The Turf Zone Podcast

MTC Turf News – Evan C. Mascitti and Andrew McNitt, PhD

A baseball often touches two different surfaces during the same play. This sets baseball apart from other ball sports. Most ground balls take their first bounce on the turf and are fielded on the infield skin (Figure 1). The concentration of play in this small area means that infield playability consumes much of the grounds crew’s focus. Experienced managers know instinctively when the ball is reacting the way they want, and they can produce a consistent surface despite changing weather conditions. Playability can be an ambiguous term because it is easy to observe but hard to describe.

This article unpacks infield playability by combining practical observations with bite-size pieces of physics. We will cover the following ideas:

1. Consistency is king

2. Components of speed

3. Corkboard = plasticity + stiffness

Figure 1: Most action occurs on the infield skin.

Consistency is king

Above all else, infielders want a consistent, predictable surface. This means no surprises about how the ball will react from one hop to the next, and that the field will play identically throughout a game and over the season. Elite athletes can field almost any ball, fast or slow – so long as the bounces are the same, each and every time. Infielders prefer ground balls to “hug” the surface: a shallow path makes the ball easier to track and collect. The grass and dirt areas should have similar speed and the transition between them should be seamless.

Predictability is crucial for players to be able to do their jobs. If the final hop is deflected by just a few degrees, the ball can easily carom off the heel of a player’s glove or scoot beyond his reach.

Components of speed

Players and coaches sometimes ask us to “speed up” or “slow down” the infield, usually by adjusting the cutting height of the turf. Ball response is more nuanced than fast vs. slow, and canopy height plays only a minor role. However, it has been said that perception is reality, so a perceived change may satisfy such a request – even if we fib about having lowered the reels by 1/8″ or so. Ball response is divisible into three important elements: pace, bounce, and spin.

Pace

Pace is the relative velocity of a ball after impact. Infield pace is mostly determined by hardness and friction. It is measured as a simple ratio, the Coefficient of Restitution (COR):

There is limited research on infield pace, but data suggest that soil properties affect COR more than cutting height or thatch. Dr. Jim Brosnan measured COR on real infields and on research plots (Brosnan and McNitt, 2008a; b; 2011). Infield COR ranged from 0.4 to 0.6, meaning a ball retained 40 to 60 % of its initial velocity after the first bounce. COR was generally higher on skinned surfaces than synthetic turf, which had a similar (but slightly higher) COR than natural grass.

In the work by Dr. Brosnan, pace was closely related to surface hardness. Hardness is easy to measure with the familiar Clegg hammer or the F-355 device (for synthetic infields). Brosnan and McNitt (2008a) found that most infield skins had Clegg values well over 100 Gmax – much higher than values recommended for turf areas (Figure 2). However, it is worth noting that some fields in this study were substantially drier than typical game moisture. In a baseball context, hardness may be more useful for managing playability than safety, as baseball players are never tackled and rarely become injured by falling on the surface.

Figure 2: Surface hardness on baseball infields generally exceeds values recommended for American football.

Ball-to-surface friction is determined by soil texture, presence of conditioner, and the all-important water content (Goodall et al., 2005).

Arkansas Turfgrass – Julie Holt, Content Director, TheTurfZone.com

Golf Course of the Year:

Magellan Golf Course, Hot Springs Village

Magellan began as a 3-hole golf school for beginners to learn the game. Because of its popularity in the Village, in 1995, it was expanded to become a full 18-hole course.

“Magellan Golf Club plays a little shorter than other courses in Hot Springs Village, but its tricky greens prove troublesome,” says superintendent Donald Jones. “Magellan continues to be one of the best practice facilities in the community with a large driving range, putting green and several short game areas. The course is a favorite of our female golfers.”

Despite the irrigation system being original to the 1995 expansion and having older equipment, Jones says, “we still find a way to provide a consistent golf course with inconsistent equipment.” In a time of reduced staffing and budgets due to COVID, this is a testament to the team of professionals who work so hard to provide a great golf experience.

 

Field of the Year:

Rambler Baseball Field at Rose Bud

Taylor Cooper took on the head baseball coach position at Rose Bud High School in 2014. The field had only just been built and was far from what the coach hoped it would be. “Although it was a new field, many things were just not done correctly, nor with much detail or care,” Cooper says. “The grass was very bare, but what grass was there seemed to mostly be pasture grass and weeds. The infield playing area was not symmetrical nor had any type of conditioner for a smooth playing surface.”

