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K-State Turfgrass

Month: July 2019

New Turfgrass Research Reports

Research Reports

K-State turfgrass specialist urges mid-summer checkup on lawns

Many Kansas landscapes include warm-season grasses, which require a little care in order to stay healthy during the hot summer months.

Hoyle says warm-season grasses may need fertilizer to remain healthy

MANHATTAN, Kan. – Kansas State University Associate Professor and Extension Turfgrass Specialist, Dr. Jared Hoyle says homeowners ought to be thinking about a mid-summer checkup on their lawns, which likely includes applying fertilizer and weed killer.

Many Kansas summer landscapes include warm-season grasses, namely bermudagrass, zoysiagrass and buffalograss. Each of those requires a little care in order to stay healthy through the hot weeks ahead.

“Those three grasses are not all created equal and some grow faster than others, which means we need to feed them a little bit different,” said Hoyle, an associate professor in the Department of Horticulture and Natural Resources.

For bermudagrass and zoysiagrass, Hoyle suggests applying a total of 1-3 pounds of nitrogen per 1000 square feet during a typical growing season, which is the beginning of May through the middle of August.

“You can split that up into multiple applications of a quick release fertilizer, or you could do fewer applications of a slower release,” he said. “But the main goal is 1-3 pounds of nitrogen per 1000 square feet regardless of what number or percentage product you’re using.”

Buffalograss does not require as much nitrogen. Studies at Kansas State University indicate that “about 1 pound of nitrogen per year for 1000 square feet is good,” according to Hoyle.

“It’s hard to split up a pound over multiple applications, so that’s one where you might want to look at a slow release to put that pound of nitrogen per 1000 square feet throughout the year,” he said. “You can do that right now and that will get you through the rest of the year with a slow release fertilizer.”

In addition to fertilizing warm-season grasses, Hoyle said homeowners should be looking at ways to control thatch and weeds in the lawn.

“We really like to preach that if you are going to do something with the lawn — whether it is fertilizing or watering — do it when it’s actively growing,” Hoyle said. “Right now, with warm-season grasses, if you have a thatch problem, you can tear that area up (with a verti-cutter or slicer), fertilize the lawn, and it will grow right back in. If you try to do that during the fall or spring months, there will be periods of time when the lawn isn’t growing, or delayed growth, and it could lead to more problems.”

Among weeds, crabgrass and yellow nutsedge are two of the most troublesome this time of year.

““I’m seeing a lot of crabgrass and yellow nutsedge and I blame it on the weather,” Hoyle said. “Yellow nutsedge loves flooded, compacted soils and because of periodic flooding around the state, I have seen a lot of areas that typically never have yellow nutsedge. It’s a weed to keep an eye out with the weather conditions as they have been.”

To control yellow nutsedge, look for products with the active ingredients halosulfuron or sulfrentrazone, he said.

Crabgrass that has already emerged can be treated with products that include the active ingredient quinclorac.

Hoyle noted that homeowners should be patient when applying herbicides to yellow nutsedge and crabgrass; it might take more than one application to control those weeds.

K-State’s Department of Horticulture and Natural Resources publishes a weekly horticulture newsletter with updated information on lawn care and other turfgrass issues. Residents may also contact their local extension agent.

Southern Blight

By: Judy O’Mara

A little unusual… this past week a fungal disease called southern blight took out a landscape planting of Lamium or dead nettle in south central Kansas. In my years at K-State, I’ve seen southern blight occur on hosta plantings a few times and  have also picked it up on Echinacea, Hibiscus, Liatris, Pasque Flower, Penstemon, Rudbeckia, Solidago, as well as, tomato. Southern blight (Sclerotium rolfsii; Athelia rolfsii) is a serious disease, particularly in the south (hence the name). It has a history of being damaging to over 500 plant species including field crops, vegetables, flowers, weeds, and even some woody landscape plants.

