LAWN CARE: Do you spoonfeed nitrogen fertilizer to cool-season turfgrass lawns during the summer?

No-single slow release spring app
0.5 lb N/M total
0.5-1.0 lb N/M total
1-1.5 lb N/M total

Update (08/27/2014)

School's In, Summer Not Over

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Lawn Care Workshop Series:
Springfield and Blue Springs, MO

Dr. Brad Fresenburg and I, along with the extension specialist teams in Springfield (Patrick Byers & Jill Scheidt) and Blue Springs, MO (Lala Kumar) will be conducting workshops next week targeted to home lawn care.  We will cover the fundamental and not-so fundamental principles of managing lawns related to soil management, fertility, irrigation, etc, and include some hands-on demonstration.  This is a great opportunity to pick up some new information, train employees within your lawn care operation, or have a homeowner/client sit in with you to reinforce maintenance concepts.  Our team conducted this workshop in St. Louis with great participation last December, and with continued success aim to make this a sustained series for both the landscape industry and the general public

The workshop in Springfield will begin at 8 am next Tuesday, September 2nd.  More details and registration information can be found here:
Springfield Lawn Care Professional Workshop.

The workshop in Kansas City (Blue Springs, MO) will begin at 8 am next Thursday, September 4th.  More details and registration information can be found here:
Kansas City Lawn Care Professional Workshop.


Weather has been and will continue to be hot over the first few days of September.

The SEC football season officially begins tomorrow, and Mother Nature looks to add sweat to the blood and tears underneath the shoulder pads.  We have endured our hottest stretch of the summer with 5 – 11 degrees above normal temperatures over the span of the last 6 days.  Most areas have also received very little rain during the period, which is pushing some non-irrigated turfgrasses towards drought dormancy.      

The good news is the current stressful environmental conditions for cool-season turfgrasses have occurred at the back end of summer, so are unlikely to continue over a sustained month or two month long period.  For warm-season zoysia and bermudagrass, which have gone through a miserable summer growth-wise, these temperatures will allow a last chance to fill in from last year’s brutal winter and prepare for the next.  The forecast has much of the same for the first few days of September, with highs in the low 90s and lows in the high 60s, low 70s.  It does look like we will have a more concerted rain chance over the next 6-14 days, however, which will be welcome.

Wonder where I get my weather information? It varies somewhat, but my first choice is my neighbor, state climatologist Dr. Pat Guina,n and my 2nd is the NOAA.  Check out these webpages for great past and future weather forecast information – National Weather Service Climate Prediction Center and NOAA Climatological Data - Missouri

Quick Hits

Cutworm outbreak at the MU Turf Research Farm.
  • Although entomology isn’t my department, I’d be remiss not to mention the large cutworm outbreak observed on our disease research green on the farm last Wednesday.  Hundreds of the little devils appeared overnight, and caused some considerable damage before we got to them that day with a high rate (4 oz/A) application of Acelepryn.  The interval was definitely up for our previous application of Meridian (17 oz/A) and Scimitar (10 fl oz/A), and the cutworms took advantage.
Yellow tuft on MU Turf Research Farm
  • Yellow Tuft on Creeping Bentgrass Putting Green:  The first incidence of yellow tuft we’ve observed at the MU turf farm was noticed last Monday, the 18th.  This disease, which can be confused with bacterial decline, yellow spot caused by cyanobacteria, or nutrient deficiency, is caused by the obligate parasite Sclerophthora macrospora.  *Note: Obligate parasite means the pathogen must live and grow within its host, and unlike many other turfgrass pathogens is not a saprophyte in soil or thatch.*  This pathogen genus also causes many other important downy mildew diseases on other grasses and crops, and is closely related to Pythium spp.  With that in mind, it’s no surprise this disease was found on our recently established ‘Penn A1’ green in the lowest green edge where water flows and collects.  Yellow tuft is also more prevalent during cool, wet periods, which is would’ve included much of July and early August. With the advent of hot weather, the disease has diminished, but should be back this fall when temperatures cool off again.  Yellow tuft can be used as an indicator of inadequate drainage, which may require attention.  If a perennial problem, curative fungicides provide little benefit, and a preventive program with mefenoxam/metalaxyl may be required to control the disease.
Leaf spot/melting out on Kentucky bluegrass
  • Late Leaf Spot/Melting Out on Kentucky Bluegrass – We recently seeded the new ‘Barvette HGT’ Kentucky bluegrass at the turf research farm and have been very impressed with its performance.  Just today, however, we noted a significant outbreak of leaf spot caused by Drechslera spp. that is a result of a combination of the recent heat wave, high humidity and heavy dews on this young turfgrass stand.  Also, according to recent NTEP data, ‘Barvette HGT’ does not have good leaf spot resistance compared to other cultivars.  In comparison, however, the cultivar has very good resistance to summer patch, which is a soilborne disease and much more difficult to control.  Cultural controls include limiting nitrogen fertilizer during conducive environmental conditions (like for brown patch and Pythium blight) , and watering early in the morning to rinse dew and break the period of leaf wetness.  Fungicides in several different chemistry classes control the disease.   

Pythium Foliar Blight on Tall Fescue

Pythium blight on tall fescue observed on tall fescue in morning shade.

The first report of Pythium blight on tall fescue this summer occurred yesterday in mid Missouri.  Symptoms were observed on green surrounds that experience considerable morning shade, and therefore longer periods of leaf wetness.  Pythium blight is known by a couple other common names, including grease spot, which characterized these symptoms perfectly.  Water-soaked lesions were apparent on these samples, and it was easily apparent how the spores and disease symptoms moved along with the mowing pattern.  In the pictures above, you can observe the difference in leaf symptoms between Pythium blight and brown patch on tall fescue. 

This outbreak and the forecasted warm temperatures indicate fall nitrogen fertilization of cool-season higher cut turfgrasses should be delayed further into September to avoid these conducive disease conditions.  Also keep in mind Kentucky bluegrass is more susceptible to this disease (so scout these areas, particularly on sports fields, heavily) and different “Pythium-specific” fungicide chemistries are required for control.  To read Dr. Peter Dernoeden’s recent post on the subject, click here.   

If you’re interested in lawncare in the Springfield or KC area, hope to see you next week & we can discuss these lawn diseases in more detail.      

Have a good rest of the week, and GO TIGERS! 


Lee Miller
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Extension Turfgrass Pathologist
University of Missouri