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K-State Turf and Landscape Blog

Category: Cultural Practices

Management Guides to Reduce Winterkill in Warm-Season Turfgrasses

Posted on by Teresa Roberts

By Ross Braun, Ph.D., Kansas State University 

It is September, winter is coming, now is the time to think about strategies to reduce winterkill risks in your warm-season turf. Last winter (2024-2025) was a tough one on some of our warm-season turfgrass managers. There were extensive reports of winterkill in zoysiagrass and bermudagrass areas on golf courses and sports fields in Kansas, Missouri, and many other areas in the transition zone. Winterkill injury is not easily identified until the warm-season grass is finished greening up in the spring (usually mid-to-late May in KS). At which point, you notice dead turf areas that never greened up with no active growth (Figure 1). What also didn’t help this spring was the below-average temperatures in May, with slightly below-normal precipitation amounts at the same time. This slowed down the spring green-up of our warm-season turfgrasses (zoysiagrass, bermudagrass, and buffalograss) and delayed the recovery needed in some areas, so that it did not start until mid-June or later. These winterkill risks will always be present, and some years we unfortunately see it more than others, but I still think warm-season turfgrasses are a solid choice for turfgrass managers in the transition zone because we can reduce a lot of management inputs (water, fertilizer, pesticides, mowing) compared to growing cool-season turfgrasses.

Over the past two years, my colleagues at other universities and I have collaborated to create “management guides” for bermudagrass and zoysiagrass managers, especially those in the transition zone that experience greater risks of winterkill. You will likely recognize that the authors include many familiar names of turfgrass scientists, as well as the wealth of knowledge they bring to these articles. These guides are written to help you identify potential vulnerable areas, the causes of winterkill, and offers solutions to prevent and recover from winterkill. I encourage you to check out these articles; they are both “open access,” meaning the authors have already paid for them to be freely available to the public (not behind a paywall). You can read them online or download each as a PDF to read on your computer or phone. I hope these management guides assist in decision-making and help to reduce potential winterkill risks in warm-season turfgrass systems.

Management strategies for preventing and recovering from zoysiagrass winterkill https://doi.org/10.1002/cft2.70050

Management strategies for preventing and recovering from bermudagrass winterkill https://doi.org/10.1002/cft2.20302

 

Figure 1. Increased winterkill in West Lafayette, IN, in 2018–2019 in low-lying, poorly drained areas. The site was ‘Meyer’ zoysiagrass (Zoysia japonica Steud.) maintained as a golf course fairway. The photo was taken on May 24, 2019 by Aaron J. Patton.

Dealing with Creeping Bentgrass During Heat

Posted on by Teresa Roberts

By Jack Fry, Professor and Commercial Turf Extension Specialist

In the midst of a summer with 100+ F temperatures, it’s worthwhile to consider some of creeping bentgrass’s preferences and management strategies that might be helpful to reduce its stress, and yours.  See, the thing about creeping bentgrass on putting greens is….

  • It came from Western Europe. You live in Kansas.
Average July maximum temperature (°F) Average July minimum temperature (°F)
London, England 72 55
Manhattan, Kansas 90 68

 

  • Its roots die first, then its leaves. Keep the roots happy and you’ll have happy bentgrass and happy golfers.
  • Its roots prefer to grow at 55 to 65 °F; root growth slows even as low as 80 °F. This summer, temperatures near the surface of greens have been over 100 °F.
  • Faults with construction, drainage, management practices may produce a quality turf surface for 10 or 11 months of the year. It’s the one or two other months that cause problems.   If you want to avoid bentgrass decline, then start with a good rootzone.
  • Rootzones that hold water are warmer and also have less oxygen for root growth. If you don’t have an ideal rootzone, work to improve it in the fall and spring with aggressive core aerification and topdressing.
  • The benefits of coring are often seen during summer stress. Why are there green polka dots within the brown turf?  Turf in those spots has roots!