Plants infected by the southern blight fungus may wilt quickly and collapse, or they may turn yellow and slowly decline. There are frequently dark stem lesions at the base of the plant, a crown rot and/or a root rot. The most distinctive symptoms of southern blight are the presence of sclerotia and a white matt of fungal mycelium. Sclerotia are small seed-shaped fungal structures that allow the disease to survive in plant debris and soil for several years. They range in color from light tan to reddish-brown becoming somewhat inconspicuous as they age. A fan of white mycelium may grow along the basal stem lesion or in the soil.

While southern blight is a serious disease, it is not that common in Kansas. When it does occur here, it tends to show up during July and August under hot, wet conditions. The limiting factor for Kansas may be that when we have high temps, it also tends to be dry. Southern blight outbreaks in Kansas have been observed in irrigated landscapes (ie hot + wet). Crowded plantings can create a humid environment that can favor the disease.

Once southern blight shows up in the landscape, it can be a challenge to manage. Infected plants (plus the root ball) should be dug up, bagged and sent to the landfill. Do not compost plants from infested locations, as this can spread the disease across the planting area when the compost material is re-incorporated into the landscape. Rotate out of the infested area for 3-4 years, but make sure to control weeds because they can also serve as a host for the disease.

The bulk of the sclerotia will survive in the upper soil, so deep plowing or inverting the soil can help to reduce the amount of disease in the infested area. Another strategy for reducing southern blight severity, is to employ solarization of the target area. This can be done by covering the area with clear plastic for 4-6 weeks. It will be important to clean and disinfect tools, gloves and shoes after working in areas with southern blight. This will help to limit movement of the disease into new areas of the garden or landscape.

An article in the University of Illinois Home Yard and Garden Pest Newsletter indicated that they are also seeing southern blight activity this summer, particularly on Hosta. Another name for the disease is Hosta Petiole Blight. The article has some great photos of the disease on Hosta, which can be seen at http://hyg.ipm.illinois.edu/article.php?id=1087.

Powdery Mildew on Ornamentals

By: Judy O’Mara

Powdery mildew is a common disease on many ornamentals. It is easy to identify because it produces a whitish-gray mold on the surface of the leaf. This fungal disease is favored by high humidity and crowded plantings (i.e. poor air flow). Powdery mildew doesn’t kill the plant but susceptible hosts that have a chronic problem with it can be weakened.  The best management strategy is through the use of resistant varieties.

The Home, Yard & Garden newsletter from the University of Illinois has a nice article on powdery mildew this week: http://hyg.ipm.illinois.edu/article.php?id=1092

***Picture provided through University of Illinois Home, Yard, & Garden newsletter.

Watering Your Lawn – Resources

(By Jared Hoyle, KSU Turfgrass Research and Extension)

I’m going to say it because everyone else is thinking of it. As soon as we started to complain about all the rain, it stops and now its hot and dry.  So to help out here are two recently updated publications with information on watering your lawn.

Did you know that about half of the water applied to lawns is wasted? This fact sheet offers tips on turfgrass selection, soil preparation, and maintenance practices to increase watering efficiency.

https://www.bookstore.ksre.ksu.edu/Item.aspx?catId=545&pubId=670

Suggestions for homeowners on maintaining a healthy, attractive lawn while conserving water.

https://www.bookstore.ksre.ksu.edu/Item.aspx?catId=363&pubId=663

**** Picture looks blurry doesn’t it!  Thats because this picture was taken when the irrigation was running while it was raining outside. Make sure you take control of your irrigation otherwise it will take control of your lawn…****

Under Attack from Weeds

(By Jared Hoyle, KSU Turfgrass Research and Extension)

As a turfgrass manager, as soon as you think you have it under control… BAM, you are under attack. Just in a short period of time Manhattan has been under attack from weeds. Now many of these weeds are large and hard to control.

With all the rain earlier in the season there was standing water in many of the low areas of the research farm. The turf did not like it and eventually died. But what did like it was yellow nutsedge. I put up some information about this in the recent past but, it is everywhere and I am still getting phone calls about it so I wanted to direct you to the most recent post on controlling yellow nutsedge.

https://blogs.k-state.edu/turf/yellow-nutsedge-reported-across-ks/

Also, you can use glyphosate to treat yellow nutsedge in landscape beds but it only provides marginal control. Remember not to use glyphosate to treat yellow nutsedge in your turf.

