Kansas State University


K-State Turf and Landscape Blog

Month: July 2015

Got perennial ryegrass? It’s the time of year to think about gray leaf spot

(Megan Kennelly, KSU Plant Pathology)

Gray leaf spot is a serious disease of perennial ryegrass that can quickly blight large areas of turf. The disease is caused by the fungus Pyricularia grisea. In Kansas, turfgrass managers with perennial ryegrass often spray fungicides preventatively right around now, in early to mid August, sometimes with a follow-up application (or 2) to provide protection through September, depending on weather. This year, I’ve heard some reports that people have seen activity earlier than usual, which is definitely possible with all the rain.

This disease can be so bad that a lot of golf courses have switched to other turfgrass species (zoysia, bluegrass, bent – though bent has some nasties, too) so that they don’t have to worry about it in their fairways.

Here is a fairway that went from healthy to severely damaged in a short time, a couple of years ago. They switched to Kentucky bluegrass.


The fungus sporulates profusely and can spread fast when weather is conducive to disease (82-90 degrees with humidity and leaf wetness). Here are some of the spores in the microscope from a sample I got a couple of years ago:

gray leaf spot wamego 2007

Early symptoms look like this – small leaf spots the color of a Hershey bar:


(Photo courtesy Ned Tisserat, Colorado State University, Bugwood.org)

The spots grow and develop a gray center.

If you are managing rye, you are probably already thinking about gray leaf spot, and maybe you’ve just done your first app or have it on the docket soon. For some more details on management and fungicides, check out the gray leaf spot section (starts on p. 13) in this publication:


There are more photos and details on the disease at this website as well, from an excellent publication by Barb Corwin and my predecessor Ned Tisserat:


Now – I gotta get back into the lab. I’ve got some more sick turf, a dying chrysanthemum, and a really nasty potato (mushy and stinky – eewww) to deal with by the end of the day.

Good Water Management will Help Get Greens Through Midsummer Stress

by Jack Fry, KSU

It’s like watching a toddler play with an open staircase nearby. You’re in a good mood and things are going reasonably well, but if you turn your head away for an instant, disaster could strike. It’s no different than managing water on putting greens during midsummer. Minor flaws in greens construction or management may go unnoticed until now; when temperatures are 85 degrees or lower, bentgrass is able to tolerate it. But, an extended stretch of 100+ degree days highs, along with high night temperatures, can bring out the weaknesses in construction or the superintendent’s management program. A rootzone that remains wetter longer can exacerbate problems. Maybe you’re dealing with push-up greens that have been topdressed for years with sand; better than nothing, but not as good as a well-constructed, well-drained profile. Maybe your greens were constructed to “almost” – USGA specifications. For example, maybe sand particle size wasn’t evaluated by a testing lab, pea gravel doesn’t meet specifications, or the rootzone is 8 inches deep on some parts of the green and 15 inches deep in others. Perhaps your topdressing sand particle size distribution, or frequency of application, are different from the previous superintendent. All of these factors can contribute to the rootzone holding too much water, or not enough.

A rootzone that stays wet too long will have limited oxygen, and also be hotter than one that drains well (water helps retain heat); neither situation bodes well for bentgrass roots. Optimum bentgrass root growth occurs at 50 to 65 F. The top two inches of most putting surfaces in full sun during mid-day during July in Kansas will be 90 degrees or higher. Up until now, we have had excessive rainfall, and roots of bentgrass and annual bluegrass on many greens are no deeper than a couple of inches, particularly if the rootzone retains more water than desired. Furthermore, the roots that are there may not be functioning at an optimum level with the ongoing heat. The plant’s water-absorbing capability has been severely limited (it’s like being really thirsty with a cold glass of ice water in front you, but you’re not able to swallow). The “deep and less frequent” strategy for irrigation is not going to be effective when roots are shallow or not effective at taking up water. Instead, match frequency of irrigation to rooting depth, which could mean irrigating at least once a day.