  • Opening the green’s surface with small, solid tines or spikes can help with water infiltration and root growth during midsummer. Don’t overdo it – the turf is under stress.
  • Although superintendents suspect (and often hope) that a disease is causing the problem in mid-summer, over half of the samples that are evaluated in our lab show no disease.
  • In our climate, air movement across the surface of the green is critical for bentgrass health. If your greens are surrounded, let them free!
  • Maximize summer airflow from the south, but also vent to the north (just like opening two windows to get cross flow in your house).
  • Hand watering can be used to address deficiencies in water distribution of the irrigation system, target localized dry spots, and deal with inconsistencies in water retention and drainage in the root zone. It shouldn’t be overdone or underdone- train and use your best help for handwatering.
  • Syringing refers to applying a light mist of water droplets to leaves only, and then relying upon evaporation of that water to help cool the leaf surface. How effective do you think that is on a humid, July day?  Not very, unless you use a fan to encourage evaporation from the leaf!
  • Trees use light for photosynthesis, so does bentgrass. If trees are shading the green, which is getting the light – the tree, or the turf?
  • Cultivars that are more dense get less Poa invasion, and Poa is more likely to die during summer stress than bentgrass. Plant newer, denser cultivars to reduce Poa.( The photo shows Poa checking out in the heat.)

  • Light applications of nitrogen can be beneficial during heat stress (0.10 lb. N/1,000 sq. ft.)
  • Newer cultivars have been shown to be more heat tolerant than Penncross, but even these will experience decline during prolonged heat.
  • Clean up laps are often the first to show symptoms of stress. Why?  Excessive traffic and wear.  Have you considered a dedicated mower with a slightly higher mowing height for the clean up lap?  Do you skip clean up laps on some days?

Chemical control of Poison Ivy (Toxicodendron radicans)

Posted on by Teresa Roberts

By Jason Griffin, Extension Specialist, Woody Ornamentals & Industrial Hemp

Here is one we have just been itching to write. How do you control poison ivy?

Recently we have had a rash of questions about this topic. During these warm days of summer poison ivy can grow at a blistering pace, so don’t delay treatment.

We all know the plant. Leaves of three let-it-be. A vining menace in the landscape that quickly gets out of control because no one volunteers to control it. For those unfortunate enough to cross its path, skin rashes, weeks of itching, and a steroid prescription may follow if it gets bad enough. Yep…been there.

The good news is that it can be controlled with some commonly available chemicals. Yes, it can be removed by hand if you are one of the lucky resistant individuals. Yes, goats will eat it too. However, our topic here is chemical control since most of us are susceptible and don’t have ready access to a herd of goats.

 

 

 

 

 

 

 

 

 

Glyphosate will take care of poison ivy, but in my experience the kill is slow, incomplete, and needs reapplication, but it does work.  If you want faster and more complete kill, there are other options. Before we go there, remember, glyphosate and any tank mix with glyphosate will kill almost any plant you spray it on. Know what is in your tank and what plants it will impact.

Keep in mind that poison ivy is a broad leaf perennial plant. Products that eliminate poison ivy will be harmful to other broadleaf plants. If you have poison ivy vining and growing among your desirable plants, chemical control may not be a good idea.

 

 

 

 

 

 

 

 

 

Our ‘go-to’ when we need to kill a heavy poison ivy infestation is a tank mix of Crossbow (triclopyr + 2,4-D) and glyphosate. It has never failed. Keep in mind that this mix will kill any plant it gets on and 2,4-D can volatilize and damage off-target plants, especially on warm summer days. Use it with caution, know your wind direction, and maybe have a dedicated sprayer just for this purpose. This combination typically results in rapid and complete kill. Crossbow (and its generic versions) will also take care of poison ivy very efficiently by itself. We use it in areas where poison ivy has mingled with any grass we want to keep, such as a brome hay field or an area prone to erosion where we want to keep the grass. There are also products available that contain triclopyr as the only active ingredient. We have used those in the past as well. They do work, but we typically reapply or tank-mix with glyphosate to get the desired result. Again, know your chemicals. Triclopyr by itself will not harm grass, but a mix with glyphosate will kill most plants.

