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Category: Diseases

Large patch in research plots

Before the snow hit I was able to view some large patch symptoms in our breeding plots with our PhD student Manoj Chhetri.

Strong large patch symptoms:

Not much symptoms here:

Definitely some differences in % green after the recent cold snaps, but before the snow and this weeks extreme cold temps:

Odd weather patterns lead to odd disease patterns

 

I saw some brown patch recently – in late September/early October!

In the meantime, our warm-season grasses are slowing down, and all the cool, cloudy, rainy weather this week may trigger some large patch in zoysiagrass.

Pathogens will take advantage of conducive conditions whenever they occur. Here are some great updates from my excellent turf pathology colleague Dr. Lee Miller, next door in Missouri:

https://turfpath.missouri.edu/reports/2018/update10_05_18.cfm

 

Flower garden sanitation to improve plant health next spring

Many plant pathogens like to survive the winter in infected crop debris. One example is iris leaf spot.

 

Here is a zoom – the black spots are structures where the fungus produces spores:

So what can we do? Here are some tips from the Horticulture News (http://www.ksuhortnewsletter.org/):

Iris are known for a couple of common problems: a fungus disease known as iris leaf spot and an insect named iris borer. Though both cause problems in the spring, now is the time to start control measures. Both the fungus and eggs of the borer overwinter on old, dead leaves. Remove dead leaves and cut back healthy leaves by ½ this fall to reduce populations of these pests. Also remove other garden debris from the iris bed.  This can significantly cut down on problems next spring. (Ward Upham)

Another disease that lurks over the winter is peony leaf blotch (also known as red spot or measles) and you can find info on that disease here on the Common Plant Problems website.

 

 

(Photos by Megan Kennelly)

Cool-season Turfgrass Lawn Care Reminders!

(By Jared Hoyle, KSU Turfgrass Research and Extension)

It is that time of year again to start working on your cool-season lawn.  To try and cover it all, I have listed a couple posts from the past that can help you get that lawn into shape.  I also have added a list of publications. Enjoy!

Time to fertilize cool-season turfgrass

http://blogs.k-state.edu/turf/time-to-fertilize-cool-season-turfgrass/ 

Monthly calendar for cool-season lawns for the rest of the year

http://blogs.k-state.edu/turf/monthly-calendar-for-cool-season-lawns-for-the-rest-of-2017/

Power raking or core aeration – That is the question!

http://blogs.k-state.edu/turf/power-raking-or-core-aeration-that-is-the-question/

The art of knowing your seed label

http://blogs.k-state.edu/turf/the-art-of-knowing-your-seed-label/

For seeding success, pay attention to other crop on the seed label

http://blogs.k-state.edu/turf/for-seeding-success-pay-attention-to-other-crop-on-the-seed-label/

Publications

Lawn Fertilizing Guide – https://www.bookstore.ksre.ksu.edu/Item.aspx?catId=545&pubId=10639

Recycling your grass clippings  – https://www.bookstore.ksre.ksu.edu/Item.aspx?catId=545&pubId=701

Mowing your lawn – https://www.bookstore.ksre.ksu.edu/Item.aspx?catId=545&pubId=615

Tall Fescue Lawns – https://www.bookstore.ksre.ksu.edu/Item.aspx?catId=545&pubId=1460

Watering New Lawns – https://www.bookstore.ksre.ksu.edu/Item.aspx?catId=545&pubId=1337

Planting a Home Lawn – https://www.bookstore.ksre.ksu.edu/Item.aspx?catId=545&pubId=595

Aerating Your Lawn – https://www.bookstore.ksre.ksu.edu/Item.aspx?catId=545&pubId=713

Kentucky Bluegrass Lawns – https://www.bookstore.ksre.ksu.edu/Item.aspx?catId=545&pubId=713

 

Check out the KSRE Bookstore for more publications – https://www.bookstore.ksre.ksu.edu/Category.aspx?id=528&catId=545

 

Dollar spot activity, and lingering brown patch

Moderate days and cool, dewy nights have increased dollar spot pressure. Check out these photos in our research plots.

Here is an untreated plot:

Here is a cleaner plot:

There are many great tips about fungicides for managing dollar spot starting on page 15 of this document:

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

In terms of varieties, like other universities, KSU does a lot of screening of new breeding lines and existing cultivars. In our research plots we like to have big blocks of different cultivars for different reasons. In my fungicide trials, often I like to use susceptible varieties to make sure we get strong disease pressure. For other types of studies we like to use more resistant varieties when developing reduced-input integrated management strategies.