Frequent scouting of greens will help identify areas that are experiencing stress first – the purple/blue color is a good indicator. Lightly watering these areas by hand will help make up for deficiencies in water distribution by the irrigation system and differences in the rate the turf uses water across the surface of the green. Pay particular attention to sloped areas that dry out faster. Hydrophobic localized dry spots will continue to exhibit stress symptoms unless a wetting agent is used in combination with probing the areas to encourage water penetration. The ability to hand water correctly is not something we’re born with – train your best people how to effectively scout and to apply the right amount in the right places. Hand-held soil moisture meters are becoming commonplace for determining volumetric water content of greens (Fig. 1). If you don’t have one, put it on your wish list. By using the probe, you or your employees will be able to identify areas of the greens that are drying faster and need water, or those that are moist enough that watering should be avoided.



Fig. 1. Soil moisture meter for measuring uniformity of rootzone water content across the putting green.


Syringing, supplying a light mist on the surface of the leaves, can be used to help cool the leaf’s surface. However, it’s most effective when the humidity is lower and/or if there is air movement to help the water evaporate. Thin out or remove trees, or install fans, before relying on syringing to get creeping bentgrass through periods of heat stress.

Managing water on greens in midsummer is tricky business. Pay attention, put up a gate, do whatever it takes to keep the toddler away from the staircase.

More info on physiological decline and diseases

(By Jared Hoyle; KSU Turfgrass Research and Extension)

One of my good friends on the other side of the river at the University of Missouri, Dr. Lee Miller, has posted some great information about physiological decline and updates on diseases that he has been seeing.

For more information on physiological decline/ wet wilt of bentgrass greens check this out – “Summer Rises” – (It’s at the bottom of the article)


For more information on diseases and more specifically brown patch control see Dr. Miller’s most recent post – “Rhizoc, Rinse, Repeat” –




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

019 020 hydrophobic-droplet-test thatch_layers

(Megan Kennelly, KSU Plant Pathology)

Losing turf and having a hard time getting it back? You aren’t alone.

It’s that time of year when turf can quickly fall into a tailspin, especially putting green turf. In the past 1-2 weeks, the number of emails, phone calls, and samples has really spiked. Jack Fry has provided a great article with tips about watering bentgrass elsewhere on the blog this week (see http://blogs.k-state.edu/turf/good-water-man…dsummer-stress/) and we  have also linked to some excellent info from Dr. Miller in Missouri (https://blogs.k-state.edu/turf/more-info-on-physiological-decline-and-diseases/). Here, I will talk about a few other topics related to summer stress in turf.  The next stretch of days are looking better with cooler highs as well as some nighttime lows in the 60’s, but the summer heat will probably be back before it’s gone for good.

Take a look at your rootzone.

If you are seeing turf decline above ground, take a peek above ground. I’ve seen a number of samples lately where the rootzone shows some clear underlying problems of organic matter buildup, thatch, or localized dry spot. I posted some example photos up above, at the top of this post. Your situation might not be as severe as those, but consider whether rootzone management could be the culprit behind the decline.

Summer heat is NOT the time to get aggressive with aerification, but put it on the agenda as a priority for fall.   Throughout the fall and next spring keep on with the best agronomic practices you can manage. Build up those roots when the turf is growing its best, during fall and spring temps. Building up the turf is like putting money in the bank to rely on during the tough times (ie, July and August of 2016). In the meantime,with cooler spells (highs in the 80’s for a few days) you can consider some gentle aerification with solid tines but be careful! Try to do it during cooler parts of the day. Watch the turf and stop operation if the turf can’t take it and is getting torn up.  We may be a long way from weather that will allow long-term recovery.

Does your profile look like a layer cake? Put some aerification and topdressing on the agenda for fall.

layers and aeration hole


Look at the roots, since they’re supporting the shoots

In addition to problems in the soil profile itself, there have been multiple samples where the roots themselves are short, brown/mushy, and lacking root hairs. Sometimes there is a root pathogen thrown in there, sometimes there isn’t and it’s just physiological decline. Either way, the turf is suffering.  How deep are your roots? Are there lots of root hair that cling to the sand, or does the sand slide right off? Try washing the soil off of a plug or two. Healthy roots are a creamy white. Brown and mushy? That’s not good. Before you start treating what looks like an above-ground problem, take a peak under the ground.

