Poa annua Greens Declining?

Dr. Kevin W. Frank

Michigan State University

In the last couple days I’ve received reports from several golf course superintendents indicating that Poa annua on putting greens that emerged from winter looking good was now declining.  It is possible that this is winterkill to the lower region of the crown that is responsible for root initiation.  For those of you that have Dr. Beard’s seminal textbook, Turfgrass: Science and Culture, on the shelf turn to page 235.  In the text Dr. Beard writes about differential low temperature tolerance between the upper portion of the Poa annua crown, responsible for new leaf initiation, and the lower portion of the crown, responsible for root initiation.  The upper portion of the crown has higher low temperature hardiness, i.e. can survive at lower temperatures. 

Green emerging from winter looking fine (March 16, 2015).

Poa annua on same green now showing stress (April 6, 2015).

Back in 2003, Dr. Beard taught the turfgrass physiology class at MSU and I was fortunate to attend many of his lectures.  I recall Dr. Beard describing a scenario in Detroit one spring when Poa annua emerged from winter looking just fine and in the matter of a couple days when the temperatures warmed everything died.  He indicated that this was the result of the lower crown suffering winterkill and although many thought the Poa was just dying over the weekend, it was in fact already dead.  Without the ability to grow roots the Poa annua didn’t survive long once the plant started ‘demanding’ water.  Take a look at the crown, if it's white and firm all is well, if it's brown and mush it's dead.  

I’m not certain that this is what happened this year or if it’s typical freezing injury that’s the result of cold night temperatures.  Freezing injury is typical this time of year and is especially evident on lawn height Kentucky bluegrass where the symptoms are tanning of the leaf blade down from the tip.  Warm temperatures and rainfall in the forecast should reveal whether or not what is being reported is indeed winterkill or hopefully, something less significant. 

Leaf tip freeze injury.

Winterkill Update Spring 2015

Dr. Kevin W. Frank and Dr. Joe Vargas, Jr.
Michigan State University

The winter of 2013-2014 produced devastating levels of winterkill, especially in the Detroit area.  As a result of the damage experienced to Poa annua putting greens last year golf course superintendents devised plans for this winter to reduce the potential for winterkill including using different cover systems and in some instances actively removing snow events to prevent any possibility of ice forming on putting greens.  Despite all of these efforts it appears that once again this spring Poa annua putting greens have been damaged.  Although the damage I’ve observed this year doesn’t appear at this time to be as severe as in 2014, the geographic extent of the damage in Michigan appears larger.  Initial observations and reports from the field indicate damage extending from at least the Grand Rapids region through greater Detroit.  Damage once again may be attributed to ice sheets on putting greens.  Many golf courses report ice sheets that formed around January 1 and in some cases didn’t melt off until early March, approximately 60 days of ice cover.  The day estimates for Poa annua survival under ice range from 45 to 90 days and for creeping bentgrass from 90 to 120 days.  For the Poa annua greens the ice cover from this winter was definitely in the range when damage can occur.  There also may be damage due to low temperature kill and/or desiccation for greens that were exposed throughout winter.  Crown hydration freeze injury also appears to be evident on some greens especially in poorly draining areas, although this injury could also be from thicker ice sheets that formed early in winter in these depressions.  

Possible winterkill following surface drainage pattern.

Poa annua loses its cold temperature hardy proteins and begins to take up water quickly as temperatures warm in the spring.  As snow melts and water collects in low lying or poorly draining areas if the temperature drops below freezing and ice forms it can crush the swollen crowns of Poa annua plants killing them.  To date, determining the extent of damage has been difficult as temperatures have been very cold and very little turf growth has occurred.  Since the snow melted it has been a very dry spring, to facilitate recovery it would be a good idea to charge up the irrigation system so when the warmer weather arrives plants emerging from dormancy will have access to water.  If the weather forecast is correct, and warmer temperatures arrive next week assessing the extent of damage will be easier. 

Steve Glossinger Receives Honorary Certificate

Steven Glossinger, CGCS, was the recipient of the Michigan State University Institute of Agriculture Technology's honorary certificate at the IAT graduation ceremony on March 22, 2015.  Mr. Glossinger began his Superintendent career in Michigan at Signal Point Club in Niles in 1977.  He was also Superintendent at Battle Creek CC, Point O'Woods G & CC, and Oakland Hills CC in Michigan.  He has been the superintendent at Caves Valley Golf Club in Owings Mills, MD since 1997.  He has provided guidance to MSU interns annually since 1988, many of whom are now at prominent clubs across the country.  He devotion to the turf program in terms of time and effort to train these young men and women cannot be overstated.  Congratulations Steve!

Steve Glossinger

'Flagstick' Dollar Spot Resistant Creeping Bentgrass

Dr. J. M. Vargas Jr., Ron Detweiler, and Nancy Dykema

Michigan State University

About 20 years ago, my laboratory personnel discovered some creeping bentgrass plants at the Hancock Turfgrass Research Center that appeared to be resistant to dollar spot, caused by Sclerotinia homoeocarpa. Thanks to funding from The Michigan Turfgrass Foundation and Project GREEEN, we were able to do some breeding with the dollar spot resistant plants. Small plots were established with these resistant lines and, throughout the years, they have remained resistant to dollar spot. Around 12 years ago we partnered with Seed Research of Oregon, a subsidiary of Pickseed USA. They continued the process of developing a dollar spot resistant creeping bentgrass cultivar. The cultivar, coded as SRP-1WM, was entered into the National Turfgrass Evaluation Program (NTEP) trials and tested at many universities through the United States where it remained resistant to dollar spot. The cultivar, now called Flagstick, is now available in limited supplies for 2015. There will be more available for the 2016 season. The importance of the first truly dollar spot resistant commercial turfgrass is enormous.  Most of the fungicide applications throughout the season in the Northeast and Midwest are for control of dollar spot.  Last year in Michigan, if it was not for dollar spot, very few fungicide applications would have been applied to golf courses. Having a dollar spot resistant cultivar on golf course greens, tees and especially fairways, which encompass acres of turf, will result in financial savings to golf courses as well as reduced environmental impact from fewer fungicide applications.

Creeping bentgrass cultivars in a fairway trial at MSU.