Here is an example of two varieties out on one of our research greens. They have not been sprayed, and they are not in use at the moment, but they show the striking differences in susceptibility:

I also noticed a tiny bit of lingering brown patch on our putting green. When we switch more solidly into cool fall weather that should fade into nothing. Ah, fall! Let’s have more nights in the 50’s!

If you squint hard, you’ll see the big brown patch circle among all the dollar spot:

Fungi thriving in wet conditions

(Megan Kennelly, KSU Plant Pathology)

Fungi love wet, humid conditions. Parts of Kansas have received a lot of moisture lately.

Here are a few recent examples:

Brown patch mycelium on a morning with fog and dew. If you look closely you’ll see the lesions, too.

 

 

Here is some foliar Pythium mycelium from another wet site:

You can see the white mycelial threads if you look closely. Also notice how the turf is so matted down and soggy/greasy in appearance.

At this location they had just sprayed tebuconazole, so how did the Pythium keep on rolling? Well, as you might remember, Pythium is not a true fungus, and some fungicides just do not work on it. Fungicides in the tebuconazole family (the DMI fungicides, FRAC code 3) have no effect on Pythium – you might as well be spraying water. For a list of products that DO have efficacy on Pythium foliar blight you can check this reference (p. 23) http://www2.ca.uky.edu/agcomm/pubs/ppa/ppa1/ppa1.pdf

Cultural practices are outlined HERE.

Conditions for both Pythium and brown patch “should” be ending soon, and cool fall weather alone acts as a natural fungicide to slow those 2 diseases down just as our cool-season grasses find themselves in optimal conditions to grow. Recovery and seeding season is right around the corner.

And, finally, after 4 inches of rains there were mushrooms everywhere:

Some mushrooms are associated with fairy rings, and there is some information about that HERE.

How do mushrooms pop up overnight? They are actually kind of pre-made, hanging out in the soil in a small egg-like structure. When moisture comes they can expand quickly, like one of those sponge-animals that expands when you put it in a bucket. There are lots of time-lapse videos out there that show mushroom growth – here is one example:

It’s kind of cool but creepy at the same time.

2018 K-State Turfgrass Research Reports Online!

 

(by Jared Hoyle, KSU Turfgrass Research and Extension )

Every year the Kansas Agriculture Experiment Station publishes research reports on projects that are being conducted around the state.  The 2018 Turfgrass Research Reports are now online!  These reports contain everything from turfgrass variety testing, weed control, disease and insect management and more.

Below are a list of the 2018 reports.  Click the title to read more.

Extent of Larval Populations of Turfgrass Insect Pests at Rocky Ford Turfgrass Research Center at Manhattan, KS
Raymond A. Cloyd

Herbicide and Application Timing Effects on Windmillgrass Control
Nicholas Mitchell and Jared Hoyle

Evaluating Small Unmanned Aerial Systems for Detecting Drought Stress on Turfgrass
Mu Hong, Dale Bremer, and Deon van der Merwe

Urban Lawn Microclimates Affect Reference Evapotranspiration
Kenton W. Peterson, Dale J. Bremer, and Jack D. Fry

Evaluating Zoysiagrass-Tall Fescue Mixtures in Kansas
Mingying Xiang, Jack D. Fry, and Megan M. Kennelly

Brown Patch Occurrence in a Zoysiagrass-Tall Fescue Polystand Compared to a Tall Fescue Monostand
Mingying Xiang, Jack D. Fry, and Megan M. Kennelly

Evaluating Large Patch-Tolerant and Cold Hardy Zoysiagrass Germplasm in the Transition Zone
Mingying Xiang, Jack D. Fry, and Megan M. Kennelly

2013 National Turfgrass Evaluation Program Bermudagrass Test: 2013–2017 Summary Report
Linda R. Parsons, Michael J. Shelton, Jason J. Griffin, and Jared A. Hoyle

2012 National Turfgrass Evaluation Program Tall Fescue Test: 2012–2017 Summary Report
Linda R. Parsons, Michael J. Shelton, Megan M. Kennelly, Jason J. Griffin, and Jared A. Hoyle

2013 National Turfgrass Evaluation Program Bermudagrass Test: 2017 Data
Linda R. Parsons, Michael J. Shelton, Jason J. Griffin, and Jared A. Hoyle

2012 National Turfgrass Evaluation Program Tall Fescue Test: 2017 Data
Linda R. Parsons, Michael J. Shelton, Megan M. Kennelly, Jason J. Griffin, and Jared A. Hoyle

 

Anthracnose crown rot in putting greens, and the turf stress behind it

(Megan Kennelly, KSU Plant Pathology)

We had a sample come in with soggy roots, algae, and a lot of thinning.