 

 

 

 

 

 

 

 

 

Dormant treatment is also possible in heavily infested areas. Crossbow (and its generic counterparts) when mixed with diesel (instead of water) and sprayed on the stem when the plant is dormant will kill poison ivy. We use it along our fence-line where the poison ivy has completely covered the chain-link. Generally, we target this treatment for mid-March, just as the poison ivy buds are starting to swell. Treatment is most effective as plants are coming out of dormancy. Spraying with diesel feels wrong (I know), but it is on the label, and it works when desperate times call for it. Be aware that this combination will kill almost anything it is sprayed on, and your sprayer pump manufacturer will strongly recommend against running diesel through it.

Plants are most easily controlled when they are small and young. A ground cover of poison ivy can be controlled more easily than a plant that is vining up a nearby tree, fence, or building. Procrastination leads to larger plants with thicker stems and a more robust root system that needs more aggressive measures. Also, birds like to eat the poison ivy fruit and spread it. Control prior to flowering and fruiting is advised.

 

 

 

 

 

 

 

 

 

A recent trip to the local big box hardware store had several products that will take care of poison ivy. Some are sold specifically for poison ivy control, but there are other products with the exact same active ingredients. Check the label and you may be able to save a few dollars by doing some homework.

 

 

 

 

 

 

Good Luck!

 

Thatch Control in Warm-Season Lawns

Posted on by Teresa Roberts

By Ward Upham, Extension Associate Emeritus, Horticultural Rapid Response Center

Thatch control for cool-season lawn grasses such as bluegrass and tall fescue is usually done in the fall but now is the time we should perform this operation for warm-season turfgrasses such as bermudagrass and zoysiagrass. Because these operations thin the lawn, they should be performed when the lawn is in the best position to recover. For warm-season grasses that time is June through July. Buffalograss, our other common warm-season grass, normally does not need to be dethatched.

When thatch is less than one-half inch thick, there is little cause for concern; on the contrary, it may provide some protection to the crown (growing point) of the turfgrass. However, when thatch exceeds one-half inch in thickness, the lawn may start to deteriorate. Thatch is best kept in check by power-raking and/or core-aerating. If thatch is more than 3/4 inch thick, the lawn should be power-raked. Set the blades just deep enough to pull out the thatch. The lawn can be severely damaged by power-raking too deeply. In some cases, it may be easier to use a sod cutter to remove the existing sod and start over with seed, sprigs or plugs.

If thatch is between one-half and a 3/4- inch, thick, core-aeration is a better choice. The soil-moisture level is important to do a good job of core-aerating. It should be neither too wet nor too dry, and the soil should crumble fairly easily when worked between your fingers. Go over the lawn enough times so that the aeration holes are about 2 inches apart.

Excessive thatch accumulation can be prevented by not over-fertilizing with nitrogen. Frequent, light watering also encourages thatch. Water only when needed, and attempt to wet the entire root zone of the turf with each irrigation.

Finally, where thatch is excessive, control should be viewed as a long-term, integrated process (i.e., to include proper mowing, watering, and fertilizing) rather than a one-shot cure. One power-raking or core-aeration will seldom solve the problem.

Fall Seeding Tips

Posted on by Teresa Roberts

By Dr. Jack Fry, Professor and Extension Specialist

  • September is the optimum time to seed cool-season grasses.
  • Use good quality, certified seed; avoid seed with significant levels of “weed” and “other crop.”  More information HERE
  • Use recommended seeding rates with good distribution – more than one direction; seeding at rates too high can cause issues with disease and environmental stress.
  • Seed to soil contact is critical!

