the Tennessee Turfgrass Association. 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 37064, (615) 7903718, Fax (615) 794-4524.
N E W S F R O M T TA Who Would You Select As TTA Professional of the Year? Do you know an outstanding turfgrass professional in Tennessee who deserves the recognition of his or her peers? If so, now’s the time to let the TTA know who you believe should receive one of the association’s highest honors — the TTA Professional of the Year Award — at the TTA Annual Conference and Tradeshow this coming January. Please take a moment to mail in the nomination form below. Nominees will be reviewed by the TTA Awards & Scholarship Committee, which will make a recommendation for approval by the TTA Board of Directors. Nominations must be postmarked no later than October 1, 2007.
TTA Professional of the Year Nomination Form Person Being Nominated: __________________________________________________________________________________ Person Making the Nomination: ______________________________________________________________________________ Reason for Nomination: ____________________________________________________________________________________ ________________________________________________________________________________________________________ ________________________________________________________________________________________________________ Nominations must be postmarked no later than October 1, 2007. Please mail nominations to: Tennessee Turfgrass Association 400 Franklin Road Franklin, TN 37069
COVER STORY
By Adam Thoms, Graduate Student; John Sorochan, Ph.D.; Scott McElroy, Ph.D.; and Tom Samples, Ph.D.; University of Tennessee
A
lthough fall is a critical time for many athletic fields to look and perform at their peak conditions, the ever-changing weather of the season can pose a real challenge for sports-turf managers. To combat the drop in temperatures — which can cause bermudagrass fields to start going dormant and, consequently, begin losing color and their ability to quickly recover from wear — many turf managers overseed their fields with perennial ryegrass for the cooler months. Timing The first step in overseeding is finding a window of opportunity to overseed during the season. Many field managers elect to overseed when the field will not be hosting an event for a couple of weeks, allowing for the seed to germinate and start maturing. Other field managers choose to put the seed out right before a game or practice, to allow the players to work the seed into the ground. Timing on some fields is based on field managers first allowing annual bluegrass (Poa annua) to germinate in early fall, applying a herbicide like Revolver or Monument to remove it and then overseeding the field the same day. Eliminating annual bluegrass can really improve a field’s aesthetics and playability, if your budget will allow for it to be managed this way. Still other field managers like to time overseeding with field aerification. They first overseed into the aerification holes and then follow up with an application of topdressing to improve seed-to-soil contact. The last aerification should be done 30 days before the bermudagrass goes dormant, so that it has time to recover from the stress before winter temperatures descend.
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TENNESSEE TURFGRASS
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CONTINUED Overseeding rates and improving germination Overseeding rates can range from as little as 4 to 6 pounds per 1,000 sq. ft. to as much as 20 pounds per 1,000 sq. ft. When selecting the rate, keep in mind not only how much money is in your budget for overseeding but also how quickly the field will host an event; often, the sooner the event, the higher the seeding rate you should likely select. In addition, when considering the seeding rate, keep in mind that not all of the seeds will germinate or survive because of competition from the existing bermudagrass and because of potential wear from an upcoming event. The next step to overseeding is to stand the bermudagrass upright, to improve the ability of the seed to fall down through the turf and into the soil, allowing for better seed protection and growing conditions. Some field managers will rake or sweep the field to try to stand the bermudagrass up for overseeding. Other field managers will first verticut or run groomers aggressively over the bermudagrass and then apply the perennial ryegrass with a slit seeder to get the seed into the soil. Remember that the more you disturb your bermudagrass, the longer it will need for spring recovery; therefore, avoid
The turf plots in the center of this photo show how much faster annual ryegrass grows than perennial ryegrass varieties, which are surrounding the annual ryegrass plots. You can also clearly see the difference in color and quality between annual and perennial varieties.
TENNESSEE TURFGRASS ASSOCIATION • TENNESSEE VALLEY SPORTS TURF MANAGERS ASSOCIATION
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COVER STORY
In this research study, conducted on the football practice field at The University of Tennessee in Knoxville, we compared the color and quality of various varieties of perennial, annual and intermediate ryegrasses.
scalping the turf. Many turfgrass managers think that scalping the bermudagrass is necessary in overseeding, but it does a lot of damage to the bermudagrass, which, in turn, takes longer to heal/recover in the spring. Scalping also allows for openings in the turf canopy for weed seeds to germinate. Instead, simply standing the bermudagrass upright will allow the overseeding to fall through the canopy without causing stress/damage to the bermudagrass, while still ensuring ideal seed-to-soil contact. Also, sand topdressing can be applied at the same time as overseeding to help even the playing surface and to provide some extra seed-to-soil contact. After overseeding, roll the field with some sort of a lightweight roller to further enhance seed-to-soil contact. Rolling is one of the most important steps to help ensure successful germination of the perennial ryegrass. Since compaction is a big concern on athletic fields, use a lightweight roller, and roll only when the soil is not saturated (too wet).