In an effort to provide a better field for his team, Cooper discovered a true passion for field work and maintenance. Through the past seven years, he has continued to put in the hours of labor required to rehab the baseball field. Through acquiring a budget for field maintenance, and with support from AgraTurf, Cooper has turned his rural high school’s baseball stadium into a shining example of sports turf maintenance.

Tennessee Turfgrass – Julie Holt, Content Director, TheTurfZone.com

We sat down with TTA member Kenny Franks to discuss his career, his advice for young turfgrass managers and his future plans.

How many years have you been in this position?

I have been with the City of Jackson for 19 years. I was first put at the City Golf Course (Bent Tree) as the superintendent, the worst two-and-a-half years of my life (besides the ones with my ex-wife). Then the city leased out the course and then-Mayor Farmer put me over all the athletic fields for the City for about two years. In 2005, the City of Jackson built the 17-field Sportsplex where I became the Sports Turf Manager.

How did you decide to pursue a career in turfgrass management?

From my college baseball to coaching and being Parks & Recreation director in two municipalities, I spent a lot of time trying to improve the athletic fields. During this time, I also attended turf seminars which increased my interest and enjoyment in development of this career. Also when I worked for the City of Portland, TN, during my spare time, I went to Nashville, and helped Tom McAfee prepare the grounds for the Nashville Sounds.

What path led you to your current position?

In addition to the Parks & Recreation director positions, I worked for the Nashville Sounds as turf manager, Tennessee Titans as groundskeeper, West TN Diamond Jaxx as turf manager, then to my current position.

What is the best part of your job?

The best part of my job is being able to maintain the best quality playing fields, making sure it is player safe and being able to communicate with staff how to properly maintain the fields.

What are some unique challenges of your job?

Unique challenges of my job include pop-up summer showers while continuing play and to have the ability to keep high school age staff interested in maintaining the highest quality fields. Another challenge I face is training a new seasonal staff each year.

How many employees are part of your team?

We maintain three full-time staff and 20–30 seasonal workers.

What do you feel is the biggest challenge facing the turfgrass industry right now?

Currently, I feel the biggest challenge is finding the best quality turf free of diseases and weeds as well as stress from the weather and the high volume of foot traffic.

What is one lesson you’ve learned the hard way in your career?

It is a struggle to make supervisors understand how or why you make decisions, spend money or others choices necessary to maintain the fields at the highest quality.

Do you have a mentor in the industry? Who?

I have several; Tom McAfee (Nashville Sounds), Terry Porch (Tennessee Titans), Tom Neilson (Louisville Bats), Billy Clark (Clarks Sports Fields), and Bill Marbet (Southern Athletic Fields).

Even though I had an idea of what I wanted to do – I would call and get their opinion. I would either use their idea or coordinate with mine.

What do you do in your free time?

I enjoy spending time with family & friends at the river, fishing, playing golf and drinking adult beverages. I have also started a Seasoned Nut business for extra income when I retire in 2022. kennysnutz.com

My wife is Kathy and we’ve been married 16 years. My children are daughter Kassi and stepsons Ryan and EJ. We have 4 grandchildren & my buddy Lacie Lou (King Charles Cavalier Spaniel).

What would your advice be for people entering the turfgrass industry now?

Never be afraid to ask for advice on problems or to get ideas from other turf managers or golf course superintendents in the turfgrass industry. You are never too old to learn new things.

I would like to give a pat on the back to the Sportsplex Ground Staff for making this Sportsplex the showplace it is.

Pennsylvania Turfgrass – Julie Holt, Content Director, TheTurfZone.com

KAFMO’s Brad Jakubowski Honored with 2020 STMA Founder’s Award

When Penn State Plant Science instructor and KAFMO Board member Brad Jakubowski learned that he was slated to receive a 2020 STMA Founder’s Award, he says he was “utterly speechless and humbled. I felt so honored being considered for an award for an association I’ve grown to love.” Brad joins three other KAFMO members as recipients of the Daniel Founder’s Award for educators (Jeff Fowler in 2005, Dr. Andrew McNitt in 2000, and Dr. Donald Waddington in 1999); he is the tenth KAFMO member to receive an STMA Founder’s Award.

