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When you’re looking for answers to specific questions about agronomy,

Pat Gross is here to help.

A 38-year veteran of the golf course maintenance industry, Pat’s wide range of experience includes 28 years as a United States Golf Association (USGA) agronomist in turfgrass management, irrigation, and water-use efficiency. During his tenure with the USGA, he completed more than 2,000 on-site consulting visits with a focus on providing practical information to help golf courses conserve water and improve course conditions.

Strengthen your agronomic program and overcome turf challenges.

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Ask Pat

Soil layers in greens

Q: When I take soil samples from my greens, I see layers of different sands and organic materials. Is that a problem? Is there anything I should be doing about it?

A: Layers are never a good thing in a putting green rootzone. Layers restrict water movement and limit root development. As you probably saw in your soil samples, the roots tend to stop at the interface of the first two layers—not a good thing if the first layer is only 1 inch deep. Layers become established when there is an arbitrary change in sand topdressing material, or when there is a buildup of organic matter from deferred aeration, or when a putting green is sodded with turf grown on a different rootzone.

One of the main goals for a healthy putting green is to have a deep, vigorous root system and that requires a deep, homogenous rootzone. Core aeration and sand topdressing is the most effective way to gradually eliminate the layers. It is best to use a topdressing sand that closely matches the material used for construction.

It may take several years and multiple aeration treatments, but it is possible to get rid of the layers and reestablish a homogenous rootzone with dedicated effort.

Ask-Pat-GCSAA-Conference-Advance-square-imageAttending the GCSAA Conference? My Top 5 Tips for Getting the Most Out of the Event

Q: How can I get the most from attending the GCSAA Conference?

A: This will be my 35th year attending the GCSAA Conference, and in my opinion, it’s the best event of the year for gathering information, renewing friendships, and getting energized for the coming year. Here are my top five tips for getting the most from your attendance at the 2023 GCSAA Conference, Feb. 6 to 9 in Orlando, Florida.

  1. Preparation—Spend one or two days before going to the conference thinking about the challenges at your golf facility and what is needed to make it better. Do the same with your professional experience and education and where you need to fill the gaps to be a more effective superintendent. This will help you to focus your time most effectively and bring home the information you really need.

  2. Get as much education as you can—The wide range of classes and seminars is amazing, not only for the information, but also for the opportunity to speak to the professors, experts and superintendents presenting the information. Chances are, you will also hear great stories and get solid information from attendees in your class to help your situation.

  3. Check out new products and trends in the industry—Every golf facility has problems and issues that need to be resolved. With over 500 exhibitors in attendance, the conference and tradeshow is the best place to investigate products and solutions. You can check out things you’ve seen in the trade magazines and compare which options might be right for your facility. Electric equipment, robotic mowing, and non-chemical pest control options are just a few of the emerging trends in the golf industry. What else might be coming your way? It’s your job to let your employer know what’s happening in the future and how to prepare for it.

  4. Plan for upcoming events—There’s no better place to investigate and plan for upcoming projects. All the manufacturers are in one place! Maybe there is a solution you haven’t considered at one of the exhibitors. Plus, you have the architects, contractors and other superintendents that have done projects that you can bounce ideas off of to fine tune your plans and avoid potential mistakes.

  5. Renew relationships and build your network—I’ve made friends from all over the country and all over the world because of attending the GCSAA Conference. Building your network and making new friends makes you a better superintendent and expands the number of people you can contact when you have questions. And isn’t it comforting to know that superintendents all over the world have some of the same problems? (How can I get my golfers to fix their ball marks and repair their divots!)

See you in Orlando!

ewing-irrigation-ask-pat-fall-fertilization-squarePerspectives on fall fertilization

Q: What should I be most focused on when selecting a fall fertilizer for turf?

A: Fall is an especially important time of year for fertilizing both warm season and cool season turfgrasses because both are actively growing and assimilating nutrients for growth and winter storage.

With so many fertilizers on the market, it can be confusing to decide which product is appropriate for a particular situation. Here is a brief checklist to help narrow down the choices:

  • Start with a soil test – Collect soil samples from an average performing area and from a poorly performing area and submit the samples to a soil testing laboratory for analysis. The report will show which nutrients are sufficient and recommendations for which ones need to be added as fertilizer.

  • Apply any soil amendments recommended by the soil test – Fall and spring are the ideal times to add soil amendments (lime, gypsum, sulfur) if recommended in the soil test report. If the soil test recommends “x” pounds per acre for the year, a good strategy is to apply half the amount in the fall and the remaining half in the spring.

  • Evaluate nutrient requirements and select an appropriate fertilizer – Fall is an appropriate time to apply a “complete fertilizer” – one containing nitrogen, phosphorus, and potassium. The soil test will report which nutrients are deficient and the amount to be added. Take a good look at the soil test and only add what is needed. As an example, if phosphorus is sufficient but potassium is deficient, consider applying a product with nitrogen and potassium such as 22-0-22.