Additional considerations Another component to successful overseeding is good fertility. Applying a starter fertilizer with adequate phosphorous levels will help provide nourishment for the ryegrass seedlings as they develop. Applications of nitrogen throughout the fall and early spring can keep healthy-looking turf throughout the year. If you are considering overseeding, be sure have your field free of any pre-emergent herbicides for at least 30 days beforehand, to allow the overseeding to germinate. Always read the labels before applying any herbicide prior to and after overseeding.
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After the Tennessee Titan’s field is overseeded, the perennial ryegrass provides the opportunity for attractive striping.
After overseeding, water becomes a necessity for the perennial ryegrass to come up quickly and evenly. Light and frequent irrigation schedules during the grow-in period are essential for the perennial rye to establish quickly. Often, this means that, for three to seven days after overseeding, you should make sure that the field’s soil remains moist. This is especially important during windy and low-humidity days, which may rapidly dry the soil surface. In some cases, your event schedule may allow for no break in field use for the overseeding process; thus, you may need to take steps to speed up the process. To shorten germination times, you can soak the perennial ryegrass seed for two days before application to the field; be sure, however, to change the water on the seeds at least twice a day. Then, mix the seed with sand topdressing (4 parts sand to 1 part seed) and apply the mix to the field. Finally, you get what you pay for, and selecting improved perennial ryegrass varieties will boost the success of your overseeding program. Although cheaper and faster to establish, annual ryegrass and intermediate ryegrass (annual ryegrass x perennial ryegrass) varieties should be avoided. Annual and intermediate ryegrasses do not hold up to traffic as well as the perennial ryegrass; therefore, in the long run, more overseeding will be necessary. In addition, the annual ryegrass and intermediate ryegrass grow much faster vertically, requiring more frequent mowing. Hopefully, these steps can make your athletic field play well and look great, even right after the overseeding process.
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TURF BASICS
By Tom Samples, Ph.D., and John Sorochan, Ph.D., The University of Tennessee, and Brad Jakubowski, The University of Nebraska
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TENNESSEE TURFGRASS
AUGUST/SEPTEMBER 2007
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CONTINUED
Photo 1. Cross-section of a monocot (grass) root showing the: (a) epidermis, (b) cortex, (c) phloem, (d) xylem, (e) vascular bundles and (f) pith. Photo courtesy of Phil Wadl.
ncreases in the cost of crude oil usually result in rising fertilizer prices. Perhaps now more than ever, to optimize turfgrass health within the constraints of their budget, turfgrass and landscape managers must focus on the seasonal fertility requirements of turfgrasses, the nutrient levels in the soil and plant tissue, and the particle size, uniformity and cost of granular fertilizers. In this first part of a three-part series on turfgrass nutrition, we introduce the 16 essential plant elements that are macronutrients or micronutrients in turfgrass nutrition. In the second part, we will describe the function of these macro- and micronutrients, with an emphasis on the consequences to turf appearance and performance of either too little or unavailable plant nutrients. Finally, in part three, we will list several common resources that provide these essential plant nutrients. The nutritional needs of turfgrasses and other plants are not met simply by adding a scoop of N, P and K macronutrients to soils. Just like humans, plants and turfgrasses also require small quantities of several “minor” elements, or micronutrients, for healthy growth and maintenance of aesthetic qualities.
I
Roots of healthy turfgrasses are ideally suited for taking up nutrients from soils. The fibrous root systems of turfgrasses have a very large surface area that is surrounded by a nutrient-rich solution in soil. Once inside a root, nutrients are transported through the vascular xylem to other areas of the plant. Several “mobile” nutrients, as well as sugars produced in leaves and stems, move through a second portion of the vascular system, the phloem (Photo 1). Nitrogen, phosphorus and potassium are classified as primary macronutrients, based on the large amounts of each required by turfgrasses. Although no more or less important than the others, primary macronutrients are the ones most commonly applied when a turf is fertilized. Turfgrasses require more N than P and K,
The essential elements for turfgrass health Turfgrasses require at least 16 essential elements to survive and reproduce. Air and water supply the carbon, hydrogen and oxygen necessary for photosynthesis (the conversion of sunlight to chemical energy). Soil furnishes the remaining 13 essential macroand micronutrients, which are nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), boron (B), chlorine (Cl), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo) and zinc (Zn) (See Table 1). Some researchers also recognize nickel as the eighth essential micronutrient.
Photo 2. Well-fertilized and healthy tall fescue turf.
TENNESSEE TURFGRASS ASSOCIATION • TENNESSEE VALLEY SPORTS TURF MANAGERS ASSOCIATION
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TURF BASICS Table 1. Essential Mineral Elements Required by Turfgrasses (See Table 2 on pages 22-23.)
Chemical Symbol
Ionic Form Absorbed by Plants
Nitrogen
N
NO3 , NH4
Phosphorus
P
H2PO4 , HPO4
Potassium
K
K
Calcium
Ca
Ca
Magnesium
Mg
Mg
Sulfur
S
SO4
Element
Mobility in Plants, Comments
MACRONUTRIENTS a Classification/Quantity Required Primary/ Largest
Secondary/ Medium
–
+
–
Mobile 2–
Mobile
+
Mobile
2+
Immobile
2+
Mobile
2–
Mobile
MICRONUTRIENTS a Classification/Quantity Required –
Primary/ Largest
H2BO , Boron
B
2–
HBO 3 ,
Immobile
3–
BO 3 , Probably does not become a structural part of organic molecules in turfgrasses.