STMA’s highest honors, the Founders’ Awards, recognize those members who have made significant contributions to STMA and to the profession. Founder Dr. William Daniel set the pattern for educator/researcher involvement in STMA. The partnership between educators and researchers and the sports turf managers who incorporate these advances on the field is key to the progress of the industry. The Daniel Award recognizes an individual who has made significant contributions to the industry through research, teaching, or extension.

Deep Roots

Brad Jakubowski is an instructor of golf course irrigation and drainage, landscape irrigation and water management, and turfgrass management in the Penn State Turfgrass Science program. He also manages PSU Turf Science’s digital presence. As a Ph.D. candidate, he is studying impact attenuation on natural and synthetic athletic turfgrass fields. Jakubowski has been involved with the green industry for nearly 30 years, working in the areas of residential/commercial irrigation, golf course, and sport field. He previously directed the two-year Sports Turf Management Pro- gram for the University of Nebraska and helped to develop their new Turfgrass and Landscape Management Degree Program.

Brad Jakubowski’s roots in Turf Management go deep. “I started in turfgrass as an eighth grader, taking care of an estate and working at a par 3 golf course,” he reminisces. “I built my first bunker with a skid steer loader back in 1987, and that bunker is still there.” His background in sports turf deepened while directing the University of Nebraska’s two-year sports turf management program. He had asked Tony Koski from Colorado State University where to take his students for a turf conference and heard about the STMA. “Tony said if you go there, you’ll never leave, and he was right. I didn’t.” He is a 15-year member of STMA, co-founder of the STMA Intercollegiate Student Challenge and recently served on the STMA board of directors. “There were and are so many mentors!” he says. Dr. Tom Samples gave him his first opportunity to speak at the Tennessee Turf Conference and is still one of his biggest supporters. He is also grateful to Mike Andresen, Lynda Wightman, Dave Minner, Tony Koski, Gwen Stahnke, Leah Brilman, and Andy McNitt. “Without them, my path in sports turf would have been extremely limited.”

Career High Points

When Jakubowski looks back on his career, this award is one of several high points. Another, he recalls, was the day they called him about his nomination to the STMA Board of Directors. “It was August, and I was working with a group of baseball players in rebuilding their pitcher’s mound. It definitely made pounding new clay a lot easier on a hot afternoon!” Another peak was helping to develop the STMA Student Challenge. He still remembers meeting with Chad Follis and Jeff Salmond in San Antonio years ago to discuss how to propose it. The first challenge in Phoenix had 13 teams competing. Since then, they commonly have over 30. “My biggest challenges have been working diligently to find or develop quality programming and education for the STMA membership. It’s a difficult association to outgive,” he says.

ATA Turf Times – Julie Holt, Content Director, TheTurfZone.com

“Be Friendly to Everyone, Whether They Purchase Your Brand of Equipment or Not!”

Mickey Pitts was born on Christmas Day in 1948, in Red Level, Alabama. Raised on a farm near Andalusia, Mickey had two sisters and no brothers, allowing him to claim the title of ‘favorite son.’ He often helped with farm chores, instilling a love of agriculture and a skill set that would inspire his later career.

Mickey graduated from Red Level High School and attended just one year of junior college before being drafted by the military. He decided then to enlist in the Air Force for four years, hoping to avoid deployment to Vietnam. Nevertheless, he deployed to Vietnam in January of 1970, serving 13 months overseas. Mickey was a crew chief on fighter jets and was under fire many times, but fortunately, made it home intact. When his active military career ended, Mickey joined the Alabama National Guard and served with them for many years.

Upon his return to the United States, Mickey met his future wife, Jenny. They married in 1971 and have two daughters, Amy and Ashley.

Mickey’s career in the turf industry started when he left the Air Force and decided to return to his roots. He started working with Don Cotton at Turf Pride in the 1980’s. Mickey found that his childhood on a farm made him a good fit for turf sales. He worked at Neary after Turf Pride, then settled at Tieco in 1993.

After working at Tieco for almost a decade, Mickey moved to Beard Equipment in 2001. Soon afterwards the World Trade Center was destroyed in a terrorist attack. Mickey, still in the Alabama National Guard, expected to be called into service in the Middle East, but fortunately, he remained stateside and retired from the National Guard in 2010.

