Kansas State University

search

K-State Turfgrass

Tag: root health

Turf health problems, above and below ground. And why your putting green soil should not look like tiramisu.

(Megan Kennelly, KSU Plant Pathology)

The soggy weather continues, and diseases are in full swing. Dewy, wet mornings lead to mycelial growth of the pathogens that cause dollar spot or foliar Pythium. These are mainly golf course concerns, but the diseases can occur at other sites.

Here is a sample that came into the lab, loaded with foliar Pythium:

IMG_3151

It is from a golf course fairway at a site that has received a lot of rain and some foggy mornings where everything is wet-wet-wet.

For management info on foliar Pythium, you can check these links:

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

(scroll through to the Pythium part on p.17)

http://extension.missouri.edu/p/IPM1029-17#Pythiumfoliarblight

 

Root health continues to be a problem, especially on putting greens. We’ve posted a lot of information this year about wet soils leading to physiological decline and triggering Pythium root rot in some cases (see links at bottom of this post). Putting greens with poor drainage, less-than-ideal construction, or a build-up of organic matter are particularly susceptible. Here are some putting green rootzones with a lot of organic matter build-up, visible as dark layers:

layers FullSizeRender

All those layers kind of look like tiramisu…mmm… yummy… getting distracted.

tiramisu

Unlike delicate layers of a tiramisu, layering in a putting green rootzone is NOT a delectable delight. Another complication of poor drainage is that it can make the turf more prone to anthracnose. I received a couple of samples in recent days with crown rot anthracnose. Both also had layering problems and root decline.

There is some information about anthracnose here:

http://www.bookstore.ksre.ksu.edu/pubs/EP147.pdf

and here is an excellent list of best management practices:

http://turf.rutgers.edu/research/bmpsanthracnose2015.pdf

Many of the practices to reduce anthracnose also promote overall turf health. That is, when you implement agronomic practices to promote good rooting you also reduce the risk of anthracnose and other problems. You may not be able to do ALL of the beneficial agronomic practices you would like, due to budgetary limits or lack of equipment or golfers’/greens committee opinions, but the more you can fit in, the better.

We posted on these topics earlier this year. If you want to go back and review, here are some links:

https://blogs.k-state.edu/turf/season-long-agronomic-practices-to-reduce-anthracnose-risk-in-putting-greens/

https://blogs.k-state.edu/turf/root-decline-it-aint-benign/

https://blogs.k-state.edu/turf/best-management-practices-for-turfgrass-anthracnose/

https://blogs.k-state.edu/turf/your-turf-is-trying-to-bike-up-a-mountain/

https://blogs.k-state.edu/turf/bentgrass-declining-its-from-western-europe-you-live-in-kansas-by-dr-fry/

 

 

“Bentgrass Declining? It’s from Western Europe – You Live in Kansas” by Dr. Fry

Our own Dr. Jack Fry is an expert on cool-season turfgrass physiology. He co-wrote a book on the topic:

book

and he developed an online GCSAA class (click HERE) as well.

So, every year, around this time, I end up asking him about mid-summer turfgrass decline. I asked Jack to write some thoughts for this blog:

 

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!green_in_aerification_holes
  • 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.)poa dying
  • 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?mow

 

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).

 

Root decline, it ain’t benign

(Megan Kennelly)

In the past 2 weeks we have posted a series of articles related to root health and rootzone management. I’m following up here with a few more photos (click to zoom any of the photos below).

Most of the samples have shown layering, thatch, and a build-up of organic matter.  These can reduce drainage, and roots suffer from lack of oxygen. Furthermore, wet soils hold heat, so the turf gets a double whammy of wet + hot. Steam-cooked turf is not happy turf. I’ve seen some very unhappy roots lately. Some have Pythium root rot as well, some appear to be in serious decline just from the physiological stress.

We already posted a bunch of information about managing rootzones and some tips on what to do in the fall and in the future, so I won’t go into that here. Glance back at our recent posts. You might also like to read pages 6-7 on the following website by Paul Vincelli and Gregg Munshaw which discusses managing summer stress in putting greens:

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

Here is some layering in several recent samples. I know it can be tough to convince golfers to let you aerify, but the consequences of NOT aerifying can be deadly when summer weather strikes.

032

002

This is an older push-up green with drainage issues in all this wet weather:

010 011

Here is a series of photos showing Pythium root rot and root decline symptoms:

Slide1 Slide2 Slide3 Slide4 Slide5

Here is a field shot of the site that goes with the microscope pictures above:

Presentation1

Here is one more set of photos showing layering and decline. This site had root decline, Pythium root rot, algae, and some anthracnose crown rot. Those factors all like to co-mingle and cause problems. This superintendent said they are working on improving some drainage and rootzone issues that built up over time.

021  027 IMG_20150730_100237320 IMG_20150802_083806451 IMG_20150803_113824539