–
Chlorine
Cl
Cl
Copper
Cu
Cu
Iron
Fe
Fe
Manganese
Mn
Mn
Molybdenum
Mo
MoO4
Zinc
Zn
Zn
2+
Content is highest in actively growing tissue.
2+
Immobile
2+
Immobile
2–
Concentration is highest in the leaf blade; tends to accumulate as plants reach maturity.
2+
Immobile
a Each of the 16 essential elements is categorized as a macronutrient (primary or secondary) or a micronutrient, based on the amount required by turfgrasses. The concentration of a macronutrient in turfgrass dry matter must be > 1,000 parts per million. Nitrogen, P, K, Ca, Mg and S, in addition to carbon, hydrogen and oxygen, are macronutrients. The concentration of each micronutrient in dry turfgrass tissue is often < 100 ppm. b Nickel, in addition to the seven micronutrients listed here, is also considered essential. 20
TENNESSEE TURFGRASS
AUGUST/SEPTEMBER 2007
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and more K than P. Although the movement of N, P and K varies in soils, once inside a plant, all three may be mobilized, moving from one plant part to another (Table 2, pages 22â&#x20AC;&#x201C;23). Calcium, magnesium and sulfur are secondary macronutrients. Turfgrasses require less of these three essential minerals than N, P and K. Magnesium and sulfur are mobile in plants, but calcium is not. As a result, symptoms of Mg and S deficiency first appear on old leaves from which these nutrients have moved. Symptoms of calcium deficiency appear on new leaves, while older leaves containing adequate Ca levels remain functional and green. Micronutrients, sometimes referred to as trace elements or minor nutrients, are required in very small amounts. Many native soils contain enough of each micronutrient to support healthy turf. Micronutrient deficiencies are most likely to occur in turfs maintained in highly organic or sandy soils. Plants growing in compacted soils may also be deficient in one or more of the micronutrients. Low levels of iron (Fe), the micronutrient most often deficient in turf, may be the result of an insolubility problem (high soil pH) rather than an absence from the soil.
Looking ahead Turfgrasses and soils can be periodically tested to determine if all required mineral nutrients are present to ensure plant health. Whether turfgrass is grown for sod, as a sport field or a home lawn, fertilizers are applied when tests indicate that nutrients are absent or present only in low concentrations. Because fertilizers come in a bewildering array of products and formulations, it can often be difficult to interpret and understand their use for specific situations. In Part 2, which will appear in the October/November 2007 issue of Tennessee Turfgrass, we will focus on the wide range of commercially available fertilizers and explore both their elemental composition and specific uses for these products. We will also look more closely at the individual macro- and micronutrients in plant nutrition. In Part 3, we will discuss strategies for integrating turfgrass nutrition into a Best Management Plan for Tennesseeâ&#x20AC;&#x2122;s managed turfs. We will investigate the value of soil and turftissue tests and discuss how several turfgrass types and environmental factors should guide turf and landscape management decisions.
TURF BASICS Table 2. Amount of Essential Mineral Elements Commonly Found in Turfgrasses and Associated Deficiency Symptoms
Element
Normal Amount in Plant Tissue
Macronutrient
Percent — Dry Weight
Deficiency Frequency, Comments and Deficiency Symptoms
Primary
Nitrogen (N)
Phosphorus (P)
Potassium (K)
3% to 5%
Deficiency frequency — common. Nitrogen is associated with turfgrass growth and color; it is found in amino acids, chlorophyll, enzymes, proteins and vitamins; it usually moves from roots to leaves quickly (e.g., 15 hours). Deficient plants lack color and vigor, and older leaves may first turn pale green, then yellow, as deficiency symptoms progress toward the base of the leaf blade.
0.2% to 0.5%
Deficiency frequency — occasional. Phosphorus is critically important in the transfer and storage of energy; it affects the transfer of genetic information; it is found in plant cell membranes and DNA; it is relatively immobile in most soils and less likely to move into soil solution and leach than nitrate. Leaves deficient in P often become narrow and have a tendency to curl, darken and develop a purple or red pigmentation. Deficiencies are most often observed as plants develop from seed.
2% to 3%
Deficiency frequency — occasional. Potassium activates enzymes and is involved in photosynthesis and the regulation of water release from the plant into the air. Plants deficient in K do not grow well and are not very tolerant of traffic, drought, heat and cold. Diseases (including dollar spot, Fusarium patch, red thread and Rhizoctonia blight) are often more severe in turfs low in K. As K becomes deficient in plants, the leaves often droop and yellow from the outer edges toward the center.
0.2% to 0.4%
Deficiency frequency — rare. Calcium is found in plant cell walls; it is required for cells to divide and flowers to form; and it maintains internal “balance” among other essential nutrients, including K and Mg. New stems and leaves deficient in Ca are often curled and stunted, and the margins of young leaves may first turn pale green, then reddish brown.