  • Apply nitrogen as needed based on growth – Nitrogen is the nutrient used most rapidly by turf and in the greatest amount. Although nitrogen may be listed on the soil test, it is best to make light and frequent applications of nitrogen throughout the year based on the desired growth rate (e.g., high traffic vs. low traffic areas). Nitrogen application in the fall is especially good for strengthening both warm and cool season grasses heading into winter and should be included in any fertilizer that is applied.

For more information, read Turfgrass Fertilization for Golf Courses by the United States Golf Association. It includes a collection of articles that provide further details on the subject of turfgrass fertilization.

ewing-irrigation-drought-stress-wetting-agents-saving-waterBest tips for saving water during drought

Q: Drought conditions are expected to be very serious this year. What are the practices that are really going to help me save water?

A: Water cutbacks are an unfortunate reality this year for many golf courses, sports fields, and turf facilities in the West. Here are the top four tips to preserve turf quality, making sure every drop of water is used effectively:

  1. Make sure the irrigation system is operating at maximum efficiency: sprinklers are raised and level, turf trimmed from around all sprinklers, arcs are properly adjusted, and nozzles are in good condition (preferably less than five years old).
  2. Make regular applications of soil wetting agents/surfactants. Wetting agents help water penetrate the soil and make water available to plant roots.
  3. Continue to apply plant growth regulators along with light rates of nitrogen. Research at UC Riverside, picture here, has shown that applications of the plant growth regulator trinexepac-ethyl (Primo Maxx, T-Nex) in combination with light rates of nitrogen helps to preserve turf quality under deficit irrigation.
  4. Constant monitoring and observation. The importance of visual observation, checking soil moisture with a soil probe or moisture meter, and checking for irrigation system leaks cannot be overemphasized. Daily checking and adjustment of the irrigation system avoids over application and water waste, allowing for early detection of potential problems.

thermometer-summertime-temperatures-cause-turf-stress-decline-squareSeaweed Biostimulant Products

Q: I’ve heard that seaweed extract is a good product to put on turf. Is that true?

A: The answer is yes. Seaweed extract contains cytokinins, which are hormones that help turf survive heat stress.

Cool season turf, especially Poa annua and creeping bentgrass putting greens, benefit from applications of seaweed extract during the summer. Research at Virginia Tech University showed that liquid applications of seaweed extract at 14-day intervals throughout the summer reduced root decline and helped to mitigate drought, salinity, and UV-light stress.

Should seaweed products be applied throughout the year? Probably not. Plants produce adequate levels of cytokinins in the spring and fall when not subjected to heat stress. It is best to focus on applications from late spring and throughout the summer when heat stress, drought, and salinity problems are most likely.

Further information and details about seaweed biostimulant products can be found on the Golfdom website here.

gypsum-saltGypsum Application Best Practices

Q: I’ve heard that applying gypsum to my turf will help reduce salts in the soil. Is that true?

A: That is partially true. Many would be surprised to know that gypsum (calcium sulfate) is actually a salt. It’s a “good salt” that contains calcium to support turf growth.

Surface-applied gypsum or gypsum added to the irrigation water increases salinity and aids in water penetration. When combined with a deep watering cycle (leaching), the gypsum helps to flush excessive salts from the soil and also helps to counteract the negative effects of excess sodium (which is a completely different animal that negatively impacts soil structure).

So gypsum alone will not reduce the level of soluble salts in the soil. It has to be combined with deep watering to be effective. If sodium levels are not a concern, wetting agents in combination with deep watering does an effective job of reducing soil salinity.

flushing-greensProper Timing for Flushing and Aeration

Q: Is it better to flush salts out of my greens before aeration or after?

A: It is better to schedule a deep irrigation cycle about four or five days prior to aeration instead of waiting until after. This allows water to penetrate evenly into the soil profile and push salts below the rootzone, creating a more uniform result.

Although aeration will greatly accelerate water infiltration in the greens, the water penetrates faster above the aeration holes and is less effective in the spaces between the holes. This ends up creating a polka-dot pattern on the greens with green turf above the aeration holes and yellow turf in between. To avoid the polka dots, flush before aeration.

ester-amineEster Vs. Amine Formulations

Q: I’ve noticed that some broadleaf herbicides, especially 2,4-D, come in an ester or an amine formulation. How do I know which one I should be using?

A: Ester formulations enter weeds more rapidly but also volatilize at warmer temperatures, which can burn the turf and harm non-target plants. In general, ester formulations are best used in early spring when temperatures are consistently cool.

Amine salt formulations are less volatile and typically used in landscape settings. Amines are better to use when temperatures are warmer and when drift to non-target plants is a concern.
As with all herbicides, always read the label for the proper rate, timing, and application instructions and to ensure that the product is registered for use in your state or county. The article Amines or Esters – Which Should You Use? from Penn State Extension provides a more detailed explanation of the topic.

