ALL: What's the best month for a turfgrass field day in MO?

Doesn't matter

Update (07/28/2017)

Double, Double Toil & Trouble

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MU Turfgrass & Landscape Field Day - August 1

Field day is right around the corner on Tuesday, and preparations are in high gear… or low gear when working in last week’s heat.  The forecast looks about as good as possible for the first of August, with highs in the mid 80s, dry and low humidity. Even better this weekend looks to be a big break for cool season turfgrass, perhaps you’d also like to take a break with us and learn about our cutting edge research. With our fraze mowing research I highlighted in the last update, this is indeed an intended pun.

Registration is open at for both attendees and vendors. We hope you can make it out to enjoy the fine weather for the August premier, as we’ve got a ton to share. Nematodes, soil sampling, fungicide resistance, weed control, hydrophobicity, and various others. If you or a friend want to learn about going native, (no pun intended), we even have a concurrent workshop geared solely towards that subject (click here for more information). Make your friend drive…

For more information, feel free to contact me at or Kevin Dern at Look forward to seeing you there.

If you don’t like the heat…

  1. Stay out of last week’s kitchen, - Source: Pat Guinan
  2. And wait for next week, which looks blue and beautiful. - Source: NOAA


Wow, what just happened. Summer went from a modest mouse to a roaring opera singer last week, hitting a crescendo of 100+ degree heat and humidity that sent “feel like” temperatures near 114-118 F. Nighttime temperatures also were astonishingly high.  At 10:30 pm on Saturday night readings in Columbia were still 87/feel like of 100 F. The last time heat occurred like this in Missouri was 2012 during the same July 16 – 22 period. Mark your calendars, that is evidently the top of summer’s bell curve.

Rain also was fairly hard to come by in July until Saturday, and more disastrously yesterday, when heavy downpours (some 7 inches) ravaged the Kansas City area and caused serious flooding. For those affected, hopefully the damage is not long lasting, and your minds can return back to turfgrass soon. In St. Louis, the rains have been brief, and deficits are nearing 2 inches for the month of July.

Heavy rains West, Dry in the East

  1. Heavy downpours in the Kansas City area yesterday. - Source: NOAA
  2. Not much rain coming next week if forecasts hold true. - Source: NOAA CPS

Quick Hits

Bouncing Basidios
Fairy ring and brown patch are coming on strong in mid summer.

  • Basidios Bubbling  – The high temperatures and sporadic rain over the last 10 days has both fairy ring and brown patch humming on tall fescue lawns and creeping bentgrass putting greens. Both of these pathogens belong to the basidiomycete group of fungi, which is most famous for producing the mushrooms on your pizza (hopefully this isn’t the only type that’s found its way on your plate). In the case of both of these diseases, once they really start firing, they are difficult to curtail. For brown patch, particularly on tall fescue, azoxystrobin has consistently worked the best in a curative situation in our trials. Fairy ring, a soilborne pathogen, is more difficult to control curatively and requires a watered in fungicide + wetting agent combination after symptoms appear in the summer. The SDHI fungicides such as flutolanil, fluxapyroxad and penthiopyrad have worked well in our trials curatively on greens. This being said, once you get these issues in summer on weakened cool season turf, it will take a while for recovery.

The Lawn of Leopards
Got a guess? See below for explanation.

  • Chill out on cool season lawns. They’ve been going through a time, and need their expectations lowered a little. Homeowners, particularly in STL, have been lighting up the help line in the last two weeks wanting to know what magical concoction they can spray to fend off brown patch, Pythium and every other disease they can point at. While these diseases are active, for the most part the brown that is most oft seen is simply caused by heat stress and drought dormancy. Rather than spray a fungicide at this point in the season, consider buying seed that can be sown in more suitable September weather. Remember, tall fescue is tough. The species can take a droughty beat down like in 2012 and come back in fairly good form if allowed to go brown. Don’t mow if it isn’t growing. When you need to mow make sure the height is at least 3.5-4”. Don't try to control weeds now, wait until the lawn's growth comes back into form with cooler weather.

    As for the picture above, this odd pattern is due to ground cracking and compaction, and the preferential flow of water (and roots) into those cracks preventing drought dormancy in scalloped lines. Probably a good sign that an aerifier should be run across the area in fall.   
  • Anthracnose, anthracnose, anthracnose. Epidemic year for this disease (see last four updates). Four more samples in the last two weeks from susceptible bentgrass putting greens (‘Pennlinks’, 2 x ‘Dominant’, and ‘Penncross’) from all over the state. Do not rely on QoI fungicides (i.e. Heritage, Insignia, Fame, etc) or benzimidazoles (i.e. thiophanate methyl) for control as resistance can, and may be developing in these pathogen populations. New SDHI fungicides such as penthiopyrad, and rotating in older DMI fungicides sparingly or the newer less growth regulating DMI difenconazole is advised.

Fire Burn & Cauldron Bubble

Cause & Effect

  1. Cake layers in putting green soil profiles leave water in the pot,
  2. causing wet wilt and bentgrass left to boil like vegetable soup.

No quote other than Shakespeare’s opening witch chorus from Macbeth could describe the weather of the last 7-10 days, and the impact it had on bentgrass putting greens. These impacts were most severely felt on greens that hadn’t been vented regularly and those with soil profiles with too much organic matter and/or too much water. The soggy hot root syndrome (SHRS) was back and with a vengeance in the last two weeks. The weather was perfectly set for it too, as high temperatures “boiled” water from below and high humidity didn’t let it escape from above. Indeed much like a witches' brew.

Particularly for those in Kansas City and other areas affected by heavy rains, venting as aggressively as possible during the cool down will go a long way when August comes back into its normal form. On tucked greens, fans may be necessary to move stagnant, humid air, and as previous research by Han et al. from Auburn University showed, critically reduce soil temperatures. Sub air type units to pull or push air should be employed, and even back back blowers plugged into some drainage lines may help. Even if using a soil moisture meter to water to a certain VWC %, take a soil core or two a few times a week to determine if water is moving below the tine depth. Use your nose. Give those lower regions of the soil profile a smell. Assess if a sulfur odor producing black layer is forming at any depth in the rootzone, indicating stagnant water – anaerobic conditions – toxic gas accumulation.   

For a flash back on this same theme, I wrote similar articles during this same time last year – (June 28, 2016 Disease Update) and one a little later (September 8, 2016 Disease Update).

Hope to see you Tuesday,


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