0.1% to 0.7%
Deficiency frequency — occasional. Magnesium is necessary for the formation of proteins; it is found at the center of the chlorophyll molecule; it improves P uptake from soil; and it is involved in many internal reactions that are regulated by a variety of enzymes. Lower, older leaves of plants deficient in Mg may first appear blotched and red in color before yellowing.
0.1% to 0.6%
Deficiency frequency — occasional. Several vitamins and the amino acids cystine and methionine contain S. Plants deficient in S cannot use N and most often have pale, yellow-green leaves, with margins that often appear scorched. A 15:1 N:S ratio is considered normal in the dry tissue of turfgrasses receiving adequate amounts of both essential mineral elements.
Secondary
Calcium (Ca)
Magnesium (Mg)
Sulfur (S)
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CONTINUED Table 2. Continued.
Element
Normal Amount in Plant Tissue
Macronutrient
Percent — Dry Weight
Deficiency Frequency, Comments and Deficiency Symptoms
3% to 5%
Deficiency frequency — rare. Boron affects the development of plant cell walls and is believed to be necessary for the transport of sugars. Plants low in B grow very slowly and do not complete their life cycle. The growing points of B-deficient plants may develop yellow streaks, and leaves are often stunted.
Chlorine (Cl)
0.2% to 0.5%
Deficiency frequency — rare. Chlorine (found in chlorides) stimulates photosynthesis, and it is believed to be involved in nutrient balance in plant cells. Cl deficiency is uncommon in turfgrasses.
Copper (Cu)
2% to 3%
Deficiency frequency — rare. Copper is involved in the formation of a number of growth-promoting compounds. The tips of the youngest leaves of Cu-deficient plants may appear bluish in color, and some axillary buds may die.
0.2% to 0.5%
Deficiency frequency — common. Iron is the micronutrient most often deficient in turf. It is associated with turfgrass color; it improves frost resistance and reduces dehydration of some turfgrasses in winter; and it is required for chlorophyll production. It is found in several enzymes that enable plants to absorb oxygen and release carbon dioxide. As Fe becomes limited, the tissue between the veins of new leaves may yellow.
2% to 3%
Deficiency frequency — occasional. Manganese is required for the formation of chlorophyll; it influences photosynthesis and plant growth rate; and it is involved in several plant enzyme systems. The leaves of Mn-deficient plants often bend, become yellow between veins and become spotted as tissue dies in distinct spots. Plants low in Mn usually feel soft to the touch, and leaves wither or roll. Note: an extremely high level of Fe in plants can result in a Mn deficiency.
0.2% to 0.5%
Deficiency frequency — rare. Molybdenum is the micronutrient required in smallest quantities. It is necessary for utilization of N; it tends to accumulate as plants mature; and its highest concentrations are usually found in leaf blades.
2% to 3%
Deficiency frequency — rare. A component of several plant enzymes, zinc is required for chlorophyll production, and it is believed to be associated with the formation of many growth-regulating compounds. In Zn-deficient plants, leaf development and growth rate are severely restricted. Stunted leaves may first turn yellow, then bronze, as Zn becomes unavailable, and leaves may dry and appear white in color as the deficiency advances. Note: too much P in the soil can precipitate Zn, making it unavailable for plant uptake.
Boron (B)
Iron (Fe)
Manganese (Mn)
Molybdenum (Mo)
Zinc (Zn)
TENNESSEE TURFGRASS ASSOCIATION • TENNESSEE VALLEY SPORTS TURF MANAGERS ASSOCIATION
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APPLIED RESEARCH
THE FACTS
ON HERBICIDE-RESISTANT WEEDS By Matt Cutulle, Graduate Student; Scott McElroy, Ph.D.; and Greg Breeden, Research Assistant; Turfgrass Science, The University of Tennessee
U
nfortunately, there is a great deal of misinformation regarding herbicide-resistant weeds. This fact-based article explains much of the terminology.
Herbicide resistance Herbicide resistance occurs when a formerly susceptible plant population demonstrates the ability to survive herbicide doses greater than doses that were originally used to control the population. This is to be distinguished from herbicide tolerance, which is the ability of plant population to withstand an original dose of herbicide that kills other plants. Two types of herbicide resistance may occur: target-site resistance and non-target-site resistance. In target-site resistance, a mutation occurs in the protein where the herbicide binds, decreasing the affinity of the protein/herbicide interaction. Typically, weeds that develop target-site resistance are resistant only to that specific herbicide or herbicide family. An example of target-site resistance is dinitroaniline-resistant goosegrass (Elesuine indica), where a mutation in the target protein (a-tubulin) decreases the dinitroaniline interaction, subsequently limiting the effectiveness of the herbicide. Non-target-site resistance involves the detoxification and metabolism of the herbicide within the plant. Non-target-site resistance can occur across herbicide families. An example of non-target-site herbicide resistance is a population of Italian ryegrass (Lolium multiflorum) that exhibited resistant to multiple ACCase inhibitors. Resistance occurred due to the expression of certain enzymes (cytochrome p450 monooxygenases and glutathione S-transferase) that are involved in detoxification and transport of the herbicide molecules.
