MTC Turf News - Spring 2011 by leadingedgepubs

CONTENTS 10

• Spring 2011

RECENT EVENT Highlights from the 2011 MTC Turfgrass Conference & Tradeshow!

TURF TALK Tall Fescue Quality in Lawns with Organic and Traditional Fertilizer and Weed Control

MTC TURF NEWS

APPLIED RESEARCH Managing Organic Matter... Core Your Way to Healthier Golf Greens

TURF TIPS FreeHand... A New Herbicide for Landscape Maintenance

DEPARTMENTS 05 06 08 30

NEWS FROM MTC PRESIDENT’S MESSAGE MEMBERSHIP APPLICATION UNIVERSITY OF MD TURF TEAM 30 CALENDAR OF EVENTS 30 ADVERTISERS INDEX

NEWS FROM MTC

MARYLAND TURFGRASS COUNCIL 12 Pressie Lane | Churchville, MD 21028 (240) 413-4312 | www.mdturfcouncil.org MTC Turf News is published quarterly for the MTC by: Leading Edge Communications, LLC 206 Bridge St. Franklin, TN 37064 615-790-3718 ( phone) 615-794-4524 (fax) info@leadingedge communications.com

2011 BOARD OF DIRECTORS PRESIDENT Vernon W. Cooper All States Turf Consultant St. Michaels, MD 410-745-9643 (office) 443-742-6618 (cell) vernon@allstatesturf.com

VICE PRESIDENT Lester Dubs Pasadena, MD 443-623-1745 (cell) ldubs@verizon.net

SECRETARY/TREASURER Cheryl A. Gaultney Churchville, MD 410-836-2876 (home) 410-322-8275 (cell) sandqueen10@aol.com

PAST PRESIDENT Nick Gammill American University W. Hyattsville, MD 202-885-2340 (office) 202-498-8020 (cell) ngammill@american.edu

EXECUTIVE DIRECTOR Michelle LoConte Montgomery Village, MD 301-990-0196 (office) 240-597-1420 (fax) mdturfcouncil@verizon.net

THREE YEAR DIRECTORS Harry Kenney Agrium Advanced Technologies Ellicott City, MD 800-235-6138 410-375-6148 (cell) hkenney@agriumat.com

Bob Shumate Calvert Co. Parks & Rec. Prince Frederick, MD 410-535-1600, ext 2225 410-610-9007 (cell) shumatrr@co.cal.md.us Bill Warpinski Central Sod Farms Centreville, MD 800-866-1387 410-827-5000 billw@centralsod.com

TWO YEAR DIRECTORS Randall Pinckney Manor Country Club Rockville, MD 301-929-1707 240-286-1989 (cell) rpinckney@mail.manorcc.org Jamie Roell Anne Arundel Co. Rec. & Parks Millersville, MD 410-222-6250 443-370-2582 (cell) rproel09@aacounty.org Gregg Rosenthal Chesapeake Hills Golf Club Lusby, MD 410-326-4653 410-326-6207 rosentgi@co.cal.md.us

ONE-YEAR DIRECTORS Rick LaNore MRW Lawns, Inc. LaPlata, MD 301-870-3411 (office) 301-609-1852 (cell) rick127928@rocketmail.com Bill Patton, Sr. Turf Center Lawns Spencerville, MD 301-384-9300 (office) 301-980-3094 (cell) turfcenterlawns@yahoo.com Kevin Monaco Turf Equip & Supply Jessup, MD 20794 410-799-5575 (office) 443-250-1182 (cell) kevinmonaco@turfequipment.com

Front row (left to right): Bill Warpinski, Director; Damian Varga, Immediate Past Director; Michelle LoConte, Executive Director; Gregg Rosenthal, Director; and Rick LaNore, Director. Second row: Bill Patton, Director; Cheryl Gaultney, Secretary/Treasurer; Lester Dubs, Vice President; Vernon Cooper, President. Third row: Dr. Peter Dernoeden, Advisor; Bob Shumate, Former Past President; Dave Funk, Advisor. Top row: Dr. Mark Carroll. Not in photo: Nick Gammill, Immediate Past President; Harry Kenney, Director; Kevin Monaco, Director; Jamie Roell, Director; Dr. Tom Turner, Advisor; Dr. Kevin Mathias, Advisor.

Welcome to MTCâ&#x20AC;&#x2122;s Newest Director! Jamie Roell Anne Arundel Parks & Recreation

PRESIDENT’S MESSAGE

THIS IS YOUR ORGANIZATION… LET US KNOW WHAT YOU NEED!

now, major snow events and winter are a thing of the past, and fortunately (unless you push snow for a living), we missed most of the big blizzards this year. Unfortunately, if you missed “Turfgrass 2011” back in January, you missed an excellent opportunity to learn of the latest turfgrass advancements, learn what is new and improved, and learn what our tradeshow exhibitors have for us for the coming year, and you missed a great opportunity to renew acquaintances, make new friends and create networks that make life so much easier. The conference is also an excellent opportunity to pick up CEUs for golf course superintendents and assistants, and to re-certify your pesticide certification, including multiple certifications from Virginia, Pennsylvania, Delaware, West Virginia and Washington, D.C. Watch for notices of the dates for Turfgrass 2012, and plan to join us. Your MTC officers and board of directors are already working to make Turfgrass 2012 even better, but we need your help! The MTC is your organization, and the Turfgrass Conference is your conference. What can we do to make it better for you? What do you want to learn about? How can we change to better meet your needs? Please take time to let any of us on the board know what we can do to assist you. The purpose of the MTC is to support turfgrass research at the University of Maryland AND to assist any group or individual within the Maryland turfgrass industry that needs assistance. We are constantly monitoring what is happening in both the federal and state legislatures. We are working with the Maryland Department of Agriculture to support Maryland’s #2 agricultural industry — turfgrass. Plus, we are always dealing with environmental issues and regulations that impact any segment of our entire industry. We are excited to be partnered with Leading Edge Communications to provide you with an excellent magazine that comes to you four times a year, chocked full of new information and data to help you and your business. Read your magazine,

MTC TURF NEWS

but don’t throw it away when you are done with it. Instead, take it with you to your doctor’s office, your dentist, your barbershop or wherever, and just leave it! There is no cheaper way to get information out to the public that there is a professional turfgrass industry in Maryland. Also, consider contacting Leading Edge, and taking out an advertisement in the magazine for even more impact for your business. The more advertising we have, the more research and information we can give you within your magazine. Take a moment, too, to check out your new MTC website at www.MDTurfCouncil.org — it’s a great place to catch up on the latest news and events, plus it’s the first place I go when looking for research and information. Remember, the MTC is your organization, and it can only be as good as you make it. So, let us hear from YOU!

VERNON W. COOPER President, Maryland Turfgrass Council

MEMBERSHIP APPLICATION

MTC Membership Application

____________________________________________________________________ Name Title ____________________________________________________________________ Address ____________________________________________________________________ City, State, Zip Code E-Mail Address ____________________________________________________________________ Company Affiliation ____________________________________________________________________ Company Address ____________________________________________________________________ Company City, State, Zip Code ____________________________________________________________________ Business Fax Business Phone ____________________________________________________________________ Cell Phone

I wish to also apply for membership for the following professional members of my crew, utilizing the company address listed above: _____________________________________ _____________________________________ _____________________________________ _____________________________________ Please list additional names on a separate sheet & attach to this form or feel free to copy this form if you desire individuals to utilize their home addresses. ENCLOSED ARE: _______ MTC Membership Dues $15.00 per person $ __________ _______ Donation to Turfgrass Survey $ _____________________ _______ Donation to Turfgrass Endowment Fund $ ___________ (tax deductible)

Member of:

Total Enclosed $ ______________________

[ ] ESGCS [ ] MAGCS [ ] MSA [ ] MSTA [ ] MTA [ ] PGMS [ ] OTHER __________________________________

Please make checks payable to: MTC or MARYLAND TURFGRASS COUNCIL

MTC TURF NEWS

SPRING 2011

RECENT EVENT

— Highlights from the —

Thank You to Our

2011 MTC TURFGRASS

Lunch Sponsors!