  • If renovating an existing stand of turf, mow low to reduce competition with seedlings and help improve seed contact with soil.
  • Aeration, slit seeding, topdressing, or raking to cover seed are methods of enhancing seed-to-soil contact contact. If thatch levels are high, seed-to-soil contact may be difficult to get without thatch reduction first.
  • Aeration brings soil the surface, and is often done in concert with vertical mowing, which breaks up cores and also creates small furrows in which seed can make contact with soil.
  • Slit seeders create furrows in the soil surface and drop the seed into them.
  • Topdressing or raking loose soil in a tilled area covers seed and ensures contact.
  • If the desire is to convert from one species to another, and a reasonable stand of turf exists, it will have to be removed before conversion happens. Removal is typically accomplished with a nonselective herbicide.
  • Managing a high-traffic athletic field? Consider allowing for presence of a “seed bank” through the playing season.  More information HERE
  • Starter fertilizers, that contain nitrogen and phosphorus, help enhance establishment.
  • Light, frequent irrigation is needed the first few weeks after planting, and may be required several times daily, depending upon weather.

Pushing Snow

Posted on by Cheryl Boyer

Many of you are busy “pushing snow” with the recent cold weather, and there will likely be more snow to push in the next couple of months. Please take a few minutes to train your staff on protecting ornamental plants when clearing hard surfaces like parking lots.

While clearing the lot, driveway, or sidewalk is the most critical objective, “do no harm” should also be a goal. Far too many plants are crushed by the push and weight of snow in winter months. Sometimes, the mystery summer problem is actually a clear winter problem.

There is a tendency to pile snow on top of green spaces in parking lots. However, plants in those spaces continue to need to photosynthesize (evergreens) and exchange gases and are likely to die or suffer severe dieback if the cold weather persists and the snow takes a significant time to melt. Piling snow in planting areas can also contribute to soil compaction and root decline, causing problems later in the growing season.

De-icing chemicals are often mixed into snow that is pushed into landscape settings. As the snow melts, it dumps salt into the planting area, damaging shoots and roots for the long term. To minimize the landscape impacts of clearing snow, consider alternative de-icing salts like calcium chloride and calcium magnesium acetate and follow the label instructions when possible. Sand can also help provide traction.

With your staff, practice identifying an appropriate place to pile snow that isn’t in landscape areas, offers a place to collect runoff, and won’t result in slush that can splash onto plants. When possible, make these decisions before snow is on the ground—snow can cover a lot of detail and make it easy to lose track of the areas that need to be preserved.

Study each site individually and develop a plan for human, pet, and plant safety when winter storms hit to avoid problems in the future and establish trust with your clients.

Fall is for Planting

Posted on by Teresa Roberts

By Jason Griffin, Professor and Extension Specialist, John C. Pair Horticultural Center Director

We’ve all heard it and probably repeated it. But why is this slogan so common-place, and is it accurate…Is Fall really a good time to plant?

First, there is the emotional side. As summer fades away and yields to cooler temperatures, more frequent rain events, and beautiful fall colors; it just feels like the right time to plant a new tree or shrub.

Second, there is the economic side. Many nurseries offer fall specials on their inventory. The simple truth is that any plant that does not sell, has to be moved and stored for overwinter survival. This involves labor, consumes valuable space, and uses mulch or plastic to protect the plants from freezing winter temperatures. Nurseries would prefer to sell plants rather than store them.

Last, there is the plant side. Is fall a good time to plant a new tree or shrub? Yes, and here is why. The primary job of a newly planted tree or shrub is to grow roots for survival. New roots are necessary for balled and burlapped plants to replace the ones lost during the harvest process at the nursery. If it’s a container plant, new roots are necessary to explore the soil and find nutrients and moisture necessary for long term survival. For the first year of a new plant’s life, it’s all about the roots!

So why plant in Fall? Woody plants have two primary seasons for growing roots, and it’s NOT winter or summer. Frozen soil and slow metabolism prevent much root growth in during winter in cold regions of the country. Frequent droughty conditions combined with searing summer temperatures limits root growth during a hot summer. In Kansas we have both. Most root growth on woody plants occurs during spring and fall in the temperate region.