Causes of herbicide resistance Factors influencing herbicide resistance in weeds include: selection pressure, generation time, mutation frequency and reproductive fitness. Selection pressure is the phenomena by which environmental influences cause the weed population to adapt. In turf, selection 24
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In one test for herbicide resistance, herbicide-treated plants are grown in soil-based containers for several weeks, and then they are removed for measurement of their dry weight.
pressure is usually initiated by utilizing a mono-herbicide system on a weed population or spraying herbicides with the same mode of action. Generation time (or plant life cycle) will influence how rapidly a weed population may develop resistance. Plants with the shortest, most frequent life cycles, and that produce the highest number of seed, will be able to develop resistance quickly if the genetic means for resistance is in the population. For instance, in turfgrass, Poa annua has a high probability of becoming resistant. Mutation frequency may have an influence on herbicide resistance if the genes conferring resistance are not in the original population. Weed populations with high mutation rates have a better probability of obtaining a gene that will confer resistance than a population with lower mutation rates. Mutation rates involve the random chance of developing resistance through changes in the weedâ&#x20AC;&#x2122;s genetic material and should not be confused with selection pressure where the genetic material conferring resistance is already in the weed population.
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CONTINUED Fitness or reproductive fitness is an important factor to consider when evaluating herbicide resistance. The ability of a herbicide-resistant weed to compete and reproduce against other species (or the sensitive plants from its own species) in nonselective conditions is important in determining future control strategies. If the fitness penalty for the weed having the resistant trait is very high, then it should be out-competed by the host turf, and the same control strategy may be used. Alternatively, if the weed has no fitness penalty for exhibiting the resistant trait, a new control strategy should be explored, such as using one or more herbicides with different modes of action.
Occurrence of herbicide-resistant weeds Due to many of the factors mentioned above, the number of herbicide-resistant weeds is increasing. Currently, over 300 biotypes of weedy plants have developed resistance to one or more of the major herbicide groups (http://www.weedscience.org). The herbicides with the most resistant-weed biotypes are the ALS-inhibitors, triazines and ACCase inhibitors. Most of the weeds that have developed resistance to these herbicides are found in the United States and Australia. Herbicides with surprisingly low incidents of resistance, despite their extensive use, are glyphosate and the dinitroanilines. However, dinitroaniline resistant has occurred in some economically important weeds. Populations from two of the most troublesome weeds in turf — goosegrass and annual bluegrass (Poa annua) — have developed resistance to dinitroanilines. Also, the development of glyphosate-resistant crop systems has increased selection pressure for glyphosate-resistant weeds such as horseweed (Conyza canadenis).
Although the petri-dish bioassay is cleaner than the soil-based bioassay, it is not sterile, which increases variability in the results.
Weeds are estimated to cost growers more than $20 billion a year. These costs will increase with the evolution of more herbicide-resistant weeds. A program is needed to limit the negative economic impact of herbicide-resistant weeds
Herbicide bioassays — dinitroaniline resistance The most important criteria in developing a program to screen, evaluate and monitor herbicide resistance is the selection of a herbicide bioassay, which is a testing method to determine if a weed is resistant to a certain herbicide. Since dinitroanilines are important preemergence herbicides used in turf, the increased reports of dinitroaniline-resistant weeds require an analysis of current mitotic-inhibiting herbicide-resistance screening methodologies. Two bioassay techniques have been utilized to test suspected resistance to mitotic-inhibiting herbicides: a soil-based bioassay and a petri-dish bioassay. The soil-based bioassay utilizes soil containers in a climate growth chamber. In research reported in 1984, a known-sensitive population of goosegrass and a suspected-resistance population were planted in the containers and sprayed with seven different dinitroaniline herbicides. After four weeks, the plants were removed from the containers, and their dry weight data was recorded. Research in 2002 utilized a petri-dish bioassay in a growth chamber to evaluate the shoot and root response of annual bluegrass to dinitroanilines. Seeds from a sensitive control population and a suspected-resistant population were placed in petri dishes with filter paper. Different dinitroanilines were pipetted onto filter paper, and root and shoot data were recorded after three weeks. Both methods, however, have drawbacks. Although the soilbased bioassay allows for uniform light and water for all experimental units (which limits confounding variables), it is not conducted in a sterile medium, which is an important variable to consider. Also, both the soil container and petri-dish bioassay need mature seed, which may take months to obtain and evaluate resistance. Distribution of herbicide in the medium may be uneven in both these bioassays. The petri-dish bioassay allows for uniform light levels and uses filter paper as the growing medium, which is cleaner than soil-based bioassays. Root and shoot length data allow resistance to be characterized. The petri-dish bioassay is not sterile, though, which increases variability in the results. Additionally, the roots grow horizontally, which increases the difficulty of taking measurements. We are currently conducting research at The University of Tennessee to improve methods of evaluating potential resistance to dinitroaniline herbicides. We hope to report on our successes at the 2008 TTA Annual Conference and Trade Show in Franklin. This will be valuable research for all turf managers who wish to determine if they have herbicide-resistant weeds.
