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Category: Diseases

The 2016 Turfgrass Research Reports Now Online!

Posted on by jahoyle

(By Jared Hoyle: KSU Turfgrass Research and Extension)

Every year we create new turfgrass research reports.  This year we have lots of new information from the release of a new zoysiagrass to unmanned aircraft systems for drought monitoring.

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Listed below is a list of topics and links to the 2016 reports.  Enjoy!

  1.  Release of KSUZ 0802 Zoysiagrass
    J. Fry and Ambika Chandra
  2. Nitrous Oxide Emissions and Carbon Sequestration in Turfgrass: Effects of Irrigation and Nitrogen Fertilization (Year 1)
    R. Braun, D. Bremer, and J. Fry
  3. Small Unmanned Aircraft Systems Detect Turfgrass Drought
    D. Bremer and Deon van der Merwe
  4. 2013 National Turfgrass Evaluation Program Bermudagrass Test: 2015 Data
    L. Parsons, J. Griffin, and J. Hoyle
  5. 2012 National Turfgrass Evaluation Program Tall Fescue Test: 2015 Data
    L. Parsons, M. Kennelly, J. Griffin, and J. Hoyle
  6. Influence of Glyphosate Timings on Conversion of Golf Course Rough from Tall Fescue to ‘Sharps Improved II’ Buffalograss
    J. Reeves, J. Hoyle, D. Bremer, and S. Keeley
  7. Late Pre-Emergent Control of Annual Bluegrass with Flazasulfuron & Indaziflam
    J. Reeves and J. Hoyle
  8. Evaluating the Effects of Simulated Golf Cart Traffic on Dormant Buffalograss and Turfgrass Colorants
    E. Alderman, J. Hoyle, J. Fry, and S. Keeley
  9. Preventative Control of Brown Patch with Select Fungicides
    E. Alderman, J. Reeves, and J. Hoyle
  10. Development of Cold Hardy, Large Patch Resistant Zoysiagrass Cultivars for the Transition Zone
    Mingying Xiang, J. Fry, and M. Kennelly
  11. Evaluating Zoysiagrass-Tall Fescue Mixtures in Kansas
    Mingying Xiang, J. Fry, and M. Kennelly

Lawn Problem Solver

Posted on by jahoyle

(By Jared Hoyle; KSU Turfgrass Research and Extension)

Do you have an unwanted weed or a disease that you can’t figure out what it is or how to control it?  Check out the Lawn Problem Solver at the KSU Turfgrass Website.  Is has information about how to identify those pesky weeds, diseases, insects and more.

Also, for homeowner extension questions please locate your local area or county extension agent here – http://www.ksre.k-state.edu/about/stateandareamaps.html 
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Sad, soggy roots and some Pythium root rot in turf

Posted on by kennelly

(Megan Kennelly, KSU Plant Pathology)

 

“We got six inches of rain, and the golfers are saying, ‘Hey, isn’t it great for the turf that we are getting all this rain?’ Hah – Not exactly!”

That was part of a recent conversation with a superintendent in south central Kansas. Yes, moisture is good, but not 6 inches all at once! It seems that this year the water is either OFF or ON. When it is OFF it is really OFF. When it is ON, it is coming down in buckets. I guess nobody gets exactly what they want when they need it.

We continue to see poor rootzones on all kinds of plants, from trees to turf to tomatoes to petunias. Putting greens are really suffering. I’m seeing lots of brown, mushy roots with tissue sloughing off.  Poa annua is also checking out in the heat, big time.

Below are some pics of roots. These are some older pics I have posted before, but they look just like most of the roots I’ve been looking at for the past couple of weeks. In some cases Pythium root rot is occurring as well, but in many cases the turf seems to be declining all on its own. For example, I had some samples where multiple plugs were submitted from multiple greens. All the roots were in poor health, but I found Pythium (at a low level) in just a few of them.

Root images:

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What to do?

Check out the post today from Dr. Fry with some tips about managing bentgrass to prevent summer decline. Click HERE.

Another great set of tips is outlined HERE, starting on page 6, from U of Kentucky.

For Pythium root rot, here is an excellent site from NCSU, where Dr. Jim Kerns has conducted research on this disease.

http://www.turffiles.ncsu.edu/diseases/pythium-root-rot

In current research, Dr. Kerns reported in a Tweet that he also saw good results with Signature Xtra watered in (click HERE).

To date, we have not had a different disease, Pythium root dysfunction, occur in Kansas. At least, I have not seen it any any samples run through KSU. I did just learn from our neighbor Dr. Lee Miller at U. of Missouri that they picked up that disease in St. Louis. Lee mentions it in his update HERE if you want to learn a little more about it.

 

HOT! Soil temps and turf decline

Posted on by kennelly

(Megan Kennelly, KSU Plant Pathology)

We all know it has been super hot lately. Yuck! We humans are suffering because of the hot air, but our cool-season turfgrasses are suffering from the high soil temperatures.

I have not had an onslaught of samples yet, but I fear that if this weather keeps up, they will be coming soon. Usually the flood of turf comes in August, but this is shaping up to be a tough year. (If we are lucky, I’ll be wrong and the weather will chill out, the turf will chill out, and WE can chill out!)