Prior to joining Beard Equipment, Mickey had been acquainted with Herman Bloch and when Beard began selling John Deere equipment, Mickey really found his sales footing. He received a John Deere ring and many other honors from John Deere over the years. Mickey’s sales strategy is to be friendly with everyone — whether they are purchasing equipment or not! “Personability and kindness to potential customers can help overcome sales challenges most of the time. Convincing potential customers that the equipment is worthwhile can be difficult, but a good product and a friendly face overcomes most obstacles, according to Mickey. “It’s simple, but the key to sales success is kindness.”

During his career, Mickey has traditionally enjoyed playing golf. He doesn’t get out to the course much anymore, but that doesn’t mean that he has slowed down — he spends time with his granddaughters, Lily and Ingram. He has also increased his travel, visiting everywhere from Alaska to Key West with his wife and friends in the past few years.

Mickey reflects on his career thus far by thanking his coworkers — “The guys I’ve worked with have always been a blessing in my life.” Mickey has never met a stranger — he loves his job and the people he does it with!

The Alabama Turfgrass Association has been blessed to have Mickey as a member for many years, and he has also served on the ATA board and then the executive board as Treasurer and Vice-President. Thank you, Mickey for your service to your country, your employers, your customers and your ATA Family!

North Carolina Turfgrass – Jeffrey Derr, Ph.D. and Adam Nichols, Virginia Tech

Herbicide-resistant weeds in turfgrass, ornamental, and nursery crop commodities have been an increasing issue over the past 10 years. It has been a while since we have seen a new herbicide mode of action so we are primarily relying on herbicides developed 20, 30, 40 or more years ago. Until new herbicide modes of action are developed, the issue of herbicide resistance will increase.

Definition of resistance

First, some definitions here. When I say “Herbicide Resistance,” I am referring to weed species that used to be controlled by a given herbicide, but now are no longer controlled. This is different from weed species that were always difficult to control — we refer to these as troublesome or tolerant weed species. Examples of troublesome weed species would include species like kyllinga, wild garlic, wild violets, Virginia buttonweed, bindweed, poison ivy, and mugwort (wild chrysanthemum). These troublesome weeds can be controlled, but it may require higher application rates or repeat applications. For herbicide-resistant weeds, increasing the application generally has no effect, as the biotype often can tolerate many times the highest use rate.

How resistance develops

It is thought that in a population of a given weed species, there may be a few individuals that, through a genetic mutation developed resistance to an herbicide. The mutation may have been present before that herbicide was ever used on the property. Current thinking is that herbicide application does not cause the genetic mutation that confers resistance, but that the mutations occur as a separate, random process. Often the herbicide provided a high level of control for the susceptible biotypes of that weed species. Repeated applications of that herbicide quickly control the susceptible biotypes, allowing the resistant biotype to spread through uninhibited seed production. If that herbicide is reapplied every year or so for say eight or nine years, the resistant population will increase until it is the dominant biotype. Over that eight or nine years, that herbicide will be less and less effective until it provides no control at all.

Examples of resistance in turf situations

There are certain weed species that appear to be prone to developing herbicide resistance, such as annual bluegrass (Poa annua). There are documented cases of annual bluegrass biotypes that have developed resistance to certain herbicides. In 2019, Ian Heap (International survey of herbicide resistant weeds, www.weedscience.org) reported that annual bluegrass ranks third among all herbicide-resistant weed species globally, with resistance to nine different herbicide sites of action. Triazine-resistant annual bluegrass has been detected in turfgrass, with simazine being the primary triazine used in turf (mainly used in bermudagrass), with specialized uses of atrazine in certain warm- season turf species. Adam Nichols and I documented triazine resistant annual bluegrass at a golf course in Virginia a number of years ago. We kept seed from that biotype and discovered that biotype was also resistant to Xonerate (amicarbazone). Simazine and amicarbazone both are photosynthetic inhibitors.

Annual bluegrass biotypes resistant to the dinitroaniline herbicides have been identified in Tennessee, North Carolina, and Georgia. The dinitroaniline herbicide class incudes prodiamine (Barricade, others), pendimethalin (Pendulum, others) , oryzalin (Surflan, others), and trifluralin (Treflan, others), key turfgrass and ornamental herbicides. Annual bluegrass resistant to glyphosate (Roundup, many others) has been identified in Tennessee and Missouri.