Here is the root zone. Lots of organic matter holds water, which holds heat. Hot, wet roots can decline quickly.

 

 

Hot, soggy roots can’t support growth.

(I did not find Pythium root rot structures in this sample, but these same conditions can lead to that disease, too.)

Looking closely, there was algae present. The dark green stringy stuff in the circled area is algae growing on the turf, viewed in the dissecting microscope. Algae is another indicator of wet conditions.

At closer inspection, in the compound microscope, spiny black structures were visible near the base of many declining plants that were just starting to fade from green to yellow or tan.

These structures are called setae, from the anthracnose pathogen, which is a fungus.

The publication Chemical Control of Turfgrass Diseases has a very detailed section about anthracnose, outlining many agronomic practices to reduce turf stress and reduce the threat of disease. You can find those tips at this link:

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

The anthracnose section starts on page 8.

As you glance through, you may notice that many of the practices to reduce anthracnose are similar to practices to reduce overall summertime stress in putting greens, such as providing enough but not too much water, raising mowing height (even a tiny bit can make a difference), skipping mowing and rolling instead, and maintaining adequate N. You can find the whole list starting on page 6 of Chemical Control of Turfgrass Diseases which, in short, includes information about mowing height, watering, fertility, foot traffic, dew, phytoxicity warnings, and more. We highlighted those a few weeks back in another post.

Hot + humid + rain = conditions for Pythium foliar blight

(Megan Kennelly, KSU Plant Pathology)

Here is a turf sample that came in this week. After one night in a moist chamber, there was an obvious cobwebby growth:

Notice how the turf looks matted down and greasy, too.

In the microscope here is what I saw – hyphae (fungal threads) with no crosswalls. This means Pythium foliar blight.

Pythium is not a true fungus, and many fungicides that work for other turf diseases do not work for Pythium blight. For a list of products that can handle Pythium, you can check out this resource (scroll to page 23-24):

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

In addition, don’t forget that foliar Pythium is different from root Pythium. With foliar Pythium, we see it most often in fairways, tees, and athletic fields. It is extremely rare in putting greens in Kansas. It is also rare in home lawns, but it can happen there from time to time.

Pythium loves water and lush turf. To reduce your risk, avoid over-watering and watering at night. Avoid excessive N. As a special bonus that will reduce the threat of brown patch too! Pythium can easily track with mowers and in with water-flow through drainage. Avoid mowing Pythium areas when it is wet, with mycelium, to avoid tracking it into other areas.

There are more tips here in Identification and Management of Turfgrass Diseases.

The cottony, cobwebby growth can be confused at times with brown patch. If you have any doubt, send some in to the lab.

Unlike Pythium, the brown patch fungus produces distinctive cross-walls in the hyphae:

And here is one more to show cross-walls vs none:

 

Here are some images of what Pythium foliar blight can look like in the field. You can see how it might be confused with other problems. When in doubt, send something in.

 

Tracking with a mower:

 

Not super distinctive…

…but upon closer inspection some mycelium was visible:

After a night in a moist chamber the mycelium was all over:

In the lab, that mycelium did not have cross walls.

 

Here’s one more shot of Pythium foliar blight in a low area on a bentgrass fairway:

 

Are you smarter than a slime mold?

 

(Megan Kennelly, KSU Plant Pathology)

Look what showed up in my mulch yesterday morning?

 

Hey, what’s that stuff? Slime molds! They can look pretty alarming, and they can pop up seemingly overnight. They are pretty harmless, and you can read more HERE and if you would like a fascinating glimpse into how these organisms work there is a short video clip HERE called “Are you smarter than a slime mold?”

Here is another version of slime mold – these photos were submitted to me this morning over email. Look closely and you’ll see little gray blobs up on stalks:

And, to round things out, here are a few from last year:

 

(Courtesy Ron Reese)

Courtesy Jacob Weber:

 

Courtesy Ron Reese: