Kansas State University


K-State Turf and Landscape Blog

Month: June 2016

Weekly top pics from the diagnostic lab

Here are a few quick pics from the diagnostic lab. These photos were taken by our summer intern, Beth McKinzie.

Rose mosaic virus:


Rose mosaic virus is caused by several viruses, sometimes in combination. There is no control for this disease once the plant is infected. Diseased plants are not killed outright but may have reduced vigor and are more prone to winterkill. Symptoms are most prominent on new growth in spring. The virus is spread by propagation practices. Remove and destroy affected plants.

Sycamore anthracnose:


Anthracnose diseases affect several tree species in Kansas. Anthracnose causes brown irregular leaf spots, often along veins. Premature leaf shedding and twig blighting can also occur. Symptoms develop during wet spring weather. Anthracnose is rarely damaging and primarily cosmetic, with no management needed. Trees usually produce new foliage and recover with the onset of warmer, drier summer weather. For more on anthracnose in shade trees, you can read more HERE.

Bacterial wetwood:


Wetwood is caused by multiple species of bacteria that reside inside the tree. It is common in elm, cottonwood, maple, mulberry, oak, willow, and sycamore. Liquid oozes from wounds and cracks and runs down the bark, leaving discolored streaks on branches or trunks. This is primarily cosmetic and no management is needed.

Season-long agronomic practices to reduce anthracnose risk in putting greens

DSCN0880 DSCN0877

The temperature dial is getting turned up, and summer stress is on the way. Unfortunately summer is often when we are sometimes pushing greens even further with low mowing heights for tournaments, etc.

Over the past few years, Rutgers University has led a multi-university research program to investigate the impact of cultural practices and fungicides on turfgrass anthracnose, including fertility (it’s really important!), mowing height (even a small increase can help!), and more.

We have some more information about anthracnose (including fungicide info) HERE.

The BMP’s from Rutgers are outlined HERE.

If you just can’t get enough, details from Rutgers are available HERE (you can click through a 54 page pdf with lots of images and data)

Here is a cheat-sheet of some tidbits from the above links about agronomic practices and anthracnose:

Fertility program: Provide adequate nitrogen to maintain turfgrass growth. Low nitrogen can increase anthracnose severity. Applications of soluble N at 0.20 to 0.25 lb N/1000 square feet every two weeks is beneficial. Apply adequate potassium.

Mowing and rolling: Low mowing heights can raise the risk of anthracnose development. Slight increases in mowing height can reduce disease pressure. Consider raising the mowing height to 3.6 mm (0.14 inches). Rolling on alternate days will increase ball roll and can slightly reduce anthracnose severity.

Irrigation and drainage: Anthracnose can be more severe with either too much or too little water. Irrigate to supply 60-80% of evapotranspiration. Avoid wilt stress. Hand-water when practical. Anthracnose tends to be more severe on putting greens with poor air movement and poor drainage. Don’t overwater putting greens: excessive soil moisture may damage roots and decrease photosynthesis, predisposing it to anthracnose injury. Aerify in the fall to improve drainage, and improve airflow to the site.

Topdressing: Light, frequent topdressing reduces the overall risk of anthracnose.

Foot traffic: In one of the more recent Rutgers studies (link to article HERE by Joseph Roberts and James Murphy), they looked at foot traffic + sand topdressing, foot traffic – sand topdressing, no foot traffic + sand topdressing, and no foot traffic and no sand topdressing. The combination of foot traffic + sand topdressing had the LEAST amount of disease.

Plant Growth Regulators: Normal use of trinexapac ethyl and ethephon has reduced anthracnose in trials. Mefluidide has had little effect in most cases.

Cultivation: Shallow verticutting (0.13 inch) has had mixed results, leading to slight increases in disease in some studies and no effect in others. If anthracnose is active, use fungicides before any cultivation.



Pythium root rot in putting greens

Jared Hoyle mentioned that he has been getting some questions on Pythium root rot, and last week, our neighbor to the east Dr. Lee Miller at University of Missouri wrote in a great post (click HERE) that he has already seen some Pythium root rot samples from putting greens with all the wet conditions. Even in the absence of Pythium in the roots, heavy rains in spring = poor root growth = turf more likely to crash and burn when summer conditions kick in. Add Pythium and that can make it even worse. In his article, Dr. Miller also provided a caution that some of the materials superintendents apply in spring such as pre-emergent herbicides, DMI fungicides, and PGRs could be limiting root growth in spring and setting up the grass for more problems. His comment is observational from comments from superintendents but is definitely interesting and as he states, probably some research is needed.