Biotypes of Poa annua resistant to the sulfonylurea herbicides have been documented in Tennessee, Alabama, and Virginia.

Arkansas Turfgrass – Jeffrey Derr, Ph.D. and Adam Nichols, Virginia Tech

Herbicide-resistant weeds in turfgrass, ornamental, and nursery crop commodities have been an increasing issue over the past 10 years. It has been a while since we have seen a new herbicide mode of action so we are primarily relying on herbicides developed 20, 30, 40 or more years ago. Until new herbicide modes of action are developed, the issue of herbicide resistance will increase.

Definition of resistance

First, some definitions here. When I say “Herbicide Resistance,” I am referring to weed species that used to be controlled by a given herbicide, but now are no longer controlled. This is different from weed species that were always difficult to control — we refer to these as troublesome or tolerant weed species. Examples of troublesome weed species would include species like kyllinga, wild garlic, wild violets, Virginia buttonweed, bindweed, poison ivy, and mugwort (wild chrysanthemum). These troublesome weeds can be controlled, but it may require higher application rates or repeat applications. For herbicide-resistant weeds, increasing the application generally has no effect, as the biotype often can tolerate many times the highest use rate.

How resistance develops

It is thought that in a population of a given weed species, there may be a few individuals that, through a genetic mutation developed resistance to an herbicide. The mutation may have been present before that herbicide was ever used on the property. Current thinking is that herbicide application does not cause the genetic mutation that confers resistance, but that the mutations occur as a separate, random process. Often the herbicide provided a high level of control for the susceptible biotypes of that weed species. Repeated applications of that herbicide quickly control the susceptible biotypes, allowing the resistant biotype to spread through uninhibited seed production. If that herbicide is reapplied every year or so for say eight or nine years, the resistant population will increase until it is the dominant biotype. Over that eight or nine years, that herbicide will be less and less effective until it provides no control at all.

Examples of resistance in turf situations

There are certain weed species that appear to be prone to developing herbicide resistance, such as annual bluegrass (Poa annua). There are documented cases of annual bluegrass biotypes that have developed resistance to certain herbicides. In 2019, Ian Heap (International survey of herbicide resistant weeds, www.weedscience.org) reported that annual bluegrass ranks third among all herbicide-resistant weed species globally, with resistance to nine different herbicide sites of action. Triazine-resistant annual bluegrass has been detected in turfgrass, with simazine being the primary triazine used in turf (mainly used in bermudagrass), with specialized uses of atrazine in certain warm- season turf species. Adam Nichols and I documented triazine resistant annual bluegrass at a golf course in Virginia a number of years ago. We kept seed from that biotype and discovered that biotype was also resistant to Xonerate (amicarbazone). Simazine and amicarbazone both are photosynthetic inhibitors.

Annual bluegrass biotypes resistant to the dinitroaniline herbicides have been identified in Tennessee, North Carolina, and Georgia. The dinitroaniline herbicide class incudes prodiamine (Barricade, others), pendimethalin (Pendulum, others) , oryzalin (Surflan, others), and trifluralin (Treflan, others), key turfgrass and ornamental herbicides. Annual bluegrass resistant to glyphosate (Roundup, many others) has been identified in Tennessee and Missouri.

Biotypes of Poa annua resistant to the sulfonylurea herbicides have been documented in Tennessee, Alabama, and Virginia.

Virginia Turfgrass Journal – Jeffrey Derr, Ph.D. and Adam Nichols, Virginia Tech

Herbicide-resistant weeds in turfgrass, ornamental, and nursery crop commodities have been an increasing issue over the past 10 years. It has been a while since we have seen a new herbicide mode of action so we are primarily relying on herbicides developed 20, 30, 40 or more years ago. Until new herbicide modes of action are developed, the issue of herbicide resistance will increase.

Definition of resistance

First, some definitions here. When I say “Herbicide Resistance,” I am referring to weed species that used to be controlled by a given herbicide, but now are no longer controlled. This is different from weed species that were always difficult to control — we refer to these as troublesome or tolerant weed species. Examples of troublesome weed species would include species like kyllinga, wild garlic, wild violets, Virginia buttonweed, bindweed, poison ivy, and mugwort (wild chrysanthemum). These troublesome weeds can be controlled, but it may require higher application rates or repeat applications. For herbicide-resistant weeds, increasing the application generally has no effect, as the biotype often can tolerate many times the highest use rate.