CONFERENCE & TRADESHOW! January 12–13 | Stamp Student Union, University of Maryland College Park, MD

2011 Green Industry Leader BASF DuPont

2011 Benefactor Bayer Environmental Science

2011 Sponsor Collins Wharf Sod Davisson Golf, Inc. Fisher & Son G.L. Cornell Co. Harrell’s, LLC MAATEM Oakwood Sod Farm Shady Oaks Turf Farm UMD — Instituted of Applied Ag.

Thanks Also to Our

Tradeshow Exhibitors! 2010 MTC President Nick Gammill (left) accepts his Immediate Past President Award from incoming President Vernon Cooper at the MTC Annual Meeting, held on January 13 during the 2011 MTC Conference & Trade Show.

2010 MTC Director Damian Varga (left) accepts his Immediate Past Director Award from 2010 MTC President Nick Gammill at the MTC Annual Meeting, held on January 13 during the 2011 MTC Conference & Trade Show.

Photos courtesy of Lauren Dubs (daughter of MTC Director Lester Dubs) and Eddie Coutras (President of Leading Edge Communications, publisher of MTC Turf News). 10

MTC TURF NEWS

Agrium Advanced Technologies BASF Bayer Environmental Science BuySod, Inc. Capitol Sports Fields Central Sod Farms Collins Wharf Sod Davisson Golf, Inc. Finch Services/John Deere Golf Fisher & Son Co. Genesis Turfgrass, Inc. G.L. Cornell Co. Harrell’s, LLC Newsom Seed Oakwood Sod Farm Spectrum Analytic, Inc. Synatek Syngenta

More Snapshots from the 2011 Conference

SPRING 2011

RECENT EVENT â&#x20AC;¢ continued

MTC TURF NEWS

TURF TALK

MTC TURF NEWS

By P.H. Dernoeden, C.P. Ryan and R.L. Pigati, Department of Plant Science & LA, University of Maryland

ewspapers and other media outlets often report on the perceived negative aspects of lawn care. In particular, homeowners often are told to beware of chemicals and fertilizers used by the professional segment of the industry, which are known as lawn care operations (or LCOs). Professional LCO services generally involve two or three applications of fertilizer, one pre-emergence herbicide that targets crabgrass, one post-emergence herbicide that targets broadleaf weeds and one insecticide that targets white grubs annually (some LCOs make applications on an asneeded basis, rather than on all lawns). Fungicides, although seldom applied, may be offered as an add-on service. Homeowners can purchase many of the same products that professional LCOs use.

Fertilizer considerations Due to water quality issues in the Chesapeake Bay, homeowners often are concerned about fertilizers, in particular nitrogen (N) and phosphorous (P).

Nitrogen Commonly used N turf fertilizers include synthetic organic fertilizers such as urea, coated urea and methylene ureas, as well as inorganic ammoniumbased fertilizers. Numerous fertilizer products contain varying amounts of synthetic organic N mixed with inorganic N sources. Many organic fertilizers (usually sewage sludge or poultry waste products) provide an excellent N response, but they generally are not superior in performance when compared to synthetic organic N fertilizers. The problem with natural organics is that they usually contain only about 5% to 6% N, whereas traditional fertilizers range from 20% to 46% N. Therefore, it takes from 4 to 9 times as much

SPRING 2011

TURF TALK â&#x20AC;˘ continued

material by weight to use an organic versus a traditional fertilizer. For example, urea (46% N) contains 23 lbs. of actual N in a 50 lb. bag, whereas most organic fertilizers contain about 2.5 to 3.0 lbs. of actual N in a 50 lb. bag. Hence, more handling is required for natural organics. The additional weight, shipping, handling and storage requirements

for organics increase the costs associated with using these products. A homeowner would have to buy about eight 50 lb. bags of a organic fertilizer to supply the same amount of N found in one 50 lb. bag of urea. Thus, natural organics will cost substantially more per pound of N to buy and apply.

Phosphorus Media reports suggest that phosphorus (P) in lawn fertilizers may travel to the Chesapeake Bay, where it promotes algal growth that competes with other aquatic life for oxygen in the water. Phosphorus, however, is so tightly held by soil that the only way that significant amounts of P in fertilizer applied to lawns can get to the Bay is if it is carried on sediment to a storm sewer or stream, which is highly unlikely to occur from an established lawn. In fact, reduction of sediment movement is a major advantage of a healthy lawn. Furthermore, overwhelming amounts of sediment losses in urban areas come from construction sites. Another source point would be if fertilizer were improperly applied and large amounts get onto the driveway or other impervious hard surfaces and are carried into a stream or storm drain after a rain. This problem can be averted by avoiding application of P to non-lawn areas and by carefully sweeping all fertilizers from hard surfaces back onto the lawn. Also, very heavy rain following the application of a fertilizer could result in some P becoming soluble. Low levels of P could run off a lawn, but it would take a major rainstorm for this to occur. A light to moderate rain or irrigation following the application of a P fertilizer would preclude soluble P from running off in storm water. Finally, some movement of applied P can occur on soils already high in P. Phosphorus should only be applied as recommended by a soil test.

Organic fertilizers Another misconception is that the N and P applied from a natural organic fertilizer are healthier for the plant and soil than traditional fertilizers. In order to be used by plants, however, all nitrogen must be converted by microbes and water to a mineral form, either inorganic nitrate or ammonium N. The grass plant cannot distinguish the source of the nitrate or ammonium N, regardless of whether it comes from an organic, synthetic organic or inorganic source.

MTC TURF NEWS

continued • TURF TALK

Like organic forms of N, organic forms of P must be converted to a mineral form in soil to be taken up by plants. Again, the plant does not distinguish whether the minerals are from an organic or inorganic source. Furthermore, research conducted at the University of Maryland has shown that natural organic fertilizers applied over a seven-year period had little or no positive impact on soil microbial activity, soil organic matter or thatch production, when compared to synthetic organic N. Some of the natural organic materials even had negative and deleterious effects, including the once popular Compro® Sewage Sludge from Washington, D.C., which is no longer commercially available.