In another excellent recent post from NCSU, Lee Butler provided some specific tips about management:

“We currently recommend that everyone start their Pythium root rot prevention program off with Segway due to it being very good in our trials over the past couple of years, even at the 0.45 oz/M rate. At the 0.45 oz/M rate, you can apply Segway 6 times instead of 3 according to the label, so you will want to rotate that in with other products like Subdue, Banol, Stellar, Appear, or Signature (in no particular order). For more information about Pythium root rot, click here. Any decent Pythium fungicide such as Subdue, Segway, Banol, Stellar, Appear, or Signature (in no particular order) should do a nice job of preventing this disease. You will likely have to make repeat applications every couple of weeks until the weather changes. Rotate through the different chemistries to help with resistance management.”

Finally, don’t forget that Pythium root rot is distinct from Pythium foliar blight. The foliar (cottony) blight is actually quite rare on putting greens. Foliar Pythium is definitely linked to warmer conditions, with nighttime lows > 68. For fungicide information on foliar Pythium, you can view the table HERE from U of Kentucky (scroll to p 17).


Best way to get your turf noticed? – Brown Patch!

(By Jared Hoyle, Evan Alderman and Jake Reeves; KSU Turfgrass Research and Extension)

Megan posted last week about brown patch already showing up at Rocky Ford Turfgrass Research Center in Manhattan, KS. So I wanted to share a little bit of research we conducted last year in Olathe about brown patch control. This way you know what to have ready to go when you need to make your brown patch application.

Rationale. Tall fescue [Festuca arundinacea Schreb.] is one of the most predominantly used cool-season turfgrass species in the transition zone. Its deep root system and coarse textured leafs lend to its ability to withstand drought, heat, and wear stress. Although it is well adapted to survive the summer months in Kansas, it can be susceptible to injury from disease. Brown patch [Rhizoctonia solani] is a disease that can damage leaf tissue, shoots, and the crown of tall fescue during the summer months. This disease is most prevalent during periods of high humidity, high temperature (above 80°F), and high nitrogen levels. During the mornings mycelia can be seen forming a “smoke ring” around the affected area. Applications of preventative fungicides have proven to be a successful management strategy in reducing the occurrence of brown patch incidences in tall fescue stands. With new fungicide formulations coming out every year, testing is needed to demonstrate the efficacy of these fungicides in reducing potential injury from disease.

Objectives. Evaluate Heritage Action and Velista for preventative control of brown patch in a perennial stand of tall fescue.

Study Description. A field study was initiated 18 June 2015 at the Kansas State University Olathe Horticultural Research Center in Olathe, KS on turf-type tall fescue maintained at 3 inch. Study was conducted as a randomized complete-block design, with three replications. Fungicides applied during this study were Heritage Action (Azoxystobin and Acibenzolar-S-methyl) and Velista (Penthiopyrad). Field study consisted of: an untreated control, Velista applied at 0.3 and 0.5 oz/1,000ft2, and Heritage Action applied at 0.2 oz/1,000ft2. Visual percent brown patch incidence was rated on a 0 to 100% scale every three weeks beginning at trial initiation. Means were separated according to Fisher’s Protected LSD test when P ≤ 0.05.

Table 1. Percent brown patch incidence on tall fescue with the application of preventative fungicides.
% Brown Patch Incidence†
Treatment 0 WAT‡ 3 WAT 6 WAT 9 WAT
Control 0 0 43.3 a§ 13.7
Velista 0.3 oz/1,000ft2 0 0 5.0 b 14.3
Velista 0.5 oz/1,000ft2 0 0 6.7 b 5.3
Heritage Action 0.2 oz/1,000ft2 0 0 0.0 b 0.3
† Percent brown patch incidence was visually rated on a 0-100% scale where 0% = no brown patch observed and 100% = plot completely affected by brown patch.
‡ Indicates weeks after treatment application.
§ Means in a column followed by the same letter are not significantly different according to Fisher’s protected LSD test, (P<0.05).

Results. All applications of the preventative fungicides resulted in minimal observations of brown patch. Six weeks after treatment application (WAT) Velista applied at 0.3 oz/1,000ft2 and 0.5 oz/1,000ft2 and Heritage Action resulted in 5%, 7%, and 0% brown patch incidence, respectively, when compared to an untreated control (43% brown patch incidence)(Table 1). Heritage Action performed best during this study with brown patch only being observed 9 WAT (0.3%). From this research, to decrease the chances of a brown patch incidence, apply a preventative fungicide before conditions are favorable for this disease. Repeat applications may be needed to ensure seasonal coverage.



brownpatch plots

Figure 1. Digital images of research plots 9 WAT, see Table 1 for the mean percent brown patch cover for each corresponding treatment.