TENNESSEE TURFGRASS ASSOCIATION • TENNESSEE VALLEY SPORTS TURF MANAGERS ASSOCIATION
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TURF TIPS
By John C. Sorochan, Ph.D.; Tom Samples, Ph.D.; and Scott McElroy, Ph.D.; Turfgrass Science, The University of Tennessee
On
an athletic field, the utility of the turfgrass is paramount, and its ability to function is expected and necessary. It is important to maintain a high-quality athletic-field stand that will hold up to aggressive wear, while continuing to provide consistent, stable cover.
Maintaining quality turf that withstands typical athletic-field conditions, however, has always been a challenge. This is particularly evident when many athletic-field events are scheduled to be played when growing conditions are not favorable for turfgrass recovery from wear. Proper implementation of the five primary cultural practices (mowing, irrigation, fertilization, cultivation and pest control) and the use of non-traditional methods are important management practices in maximizing turfgrass vigor. Non-traditional methods can be cost beneficial and can extend the performance of the athletic field in the long run. For instance, the use of crumb rubber as a topdressing material has demonstrated improved turfgrass functionality. In fact, crumb rubber can be a valuable tool in your arsenal.
What is crumb rubber? Crumb rubber is simply used car tires that, after removal of the steel belts, have been ground into small rubber particles or crumbs. The size of the ground rubber varies and is similar to the particle-size distribution of sands and fine gravel.
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CONTINUED
Shown here topdressed onto a bermudagrass sports field, crumb rubber reduces soil compaction and improves wear tolerance of the turfgrass stand.
Much like padding helps protect football players from hard hits, crumb rubber can help protect the crowns and stolons of bermudagrass from “hits” from athletes’ cleats.
Research that was completed in the early 1990s at Michigan State University assessed the dynamics and versatility of crumb rubber in a turfgrass situation for athletic-field use. Earlier research had evaluated the use of crumb rubber tilled into the soil profile of an existing athletic field. Although the results showed that crumb rubber was an effective soil amendment, taking the field out of play to add the crumb rubber was too time-consuming and cost ineffective. Therefore, the 1990s research at Michigan State evaluated cultural practices that would be more effective at introducing crumb rubber to the turfgrass/soil interface. Core cultivation and topdressing practices were evaluated in introducing crumb rubber to established athletic fields. Crumb-rubber particle size was also researched, looking at 1/4" and 10/20 mesh sizes. Both core cultivation and topdressing were effective, but topdressing crumb rubber was the most effective. Plus, the 10/20 mesh was the best particle size, over time, to introduce crumb rubber to the turfgrass/soil interface.
pounds crumb rubber per 1,000 ft2) intervals until you have added 1/2" to 3/4" of crumb rubber.
How do you use crumb rubber? The best method for adding crumb rubber to an existing athletic field is to topdress it. It is important to start off with as close to a 100 percent turfgrass stand as possible, since crumb rubber will not resurrect your turfgrass after wear damage has already occurred. Therefore, for an existing athletic field, the best time to add crumb rubber is prior to the start of a new season, when your turf cover is greatest. Use crumb rubber that has a 10/20 mesh particle size (see Table 1), and topdress it in at 1/4" (1/4" = 600
How does crumb rubber benefit athletic fields? When topdressed, crumb rubber serves two functions — this blanket of rubber (or “rubber thatch”) reduces soil compaction, and it improves wear tolerance of the turfgrass stand. No different than the “padding” used to protect an athlete, crumb rubber on an athletic field acts as a “padding” for protecting the turfgrass. If the cleats of an athlete damage the crown-tissue area of a turfgrass plant, the turf will quickly die because the point of rejuvenation has been damaged beyond repair. By limiting the direct impact of an athlete’s cleats/shoe, however, crumb rubber Table 1. Percent turfgrass cover as affected by crumb rubber after simulating 14 and 42 football games. Fall 2005.
Crumb Rubber 0" 3/4"
Location
Traffic
Arkansas
Low (14) High (42)
76% A 21% C
74% A 42% B
Tennessee
Low (14) High (42)
76% B 40% D
87% A 63% C
* Turfgrass cover was visually estimated using a 1–100 percent scale.
TENNESSEE TURFGRASS ASSOCIATION • TENNESSEE VALLEY SPORTS TURF MANAGERS ASSOCIATION
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TURF TIPS protects the crown tissue of the turfgrass, thus resulting in the prolonged wear tolerance of the turf stand. The increase in wear tolerance due to crumb-rubber topdressing was originally demonstrated in a study done on Kentucky bluegrass at Michigan State University in the 1990s. After a fall season of testing (using simulated football traffic), 50 percent more turf cover could be maintained by topdressing 3/4" crumb rubber onto a sand-based athletic field. Similar research was done at the University of Tennessee and the University of Arkansas in 2005 on both bermudagrass and Kentucky bluegrass (Table 1). Regardless of turfgrass species, crumb-rubber topdressing maintained greater turfgrass cover. In addition, the more intense the level of use (traffic), the more the crumb rubber benefited the turf. Another benefit of crumb rubber is that it will not break down with repeated wear in high-traffic areas on an athletic field. Thus, it will provide a cushioning benefit for maintaining increased turfgrass cover. As a result, your athletic field will be able to tolerate more traffic, which in turn translates into more events, which in turn translate into increased revenue potential.