Nontraditional products Nontraditional nutrient products have received much media attention lately. For example, compost teas are being marketed throughout the northeastern U.S. for use on lawns and landscape plants. Pogo Organics® (Sunshine, MD) markets a compost tea made of shredded yard waste (i.e., leaves, brush, stems, branches, etc.). To make compost tea, compost is placed in aerated water for 24 hours. Some people believe that compost tea can be used to maintain a low-cost sustainable lawn and that it provides diseasesuppressive benefits. Dry compost applications are also of interest, especially to organic gardeners. Leafgro®, a compost product marketed by Maryland Environmental Services (Millersville, MD), consists of leaves and grass clippings that are composted with yard wastes, then shredded, dried and screened. According to one technical data sheet, Leafgro contains about 0.47% N, 0.14% P and 0.31% K as measured on a percent wet weight basis. Leafgro consists of about 30% organic matter, has an 18:1 C:N ratio and a pH of about 8.0. Said to replenish “vital organic matter and beneficial micro-organisms” in the soil, Leafgro is largely used by landscapers as a soil conditioner and is mixed with existing soil when planting

The grass plant cannot distinguish the source of the nitrate or ammonium N, regardless of whether it comes from an organic, synthetic organic or inorganic source. trees and shrubs or when establishing lawns. For establishing lawns, it is recommended that Leafgro be spread on bare soil and rototilled to a soil depth of about 4" to 6". There are no recommendations for using Leafgro on top of established turf. Using any dry compost as a topdress material to established turf over time could lead to a harmful surface organic layer. Another producer that markets in Maryland is 3Tier Technologies®, Inc. (Southlake, Texas). The 3Tier Lawn Care Program involves applying a combination of three products, 5 or 6 times on a 30-day interval from spring to late summer. The 3Tier products contain humates (i.e., humic and fulvic acids), microbial inoculants (i.e., 5 species and numerous strains of Bacillus spp.) and very low amounts of nitrogen (usually < 0.02 lb. N/1,000 ft2 per application from urea or ammonical N) in combination with equally minute amounts of phosphorus, potassium, manganese and iron. The 3Tier Technologies products claim to “provide a costeffective tool to cleanse your soils, restore nutritional and microbial balance, increase natural disease and insect suppression, and provide an advanced platform for nutrient delivery, whether by foliar or soil applications.”

Weed control Crabgrass (Digitaria spp.) is the most invasive weed in Maryland lawns. If not controlled, crabgrass can dominate a lawn in two to four years and push the desirable turf out of the stand. Most people who desire a nice-looking, functional lawn would agree that crabgrass must be controlled to maintain the sustainability of the turfgrass and to reduce the potential for soil erosion.

Chemical herbicides Chemical pre-emergence herbicides have been used on lawns since the 1950’s. These insoluble herbicides bind to soil and do not move significantly in the environment unless carried on sediments or in runoff from improper application (on hard surfaces).

Natural products There is a large homeowner market for natural weed-control products. Corn gluten meal, for instance, was shown to be an effective pre-emergence crabgrass herbicide in Iowa, but it has had mixed performances in Maryland studies. To date, corn gluten meal is the only natural product that has been shown by university researchers to provide a significant level of herbicidal activity on crabgrass (as well as on several broadleaf weed species). It also contains significant amounts of nitrogen. While other commercially available organic products may claim weed control, few other than corn gluten have been shown through research to be safe and effective.

OUR RESEARCH This study involved a turf-performance comparison among several different programs, focusing on fertilizers and herbicides and ranging from completely organic to completely synthetic. The site had no history of insect pest problems and few disease problems. Hence, insect pests and disease-control programs were not factored into the protocols. Tall fescue (Festuca arundinacea) is the most highly recommended and widely planted lawn species in Maryland, so an established stand of this turf species was used in this study.

SPRING 2011

TURF TALK • continued

Tall fescue (Festuca arundinacea) is the most highly recommended and widely planted lawn species in Maryland, so an established stand of this turf species was used in this study. Treatment programs tested 1) LCO Synthetic Organic (referred to below as LCO) Products used: Stonewall (Lesco Poly Plus SCU + prodiamine, a fertilizer/ preemergence herbicide “weed and feed” product), Lesco SCU 34-0-0, and Synatech 20-0-3, plus Speedzone (postemergence herbicide) 2) 3Tier (3Tier) Products used: Pre-Mix Blue XL, Huma Fe, Growth 16-4-8, HumaBalance XL w/ Bio-Cat Booster, Huma-MnFe, Nitro 21-0-0, and Maintain 8-16-8 3) 3Tier + Weed Control (3Tier+WC) Products used: same products listed in treatment #2, plus Dimension (preemergence herbicide) and Speedzone 4) Organic + CGM (O+CGM) Products used: Oceangro 5-5-0 (a composted sewage sludge), plus Espoma corn gluten meal (CGM, as an organic preemergence herbicide) and Ecosense Lawn Weed Killer (spot application, in 2010 only) 5) Organic + Weed Control (O+WC) Products used: Oceangro 5-5-0, plus Dimension and Speedzone 6) Urea 46-0-0 7) Urea + Weed Control (Urea+WC) Products used: Urea 46-0-0, plus Dimension and Speedzone 8) Compost Tea or Leafgro Products used: Compost Tea (2009) or Leafgro (2010) 9) Compost Tea or Leafgro + Weed Control Products used: Compost Tea

MTC TURF NEWS

(2009) or Leafgro (2010), plus Dimension and Speedzone 10) Golf Course Rough (referred to below as Golf Rough) Products used: Harrell’s Polyon Urea (26-0-12) and Lesco Polycoat urea (25-3-10), plus Dimension and Speedzone The following treatments served as standards: Weed Control Only (no N fertilizer), N Only (urea alone, with no weed control) and untreated control (no N/no weed control).

Methods This study was conducted over a twoyear period (2009 and 2010) at the University of Maryland Paint Branch Turfgrass Research Facility in College Park. Turf was maintained to a height of 2.5" and generally was only irrigated to water-in the treatments; however, the site was irrigated for two weeks in July 2010 after turf had become drought dormant. To ensure uniform smooth crabgrass development (for the herbicide testing), the site was broadcast overseeded with 1.4 lb. of smooth crabgrass seed/1,000 ft2 on March 25, 2009. All treatments were applied initially on April 2, 2009 (March 31 in 2010), with additional N fertilizer applications made to the LCO, Organic, Urea and Golf Rough programs in early July and September (both years). Due to the N contained in corn gluten (9-0-0), the O+CGM plots received 1.8 lb. N/1000 ft2 in the initial application in both years, whereas all other N treatments were applied at 0.75 lb. N/ 1000 ft2 on April 2, 2009, and March 31, 2010. The LCO, Golf Rough, Urea and both organic programs (O+CGM

and O+WC) received another 0.50 lb. N on July 8 and an additional 0.75 lb. N on Sept. 2 of each year. Hence, corn gluten plots received a total of 3.05 lb. N/1000 ft2 per year, and the O+CGM and O+WC, LCO, Urea and Golf Rough programs received 2.0 lb. N/1000 ft2 per year. Generally, lawncare operators apply between 2.0 and 3.0 lb. N/1000 ft2 annually, so in this study, we were on the low side on N use in these treatments. The 3Tier Program involved six applications of nutrients and humates on a 30-day interval from roughly early April to early September. In 2009, the total amounts of major nutrients applied were as follows: 0.11 lb. N/1000 ft2, 0.053 lb. P/1000 ft2 and 0.047 lb K/1000 ft2. In 2010, major nutrient total amounts applied were increased as follows: 0.17 lb. N/1000 ft2, 0.08 lb. P/1000 ft2 and 0.082 lb. K/1000 ft2. Minute amounts of manganese, zinc, copper, calcium and purified humic acids also were applied on each occasion. Because there was little or no response from the Compost Tea in 2009, Leafgro was used as a substitute treatment to these plots in 2010; however, Compost Tea was also applied on two (June 15 and July 15) occasions in 2010. Leafgro was applied at a rate of 80 lb. product/1000 ft2 on five occasions (total 1.9 lb. N/1000 ft2) between March 31 and Sept. 7, 2010. The preemergence herbicide Stonewall (prodiamine) was applied in the LCO program at 0.75 lb. ai/A in both years. Dimension treatments were applied at 0.50 and 0.38 lb. ai/A in 2009 and 2010, respectively, in the following programs: 3Tier+WC, O+ WC, Urea+WC, Compost Tea/Leafgro +WC, and WC Only (2010). In the WC Only program in 2009, Drive (quinclorac) was used to control crabgrass postemergence. In the Golf Rough program, Dimension was applied at a rate of 0.28 lb. ai/A rate in both years. These preemergence herbicides, as well as corn gluten, were applied April 2, 2009, and March 31, 2010, and were watered-in by irrigation or timely rainfall.