Check your roots and plan ahead to build more for NEXT summer


Brown and mushy is not good



Hot underground = little growth to be found

When it’s 100 degrees outside in the air, we feel it. But, what the turf is really feeling is heat in the soil. When soil temps get into the upper 70’s and 80’s, root growth starts to shut down. When soil temps get into the 90’s, shoot growth stops too. What this means is that if you have any damage from disease/insects/stress, the turf will have a hard time growing out of it.

Use a soil thermometer to check your soil temps. It may not be pretty. The next week or so will give us a nice break, though.


Too much water can be worse than not enough.

If the soil is wet, it holds more heat so turf does not cool off well overnight, and this can really trigger a spiral of decline.  Check Jack’s article for some tips (http://blogs.k-state.edu/turf/good-water-man…dsummer-stress/)


“I sprayed a fungicide and it didn’t seem to work”

Okay – let’s talk about diseases for a minute. You might be seeing dollar spot, brown patch, anthracnose, or Pythium root rot. For this discussion, let’s assume that you diagnosed it correctly and applied a great chemical at optimal rates with impeccable coverage.

But – you still might not see improvement. In fact, the disease could still get a little worse at first. Keep in mind, diseases have a latent period, and there could be more “infected” tissue than “symptomatic” tissue. So, for a couple of days, you could still see some symptoms develop from tissue  that was actually colonized before you even knew it and got the product down.

Then, once that phase is done, even with the pathogen shut down and not infecting more tissue, you still have the problem that the turf isn’t growing well. That is, you might not have new green, good-looking turf for awhile even if the disease itself is under control. The aesthetics won’t improve until there is some new growth to fill in the damaged areas. Hopefully we will get some recovery in the next few days, with the milder temps.

As a final point on fungicides (and any product), be very careful to heed any warnings about use in hot weather. Test any new tank-mix concoctions on a small scale first to avoid unfortunate surprises. There are some excellent details about specific products in this publication: http://www2.ca.uky.edu/agc/pubs/ppa/ppa1/ppa1.pdf


Got Poa?

Annual bluegrass is pretty wimpy stuff. Here it is checking out in the heat:

poa dying

Poa triv is checking out, too. If you have problems with these pesky invaders try to reduce their populations for next year.  It’s easy to forget about them a little bit when everything is green and happy, but there’s no ignoring them now.

Do you become a little more devout in August?

Over the years, I’ve heard several superintendents say variations of, “God grows the turf from Labor Day through Memorial Day. Then, it’s our job June, and July… and August? That’s when we start to pray.”

The next week or so is looking better, and maybe we will be lucky and August will be mild. Let’s hope so.

2015 KSU Turfgrass Research Reports Now Online!

(By Jared Hoyle; KSU Turfgrass Research and Extension)

Every year all the KSU Turfgrass Faculty, Staff, and Students prepare research reports for all the turfgrass managers out there.  The 2015 Edition is now ONLINE!  There is information from new zoysiagrass varieties, buffalograss establishment, moss control to watering practices.

Check it out here!



Paint and Glyphosate Research Update Published in GCM

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

In July’s issue of Golf Course Management Magazine on page 95,  Jake Reeves’s (KSU Turfgrass Research Technician /Graduate Assistant) and Jared Hoyle’s research was featured in the Cutting Edge section by Teresa Carson.

Take a look on page 95 and read more about “Timing effects of turf paint + glyphosate applicant on grassy weed control”


2014-2015 Research Plots at Stagg Hill Golf Course in Manhattan, KS.
2014-2015 Research Plots at Stagg Hill Golf Course in Manhattan, KS.

We repeated the research in 2014-2013 and will have the final results out soon.  The results so far demonstrate that adding turfgrass paints to dormant zoyisagrass glyphosate applications can increase gassy weed control.


Whats new at #ksuturf farms in Manhattan and Olathe?

(By Jared Hoyle; KSU Turfgrass Research and Extension)

This summer has been a crazy one.  We have been getting ready for field day in Olathe on August 6th (Hope to see everyone out there! – Register here – http://www.eventbrite.com/e/kansas-turf-ornamentals-field-day-tickets-16109376579) but there are a lot of new projects that graduate students, faculty and staff are up to.  Here is just a list of what is going on and we will be talking more about it at field day and at Annual Turfgrass Conference in December!