How resistance develops

It is thought that in a population of a given weed species, there may be a few individuals that, through a genetic mutation developed resistance to an herbicide. The mutation may have been present before that herbicide was ever used on the property. Current thinking is that herbicide application does not cause the genetic mutation that confers resistance, but that the mutations occur as a separate, random process. Often the herbicide provided a high level of control for the susceptible biotypes of that weed species. Repeated applications of that herbicide quickly control the susceptible biotypes, allowing the resistant biotype to spread through uninhibited seed production. If that herbicide is reapplied every year or so for say eight or nine years, the resistant population will increase until it is the dominant biotype. Over that eight or nine years, that herbicide will be less and less effective until it provides no control at all.

Examples of resistance in turf situations

There are certain weed species that appear to be prone to developing herbicide resistance, such as annual bluegrass (Poa annua). There are documented cases of annual bluegrass biotypes that have developed resistance to certain herbicides. In 2019, Ian Heap (International survey of herbicide resistant weeds, www.weedscience.org) reported that annual bluegrass ranks third among all herbicide-resistant weed species globally, with resistance to nine different herbicide sites of action. Triazine-resistant annual bluegrass has been detected in turfgrass, with simazine being the primary triazine used in turf (mainly used in bermudagrass), with specialized uses of atrazine in certain warm- season turf species. Adam Nichols and I documented triazine resistant annual bluegrass at a golf course in Virginia a number of years ago. We kept seed from that biotype and discovered that biotype was also resistant to Xonerate (amicarbazone). Simazine and amicarbazone both are photosynthetic inhibitors.

Annual bluegrass biotypes resistant to the dinitroaniline herbicides have been identified in Tennessee, North Carolina, and Georgia. The dinitroaniline herbicide class incudes prodiamine (Barricade, others), pendimethalin (Pendulum, others) , oryzalin (Surflan, others), and trifluralin (Treflan, others), key turfgrass and ornamental herbicides. Annual bluegrass resistant to glyphosate (Roundup, many others) has been identified in Tennessee and Missouri.

Biotypes of Poa annua resistant to the sulfonylurea herbicides have been documented in Tennessee, Alabama, and Virginia.

New England Blade – Jeffrey Derr, Ph.D. and Adam Nichols, Virginia Tech

Herbicide-resistant weeds in turfgrass, ornamental, and nursery crop commodities have been an increasing issue over the past 10 years. It has been a while since we have seen a new herbicide mode of action so we are primarily relying on herbicides developed 20, 30, 40 or more years ago. Until new herbicide modes of action are developed, the issue of herbicide resistance will increase.

Definition of resistance

First, some definitions here. When I say “Herbicide Resistance,” I am referring to weed species that used to be controlled by a given herbicide, but now are no longer controlled. This is different from weed species that were always difficult to control — we refer to these as troublesome or tolerant weed species. Examples of troublesome weed species would include species like kyllinga, wild garlic, wild violets, Virginia buttonweed, bindweed, poison ivy, and mugwort (wild chrysanthemum). These troublesome weeds can be controlled, but it may require higher application rates or repeat applications. For herbicide-resistant weeds, increasing the application generally has no effect, as the biotype often can tolerate many times the highest use rate.

How resistance develops

It is thought that in a population of a given weed species, there may be a few individuals that, through a genetic mutation developed resistance to an herbicide. The mutation may have been present before that herbicide was ever used on the property. Current thinking is that herbicide application does not cause the genetic mutation that confers resistance, but that the mutations occur as a separate, random process. Often the herbicide provided a high level of control for the susceptible biotypes of that weed species. Repeated applications of that herbicide quickly control the susceptible biotypes, allowing the resistant biotype to spread through uninhibited seed production. If that herbicide is reapplied every year or so for say eight or nine years, the resistant population will increase until it is the dominant biotype. Over that eight or nine years, that herbicide will be less and less effective until it provides no control at all.