continued • TURF TALK

Table 1. Tall fescue quality in response to organic and synthetic organic fertilizer and weed control programs. College Park, MD, 2009. Turf Quality (0–10 scale) Program

July 1

July 21

Aug. 3

Aug. 13

Aug. 23

Sept. 16

Sept. 28

LCO

8.3 ab***

8.1 ab

7.9 ab

6.6 ab

6.1 cde

8.4 ab

9.5 a

3Tier

7.3 def

6.5 f

6.1 ef

5.4 e

5.0 g

5.1 d

6.4 d

3Tier + Weed Control*

8.5 a

7.7 abc

7.5 bc

6.4 bc

6.0 de

7.7 b

8.4 bc

Organic + CGM**

7.8 bc

7.3 cde

7.1 cd

6.3 bc

5.6 ef

6.4 c

8.0 c

Organic + Weed Control

8.4 a

7.7 abc

6.6 ab

6.8 ab

8.5 ab

9.4 ab

7.8 bcd

7.9 abc

6.8 de

6.0 cd

5.4 fg

6.2 c

8.0 c

Urea + Weed Control

8.5 a

8.3 a

7.1 a

6.6 abc

8.7 a

9.8 a

Compost Tea (CT)

7.0 f

6.5 f

6.3 ef

5.5 de

5.0 g

5.3 d

6.4 d

CT + Weed Control

8.2 ab

7.3 cde

7.7 abc

6.6 ab

6.6 abc

8.0 ab

8.3 c

Golf Course Rough

8.4 a

7.5 bcd

8.3 a

7.1 a

8.4 ab

9.5 a

Weed Control Only

7.6 cde

6.6 ef

7.1 cd

6.5 bc

5.8 def

6.6 c

8.0 c

7.1 ef

6.8 def

6.0 f

5.4 e

5.0 g

5.1 d

6.4 d

Urea

Untreated

*Weed control included one application of a preemergence herbicide for crabgrass control and one application of a postemergence herbicide for broadleaf weed control. **CGM = Corn gluten meal is an organic preemergence herbicide. ***Means in a column followed by the same letter are not significantly different according to Fisher’s protected LSD, P = 0.05.

Speedzone (1.1 lb. ai/A) was applied to the appropriate plots to control broadleaf weeds on May 19, 2009, and May 21, 2010. On May 21, 2010, the broadleaf weeds in plots of the O+ CGM Program received a spot application of Ecosense Lawn Weed Killer, which contains 1.5% Iron HEDTA. Plots were rated visually for color and quality, where 0 = entire plot area brown or dead; 7.0 = minimal acceptable color and/or quality; 8.0 = very good summer color and/or quality and 10 = optimum green color, density and freedom of weeds. Weeds were visually estimated on a linear 0% to 100% scale, where 0 = no weeds and 100 = entire plot area covered. Percent of plot area brown or dormant from summer stress (i.e., heat and drought induced dormancy or injury) was rated visually on a 0% to 100% scale, where 0 = entire plot area green and 100 = entire plot area brown or dead.

RESULTS SUMMARY (Some data are not shown in this article. The full report, with details

on results for both 2009 and 2010, is posted on the following website: www.mdturfcouncil.org).

2009 Turf color Turf color ratings reflect mostly the performance of the N fertilizers, whereas turf quality ratings include color, density and the presence or absence of weeds. Hence, color ratings usually are higher than quality ratings. Programs receiving 2.0 lb. N/1000 ft2 or more provided generally good color responses. Urea gave the most rapid response following the April, July and September applications. Following the initial application of N on April 2, the corn gluten meal (applied once in April and then followed with sewage sludge) and the polymer-coated urea gave the best color responses in May and June, although data did not vary significantly from Oceangro, urea or the SCU in the LCO program. Compost Tea and 3Tier programs provided little or no improvements in turf color.

A color rating of 7.0 was considered the minimum acceptable, but color ratings of 8.0 or greater would constitute very good color (especially in the summer) and is used here as a subjective threshold for comparative purposes. It again is noted that the study area had received no fertilizer in the prior two years to initiating this study. Turf color in the untreated control and Weed Control Only program achieved ratings below 8.0 on 9 of 10 rating dates. The number of times in the 10 summer rating dates in which programs achieved color ratings above 8.0 were as follows: Urea+WC = 9 times

3Tier+WC = 6 times

Golf Rough = 8 times

O+WC = 6 times

O+CGM = 8 times

3Tier Alone = 4 times

LCO = 7 times

Compost Tea+WC = 3 times

Urea Alone = 7 times

Compost Tea Alone = 1 time

SPRING 2011

TURF TALK • continued

Table 2. Tall fescue quality response to organic and synthetic organic fertilizer and weed control programs, College Park, MD, 2010. Overall Quality (0–10 scale) Program

April 12

May 12

June 15

July 27

Aug. 13

Sept. 9

Oct. 6

Nov. 2

LCO

9.3 ab***

9.7 a

8.3 a-d

7.0 ab

7.3 a

8.0 a

8.4 a

9.2 a

5.6 d

6.1 d

5.8 e

5.1 d

4.0 c

4.4 e

4.0 f

2.3 e

8.9 abc

8.5 c

7.8 cd

6.8 bc

6.7 ab

6.4 bc

5.8 c

7.1 bc

Organic + CGM**

7.8 c

8.3 c

8.4 abc

6.8 bc

5.9 b

5.8 cd

5.6 cd

5.3 d

Organic + Weed Control

9.6 ab

8.4 abc

7.0 ab

6.6 ab

6.8 b

6.5 b

7.5 b

Urea

9.2 ab

8.5 c

8.3 a-d

6.5 bc

5.7 b

5.6 d

5.0 de

5.5 cd

Urea + Weed Control

9.9 a

10.0 a

8.5 ab

7.6 a

7.2 a

6.9 b

6.6 b

7.8 ab

LeafGro

5.9 d

6.1 d

5.8 e

5.3 d

4.0 c

4.5 e

4.1 f

3.1 e

LeafGro + Weed Control

9.1 ab

8.6 bc

7.6 d

6.2 c

6.0 b

5.7 cd

5.1 cd

6.4 bcd

Golf Course Rough

9.2 ab

9.6 a

8.8 a

6.8 bc

6.2 b

5.7 cd

5.5 cd

6.6 bcd

Weed Control Only

8.8 bc

8.3 c

7.9 bcd

6.5 bc

5.8 b

5.5 d

4.4 ef

5.3 d

Untreated

6.1 d

5.4 e

5.3 d

3.4 c

4.0 e

4.0 f

1.5 e

3-Tier 3-Tier + Weed Control*

Table 3. Weed cover in tall fescue in response to organic and synthetic organic fertilizer and weed control programs, College Park, MD, 2009–2010. 2009

2010

% Broadleaf Aug. 13

% Crabgrass Aug. 23

% Clover Aug. 13

July 27

% Crabgrass Aug. 13

Sept. 9

LCO

0.0 c

1.3 e

0.0 b

0.0 c

1.5 b

3.0 e

3-Tier

5.3 a

21.3 ab

15.5 a

38.0 a

64.5 a

82.5 a

3-Tier + Weed Control*

0.0 c

0.8 e

0.3 b

0.3 c

5.3 b

23.8 cde

3.5 abc

11.8 cd

1.0 b

7.4 bc

18.3 b

48.0 bc

Organic + Weed Control

0.0 c

1.0 e

0.0 b

1.3 c

4.8 b

13.0 de

Urea

0.5 bc

17.8 bc

1.5 b

5.8 c

18.5 b

51.5 b

Urea + Weed Control

0.0 c

1.2 e

0.0 b

0.1 c

4.3 b

16.8 de

Compost Tea (CT)

