ALL: Will the cool weather in August cause you to manage cool season turf differently?

No - stay the course
Yes - fertilize earlier
Yes - aerify earlier
Yes - overseed earlier
Yes - fert/aerify/overseed earlier

Update (08/11/2017)

Dancing Faeries

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August? Shh.. don’t jinx it.

  1. The state is 5 -7 degrees below normal thus far in August - Source: Pat Guinan
  2. Mid August looks to return to normal, or highs in the mid to upper 80s - Source: NOAA


August in Missouri is currently 5 – 7 degrees below normal, and it’s well… just awesome. The first ten days of August have felt like fall, and cool season grasses are reaping the benefits of this early break from summer’s swelter. Daylength is also beginning its gradual slide from a height of 14 h 52 min on June 21 down to 13 h 48 min today. Think an hour’s not that big a deal? Ask bentgrass how much it enjoys the extra hour off per day from the beating down of the sun’s heavy glare. Not to mention in just a little over a week, they’ll also be a midday break. Mid to upper 80s return next week for highs, but at least it’s an hour less of those highs.

The consistency of reduced temperatures may be welcome, but the inconsistency of rainfall in the region is pronounced. Missouri has been a split of the have too much and the have too little over the last 30 days. To the east in STL, precipitation is an inch below normal already for August after being below normal in July as well. Non-irrigated tall fescue lawns are dormant in much of the east, and should be left that way until rains return. On the flip side, is the Kansas City area which got walloped with another 5” + rainfall event again last Saturday (see below).  Our rainfall chances do stick around through mid-August, so even though the temperatures are mild it’s not time to put away the scouting eyes or disease prevention quite yet. As you can see below, some soilborne diseases on putting greens are still working.

Heavy rains West, Dry in the East

  1. Heavy downpours hit the KC and west MO again last weekend. - Source: NOAA CPS
  2. Rain is forecasted frequently over the next 6 - 14 days. - Source: NOAA CPS

Quick Hits

Pythium Swimming in the Pool

  1. Thinned, declining areas in the waterlogged West could be PRR.
  2. Infected roots and crowns are clouded and appear necrotic.

Pythium Root Rot  – Not surprisingly, several bentgrass putting green samples from Kansas City and Springfield have come into the diagnostic lab in the past week with significant amounts of Pythium root rot. Two rain events ranging from 5-7” in a two week span will show how fast the greens are perking, and how much organic matter has built up to stop it. Poke holes and use penetrant type wetting agents to move the water through and out. A submerged Pythium pathogen is a dangerous one, since sporangia are “designed” to be created and produce motile zoospores quickly for dissemination. I often can see motile zoospores moving and encysting on roots when I flood a slide with water to mount the cover slip, which is exactly what is occurring when your root zone is saturated. In a curative situation, ethazole or etridiazole (Koban or Terrazole) is recommended for a quick knock down, followed up 3-5 days later with a Segway + QoI (i.e. Fame, Insignia, Heritage) application for more sustained preventive control. These applications should be watered in to get the fungicide into the soil profile and for Koban/Terrazole to avoid foliar phytotoxicity. At this time of the season, take stock of your root depth. As little as 0.1” may be necessary for short rootzones, whereas moderate depth rootzones may require 0.125”. 

  • Algae in Bentgrass Leaf Sheath
    A mat of algae is one thing, but climbing up into the leaf sheath? No thanks.

    • Algae: In several instances over the last two weeks, we’ve also noticed quite a bit of algae/cyanobacteria getting a little too frisky with bentgrass. These samples have been from both the KC/Springfield where rain is doing much of the work, and also in STL where constant irrigation has been needed. Algae is often observed this time of year as mat along the soil surface or interweaved among the stolons, but in these cases the algae is closely tied with the leaves, and within the base of the leaf sheath. Presence here can be a bit uncomfortable since we know some algae species can produce a phytotoxin and yield chlorotic symptoms like yellow spot. Particularly if you have been relying heavily on the QoI fungicides for control, consider rotating to a chlorothalonil (Daconil Ultrex, Zn or Action) tank mixed with mancozeb to knock the algae back.  I also noted this back in early June.   

    Take-all patch on a putting green

    1. Chlorotic scalloped areas of take all patch infection.
    2. Masses of ETRI hyphae and simple hyphopodia of the pathogen.

    • Take-all patch. Take all patch was also confirmed in a sample early this week. This pathogen is often observed in roots, and it takes quite a bit of it to lead to a diagnosis of it being the primary pathogen causing decline. In this case, the pathogen was also in the crown of the plant at the base of the leaf sheath, the ring symptoms, the propensity to hit bentgrass rather than Poa, all matched up. A watered in, high rate application of a QoI fungicide (i.e. Heritage, Insignia) or QoI + partner product (i.e. Briskway/Lexicon) is suggested for control since we are technically in summer. A small shot of ammonium sulfate may also be incorporated to spur recovery.

    • Gray Leaf Spot on Tall Fescue Warning: As pointed out by Dr. Jim Kerns on Twitter last week, we are in the time of year when brown patch can yield to the heavily sporulating, and more rapidly spreading gray leaf spot. Look for smaller spot symptoms and a characteristic buggy whipping of heavily infected leaves. I have seen the disease  on crabgrass (which unfortunately is just a cosmetic symptom), but not yet on tall fescue. See this previous post for more information.

    Fairy Rings not so Rosie

    Fairies Dancing on Greens

    1. Brilliant fairy ring symptoms on our research putting green.
    2. Important to remember that symptoms also result from change in soil properties.

    While Snopes indicates the “Ring Around the Rosie” nursery rhyme may not in fact refer to the black plague, when fairies start to dance to this tune on putting greens, ashes of bentgrass can definitely be involved. Within the last three – four weeks, reports of fairy ring outbreaks have been common in the region, even showing up on our research green (finally in a trial!). These outbreaks seem to correspond to our July heat wave and some of the following rains, which seem to have spurred the disease along   

    Several previous reports have focused on this disease, so this post won’t reinvent the wheel. For diagnosis, look for the obvious green ring symptom, but also do a bit of digging particularly along the margin of the ring. An intense outbreak will cause an orange discoloration of the thatch layer, and in this case you can use your nose to detect the musty tent-like or mushroom-like odor of the basidiomycete fungus. At this point of the season after symptoms develop, it’s important to realize that not only the pathogen needs to be suppressed but also the soil physical properties may need to be remediated. Simply masking rings with iron or nitrogen may be possible in light infestations, but fairy rings often cause decline in putting greens by forming a hydrophobic or water repellant soil layer. This situation needs to be attacked on two fronts, with a fungicide tank mixed with a wetting agent. The SDHI and QoI fungicide chemistries (i.e. ProStar, Velista, Lexicon) are effective in reducing symptoms, but curatively they must be watered in and tank mixed with a wetting agent to get to the target zone. How much to water in? At least 0.125” and preferably 0.25”. The question often arises as to which wetting agent to pick for this application, and I’m unaware of any research that specifically looks at differences among them for control.   

    Field Day Wrap-up

    Last but not least, thank you to all the speakers, vendors, sponsors, and especially the attendees who visited us last week for field day. The great participation, mild temperatures, and light breeze made for a great day. If you couldn’t attend, or forgot to take home a booklet, go to to get a taste of our current research activities.


    Lee Miller
    Follow on Twitter!  @muturfpath
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    Extension Turfgrass Pathologist
    University of Missouri