Examples of resistance in turf situations

There are certain weed species that appear to be prone to developing herbicide resistance, such as annual bluegrass (Poa annua). There are documented cases of annual bluegrass biotypes that have developed resistance to certain herbicides. In 2019, Ian Heap (International survey of herbicide resistant weeds, www.weedscience.org) reported that annual bluegrass ranks third among all herbicide-resistant weed species globally, with resistance to nine different herbicide sites of action. Triazine-resistant annual bluegrass has been detected in turfgrass, with simazine being the primary triazine used in turf (mainly used in bermudagrass), with specialized uses of atrazine in certain warm- season turf species. Adam Nichols and I documented triazine resistant annual bluegrass at a golf course in Virginia a number of years ago. We kept seed from that biotype and discovered that biotype was also resistant to Xonerate (amicarbazone). Simazine and amicarbazone both are photosynthetic inhibitors.

Annual bluegrass biotypes resistant to the dinitroaniline herbicides have been identified in Tennessee, North Carolina, and Georgia. The dinitroaniline herbicide class incudes prodiamine (Barricade, others), pendimethalin (Pendulum, others) , oryzalin (Surflan, others), and trifluralin (Treflan, others), key turfgrass and ornamental herbicides. Annual bluegrass resistant to glyphosate (Roundup, many others) has been identified in Tennessee and Missouri.

Biotypes of Poa annua resistant to the sulfonylurea herbicides have been documented in Tennessee, Alabama, and Virginia.

Mississippi Turfgrass – Jeffrey Derr, Ph.D. and Adam Nichols, Virginia Tech

Herbicide-resistant weeds in turfgrass, ornamental, and nursery crop commodities have been an increasing issue over the past 10 years. It has been a while since we have seen a new herbicide mode of action so we are primarily relying on herbicides developed 20, 30, 40 or more years ago. Until new herbicide modes of action are developed, the issue of herbicide resistance will increase.

Definition of resistance

First, some definitions here. When I say “Herbicide Resistance,” I am referring to weed species that used to be controlled by a given herbicide, but now are no longer controlled. This is different from weed species that were always difficult to control — we refer to these as troublesome or tolerant weed species. Examples of troublesome weed species would include species like kyllinga, wild garlic, wild violets, Virginia buttonweed, bindweed, poison ivy, and mugwort (wild chrysanthemum). These troublesome weeds can be controlled, but it may require higher application rates or repeat applications. For herbicide-resistant weeds, increasing the application generally has no effect, as the biotype often can tolerate many times the highest use rate.

How resistance develops

It is thought that in a population of a given weed species, there may be a few individuals that, through a genetic mutation developed resistance to an herbicide. The mutation may have been present before that herbicide was ever used on the property. Current thinking is that herbicide application does not cause the genetic mutation that confers resistance, but that the mutations occur as a separate, random process. Often the herbicide provided a high level of control for the susceptible biotypes of that weed species. Repeated applications of that herbicide quickly control the susceptible biotypes, allowing the resistant biotype to spread through uninhibited seed production. If that herbicide is reapplied every year or so for say eight or nine years, the resistant population will increase until it is the dominant biotype. Over that eight or nine years, that herbicide will be less and less effective until it provides no control at all.

Examples of resistance in turf situations

There are certain weed species that appear to be prone to developing herbicide resistance, such as annual bluegrass (Poa annua). There are documented cases of annual bluegrass biotypes that have developed resistance to certain herbicides. In 2019, Ian Heap (International survey of herbicide resistant weeds, www.weedscience.org) reported that annual bluegrass ranks third among all herbicide-resistant weed species globally, with resistance to nine different herbicide sites of action. Triazine-resistant annual bluegrass has been detected in turfgrass, with simazine being the primary triazine used in turf (mainly used in bermudagrass), with specialized uses of atrazine in certain warm- season turf species. Adam Nichols and I documented triazine resistant annual bluegrass at a golf course in Virginia a number of years ago. We kept seed from that biotype and discovered that biotype was also resistant to Xonerate (amicarbazone). Simazine and amicarbazone both are photosynthetic inhibitors.

Annual bluegrass biotypes resistant to the dinitroaniline herbicides have been identified in Tennessee, North Carolina, and Georgia. The dinitroaniline herbicide class incudes prodiamine (Barricade, others), pendimethalin (Pendulum, others) , oryzalin (Surflan, others), and trifluralin (Treflan, others), key turfgrass and ornamental herbicides. Annual bluegrass resistant to glyphosate (Roundup, many others) has been identified in Tennessee and Missouri.

Biotypes of Poa annua resistant to the sulfonylurea herbicides have been documented in Tennessee, Alabama, and Virginia.