6.3 a

19.0 abc

CT + Weed Control

0.0 c

1.2 e 17.5 a

28.0 ab

55.8 a

83.3 a

0.0b

1.0 c

9.8 b

35.8 bcd

Program

Organic + CGM**

LeafGro LeafGro + Weed Control Golf Course Rough

0.0 c

0.8 e

0.0 b

2.1 c

10.0 b

38.8 bcd

Weed Control Only

0.0 c

4.3 de

0.0 b

3.9 c

18.3 b

51.3 b

Untreated

4.0 ab

27.8 a

11.5 a

44.5 a

75.0 a

89.3 a

MTC TURF NEWS

continued â&#x20AC;˘ TURF TALK

Turf quality Weeds and summer wilt stress became significant factors affecting turf quality in July and August. Programs with weed-control options generally provided for superior quality versus treatments without weed control. The O+CGM and Urea Alone programs did reduce crabgrass populations significantly compared to the untreated control, but weed levels were still objectionable. No program impacted broadleaf weed populations in the absence of the application of Speedzone in 2009. Dormancy or turf browning generally was least severe in the O+CGM and Golf Rough programs. Compost Tea Alone, 3Tier Alone, Weed Control Only and the untreated control programs had the highest dormancy ratings; the other programs were intermediate on their effect on turf dormancy. Best summer quality (see Table 1) generally was observed in the O+WC, Urea+WC and Golf Rough programs. However, all programs that included weed control (with the exception of Weed Control Only) generally had summer quality ratings statistically similar to those. Compost Tea+WC (on one date) and 3Tier+WC (on three dates) provided a higher level of quality than the untreated control. Compost Tea and 3Tier applied alone provided a level of quality similar to the untreated control. Conversely, Urea Alone generally improved quality relative to the untreated control, despite the presence of crabgrass.

All programs containing Stonewall (LCO only) or Dimension provided commercially acceptable (<5% crabgrass cover) crabgrass control. The O+CGM program provided a statistically equivalent level of crabgrass control compared to the programs involving Stonewall and Dimension, but crabgrass levels were unacceptable. These unacceptable levels of crabgrass resulted in unacceptable turf quality between Aug. 13 and Sept. 16 in the O+CGM Program. The quality of tall fescue in all programs, except 3Tier Alone and the untreated control, was in the acceptable range by Sept. 28, 2009.

2010 Turf color ratings Winter and spring color ratings were equally high among the LCO, Organic, Urea and Golf Rough programs. Summer drought dormancy precluded turf color ratings until autumn. At that point, tall fescue color was generally improved in programs involving weed control. There was little indication that any improvement in turf color was accorded by the 3Tier or Leafgro programs. It is possible that 3Tier and Leafgro may have had a greater impact on turf grown in a sandy soil rather than the silt loam soil in this study. Furthermore, it may take more time for the nutrients in the organic matter in Leafgro (applied 5 times in 2010 only) to be released. The Weed Control Only program provided higher color ratings versus 3Tier Alone or

Leafgro Alone on the final rating on October 6.

Turf quality ratings As discussed below, the LCO program had best quality at the end of the study because the rate of prodiamine (i.e., Stonewall) was maintained at the high label rate (0.75 lb. ai/A), whereas the Dimension rate was lowered from 0.50 lb. ai/A in 2009 to 0.38 lb. ai/A in 2010 (except Golf Rough, where Dimension was applied at 0.28 lb. ai/A in both years). Hence, it was the superior level of crabgrass control provided in the LCO program that ultimately provided for the best quality at the end of the study (see Table 2). The 3Tier+WC program had improved quality compared to Weed Control Only on the last three rating dates in 2010, indicating that some benefit had been provided by the low levels of nutrients and humic acid that had been applied 12 times over the course of the two-year study.

Turf dormancy in summer The June drought that lead to near complete tall fescue dormancy was the big story in 2010. The Golf Rough program appeared to delay dormancy in both 2009 and 2010. Following N applications in July 2010, tall fescue in the LCO, O+WC (but not O+CGM) and Urea+WC (but not Urea Alone) programs were most rapid in recovering, according to quality ratings obtained on July 27, 2010.

Crabgrass Weed pressure was a major factor affecting quality (see Table 3), and data showed that effective crabgrass control was essential for improving and maintaining summer tall fescue quality. Despite little or no N being applied to plots in the 3Tier+WC, Compost Tea+WC and Weed Control Only Programs, turf color and quality rose to a good level (> 8.0) by late September.

SPRING 2011

TURF TALK • continued

Weed control Thereafter, it was crabgrass encroachment that impacted quality most (see Table 3). Between July 27 and Aug. 13, crabgrass cover ratings had more than doubled in most plots. By Sept. 9, crabgrass plants had greatly increased in size due to continued high temperatures and good soil moisture from rain. All programs reduced crabgrass cover compared to the untreated control (which had 89% crabgrass cover). The LCO (3% cover = 97% control), O+WC (13% cover = 85% control) and Urea+WC (17% cover = 81% control) had statistically equivalent levels of crabgrass cover. Crabgrass cover was reduced to commercially acceptable levels (< 5%) in the LCO program only, and thus this was the only program to provide acceptable quality at the end of summer (i.e., Sept. 9). Poor to very poor crabgrass control was observed in plots treated with O+CGM (48% cover = 46% control), Leafgro+WC (36% cover = 60% control), Golf Rough (39% cover = 56% control), Weed Control Only (51% cover = 43% control) and Urea Alone (52% cover = 42% control). The data showed that the performance of Dimension was improved by using it in conjunction with N (organic or urea) and that N alone from urea was as effective in suppressing crabgrass as corn gluten. As stated previously, the LCO program was superior because the Stonewall (prodiamine) level was maintained at the high label rate (0.75 lb. ai/A). The Dimension rate was reduced in the O+WC, Urea+WC, Leafgro+WC and Weed Control Only programs from 0.50 lb. ai/A in 2009 to 0.38 lb. ai/A in 2010 because previous research (Dernoeden, 2001) indicated that once crabgrass was effectively controlled in a site, the rate of Dimension could be reduced (to 0.38 lb.) without loss of effective crabgrass control. This approach failed in 2010, however, because of several factors that created the so-called “perfect storm.”

MTC TURF NEWS

The drought dormancy of tall fescue in late June was followed by 10 rain events in July and August. The rain events stimulated continuous crabgrass emergence at a time that soils were hot and wet, which would speed microbial dissipation of the reduced rates of Dimension. Furthermore, the dormant tall fescue lacked competitiveness with crabgrass plants until late July when dormancy was broken; however, tall fescue density was less than that prior to the drought. High temperature conditions persisted throughout August and into September, which stimulated crabgrass to tiller more aggressively than if conditions had been dry and mild. Despite the failure of the lower use rate of Dimension to provide acceptable crabgrass control in 2010, tall fescue cover was improved by its use. For example, plots receiving the 3Tier+WC, O+WC, Urea+WC, Leafgro+WC and Golf Rough (only 0.28 lb. ai/A Dimension) programs had 94% to 98% tall fescue cover prior to winter. With sound fertility and appropriate weed control practices, the tall fescue in these programs will improve and likely will once again exhibit good to excellent quality by May 2011. Conversely, all fescue in the O+CGM, Urea Alone and Weed Control Only programs (resulting in 80% to 83% tall fescue cover on Nov. 2) will require spring overseeding and much more inputs of fertilizer and herbicides to fully recover. Tall fescue cover in the 3Tier Alone (30% cover), Leafgro Alone (51% cover) and the untreated control (19% cover) programs will not recover (functionally or aesthetically) and will require extensive (possibly total) renovation.