Clumpy Poa Solutions

Q: What can I do in the spring to get rid of clumps of Poa annua in my bermudagrass, especially on fairways and in the rough?

A: The clumpy growth habit of Poa annua is very prominent in the spring, especially on bermudagrass fairways and rough. Not only do the clumps look bad, they negatively affect playability. The challenge is how to control the clumps of Poa without harming the bermudagrass that is coming out of dormancy.

Here are four strategies to deal with clumpy Poa in the spring:

  1. Lower the cutting height and mow more frequently. This will improve playability and will help to stimulate bermudagrass growth for a more even playing surface.

  2. Slightly reduce irrigation to stress the Poa annua. Stretching irrigation applications will help to stress the clumps of Poa annua. Keep in mind that shutting off the water completely is not a good strategy because bermudagrass coming out of dormancy needs adequate soil moisture for healthy growth.

  3. Apply selective herbicides. There are several herbicides that kill Poa annua without harming bermudagrass. The most popular for use in the spring are the sulfonylurea herbicides Revolver® (foramsulfuron), Monument® (trifloxysulfuron), and Katana® (flazasulfuron). These herbicides can be moved with irrigation runoff or foot traffic when the turf is wet, so it’s important to be careful with applications near desirable cool season grasses. Always read and follow the product label with any herbicide application.

  4. Plan to make preemergence herbicide applications in the fall. Consider making a map of current infestation and plan to apply a preemergence herbicide in the fall to prevent Poa annua growth the following winter and spring.

Flooding-on-turf-Bethpage_coverTurfgrass Flooding

Q: How long will my grass survive under flooded conditions?

A: Whether grass is damaged by flooding depends on several factors:

  • Turf species (bermudagrass and creeping bentgrass, Kentucky bluegrass, perennial ryegrass and annual bluegrass)
  • Amount of time the turf is submerged
  • Depth of water
  • Light intensity
  • Temperature of the water

In one experiment, creeping bentgrass survived 60 days of flooding at a water temperature of 50°F but less than 10 days at a water temperature of 86°F (Beard 1973). The good news is that many turf species have the ability to survive adverse conditions, including flooding. The following articles provide further information and details about turfgrass flooding and recommendations for recovery:

Will my turf recover from recent flooding? - Michigan State

It's Raining, It's Pouring, The Golf Course is Flooding - USGA

ewing-irrigation-ask-pat-soil-wetting-agents-squareSoil Wetting Agents

Q: What are wetting agents, and what are they used for on turf?

A: Wetting agents are surfactants that help water penetrate the soil and thatch layer in turf. As soil and thatch dries out, they tend to repel water causing irrigation to run off the surface and creating localized dry spots. Even with prolonged irrigation, the water doesn’t get into the soil and to the roots where it is need by the plant. Ironically, this is especially true for sandy soils such as sand-based putting greens and tees.

Wetting agent use is a proven water conservation practice that helps maintain uniform soil moisture and avoid any runoff and waste from irrigation applications. Routine applications are typically made throughout the summer and fall by injecting material through the irrigation system or spray application, along with directed applications to treat localized dry spots.

Visit GCMonline.com for further information and details on the subset of wetting agents.

ewing-irrigation-golf-ask-pat-mix-and-load-closeup-squareWater Quality and Pesticides

Q: Does water quality have any impact on the effectiveness of pesticide applications?

A: The answer is yes. Considering that water comprises 95% or more of the spray solution, it makes sense that water quality can have a big impact on the effectiveness of pesticide products.

Water quality factors that affect performance include turbidity, hardness, and pH. In general, most herbicides, fungicides, and insecticides perform best in slightly acidic water with a pH of 4.0 to 6.5. Sulfonylurea herbicides perform best in slightly alkaline water with a pH above 7.0. Water with a pH outside of these ranges can accelerate the breakdown and effectiveness of the active ingredients.

How is it possible to know if water quality is an issue with a particular product? Carefully read the pesticide label. In most cases, the label will specify if water conditioners, additives, or adjuvants are recommended as part of the spray mixture. If not specified on the label, the product should be effective in a wide range of water conditions.

Here are some general recommendations and specific situations to be aware of:

  • Test your water regularly to know pH, hardness, and turbidity. This is especially important if recycled water is used in the spray solution.
  • Have pH test strips on hand to check the spray solution.
  • Be careful of using water from ponds or ditches that tend to have suspended solids that can bind to pesticides and reduce effectiveness.

The publication The Impact of Water Quality on Pesticide Performance from Purdue University provides further information and details on the subject of water quality and pesticide applications.

aeration-programDeveloping a Core Aeration Program

Q: How many times per year should I aerate greens?