I took a look at soil temperatures at the Kansas Mesonet website (click HERE to access it), and I saw that our 2-inch daily max soil temps in Manhattan have been soaring into the 90’s and our 4 inch daily max soil temps have been solidly in the mid to upper 80’s.

Pop quiz – do you remember the optimal 4-inch soil temperature range for root growth in cool-season turf?

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Got your guess?

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The answer – 50-65 degrees Fahrenheit. We will not be seeing that again for several months.

When we get into our current range of steamy 80’s and 90’s in the soil, root growth shuts down. Shoot growth is shutting down too. That means, if you lose cool-season turf now it will be very hard to get it back again.

Now, I’ll point you to some prior posts and references that outline some tips on summer stress management.

We sent these two last week, but I’ll post again here.

By Jack Fry: - general tips for water management:

https://blogs.k-state.edu/turf/good-water-management-will-help-get-greens-through-midsummer-stress/

By Dale Bremer - using moisture sensors:

https://blogs.k-state.edu/turf/water-management-on-greens-with-soil-moisture-sensors/

 

Here is another old post from last year:

Summer weather can be ruthless when the turf is stressed and rootless

And, finally, in this page, starting on page 6, there is an excellent, clearly-written set of tips on reducing summer stress in putting greens. Really – if you manage putting greens, take a couple of minutes, click here, scroll to page 6, and read these tips.

http://www2.ca.uky.edu/agcomm/pubs/ppa/ppa1/ppa1.pdf

 

 

 

Pythium foliar blight in ryegrass and bentgrass tees and fairways

Posted on by kennelly

(Megan Kennelly, KSU Plant Pathology)

I haven’t received any Pythium foliar blight samples yet, but I wanted to provide a heads up and reminder.

Pythium foliar blight, sometimes called cottony blight, is one of the most destructive turfgrass diseases.  The disease can explode in only a few days if conditions are right. Perennial ryegrass and tee- or fairway-height creeping bentgrass are the most common hosts in Kansas. Though Pythium root rot (caused by different species) is common in putting greens, Pythium foliar blight is rare in putting greens. In 10 years, I have seen it only ONE time on a putting green. Tall fescue, Kentucky bluegrass, bermudagrass, and zoysiagrass can become infected, but this is extremely rare.

Conditions for Disease Development

The risk of Pythium blight is highest during humid weather when day temperatures are 86 to 95 degrees Fahrenheit and overnight lows are consistently at least 68 degrees Fahrenheit.

The disease is most common when soils are saturated with water, due to excessive rainfall or irrigation. Long dew periods, high relative humidity, and lush, dense turfgrass growth also favors disease development. Low areas, sites with poor air flow, and sites with poor drainage are particularly vulnerable.

Symptoms

In fairway-height bentgrass and perennial ryegrass, the first symptoms are irregularly shaped, water-soaked, greasy patches up to 4 inches in diameter.

Pythium in rye fairway

If it is humid, a cottony growth may be present early in the morning.

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The patches may merge into larger blighted areas.

pythium 2006-2

The pathogen can be spread by equipment  and in water drainage patterns. Here is some Pythium blight at Rocky Ford a couple of years ago, following the pattern where heavy rain caused a water flow across this plot from left to right.

r ford pythium blight

Look-alikes: Pythium blight can be confused with brown patch, damage due to thick thatch, drought stress, or grubs. Brown patch is active during these same conditions. If you have any doubt, you can always send a sample to the diagnostic lab.

Management

Pythium thrives in water, so water management is the key to Pythium blight control. The following practices will reduce the risk of other diseases (and stresses), too:

  • Improve drainage in areas where water is likely to stand for any length of time.
  • Avoid overwatering, especially during hot, humid periods.
  • Promote rapid turfgrass drying by proper spacing and pruning of shrubs and trees.
  • Fans can improve airflow in closed-in areas where collars and approaches have a history of disease.
  • Irrigate in the early morning to reduce the number of hours of leaf wetness.
  • Excessive nitrogen fertilization stimulates lush growth that is more susceptible to Pythium blight. Maintain a proper balance of nutrients and avoid fertilizing during periods of Pythium blight activity.
  • If active mycelium is present, avoid mowing, which can spread the pathogen.

Preventive fungicide applications during the summer months may be necessary on perennial ryegrass or creeping bentgrass golf fairways.

Below is the Pythium blight fungicide information from Chemical Control of Turfgrass Diseases by Paul Vincelli and Gregg Munshaw at University of Kentucky. You can click the image below to zoom. For the full guide, visit HERE.

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Weekly top pics from the diagnostic lab

Posted on by kennelly

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

Rose mosaic virus:

rosemosaic

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:

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

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

Posted on by kennelly

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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

Posted on by kennelly

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!

Posted on by jahoyle

(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.

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

Posted on by jahoyle

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.

Enjoy!

https://growinggreengrass.net/2016/05/16/transition-zone-bermudagrass-out-of-gas-this-spring/