Key Summary Points • Corn gluten (9-0-0) is a good, but very expensive source of nitrogen. • Corn gluten can reduce crabgrass invasion under low weed pressure, which probably is due to enhanced turf density promoted by the N in the product.

• Urea (2.0 lb. N/1000 ft2/year) was as effective as corn gluten (20 lb. product/1000 ft2) in reducing crabgrass levels. • Corn gluten used as recommended did not provide commercially acceptable crabgrass control in either year. • Little or no improvement in tall fescue quality was provided by 3Tier products, Compost Tea or Leafgro. Some improvement in tall fescue quality, however, was observed at the end of the study in the 3Tier + Weed Control program compared to the Weed Control Only program. • Organic (sewage sludge and corn gluten meal) and synthetic organic N sources (urea, polymer-coated urea, SCU) generally performed equally in promoting turf color and quality. • Nitrogen (2.0 lb. N/1000 ft2/year) from either organic or synthetic organic sources reduced crabgrass and broadleaf weed populations by promoting turf vigor and density. • Controlling weeds with one annual application of a preemergence herbicide targeting crabgrass and one annual application of a herbicide targeting broadleaf weeds was needed to maintain tall fescue density and quality, even in the absence or presence of nitrogen use. • Use of nitrogen (organic or synthetic organic) in conjunction with Dimension improved the level of crabgrass control. • In 2010, a late-spring drought that induced tall fescue dormancy, followed by frequent rain events, created a “perfect storm” for crabgrass encroachment and, in some cases, dominance. • Crabgrass control is required where this weed exists, even in initially low populations, to maintain long-term functional and aesthetic tall fescue turf. • Maintaining a high label rate of Stonewall (prodiamine) resulted in effective crabgrass control in

both years and provided the best turf quality among all programs evaluated at the end of the second study year. • Reducing the rate of Dimension (dithiopyr; from 0.50 to 0.38 lb. ai/A) resulted in unacceptable crabgrass levels in the second study year, but use of the herbicide did reduce crabgrass invasiveness and helped maintain tall fescue density. • Plots treated with Compost Tea, Leafgro or 3Tier products without herbicides (as well as the untreated control) resulted in a turf requiring complete renovation. Disclaimer: The findings of this study may only apply to tall fescue turf grown in the transition zone region of Maryland where summer heat stress and crabgrass are major problems. It also is noted that the study was conducted on a silt loam soil and that results may vary in different soil types. The study was conducted for two years, and a longer study may have yielded additional information. •

SPRING 2011

APPLIED RESEARCH

MTC TURF NEWS

By Brandon Horvath, Ph.D., Turfgrass Pathologist, The University of Tennessee many golf course superintendents, the pressures of play and the bottom line interfere in conducting what they know to be the right cultural practices for turfgrass health. For instance, although core aerification and topdressing help dilute the damaging forces of organic-matter deposition, they both can disrupt the playing surface. Unfortunately, in milder parts of the country (such as along the MidAtlantic transition zone), cultivation is really a year-round practice that must be performed to avoid destructive consequences in the following summer. To keep your course ahead of next summer’s stress, be sure to thoroughly plan out your cultivation practices for the next several months. The USGA recommendations for putting-green construction focus on a high-sand rootzone that creates good physical stability, high waterinfiltration rates, high oxygen content and resistance to compaction. The production of organic matter by the growing turfgrass plants, however, limits each of these desirable traits. Once organic-matter content gets too high, the benefits of the high-sand rootzone diminishes or disappears, and turf health is not far behind. If this condition is allowed to persist, the quality of the playing surface will drop, and cultivation practices that could have addressed the situation beforehand, on a preventative basis, will need to be performed much more aggressively to recover turfgrass quality. Wherever high-quality putting greens exist, you can bet that the superintendent focuses on how to best accomplish the goals of aerification and topdressing (to maintain the sandbased rootzone) while minimizing the disruption to the golfer or customer.

For

Why cultivate? Cultivation practices share a long and storied history with the development

of golf courses. As legend has it, ever since old Tom Morris accidentally dumped some sand on the greens and noticed the improvement to turf quality, cultivation practices have been a necessary evil. You can be assured, though, that these practices will continue to change over time. Even as recently as the mid-1990s, superintendents tended to view major cultivation practices as spring and fall activities. Generally, the recommendations were to core cultivate in the spring, followed by sand topdressing to fill the holes, with a similar practice in the fall. If cultivations were performed mid-season, they generally consisted of lighter sand topdressings and an occasional core cultivation using small “needle tines.” However, these practices are not adequate to significantly reduce the organic matter that some of the more aggressive cultivars produce. Pat O’Brien and Chris Hartwiger from the USGA published an article in 2000 that detailed cultivation practices and recommended that 15% to 20% of the surface area should be disrupted each year. In 2004, Dr. Bob Carrow (of the University of Georgia) published an excellent article describing the physical properties associated with the summer decline of bentgrass and emphasizing the need for adequate core cultivation. His research shows that when the percentage of organic matter in the upper 2" of the soil exceeds 3% to 4%, problems with summer decline are magnified. As the percentage of organic matter increases in the upper profile of the rootzone, the large water- and aircarrying pores (macropores) begin to plug. Then, when summer temperatures increase, the organic matter breaks down at an elevated rate due to an increase in microbial activity. The decomposing organic matter forms a mucilaginous, sticky substance that further plugs macropores and holds water.

Dr. Carrow has shown that this change in the organic matter precedes the development of summer problems on putting surfaces. Cultivation and topdressing are critical to diluting and removing the buildup of organic matter before it causes problems. Ultimately, developing a cultivation and topdressing program that proactively addresses these concerns will be much more cost effective than the curative approach of throwing expensive fungicides at the secondary problems.

Developing a program for cultivation and topdressing When designing a cultivation and topdressing program, several factors should be at the forefront of this discussion. As the organic matter increases above 3% to 4% by weight, the following also occur: (1) macroporosity decreases, (2) water-holding content increases and (3) surfaces become less firm, as a result. The key to developing a successful program is to combine core aerification and topdressing practices into an integrated approach that addresses the need to dilute the buildup of organic matter throughout the year. The goal is to manage organic matter in the upper 2" of the soil so that it is less than 3% to 4% by weight. Several overall recommendations can be made at this point: • Topdressing applications are used to dilute the buildup of organic matter. • Core aeration followed by filling the holes with sand is used to make larger changes in the organic matter. • “Correct” organic-matter programs should address your particular situation. No single program is effective for all situations. In general, to keep organic matter levels within an acceptable range, 40 to 50 cubic feet of sand per 1,000 ft2 should be applied over the year.

SPRING 2011

APPLIED RESEARCH • continued

Caution should be applied here to the thinking that, “If I apply 50 cubic feet of sand through topdressings, I don’t need to aerify.” Nothing could be farther from the truth, because a topdressing-only program does not remove enough organic matter to maintain desirable organic-matter composition without unduly injuring the turf, and a twice-yearly program does not adequately distribute the applied sand evenly enough. By blending the two practices, however, you can match the demands of your course while addressing the organic matter issues.