A: If you ask golfers, one time is too many, and if you ask superintendents, it’s impossible to aerate the greens too much.

From a practical and agronomic standpoint, the answer is somewhere in between. Some agronomists recommend a minimum of twice per year (spring and fall). Others have offered a guideline of impacting 20% of the total surface area each year— the frequency being determined by the size and spacing of the tines to achieve the 20% surface impact (smaller tines more frequently or larger tines less frequently). Both are plausible guidelines.

Here are three guiding principles to keep in mind when developing a core aeration program for greens:

  • Aeration is primarily done to reduce and dilute thatch and organic matter in greens, so the procedure needs to be done enough to cause a net decrease in the amount of thatch and organic matter each year. Periodic testing should be done to measure the amount of organic matter in the soil and determine if the program is working or if changes need to be made.
  • Poking holes in the greens with hollow or solid tines provides an avenue to incorporate sand topdressing to dilute thatch and organic matter. Any method that can incorporate sand into the surface of the greens will help to achieve the desired goal. It’s all about the sand.
  • Aerating greens with ½-inch-diameter hollow tines or larger should be done when the turf can recover as quickly as possible. For Poa annua and creeping bentgrass greens, that is the spring and the fall. For bermudagrass and seashore paspalum greens, that would be the summer.

ewing-irrigation-ask-pat-play-defense-hot-weather-squarePlay Defense During Hot Weather

Q: What maintenance practices should I be doing when the weather is really hot and the turf is showing signs of wilt and stress?

A: When temperatures are hot and we see turf that is stressed, the tendency is to want to DO something, but overreacting can end up causing more stress and damage to the turf. The best thing to do in hot weather is do less, and focus on defensive maintenance strategies such as:

  • Suspend mowing – The turf is stressed and not growing much during hot weather, and the added traffic from mowers usually ends up causing more damage.

  • Suspend fertilizer applications – If a fertilizer application is scheduled, it is best to wait until the weather cools off (around 85 F) and the plant resumes active growth so it can utilize the nutrients.

  • Avoid overwatering - When it’s hot, the tendency is to dump a lot of water on the turf to get it to spring back. This is not always a good idea. Water conducts heat, and a saturated soil can end up cooking the roots, a condition known as “wet wilt”. When turf is wilted, it is best to lightly water the surface to cool the plant and then focus on rehydrating the soil at night. The goal is to maintain balance of air and moisture in the soil while avoiding over-saturation.

  • Make sure the irrigation system is operating properly – If the turf is showing wilt and stress, make sure sprinklers are popping up, nozzles aren’t clogged, and tall grass is not interfering with sprinkler spray.

frost-tracking-issuesFrost Tracking Tips

Q: Is it OK to allow traffic when there is frost on the turf? I’ve heard some people say it doesn’t do any harm while others say it will kill the turf. Which is correct?

A: Traffic on frosted turf can damage or even kill the turf depending on how frozen it is.

Many don’t realize that a turfgrass plant is about 75% water by weight. As temperatures reach 32 F and below, the water inside the plant cells freezes and forms ice crystals that can rupture plant tissue when traffic is applied, causing leaf discoloration and dieback.

If the growing points are damaged (the crown and collar regions), then it could kill the entire plant. Sometimes the inside of the plant isn’t affected, and it’s just water and dew on the outside of the plant that freezes, which some people call “superficial frost.” The difficulty is determining the extent and intensity of the frost. Is it just superficial frost on the surface or is the entire plant completely frozen? Is it in all areas or just a few low spots?

In northern climates, it is usually a deep freeze affecting an entire area. In southern climates, it is usually a combination, making it difficult to determine whether traffic is going to cause damage or not.

The safest default position is to keep traffic off until the frost has melted. Some foot traffic will probably not cause much damage, but carts and equipment sliding around on frosted turf is not safe.

If revenue is the top priority, some facilities opt to open and accept any damage that occurs. Sometimes it’s nothing, and other times you can be looking at tire tracks and dead footprints until spring. Read The Icing on the Turf from GCMOnline.com for additional information and details on the topic of frost.

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Here are a few of the most popular blog articles from Pat


Golf Courses Save Water by Utilizing Smart Irrigation Technology

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Sustainable and Smart Irrigation Practices for Golf Courses Save Water

The current drought in the Western U.S. has many taking a closer look at how water is used. Here's how golf courses can save water in an efficient manner. Learn how one course saw a 27% decrease in water use by reducing their turf area.


Golf Course Irrigation Systems Benefit from Uniformity and Efficiency

A focus on the uniformity and efficiency of a golf course irrigation system plays a huge role in conserving water. Learn how to optimize for it, and how one golf course improved its efficiency resulting in a 20% reduction in irrigation run times.

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Review Pat’s blog articles covering topics from golf course agronomy
to water conservation and turfgrass management.
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