SURVEY QUESTION

ALL: Have you observed decline in zoysia this summer?

Yes - Golf
Yes - Lawn
No

Update (06/30/2017)

Et tu, Zoysia?

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MU Turfgrass & Landscape Field Day - August 1

Registration is open and the schedule is set for the 2017 Mizzou Turfgrass & Landscape Field Day!  Come on out August 1 to our research facility at South Farms, and we’ll give you the latest on our ongoing research and regional topics of interest. New developments in weed control, disease and nematode control, fraze mowing, invasive pests and others will be discussed.

Registration for both attendees and exhibitors can be found at the site - http://www.mufieldday.org. For more information, feel free to contact me at turfpath@missouri.edu or Kevin Dern at mufieldday@gmail.com. Look forward to seeing you there.

As an addition this year, a parallel workshop will occur for horticulturists and others interested in native plantings. This track, put on by the GrowNative! Association, will take place concurrently with the normal field day in the morning and will have an extra afternoon session for those interested. To learn more, click here.   

Mild End to June

  1. Wonderfully low nighttime temperatures over the past 7 days. - Source: Pat Guinan
  2. A large storm walloped the western part of the state in the last 24 h. - Source: NOAA

Weather

June will end with near or just slightly above average temperatures, but for most that will be just fine. Extremely mild nighttime temperatures graced the region over the last week, giving cool season turfgrass and its managers a break from the earlier June onslaught of heat stress and summer disease pressure. Rainfall totals for June, prior to this month ending storm, were below normal. This will not remain the case for the western part of the state, as the KC metro area received 3-4” of rainfall in localized spots over the last 24 to 48 hours.  The St. Louis area received an inch or slightly more this morning, and will end up just about normal.  
 
The 6-10 and 8-14 day forecasts indicate the return of high temperatures in early through mid-July. With the current rainfall, and further predicted rainfall during this period, fueling the fire, expect the rapid return of summer disease pressure.

6 - 10 d outlook: Early July Heat

  1. Heat expected to return in July - Source: NOAA CPS
  2. Rain chances for the region are above normal. - Source: NOAA CPS

Quick Hits

  • Brown Patch on Tall Fescue – We are just starting to see the signs of tall fescue stress beginning in mid-Missouri, and had a tall fescue sample submitted from St. Louis this week with considerable symptoms. Scout for this disease heavily in the next few weeks, as the conditions will be ripe for substantial outbreaks. In high amenity tall fescue areas, a preventive application of a strobilurin (i.e. Heritage) has worked well in our trials. If a granular application is more feasible and desired, Heritage G has worked well on a curative basis in our trials.  See this previous update for more information.

  • Pythium root rot on creeping bentgrass putting greens – Heavy rain over the previous two days, and summer heat set to return, has Pythium root rot again on the mind as a serious concern. Make sure your greens drain well and dry out after all this rain, or your roots will be much more susceptible to the pinch of this Pythium pain. Punch holes and vent to let oxygen in and get water out, but a fungicide such as Segway or Signature may be necessary to lessen any doubt.   

Healthy vs. Declining Roots

  1. Healthy root with copious root hairs and clear vascular cylinder.
  2. Declining roots with sloughed off cortex and exposed vascular cylinder.

  • Bentgrass Root Decline – Late June was awful kind to the region with several nights with lows in the middle and high 50s. The calendar is turning to July, however, meaning abiotic stresses on bentgrass are set to go into high throttle. Soggy hot root syndrome is most often observed on samples submitted to the lab, and this current weather pattern, together with the forecasted heat, should put the pressure on again. The above micrograph demonstrates the difference between a healthy root and a soggy hot declining root. While wind and high temperatures may cause wilt due to dry soils, erring on that side is often better than watering too much. It’s always easier to put water in than take it out.

Et tu, Zoysia?

Zoysia Struggles

  1. Some zoysia areas simply didn’t wake up from their winter slumber.
  2. Pathogens such as Gaeummanomyces spp. may be taking advantage of weak zoysia.

 

What’s good for the goose is not always good for the gander. While bentgrass, fescue and bluegrass enjoyed the cool end to June, warm season turfgrasses did not get exactly the growing start they are used to. Numerous reports, and a few samples, have been received in the last few weeks of underperforming zoysia on both home lawns and golf course fairways in St. Louis and Kansas City. In many of these instances, the zoysia reportedly did not come out of dormancy at all, indicating a winterkill event may have occurred.

While low temperature injury may have been the prime factor in these cases, several biotic issues can also impact zoysia health. At this time of year, chinch bug and billbug feeding can cause decline. Billbug larvae are active now, so dig in poorly performing zoysia areas to investigate for billbug larvae or put a few pitfall (buried cup) traps to monitor for billbug adults. For monitoring chinch bug problems, either look for the critters along sidewalks and driveways or put a piece of declined turf in a plastic bag and leave it in the sun for a few minutes.

As shown above, Gaeummanomyces spp, the cause of take all patch or warm season turfgrass decline, was observed in spades on the leaf sheaths and roots of a submitted sample. The large patch pathogen, Rhizoctonia solani AG2-2 LP, also was observed working in cahoots to take advantage of these weakened plants that were subjected to a wild spring. Interestingly, none of the samples submitted or reported with decline had a spring fungicide application, indicating both the importance of this timing and the likely role these pathogens play in inhibiting recovery from winter injury.

Feb - Mar Low Temperatures: 2014 - 2017
2017 had the most severe & precipitous drop in low temperatures.

 

As alluded to, this past spring was wild. February broke the record with temperatures 11-12 degrees above normal, and by the end of the month forsythia was blooming. Contrasting this to previous years, it’s easy to determine just how abnormal these temperatures were. The graph above compares the minimum temperatures for both February and March in the last four years.  The low temperatures on February 20, 21, and 28 and March 5 and 6 (indicated by red stars) were in the 50s and are obviously abnormally high. Fast forward just 10 days later to March 15th, or the Ides of March. Low temperatures plummeted more than 30 degrees to 11 – 14 F in some areas… temperatures which hadn’t been felt since early January 2017.  In theory, zoysia turned on the growth and wasn’t able to switch it back off before it got zapped. ‘Meyer’ zoysia is normally very cold tolerant, but is not a “miracle grass”, and particularly in wet areas or on slopes may have incurred winter injury. Some homeowners who thought zoysia doesn’t need fertilization and could indeed pull off the miracle of no maintenance in the transition zone, may be thinking “Et tu, zoysia?” after this spring.  

In areas that are struggling now, the best recourse is to rake lightly through the declined mat and permit heat and air to hopefully some working stolons and rhizomes. Fertilize and perhaps monitor for a little while longer. Don’t wait too much longer, however, before sprigging, plugging or resodding areas that aren’t coming back, since the summer heat will be necessary to allow for establishment before next winter.    

Lee

Lee Miller
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Extension Turfgrass Pathologist
University of Missouri