MTC TURF NEWS

One option is to use big holes (> 1/2") on a big spacing (> 2" x 2") to core cultivate your greens once in spring and once in fall. This option has the advantage of disturbing a larger surface area, but recovery will be somewhat slower due to the larger holes. Sand volume and amounts are often debated, but for the purpose of this article, volumes will be expressed based on the calculation that 100 lbs. of dry sand equals 1 cubic foot. This option will require approximately 3,600 lbs. of sand per 1,000 ft2, or 36 cubic feet of dry sand (100 lbs of dry sand = 1 ft3). The remaining 14 ft3 per

1,000 ft2 is applied through 7 to 28 moderate to light topdressings (2 ft3/1,000 ft2 to 0.5 ft3/1,000 ft2). The exact amount and frequency of these topdressings should be determined based on your particular course. A second option is to use smaller holes (< 1/2") on a small spacing (1" x 1") using quad tines and more advanced cultivation equipment to core once or twice in the spring and once or twice in the fall. The advantage of this option is that the smaller holes heal more rapidly. The disadvantages are that multiple coring events are required in order to disturb a larger surface area, and the holes will be more difficult to completely fill due to bridging of the particles in the holes. Using sand that is as dry as possible will minimize the difficulties with bridging the holes. Using a slightly less than 1/2" tine (about 0.4") will require about 6 cubic feet of sand to fill the holes for each cultivation event. Therefore, the total sand applied for these events will be 18 to 24 ft3 for the year. This leaves 16 to 32 ft3 to be applied through light to moderate topdressings throughout the year. This would result in approximately 8 to 16 moderate topdressing applications of 2.0 ft3/1,000 ft2. In areas where temperatures remain moderate throughout the winter, it is important to employ the organic-matter management practices throughout the year. Microbial activity is reduced when temperatures are below 55° F, resulting in increases in organic-matter accumulation. Moderate applications of topdressing can be made throughout the spring, fall and, especially, winter periods, while light applications can be made during the summer stress periods. A sample program using the second option discussed above, with a yearly target of 50 ft3, might consist of 4 cultivation events (2 in spring plus 2 in fall, for a total of 24 ft3/1,000 ft2) with 8 moderate applications (2 ft3/ 1,000 ft2) of topdressing applied about every three weeks during the winter, and then 10 light/moderate topdress-

continued • APPLIED RESEARCH

ings (1 ft3/1,000 ft2) applied about every 2–3 weeks in summer. This last amount could also be broken into 4 moderate topdressings at the 2 ft3/ 1,000 ft2 rate when the temperatures are still moderate, with a rate of 0.5 ft3/1,000 ft2 for the remaining 4 light topdressings during the summer heat period about every 2–3 weeks. This is only an example program that could be used to address the dilution of organic matter throughout the year in the transition zone. I would encourage you to consider your organicmatter management plan and how it fits within these recommendations. Extenuating circumstances, however, exist at many locations. The following points suggest possible alterations that you might make to your cultivation and topdressing program, given some of the more common circumstances you might face on your course.

not been followed, these varieties will also need more-frequent core cultivation and topdressing to curatively address the situation and to avoid problems during the summer.

Evaluating the situation The bottom line is that, to help limit the problems associated with summer stress, you should evaluate where your greens currently stand and make adjustments to your program to bring them in line with the recommendations of less than 3% to 4% by weight organic matter. So, how do you evaluate where you stand? The easiest way is to visually examine your soil profiles throughout the season and take note of the depth of the dark organic layer and how well the sand is incorporated in that layer in the upper 2" of the profile. Having accurate information is critical, however, so the best possible

solution is to have an accredited soil-testing lab evaluate profiles from several of your greens for the percentage by weight organic matter in the soil profile’s upper 2". Having this information, and regularly testing thereafter, will allow you to monitor how your organic-matter dilution practices are working, and they will allow you to evaluate changes to your program. The best time to sample for testing is in late spring (May) and early fall (September), when organic matter will be at their highest (spring) and lowest (fall) levels during the year. Evaluating your cultivation practices will help lead to improved conditions during summer stress by enabling the soil profile to (1) have adequate oxygen in the rootzone, (2) maintain good infiltration rates and (3) provide a high-quality, firm playing surface for players to enjoy year-round. •

• High traffic: Generally, high traffic courses need more N fertility to maintain quality and, as a result, can expect high organic-matter accumulations. Therefore, increased frequencies of light topdressings and more cultivation events may be required. • Turfgrass varieties: The more aggressive bentgrasses (Penn A series, G series, etc.) require more aggressive management of organic matter. These practices should be employed immediately, in order to maintain control of organic-matter buildup. Courses with these varieties that have not been practicing aggressive dilution practices can expect to significantly increase the need for core cultivation and topdressing frequencies, in order to curatively address this issue. Older varieties of bentgrass (L-93, Providence, Crenshaw, Penncross, etc.) may not need as aggressive management, if good practices have been followed since establishment. However, if good practices have

SPRING 2011

TURF TIPS

By Jeffrey Derr, Ph.D., Weed Scientist, Hampton Roads AREC, Virginia Tech

urrently, there are limited options for weed control in landscape ornamentals, especially for plantings of annual bedding plants and perennials. One new chemical that has been introduced recently for the nursery and landscape industries is dimethenamid, sold in a sprayable form as Tower and in a combination granular formulation as FreeHand. FreeHand contains 1% pendimethalin (the active ingredient in Pendulum), as well as 0.75% dimethenamid. I have been evaluating these two herbicides for several years in a range of ornamental species, but I have focused primarily on annual bedding plants and perennials.

How these herbicides work Dimethenamid is in the same herbicide class as metolachlor, an emulsifiable concentrate (EC) formulation sold in the nursery industry as Pennant Magnum. These pre-emergence herbicides need to be applied prior to weed germination or applied with a postemergence herbicide if emerged weeds are present. As an EC formulation, Tower contains an oil solvent, with the potential for burning of tender new leaves if applied under hot, humid conditions. In general, granular products tend to be safer in nursery crops since they limit the potential for leaf uptake. FreeHand, the granular form, therefore has the best fit for use in landscape beds and is the product I will focus on in this article.

MTC TURF NEWS

The two herbicides in Freehand have different modes of action and a different weed-control spectrum, so there are advantages in combining dimethenamid and pendimethalin into a granular product. The use rate for FreeHand is 100 to 200 pounds product per acre, which corresponds to 2.3 to 4.6 pounds per 1,000 square feet.

Weed control In my trials, FreeHand has provided excellent preemergence control of spotted spurge, often referred to as prostrate spurge, a common weed in flowerbeds. Freehand also controls other annual broadleaf weeds, such as carpetweed, common chickweed and henbit. FreeHand may suppress (but not provide complete control of) composite weeds like eclipta, common groundsel, tasselflower and sowthistle. It has effectively controlled annual grasses, like crabgrass, goosegrass and annual bluegrass. Of special interest is Freehandâ&#x20AC;&#x2122;s excellent control of annual sedges like fragrant flatsedge and rice flatsedge, as well as suppression/control of yellow nutsedge, a perennial weed that is a major landscape bed problem. FreeHand, however, will not control perennial grass or broadleaf weeds such as bermudagrass or poison ivy.

Bedding plants tolerance In one study, I applied FreeHand at varying rates to gazania, marigold, vinca, lanceleaf coreopsis, geranium

and coleus. These six bedding-plant species appear to have good tolerance to FreeHand at the 100 lb./acre rate, but some reduction in flowering occurs at 4 times that rate (400 lbs./A) in marigold, gazania and vinca. The 400 lb./acre rate is twice the maximum use rate. Ideally, we would like to see desired plants tolerate at least twice, and ideally four times, the use rate, so that is why I test at rates above the maximum use rate. In another trial, I treated impatiens, alyssum, petunia, vinca, geranium and zinnia. Vinca, geranium, petunia and zinnia have acceptable tolerance to FreeHand. Flowering in impatiens, however, decreases as the FreeHand rate increases. Additional data is need on alyssum, although it appears to respond like impatiens.

