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K-State Turfgrass

Tag: thatch

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.

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:


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.



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

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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:


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.

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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.

Don’t let your turf get puft up

(Megan Kennelly, KSU Plant Pathology)



“Stay-Puft” marshmallows might be tasty, but  puffy, thatchy turf can lead to desiccation, scalping and other problems. Each year in the diagnostic lab I receive samples where thatch-related problems were mistaken for disease.

Fall aerification season is just around the corner for cool-season grasses, and thatch management should be on the agenda. Make sure you have a plan to deal with any problem spots. Also, don’t forget about the link between agronomic practices and thatch. For example, excess irrigation and fertilizer can exacerbate the buildup of thatch.


Need some info on thatch and related topics? Check out these links:

Fairways:   http://www.usga.org/news/2012/October/Thatch-Control-Key-To-Firm-Fairways/




Finally – hey, who is this Stay-Puft?

If you need an idea for Halloween (or a Halloween 5k race as shown here), just order up a clean tyvek suit, at least 3 sizes too big, add some cheap hand-made accessories, and get Puft!  (But don’t let your turf get Puft).


(Top Stay Puft image from http://www.comicvine.com/stay-puft-marshmallow-man/4005-54956/)