Potential problems with topdressing crumb rubber Without question, there have been concerns about topdressing crumb rubber if too much water takes over an area (i.e., rainfall or excessive irrigation). Crumb rubber is half the density of a soil particle, thus causing it to float. Strategies to deal with this problem are: (1) be in tune with the weather and (2) do not put too much crumb rubber down at one time. Our recommendation is that no more than 1/4" of crumb rubber should be topdressed in a single application. Remember, you can always add more crumb rubber. A final strategy is to fertilize more frequently, budget permitting. Obviously, the grass will grow more vigorously, and the crumb rubber will gravitate more quickly down to the surface.
Take-Home Message Getting a simple answer to a complex question is not easy. No matter the level 28
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— professional, college or high school — expectations of athletic fields are increasing. Much like the athletes who play on them, today’s athletic fields are stronger than they were yesterday, and they are expected to constantly perform at a peak level. By topdressing crumb rubber, the athletic-field manager will prolong the wear tolerance of the turfgrass stand and improve the playability of the field for a longer period of time. Depending on your turfgrass selection and other management practices, re-establishment will be minimal (in terms of cost) over the long period.
T TA S c h o l a r s h i p s
The Ernest Hardison Memorial Scholarship General The Ernest Hardison Memorial Scholarship offers financial aid to students interested in pursuing a career in turf management. The scholarship is funded and administered by the TTA.
General The TTA Legacy Scholarship offers financial aid to children, stepchildren and grandchildren of current TTA members. The scholarship is funded and administered by the TTA.
Eligibility Applicant must be enrolled full-time at a Tennessee accredited institution of higher learning, in a turfmanagement related field of study. Applicants who are enrolled in online and/or correspondence courses must be currently employed in a turf-management related field in Tennessee.
Eligibility 1. One or more of the applicant’s parents, stepparents or grandparents must have been a TTA member for at least one year and must currently be a member of the TTA. 2. Students who are not eligible for any other TTA scholarships may apply (i.e., non-turf majors). 3. Applicant must be enrolled full-time at an accredited institution of higher learning. 4. Previous recipients are ineligible to apply.
Criteria for Selection Selection will be based on academic achievement, work experience, extracurricular and community involvement and leadership, financial need and the applicant’s resume and essay.
All applications must be POSTMARKED by October 31. The TTA Scholarship and Awards Committee will review all applications and select the scholarship recipient. All decisions of the committee will be final. This scholarship will be awarded at the TTA Annual Conference, and a check will be made payable to the recipient.
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The TTA Legacy Scholarship
TENNESSEE TURFGRASS
AUGUST/SEPTEMBER 2007
Criteria for Selection Selection will be based on academic achievement, extracurricular and community involvement and leadership, outside employment, financial need and the student’s essay.
How To Apply To request an application for either scholarship or to return an application, contact: Mr. Jim Uden, Executive Secretary Tennessee Turfgrass Association 400 Franklin Road Franklin, Tennessee 37069 (615) 591-8286
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T U R F TA L K The Rules, Your Course and Your Staff Presented by the Golf Course Superintendents Association of America
is not uncommon to hear a golfer say, "The Rules of Golf are too complicated." What is most important for golfers to understand, though, is that many of the rules are actually intended to help them out. One way to make your job easier, as a golf course superintendent, is to help educate (or remind) your players on those advantages. For instance, most golf courses have cart paths, sign posts, permanently anchored yardage markers, ball washers, etc. These are immovable obstructions, and golfers are permitted relief from them under Rule 24-2. In addition to those permanent features of the course, golfers and/or their golf ball will interact with the work of the golf course maintenance staff or with natural situations that affect the course. These “abnormal ground conditions” also offer relief, under Rule 25. For instance, in wet weather, portions of the course can have standing water outside of a water hazard. Under Rule 25, golfers can get relief from this “casual water.” When your staff is working on projects such as resodding, maintaining or repairing the irrigation system, or renovating bunkers, these areas maybe marked as “ground under repair.” In such cases, golfers are entitled to relief from the area. If the committee wishes to protect an area of the course (such as new sod), The Rules of Golf also recommend identifying the area as “ground under repair,” requiring players to take relief from it. The recommended local rule is:
It
“The _____________(defined by ____) is ground under repair, from which play is prohibited. If a player’s ball lies in the area, or if it interferes with the player’s stance or the area of his intended swing, the player must take relief under Rule 25-1.” Of course, there are other times when The Rules of Golf can help golfers on the course. One of the regular maintenance practices that can have an effect on play is the aerification of greens, tees and fairways. According to The Rules of Golf: 32
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“When a course has been aerated, a Local Rule permitting relief, without penalty, from an aeration hole may be warranted. The following Local Rule is recommended: “Through the green, a ball that comes to rest in or on an aeration hole may be lifted without penalty, cleaned and dropped, as near as possible to the spot where it lay but not nearer the hole. The ball when dropped must first strike a part of the course through the green. On the putting green, a ball that comes to rest in or on an aeration hole may be placed at the nearest spot not nearer the hole that avoids the situation.” The Rules even offer a specimen local rule for trees that have been planted:
“When it is desired to prevent damage to young trees, the following Local Rule is recommended: “Protection of young trees identified by ______ — If such a tree interferes with a player’s stance or the area of his intended swing, the ball must be lifted, without penalty, and dropped in accordance with the procedure prescribed in Rule 24-2b (Immovable
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Obstruction). If the ball lies in a water hazard, the player must lift and drop the ball in accordance with Rule 24-2b(i), except that the nearest point of relief must be in the water hazard and the ball must be dropped in the water hazard or the player may proceed under Rule 26. The ball may be cleaned when lifted. While the rules donâ&#x20AC;&#x2122;t specifically address the maintenance staff itself, golfers need to remember that sometimes the work to be done puts golfers and the staff on the course at the same time. At those times, a little patience (on the part of the players) can make for a safer, more productive day for the staff, while producing better golf course conditions when the project is done.