Crabgrass galore! Slow to start but it is going strong now! Anywhere we didn’t put down a preemergent herbicide this year crabgrass has started to take over. Good thing there is options for control. Check out my earlier post for crabgrass options. Pay attention to control options for larger tillered crabgrass.

http://blogs.k-state.edu/turf/postemergent-crabgrass-control-2/


If it is not yellow nutsedge or crabgrass it is goosegrass. Back in early June, goosegrass emergence was reported across Kansas. Now the goosegrass is growing and going to be more difficult to control because it has tillered out. Make sure you make your follow-up applications when recommended and choose your control options that are effective on larger goosegrass.

If you have cool-season turfgrass then you can use fenoxaprop (Acclaim Extra), fluazifop (Fusilade II), tropramizone (Pylex), or MSMA (golf courses and sod farms only!).  You will have to do more than one application since the goosegrass is tillered out.  Sulfentrazone (Dismiss) is also effective on goosegrass if it has not tillered out yet so might want to go with another option since now the goosegrass is big.

For all you golf courses out there that have creeping bentgrass fairways it is going to be a little bit more difficult because the herbicides that work best tend to injure the turf.  1-Tiller or smaller can be controlled with fenoxaprop (Acclaim Extra) at 3.5 fl oz/A but you will need to re-apply every two weeks to make sure you are applying to small plants. This could be a follow-up option if new goosegrass starts to emerge before the season it over.

As crazy as it sounds a herbicide that has commonly been used for broadleaf weeds has shown control on goosegrass.  SpeedZone (2,4-D +dicamba + MCPP) has shown control but a follow up application is going to be needed 30 days after initial application. Pay attention to the temperature restrictions in this heat!

Tropramizone (Pylex) can be used on bentgrass at lower rates (0.25 fl oz/A) but definitely need a repeat application at 21 days

Now if you have bermudagrass or zoysiagrass then you can use Tribute TOTAL (thiencarbazone + foramsulfuron + halosulfuron).  Fusilade II and Acclaim Extra that works in cool-season grass can also be used on zoysiagrass.  If you mix these products with triclopyr (Turflon Ester Ultra or Triclopyr 4) then you will get better results.

Always remember to READ THE LABEL for the correct rate, turfgrass tolerance, and specific instructions before application!!!

Information in this article is from Turfgrass Weed Control for Professionals.

Patton, A.J., M. Elmore, J. Hoyle, J. Kao-Kniffin, B. Branham, T. Voigt, N. Christians, A. Thoms, G. Munshaw, A. Hathaway, T. Nikolai, B. Horgan, L. Miller, X. Xiong, W. Kreuser, R. Gaussoin, D. Gardner, Z. Raudenbush, D. Li, P. Landschoot, D. Soldat, and P. Koch. 2019 Turfgrass Weed Control for Professionals. Purdue University Extension Publication. TURF-100. pp. 128.

Get your copy here – https://www.bookstore.ksre.ksu.edu/Item.aspx?catId=545&pubId=20239

***Mention of trade names or commercial products in this article is solely for identification purposes and does not imply recommendation or endorsement, nor is criticism implied of similar products not mentioned by Kansas State University.***

Don’t forget to follow me on twitter @KSUTurf.

Also, visit our facebook page www.facebook.com/KSUTurf

In the midst of a summer with 100+ F temperatures

In 2016, Dr. Fry wrote a blog post titled “Bentgrass Declining? It’s from Western Europe – You Live in Kansas”. Last year we faced high summer temperatures and this year we are facing the same. Like many across the state and beyond, the bentgrass greens at Rocky Ford Turfgrass Research Center are stressed.  To address the summer stress on bentgrass greens I think that it is a good idea to revisit this topic.

Below is Dr. Fry’s article. Enjoy!

