Warm Season Turf Managers: If growing zoysia or bermuda, do you perform a greenhouse test to assess metabolism or winter injury?

Once in a while
Depends on winter severity

Update (02/28/2018)

Delayed Start

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Not the Same Pattern as 2017

  1. February 2018 is not like last year, holding with average temps. - Source: Missouri Climate Center
  2. Mild, cool pattern is forecasted to stick around through early March. - Source: MCC


February 2018 was nothing like its 2017 predecessor as temperatures fluctuated wildly, yet stayed right about on average in MO. Recall last year at this time (see March 2017 report here), that February set a record for high temperatures and set the daffodils and forsythia blooming early. Compared to last year, this late winter feels like a delayed start, a term all too familiar with parents of school children in the last few weeks. The excellent growing degree day tracker maintained by Michigan State University ( echoes this striking difference with the “Flashback to 2017” feature.

The next two weeks are forecasted to remain cool, so necessary preventive applications are presumably still a few weeks away. Unlike last year, crabgrass preemergents (which may be necessary in the warmer east coast) can be delayed, particularly since in 50% of the years on record a killing frost (28 F) has occurred into early April for much of Missouri (MU Frost/Freeze Probabilities Guide).

The temperature swings are nothing compared to the drastic change in precipitation occurrence in the last 7 days. Missouri has been in a drought situation since September 2017, with very little occurring this past winter. In the past week, two to upwards of ten inches of rainfall occurred across Missouri, with most occurring south and east into Springfield, the southern portions of St. Louis, and particularly the Bootheel. According to preliminary data, these rainfall events may result in the wettest February on record (Pat Guinan, state climatologist). These events also caused widescale flooding east of us, particularly in the Ohio river in Louisville and Cincinnati. In Missouri and northern Arkansas, the rainfall was a needed drought buster, as the area was categorized in moderate, severe, or extreme drought conditions. Rainfall is expected to be at or above normal for the region into early March, so the drought end seems to be the silver lining in the clouds.

Unprecedented February Rains

  1. Impressive, drought busting rainfall totals over the last 7 days. - Source: Midwest Climate Center
  2. At or above average rainfall expected through early March. - Source: NOAA CPS

Purple or a Patch?

Just Purple or a Patch?

  1. Sloped or dry areas may have prolonged purpling prior to properly waking up.
  2. This patch is a little more defined, and could be Microdochium at work.

Bentgrass greens are starting to perk up, particularly in Springfield and southern areas of the region. As they do, some are noticing purple patches that may be Microdochium patch, or simply purple bentgrass. Purple bentgrass is often observed at this time of year as wild temperature swings (which have occurred) temporarily mute chlorophyll and expose anthocyanin pigment. Dry and windy weather (which has also occurred), the use of plant growth regulators, or excessive traffic or maintenance practices during cooler weather can exacerbate this purpling or reddening of the plant. Purple can also be a sign of phosphorous deficiency, which is normally associated with newly seeded greens. If the symptoms last, a soil test should be assessed and perhaps a shot of P may help with the purpling. Dr. Peter Dernoeden wrote a great reference article on this subject.

Microdochium patch is also a notorious purple, or more accurately brick red, patch maker.  This late winter shot of precipitation and cool days can spark this disease now, even through a preventive application made last fall. In the first picture above (A), symptoms appear to be more in line with purple bentgrass spurred by a drier sloped area. Picture B, however, could be Microdochium patch. One potential way to diagnose Microdochium patch is to incubate a plug inside the office in a Tupperware container with a wet paper towel. After 24-48 hours, fuzzy mycelium or pink sporodochia may be observed with a 10X hand lens on leaf blades. A better method would be to send in a sample for diagnosis. If Microdochium patch is the culprit, a fungicide application such as chlorothalonil + iprodione, Headway, or several others will be necessary to prevent further spread and damage. On this note, Dr. Alec Kowalewski at Oregon State University grows some fine Microdochium patch on his research plots, and posted a fascinating time lapse video of disease development on Twitter (@osubeaverturf).

Warming Up Some Grass Cookies

Warm Season Waking Slowly

  1. Zoysia emerging from dormancy more quickly than bermuda in the MU greenhouse.
  2. Bermuda varieties greening up differently in the Fresenburg lab. - B. Fresenburg

The droughty winter weather was worrisome for warm season turfgrass managers in Missouri, specifically the mornings with sub-zero wind chills and no snow cover. On February 15, we took a few samples into the warmer (mid 70s – low 80s) greenhouse from well-established zoysia plots and from some of our bermudagrass areas. The retired, but always engaged, Brad Fresenburg also did the same for bermudagrass from the MU research farm and MU athletic fields and put them under grow lights.

Not surprisingly, the ‘Meyer’ zoysia as shown in picture A came busting out of the gate first. In our greenhouse, ‘Riviera’ and ‘Yukon’ bermudagrass put on the first few green shoots, with one or two peaking out from ‘Ironheart’. In Dr. Fresenburg’s grow house, ‘Northbridge’ from the MU athletic fields came out first, followed by ‘Riviera’, ‘Yukon’ and ‘Ironheart’. In both our greenhouse and under Brad’s lights, ‘Patriot’ and ‘Latitude 36’ were lagging behind the others.

This is not a replicated study by any means, not standardized, and the age of these plants and the site they were taken from (edges of smaller plots vs. center of a bigger one) were considerably variable. Therefore, no definitive attributes of the particular cultivars should be made. This is an example of a methodology that perhaps should be applied more often in this upper transition zone prior to applying a preemergent or non-selective herbicide. In early spring, dinged bermudagrass is often reported due to a herbicide application made too late in the season while the turfgrass was active, or a long lasting herbicide was applied to warm season turf compromised by winter injury.

Based on these results, I do not expect wide scale winter injury to fairway height warm season turfgrass in the area due to dessication. Site conditions may vary from our single locale in Columbia, however, and younger stands that haven’t hardened off or those in more exposed environments (low, wet areas or northern facing slopes) could be more impacted.   


Lee Miller
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Extension Turfgrass Pathologist
University of Missouri