The Kansas Turfgrass Field Day – Manhattan, KS – August 4, 2016

(By Jared Hoyle; KSU Turfgrass Research and Extension)

It’s almost here! The 2016 Kansas Turfgrass Field Day in Manhattan, KS on August 4th! This year we have lots of field research to show you anything from new products to new things with old products.


The link below has all the information from vendor registration to registration!  Hope to see you there.


Some of the tour highlights include;

  • Turfgrass Weed Research Trials – Jared Hoyle
  • Herbicide Option for Converting Tall Fescue to Buffalograss – Jake Reeves
  • Carts During Drought – How Does the Turf Respond? – Ross Braun
  • Zoysia Update – Jack Fry
  • Landscape & Turf Diseas Potpourri – Megan Kennelly
  • New Bentgrasses for Greens and Fairways – Steve Keeley
  • Drones for Detecting Stress – Dale Bremer
  • Auditing your Irrigation System – Cathie Lavis


Time to Think About Managing Your Warm-season Home Lawn

Time to Fertilize Warm-Season Grasses    

    June is the time to fertilize warm-season lawn grasses such as bermudagrass, buffalograss, and zoysiagrass. These species all thrive in warmer summer weather, so this is the time they respond best to fertilization. The most important nutrient is nitrogen (N), and these three species need it in varying amounts.

buffalograss fairway

    Bermudagrass requires the most nitrogen.  High-quality bermuda stands need about 4 lbs. nitrogen per 1,000 sq. ft. during the season (low maintenance areas can get by on 2 lbs.). Apply this as four separate applications, about 4 weeks apart, of 1 lb. N per 1,000 sq. ft. starting in early May. It is already too late for the May application, but the June application is just around the corner. The nitrogen can come from either a quick- or slow-release source. So any lawn fertilizer will work.  Plan the last application for no later than August 15. This helps ensure the bermudagrass is not overstimulated, making it susceptible to winter-kill.

    Zoysiagrass grows more slowly than bermudagrass and is prone to develop thatch.   Consequently, it does not need as much nitrogen. In fact, too much is worse than too little. One and one-half to 2 pounds N per 1,000 sq. ft. during the season is sufficient. Split the total in two and apply once in early June and again around mid-July. Slow-release nitrogen is preferable but quick-release is acceptable.  Slow-release nitrogen is sometimes listed as “slowly available” or “water insoluble.”


    Buffalograss requires the least nitrogen of all lawn species commonly grown in Kansas. It will survive and persist with no supplemental nitrogen, but giving it 1 lb. N per 1,000 sq. ft. will improve color and density. This application should be made in early June. For a little darker color, fertilize it as described for zoysiagrass in the previous paragraph, but do not apply more than a total of 2 lb. N per 1,000 sq. ft. in one season. Buffalograss tends to get weedy when given too much nitrogen. As with zoysia, slow-release nitrogen is preferable, but fast-release is also OK. As for all turfgrasses, phosphorus and potassium are best applied according to soil test results because many soils already have adequate amounts of these nutrients for turfgrass growth. If you need to apply phosphorus or potassium, it is best to core aerate beforehand to ensure the nutrients reach the roots. 

Thatch Control in Warm-Season Lawns      

    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 overfertilizing 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.

Is you transition zone Bermudagrass “Out of Gas” This Spring?

I saw this online the other day and thought it would be a good blog post to share from one of my good friends Jerad Minnick, and independent advisor and teacher for natural grass sports surfaces.

Jerad talks about how our bermduagrass is confused from the spring in the Mid-west to light requirements for bermudagrass to de-compacting the soil.




Kick it in the tuber – yellow nutsedge control!

(By Jared Hoyle, KSU Turfgrass Research and Extension)

Slide1Last year about this time I posted about yellow nutsedge control in home lawns and just in case you missed it here is the link;

Revisiting Yellow Nutsedge Control in Home Lawns

But for all you commercial turfgrassmanagers today’s nutsedge control blog is for you.  There are many herbicides available for control but there are some things to do before you apply herbicides and those are making sure that the turf has a healthy environment to grow.  Sometimes that is easier said than done.  If you can improve drainage and compaction that would increase the health of the turf and help out compete yellow nutsedge.


If using a herbicide application timing is critical.  During mid summer yellow nutsedge starts making tubers and if you apply herbicides before tuber production you will get better control.  If you wait until the yellow nutsedge is big and starting to make tubers then you will be playing catch-up all year. So sooner is better.  Don’t wait for it to get too big.

Here are some options for yellow nutsedge control;

  • sulfentrazone
  • halosulfuron
  • iodosulfuron
  • mesotrione
  • bentazon
  • triflozysulfuron
  • flazasulfuron
  • sulfosulfuron

There are many different products out there that contain these active ingredients so just make sure you have an active ingredient that has yellow nutsedge control!

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

***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.***

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