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?

Hydrangea Decline + Root Rot on Coreopsis

Wet then Hot….Hydrangea shrubs crash and burn

By: Judy O’Mara

At first glance, the declining hydrangea makes you think that they were wiped out by a disease. A quick check of the very useful K-State website (http://mesonet.k-state.edu/weather/historical) for historical weather data for Morris County (where hydrangea plants were grown) shows that it got 27.83″ of rain in the first half of the year (January 1 -July 7, 2019). Of that amount, almost 23″ (22.95”) of rain was received during April 29 –July 7th with several periods of 4-6″ over that ten week period. Basically that is a lot of rain.

The impact here is that lots of rain can keep soils wet and soggy, which in turn damages the root system. Plants with damaged roots may not have expressed symptoms during May or June because temperatures during that period were fairly moderate. More recently temps jumped into the 90s and damaged root system were unable to support the tops of the plant. Affected Hydrangeas crashed and burned. Mulch is generally a useful tool to help suppress weeds and keeps soils moist. Too much mulch over heavy clay soils can aggravate the problem by keeping soils too wet.  It can be very hard to regrow damaged root systems so, recovery potential for these plants isn’t very good.

Rhizoctonia Root Rot on Coreopsis

Many plants with poor growth this summer have been suffering due to saturated soils and high temperatures. However, sometimes plant decline is due to a disease. This Coreopsis bed sustained damage from a fungal disease called Rhizoctonia crown and root rot. The disease can survive in the soil for long periods and is triggered by high temperatures and moist soils. Long-term the best management option is to start over with new Coreopsis plants in a new location.

Developing a Weed Control Program

(By Jared Hoyle, KSU Turfgrass Research and Extension)

There are many important factors to consider when you are developing a weed control program.  Here is a list of information you should have to help you develop your program.

  1. Turfgrass species
  2. Area needing to be treated.
  3. Correct identification of the problematic weeds.
  4. The time of year the weeds are present.
  5. Determine why the weeds are invading and correct the conditions or cultural practice that are leading to the weed invasion.
  6. Select a chemical that is effective and label for control of the weeds you are treating.
  7. Follow all label instructions!!!!!!!
  8. Apply at the correct time and rate.
  9. Apply herbicides evenly.
  10. Follow up with repeat applications if recommended on the label.

This is also great information to have if you can’t figure out why a weed control method didn’t work.  For more information on diagnosing why a weed control method didn’t work, click here – https://blogs.k-state.edu/turf/i-sprayed-but-i-didnt-kill-the-weed/

Information in this article is from Turfgrass Weed Control for Professionals.

Patton, A.J., M. Elmore, J. Hoyle, J. Kao-Kniffin, B. Branham, T. Voigt, N. Christians, A. Thoms, G. Munshaw, A. Hathaway, T. Nikolai, B. Horgan, L. Miller, X. Xiong, W. Kreuser, R. Gaussoin, D. Gardner, Z. Raudenbush, D. Li, P. Landschoot, D. Soldat, and P. Koch. 2019 Turfgrass Weed Control for Professionals. Purdue University Extension Publication. TURF-100. pp. 128.

Get your copy here – https://www.bookstore.ksre.ksu.edu/Item.aspx?catId=545&pubId=20239

***Mention of trade names or commercial products in this article is solely for identification purposes and does not imply recommendation or endorsement, nor is criticism implied of similar products not mentioned by Kansas State University.***

Don’t forget to follow me on twitter @KSUTurf.

Also, visit our facebook page www.facebook.com/KSUTurf

Bermudagrass Control Options for Reseeding

(By Jared Hoyle, KSU Turfgrass Research and Extension)

Last week Ward Upham wrote an article on bermudagrass control in the KSU Horticulture Newsletter.  In the article below he explains the difficulty of controlling bermudgrass, the process and the multiple applications of a non-selective herbicide.