TENNESSEE TURFGRASS ASSOCIATION â&#x20AC;˘ TENNESSEE VALLEY SPORTS TURF MANAGERS ASSOCIATION
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I N D E X O F A DV E RT I S E R S Barenbrug USA www.barusa.com . . . . . . . . . . . . . . . . . . . . . . .15
CA L E N DA R O F E V E N T S August 10
TVSTMA Upper East Tennessee Field Day Location: Pioneer Park, home of the Greenville Astros and Tusculum College, Greenville, TN
August 20–21
TNLA/HRI Golf Tournament & Tennessee Green Industry Field Day (TN Nursery & Landscape Association) Location: Williamson County Ag. Expo Center, Franklin, TN
September 25–29
NRPA Congress and Exposition (National Recreation and Parks Assn.) Location: Indianapolis, IN
October 16
ETGCSA Scholarship & Research Tournament Location: Council Fire G.C., Chattanooga, TN
October 22
MAGCSA Scholarship & Research Tournament Location: Colonial Country Club, Memphis, TN
October TBA
MTGCSA Scholarship & Research Tournament Location: Old Hickory C.C., Nashville, TN
November TBA
TVSTMA Lower East Tennessee Field Day Location: To be announced
December 9–11
28th International Irrigation Show Location: San Diego, CA
January 13–15, 2008
42nd Annual TTA Conference & Trade Show Location: Marriott Cool Springs, Franklin, TN
January 16, 2008
GCSAA Seminar Location: Marriott Cool Springs, Franklin, TN
Bayer Environmental Science www.bayerprocentral.com . . . . . . . .9 BWI Companies www.bwicompanies.com . . . . . . . . . . . . . . . .7, 15 Covermaster, Inc. www.covermaster.com . . . . . . . . . . . . . . . . . . .9 E & S Soil and Peat www.eandssoil.com . . . . . . . . . . . . . . . . . .31 Ewing Irrigation www.Ewing1.com . . . . . . . . . . .Inside Back Cover Greenville Turf & Tractor, Inc. www.JohnDeere.com . . . . . . . . . . .3 Jackson Sand
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33
John Deere Landscapes www.johndeerelandscapes.com . . . . . . .29 K-Rain Manufacturing Corp. www.krain.com . . . . . . . . . . . . . . .21 Keeling Company www.keelingcompany.com . . . . . . . . . . . . . . .21 Ladd’s www.bobladd.com . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16 Mid Tenn Turf, Inc. www.midtennturf.com . . . . . . . . . . . . . . . . . .31 Patten Seed Company/Super Sod www.zoysiagolf.com . . . . . . .33 Pennington Seed, Inc. . . . . . . . . . . . . . . . . . .Inside Front Cover www.penningtonseed.com
ProSource One www.prosourceone.com . . . . . . . . . . . . . . . . . . .10 RCH Distributors www.seriousred.com . . . . . . . . . . . . . . . . . . . .17 Regal Chemical www.regalchem.com . . . . . . . . . . . . . . . . . . . . .5 Sigma Organics, Inc.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33
Smith Turf & Irrigation www.smithturf.com . . . . . . . . . .Back Cover Southeastern Turf, LLC www.southeasternturf.com . . . . . . . . . . .33 Sur-Line Turf, Inc.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
Syngenta www.syngentaprofessionalproducts.com . . . . . . . . . . . . . .31 The Pond Lady www.thepondlady.com . . . . . . . . . . . . . . . . . . . .28 The Turfgrass Group
. . . . . . . . . . . . . . . . . . . . . . . . . . .13, 17
Turf Mountain Sod, Inc. www.turfmountain.com . . . . . . . . . . . . .28 Turf Specialties
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
Turfgrass America www.turfgrassamerica.com . . . . . . . . . . . . . . .7 Winstead Turf Farms, Inc. www.winsteadturf.com . . . . . . . . . . .11
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