Get With The Program

Implement a programmatic approach to weed control in 2018

Jim Brosnan, Ph.D.
5 min readNov 16, 2017


In the world of turfgrass education, many refer to winter as “conference season.” All over the country there are numerous meetings that bring together turfgrass professionals from far and wide to learn about the latest trends in turfgrass management. Last week was the Deep South Turf Expo; this week the Carolinas Show and the Penn State Golf Turf Conference. The beat goes on like this until temperatures warm again in spring. As a turfgrass educator, it is an honor to be part of these events in that they provide great opportunties for both networking and learning; often some of the best research concepts come from thoughtful conversations with golf course superintendents, athletic managers, and lawn care professionals at winter meetings. This season nearly all of my educational presentations at these meetings will focus on the same concept: weed control programming.

What is a weed control program?

A weed control program is the collective series of techniques (both cultural and herbicidal) that will be used to provide weed-free turfgrass for the duration of the year. This idea is well accepted by turfgrass managers when controlling disease; nearly all golf course superintendents have wonderful disease management programs that incorporate a diversity of fungicides, varying in mode of action, that are applied alone or in combination with one another. Appropriate cultural practices are also implemented to complement these fungicide programs to maximize playability and ensure that the growing environment discourages disease infestation as well. Most importantly though, a substantial amount of “mental capital” is spent designing these programs before the season to decipher what will be most effective at a given facility while stewarding the effectiveness of products used.

“If you fail to plan, you are planning to fail” — Ben Franklin

Why are weed control programs needed?

The current paradigm in weed management is very different; it’s reactionary. Far too often, turfgrass managers simply pick a single herbicide for a given weed and apply as needed with little thought given to diversification. Moreover, little attention is paid to the cultural factors that can affect weed incidence such as nutrient availability, shade, drought, and traffic stress. In my experience, many turfgrass managers operate with a mindset of “if Product X has worked to control a weed like Poa annua in the past, why change?”

The problem with this mindset is that it drives selection pressure for herbicide resistant weeds. It is well chronicled that herbicide resistance is on the rise in turfgrass, particularly in the southeastern United States. Annual bluegrass and goosegrass are the main culprits with golf course superintendents battling populations that have evolved resistance to numerous herbicidal modes of action. Albeit fewer in numbers, herbicide resistance has been confirmed in sedge and broadleaf weed species as well. Compounding this problem is the fact that a new mode of action for controlling weed hasn’t been introduced into the market in nearly 30 years.

The reality is that many in the turfgrass industry are very lucky to have a large suite of herbicides that are still effective on many of our problematic weeds like Poa, goosegrass, and sedge. Turfgrass managers who are battling resistance at their facilities can attest to how difficult (and expensive) weed management can become when one or two modes of action are lost. The only way to ensure the long-term effectiveness of the herbicides we have available today is to implement programs that diversify what is applied at a given facility. The best turfgrass managers in our industry are operating 2 to 3 years ahead when it comes to controlling problematic weeds — they’re asking questions now (in 2017) about Poa control in 2018–2019.

Turfgrass Herbicide Programs Trial at the 2017 Univ. of Tennessee Turf & Ornamental Field Day in Knoxville, TN
Example weed control programs evaluated in the 2017 Univ. of Tennessee Turfgrass Herbicide Programs Trial. Each program targets the same weed species but varies in mode of action at each timing.

Barriers to adoption?

It’s not clear why weed control programs have not been adopted similar to what is common when managing turfgrass diseases. The task of managing weeds is substantial, particularly in the transition zone and southern United States. I’ve heard some comment that they don’t have time to build a weed management program. Others have said that they won’t build a weed management program because it would only be implemented on fairways and roughs- not putting greens. In all honesty, these are excuses. Fairways and roughs constitute substantial acreage at any given golf course, far more than putting greens. Why not put advance thought into how weeds will be treated in these areas, particularly species such as Poa and goosegrass that produce millions of progeny every season (via seed production), are highly adaptive to a variety of growing conditions, and persist in climates with favorable conditions for weed infestation 12 months of the year? Would golfers not notice massive outbreaks of goosegrass in fairways or delayed bermudagrass green-up in spring due to Poa infestation?

Another barrier to adoption is an over reliance on early-order programs. Many of our chemical suppliers offer wonderful early-order programs that allow turfgrass managers to save substantial amounts of money and maximize budget resources. However, these programs should not dictate agronomic decision making at a golf course, sports field, or lawn care operation. Many turfgrass managers pride themselves on being on-site everyday and having an intimate knowledge of every corner of the property they care for. Why not use this knowledge to build a weed control program that takes into account microclimates that are more (or less) favorable for weed infestation at a given property, historical records of what’s been implemented in the past, and outlines contingencies that could be acceptable if a component of the program were not to work optimally? Rather than relying the lowest-priced canned program, use early-order to your advantage. See it as an opportunity to acquire all of the components of your comprehensive weed control program in the most economical manner — think of it as à la carte ordering in a restaurant rather than selecting the lowest priced menu item.

Challenge for 2018

My challenge for all turfgrass managers in 2018 is to work on implementing a growth mindset within themselves and their staff. As explained by Carol Dweck, Ph.D., in her book “Mindset,” individuals with a growth mindset feel that they are in the process of constantly improving in all areas of life, both professional and personal. Rather than operating with a fixed mindset and tackling weeds in the same manner as always, attempt to improve overall weed control in 2018 by taking the time to build a year-long program for problematic weeds that incorporates a diversity of control strategies.



Jim Brosnan, Ph.D.

Professor, Univ. of Tennessee #Turf | #Grass | #Weeds | #Science | #Golf | #Sports | #Lawn | #Resistance | #Offtype IG: jim.brosnan.UT