We have a new GPS navigated robot mower being tested out at Rocky Ford in Manhattan.


Pre- and Post-emergent herbicide trials at Olathe and and Manhattan. (Photo form Olathe).


Influence of tall fescue mowing height on crabgrass populations demonstration at Olathe.


I have been traveling everywhere. (Had to throw that in there)


New zoysaigrass variety trials at Rocky Ford in Manhattan.


Ross Braun (KSU Turfgrass PhD Graduate Student) has been evaluating multiple turfgrass species, mowing height and traffic in drought conditions.


Evan Alderman (KSU Turfgrass MS Graduate Student) installed a new fairway (5/8″) of ‘Cody’ buffalograss at Rocky Ford.


There is a new ornamental herbicide testing facility installed at the forest research center in Manhattan to evaluate potential turfgrass herbicides to ornamental plants.


The use of adjuvants with Pylex  and triclopyr combination demonstration trial at Olathe. Brown patch control research trial was installed at Olathe this summer. New granular products for broadleaf weed control (Olathe – Photos not shown).

Dr. Bremer and Ross Braun (KSU Turfgrass PhD Graduate Student) has been studying greenhouse gas emissions under drought conditions at Rocky Ford.


More traveling…


Lastly, I would like to congratulate Dr. Zane Raudembush for completing his PhD this past spring.  Good luck in all your do Zane.


This is not all of what have been going on but just wanted to share some of the pictures of some of the new things that are going on here in the KSU Turfgrass Program.

Don’t forget to come out to field day August 6th and see some of the research that we have been conducting.  Thanks and have a great rest of the week!



Oops… I think I sprayed when there was a little too much wind…

(By Jared Hoyle; KSU Turfgrass Research and Extension)

I have been in Kansas for awhile now and it still amazes me how much the wind blows.  As a turfgrass manager that makes it hard to find times when it is ok to apply a herbicide.  Drift is a major concern for all agronomic crops including turfgrass.  The picture below is an application of glyphosate that drifted into an adjacent plot out at one of the KSU Turfgrass Research Farms.


So be careful of drift.  I know it is easier said than done but a couple of pointers to help reduce off target injury to plants are;

1.  Avoid making applicants when particles can be carried by air.

2. Do not spray near sensitive plants or other crops.

3. Do not spray in gusty winds.

4. Always make application with minimal air movement (<3 mph) to determine direction and distance of possible drift.

5. Know your surroundings.  Houses, buildings, trees, hills, etc can influence wind direction and gusts.

6. Use a boom height lowest as possible that will still give uniform coverage.

7. Be aware of nozzle size and spray pressure.  Too much pressure will make smaller spray particles that can drift further.

8. Last but not least  – BE SMART and always follow the herbicide label.



Recent turf problems – a few photos

(Megan Kennelly, KSU Plant Pathology)

It’s mid-July, and much of Kansas continues to be pretty wet. Here are some recent turf issues I’ve been seeing and hearing about. I won’t go into details – this is just a photo collection for now.

(1)Brown patch in tall fescue lawns.

When you get all sweaty just from dragging the trash can down the driveway out to the curb on trash day, you know it’s brown patch season. Here are some symptoms in my neighborhood.

011 012 008

(2) Summer patch

023 020 022

Summer patch is a root disease of Kentucky bluegrass. Infection occurs in the spring, when soil temperatures hit 65. Symptoms pop out in mid-summer, when those poor plants with their compromised root systems just can’t take it anymore.

(3) Dollar spot

Sometimes dollar spot checks out during the summer, if conditions are hot and dry. We’ve had enough warm/wet weather to keep it rolling. Here are some photos in Kentucky bluegrass as well as in creeping bentgrass, especially in highly susceptible varieties.

dollar spot in low and hi cut029 028

(4) And, “it’s not a disease”

Turf sites with heavy clay soils, low areas with poor drainage, and shady sites = high stress. I received a sample the other day with some of the heaviest clay I’ve seen in awhile. It was so clay-ey that I took a moment to sculpt it into this little soil person:


If your soil is heavy enough to use in art projects, you may have a problem. As you look forward to fall, think about aerification, drainage improvements, reducing shade, and other practices to improve conditions in tough sites.