Trees planted in spring have only a few weeks of peak root growth before Mother Nature unleashes the environmental stresses that come with summer weather. However, trees planted in fall have the long fall and early winter season to grow roots before they go dormant. As the soil warms in spring, they get another season of root growth prior to the stress of summer in Kansas. Fall planted trees, therefore, have the advantage of two full seasons of root growth before summer drought and heat strike. It’s not too late. As long as the soil isn’t frozen at your planting site, you can still get plants in the ground. So is spring a bad time to plant? No, spring is a great time to plant. Those trees just need a little more TLC during that first summer than fall planted trees.

Happy planting!

Water Conservation Practices in Kansas Landscapes

Posted on by Teresa Roberts

By Cheryl Boyer, Professor and Extension Specialist

While some parts of Kansas are experiencing relief from drought (let’s celebrate with far Western Kansas!), significant portions of the state continue to need water. The current map of Kansas on the U.S. Drought Monitor shows only 9 of our 105 counties with no drought. That means that 91% of Kansas counties are experiencing some combination of abnormally dry, moderate drought, severe drought, extreme drought, or exceptional drought.

Having enough water for human needs and health will always (and should) take priority over landscape use. So how do we adapt? Here are some best practices for water conservation in the landscape. Use these ideas as regular practices for your work and as opportunities to educate consumers on ways they can contribute to our ongoing water needs.

  1. Make a plan.
    • Consider factors on each site that may affect water use, like steep slopes, shading, and overall landscape goals.
  2. Improve soil conditions.
    • Get a soil test! Identify nutrient status, organic matter content, and pH to help you identify needs and approaches.
  3. Choose appropriate plants.
    • Understanding which plants can tolerate Kansas conditions, as well as the specific site conditions for the project, will help place the right plants in the right place.
  4. Water slowly, deeply, and infrequently.
    • Observe the weather and water based on plant needs. Soaker hoses, drip irrigation, sprinkler systems, and micro-drip water bags/buckets are all good options to achieve this best practice.
  5. Use mulch.
    • Organic mulch will increase soil quality as it breaks down while keeping soil cooler, reducing weed pressure, and helping soil retain water.

 

For more information (for yourself or to share on your organization’s online platforms) based on learning style, check out:

Boxwood Leafminer

Posted on by Teresa Roberts

From the KSU Entomology Newsletter

Figure 1. Boxwood leafminer adult (Joe Boggs, OSU)

The boxwood leafminer, Monarthropalpus flavus, is a major insect pest of the common boxwood, Buxus sempervirens, which is a plant commonly used in landscapes throughout Kansas.

Boxwood leafminer adults emerge (eclose) from pupae when Weigela florida is flowering in the spring. Adults are 1/15 to 1/9 of an inch (2 to 3 millimeters) long, yellow-orange, and resemble mosquitoes or gnats (Figure 1).

Figure 2. Boxwood leafminer larvae (Howard Russell, MSU)

 

 

Adults leave behind pupal cases attached to the leaf after emergence. After mating, females insert eggs inside the tissue of new leaves. A single female lays approximately 29 eggs and then dies afterward.

Larvae emerge (eclose) from the eggs in about three weeks. Larvae are legless maggots, yellow-white to green, and about 1/9 of an inch (3 millimeters) in length (Figure 2).

Figure 3. Boxwood leafminer larvae (Joe Boggs, OSU)

 

 

 

The larvae feed on the leaf tissue inside the leaf (Figure 3). Boxwood leafminer larvae tunnel between the upper and lower parts of leaf tissue creating blotched or irregular-shaped blisters on the lower leaf surface and raised areas on the upper leaf surface.

Learn more about boxwood leafminer and their control in an article by Dr. Raymond Cloyd by clicking HERE.

Preparing Putting Greens for a Summer Marathon

Posted on by Jack Fry
Potential summer decline of putting greens can be reduced by taking advantage of seasons in which they’re most efficient.