Perennial plant tolerance In one study, I applied FreeHand to black-eyed Susan, purple coneflower, pinchusion flower, verbena, coreopsis, lantana, sedum, ice plant, daylily and dianthus. At the 150 pounds per acre rate of FreeHand, a typical use rate, I observed no injury to any of these species. When I applied 300 and 600 pounds FreeHand per acre, I did observe slight injury in purple coneflower and in pinchusion flower, but no injury was seen in the other species. So, it appears that all of these species have good tolerance to FreeHand at the labeled rate. In another trial, I treated purple coneflower, columbine, gaura, clematis,

butterfly milkweed, pinchusion flower, blanket flower, Nepeta, Shasta daisy, astilbe, caladium and primrose. As in the previous trial, I observed slight injury in purple coneflower only when I applied higher-than-labeled rates of FreeHand. I saw a similar pattern in columbine. When I applied Freehand at 150 pounds per acre, I saw no injury in purple coneflower, columbine, gaura or clematis. At 41 days after treatment, all herbicides appeared to reduce flowering in purple coneflower and gaura, while no adverse impact on clematis flowering was seen. Total flower count in purple coneflower appeared to decrease as the FreeHand rate increased. Slight injury to butterfly milkweed was seen at the highest rate of FreeHand, but lower rates did not cause injury. There was a trend towards lower butterfly milkweed flowering at the two higher rates of FreeHand. In my trial this past year, FreeHand caused no reductions in plant stand for either scaevola or butterfly milkweed. At the two lower rates of FreeHand, no injury or reductions in flowering were noted for either species. The highest rate of FreeHand did not injure scaevola or reduce the number of flower clusters, but they appeared to cause a reduction in flower quality (smaller flower size) at 14 days after the second application (this effect was not seen two weeks later). The highest rate of FreeHand appeared to cause slight injury in butterfly milk-weed but caused no reductions in flowering. Caladium appears to be very tolerant to Freehand. I observed no injury, even when applied at rates higher than the use rates, when making applications either before or after emergence of caladium. In another of my trials at the station, I did not see injury in blanket flower, Nepeta, astilbe, Shasta daisy or primrose at 150 pounds of FreeHand per acre. Slight injury (11% to 15%) was observed in pinchusion flower at 34 days after treatment, but the injury decreased by 50 days after treatment. Slight injury (7%) was seen in blanket

flower at the three-times FreeHand rate at 34 DAT, with no injury seen at 50 days after treatment. No injury was seen in primrose or Nepeta. No reduction in flowering or plant stand was noted with any FreeHand rate in pinchusion flower, blanket flower, primrose or Nepeta. Little to no injury was seen in astilbe or Shasta daisy.

Conclusion Based on the research I have conducted, Freehand appears to be an effective herbicide for control of annual grasses, annual sedges, yellow nutsedge and certain annual

broadleaf weeds in landscape beds. Most of the bedding plants tested tolerated FreeHand at 100 lb./A, although higher rates may cause some decline in flowering. Similarly, perennials also have very good tolerance to FreeHand at 100 lb./acre, although higher rates may cause some injury in certain species. If you prefer to use the 150 or 200 lb./acre rate, test FreeHand in small areas first. Increasing the application rate will improve broadleaf weed control and lengthen soil residual control, but it may reduce flower count in certain ornamental species. â&#x20AC;˘

Photo 1. Tolerance of bedding plants to FreeHand was determined in research trials.

Photo 2. FreeHand controls annual sedges and yellow nutsedge.

SPRING 2011

TURF INDUSTRY CALENDAR OF EVENTS

INDEX OF ADVERTISERS

April 19

October 27–29

All States Turfgrass Consultants, LLC .............16

MNLA — CPH Basic Exam

Green Industry & Equipment Expo

BASF .......................................Inside Back Cover

Contact: www.mnlaonline.org or 410-823-8684

Kentucky Exposition Center Louisville, KY

Buy Sod ............................................................5

www.basf.com www.buysod.com

July 19

January 11–13, 2012

MNLA — CPH Specialist Tests (Herbaceous Perennials and Integrated Pest Management)

Mid-Atlantic Nursery Trade Show

Contact: www.mnlaonline.org or 410-823-8684

July 17–18 ANLA Annual Meeting (American Nursery & Landscape Assn.) Liaison Capital Hill Washington, DC

Capitol Sports Fields ........................................9 www.capitolsportsfields.com

Collins Wharf Sod Farm...................................21

Baltimore Convention Center Baltimore, MD

www.collinswharfsod.com

CoverSports USA...............................................8 www.coversports.com

January 2012

East Coast Sod & Seed .....................................7

35th Annual MTC Turfgrass Conference & Trade Show

Ernst Conservation Seeds ...............................23

www.eastcoastsod.com www.ernstseed.com

Adele H. Stamp Student Union University of Maryland College Park, MD

Mid-Atlantic Turf Equipment, LLC ...................27 www.midatlanticturfequipment.com

Oakwood Sod Farm, Inc. .................................16 www.oakwoodsod.com

Quali-Pro.................................Inside Front Cover

July 18–20

www.quali-pro.com

ANLA Legislative Conference

Summit Hall Turf, Inc. ........................Back Cover

Liaison Capital Hill Washington, DC

Syngenta Professional Products .....................23 The Turfgrass Group....................................3, 13 www.theturfgrassgroup.com

July 18–22

WinField Solutions, LLC.....................................6

TPI Summer Convention & Field Days (Turfgrass Producers International)

Wood Bay Enterprises Inc. ................................9 www.woodbayturftech.com

Grand Sierra Resort Reno, NV

UNIVERSITY OF MARYLAND TURFGRASS TEAM Pete Dernoeden, Ph.D.

Tom Turner, Ph.D.

Mark Carroll, Ph.D.

Kevin Mathias, Ph.D.

Dave Funk

Dept. of Agronomy University of Maryland College Park, MD 301-405-1337 pd@umd.edu

Paint Branch Turfgrass Research Facility University of Maryland College Park, MD 301-403-4431 tturner@umd.edu

Dept. of Agronomy University of Maryland College Park, MD 301-405-1339 mcarroll@umd.edu

Institute of Applied Ag. University of Maryland College Park, MD 301-405-4692 jkm@umd.edu

Paint Branch Turfgrass Research Facility University of Maryland College Park, MD 301-403-8195 dfunk@umd.edu

MTC Turf News is the Maryland Turfgrass Council magazine. Subscriptions are complimentary to MTC members. The statements and opinions expressed herein are those of the individual authors and do not necessarily represent the views of the association, its staff, its board of directors, MTC Turf News, or its editors. Likewise, the appearance of advertisers, or their identification as MTC members, does not constitute an endorsement of the products or services featured in any issue of MTC Turf News. Copyright ©2011 by the Maryland Turfgrass Council. MTC Turf News is published quarterly. POSTMASTER: Send change of address notification to Maryland Turfgrass Council: 12 Pressie Lane, Churchville, MD 21028. Postage guaranteed. Presorted standard postage is paid at Nashville, TN. Printed in the U.S.A. Reprints and Submissions: MTC allows reprinting of material published here. Permission requests should be directed to MTC. 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) 790-3718, Fax (615) 794-4524.

MTC TURF NEWS