Bermudagrass Control by Ward Upham

Bermudagrass can make a nice lawn if you don’t mind its
invasiveness and short growing season. But many people dislike both
these characteristics. Warm-season grasses, such as bermudagrass,
zoysiagrass and buffalograss, green up later than cool-season grasses
such as tall fescue and Kentucky bluegrass. They also go dormant earlier
in the fall, which can make a lawn unattractive. Bermuda that invades a cool-season lawn will be brown during much of the spring and fall while the tall fescue portion of the lawn is green. Bermuda is much more drought and heat resistant than cool-season grasses, so it will take over a cool-season lawn during the summer months if it is in full sun.

So, how do you control bermudagrass that has invaded a cool-season
lawn? Research conducted in 1996 showed that glyphosate is the best herbicide for the job. Glyphosate is a nonselective herbicide and will kill everything—
including tall fescue or Kentucky bluegrass. Therefore, you will need to
reseed treated areas. In our study, we applied a 2% solution of
glyphosate on July 15 and again on August 15 on a bermudagrass plot that
was more than 15 years old. More than one year later, we saw no
regrowth. Glyphosate works best if bermuda is growing well. The better
the bermudagrass is growing, the more chemical is taken up and pushed
into the roots. Water and fertilize if needed to get it going.
Spray about the middle of July (or when the bermuda is growing
well). Use glyphosate (2% solution). Wait two weeks and scalp the lawn
(mow as low as possible and remove clippings.) This will prevent dead
grass from covering any bermuda that starts to recover. Wait another two
weeks and spray again with glyphosate if there is any green. Wait two
more weeks and reseed. (Ward Upham)

(For the KSU Horticulture Newsletter click here – https://hnr.k-state.edu/extension/info-center/newsletters/index.html)

But during this time areas are dead, may not be acceptable and re-seeding must be done in the fall.  What if you are wanting to seed in the spring (Especially if you ware wanting to convert to buffalograss)? This process might not work due to the timeline. Therefore, a couple years ago we looked into some other options and combinations for bermudagrass control. Here is a brief overview of the project.

Multiple summer applications of glyphosate are commonly recommended for bermudagrass (Cynodon spp.) control. However, this regime results in an extended period of displeasing and nonfunctional turfgrass, and is not ideal for spring establishment. An autumn glyphosate application prior to winter dormancy can control bermudagrass and may benefit spring  establishment projects. However, research is needed to more precisely define the parameters of efficacious late-season herbicide applications for bermudagrass control as it transitions into dormancy. Therefore, our objective was to examine late-season bermudagrass removal using combinations of glyphosate, fluazifop, and mesotrione. Experiments were initiated in October 2013 at the Rocky Ford Turfgrass Research Center in Manhattan, KS, on mature ‘Midlawn’ hybrid bermudagrass, and at Stagg Hill Golf Course in Manhattan, KS, on mature common bermudagrass. Seven herbicide treatments containing combinations of glyphosate, fluazifop, and mesotrione were evaluated. Green bermudagrass cover (0–100%) was visually estimated when treatments were applied and every 14 d after application. Only treatments containing glyphosate reduced the green cover of bermudagrass at each site the following year. Across all ratings dates and locations, adding mesotrione, fluazifop, or both to glyphosate did not further reduce green bermudagrass cover. Overall, results indicate that a single autumn application of glyphosate prior to bermudagrass dormancy reduces bermudagrass cover the following spring. The significant reduction at spring green-up may allow turf managers to make additional applications in the spring for increased control before spring establishment.

For the full article;

Hoyle, J.A.,C. Braun, C.S. Thompson and J.A. Reeves. 2018. Late-Season Bermudagrass Control with Glyphosate, Fluazifop, and Mesotrione Combinations. Agrosystems, Geosciences & Environ. 1:180014 (2018) doi:10.2134/age2018.06.0014

https://dl.sciencesocieties.org/publications/age/pdfs/1/1/180014

***Mention of trade names or commercial products in this article is solely for identification purposes and does not imply recommendation or endorsement, nor is criticism implied of similar products not mentioned by Kansas State University.***

Don’t forget to follow me on twitter @KSUTurf.

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