I’m not a marathoner, but I’ve heard those that do run marathons prepare not only through extensive training, but also by consuming the appropriate food for weeks before the race.  Examples include fruits, vegetables, whole grains, lean proteins, and healthy fats.  Fasting or an improper diet wouldn’t result in a good marathon, and would likely require someone to withdraw during the race.

Creeping bentgrass and annual bluegrass, cool-season grasses, are also participants in summer marathons in many parts of the world.  They enjoy the cool climate in spring and autumn and prefer to prepare for the marathon during these seasons. Of course, grasses don’t rely on consumption of food, but they do create their own carbohydrates through photosynthesis.  Plants take in carbon dioxide through stomates on leaves, which is used in combination with light and water in the photosynthetic process to manufacture carbohydrates that include glucose, sucrose, and fructose which promote plant growth and health.  Carbohydrate storage is also a critical to finish the summer marathon.

If creeping bentgrass and annual bluegrass have met nutritional demands to sustain health and promote growth, they may then be able to store carbohydrates (fructan and starch) in crowns or stolons for use later in the season. This is critical for summer survival, as the ability to manufacture carbohydrates declines as temperatures rise.  If nothing’s left in the refrigerator, and a runner can’t go shopping, that would also create pre-marathon issues.  To maximize the ability of these grasses to store carbohydrates in preparation for the summer marathon, two things other than cool air temperatures are desired – leaf area and no seedheads (annual bluegrass).

Grasses on putting greens are mowed at heights that minimize leaf area.  Years ago, one-eighth of an inch (0.125 inches; 3.2 mm) was considered very low.  Now, it’s not unusual to hear from superintendents who may mow at heights lower than one-tenth of an inch (0.100 inches; 2.5 mm).  Lower mowing heights increase green speed (ball roll), but keep in mind that whenever a portion of a leaf is removed, chlorophyll, which captures sunlight for photosynthesis, and stomates, the entry points for carbon dioxide, go away with that portion of the leaf, which reduces carbohydrate manufacturing capability.  Leaf area is increased by mowing higher or less frequently.  If either is done, speed can be enhanced by rolling rather than mowing, which allows the leaf area to remain.  Many superintendents have incorporated rolling as a mechanism to enhance green speed and leaf area.

Cool-season grasses tolerate lower mowing heights better during spring and autumn months than in the summer.  This has encouraged many superintendents to consider mowing lower during cooler months, and then raising the mowing height when summer stress occurs.  However, keep in mind that the efficiency of carbohydrate production is greater during the cooler months than it is in the summer.  As such, the potential to accumulate carbohydrates for the summer marathon is enhanced by allowing greater leaf area in spring and autumn.*

Annual bluegrass can be a prolific seedhead producer, even at very low mowing heights.  Seedhead emergence tends to drop the level of carbohydrates in the plant, and can also reduce rooting.  Suppressing annual bluegrass seedheads by using plant growth regulators can help annual bluegrass get through the summer marathon.

A pastor in Kansas City recently spoke about how he was training for several weeks prior to a marathon and was excited about it.  He also considered that his diet at the time was critical, and adjusted it several weeks before the race.  Once the marathon began and the physical demand had started, he asked himself “why am I doing this?”.  He struggled through the first 10 miles of the marathon, but at the halfway point, his attitude improved, and the healthy food consumed prior to the marathon began to take effect.  He finished the marathon with a smile (but hasn’t run another) and followed it with a beer – first attempt to get carbohydrate levels back up!  Superintendents in areas where a summer marathon is on schedule should consider enhancing leaf area when creeping bentgrass and annual bluegrass are most efficient at fixing carbon.  You may not see the putting greens smile at the end of the summer, but quality may likely be enhanced!

(Article appears in Golf Course Management magazine, April 2022; *Dr. Bingru Huang, Distinguished Professor at Rutgers University, has conducted extensive research on creeping bentgrass heat tolerance and has enhanced our knowledge in this area.)