Creeping Bentgrass Establishment

Eric Chestnut, Thomas Green, and Dr. John N. Rogers, III

Michigan State University

Due to the recent harsh winter and new bentgrass varieties that have come into the market, a study currently underway at the Hancock Turfgrass Research Center at Michigan State University has become quite timely and relevant. Pure Distinction creeping bentgrass was seeded into a bare soil profile last August with the intent of using four factors (nitrogen fertilizer rate, mowing height, PGR use, and verticutting) to discover the fastest way to get a plot of turf capable of withstanding putting green traffic. Although the following observations are preliminary, we hope that those interested may find them useful.

Pure Distinction 5/5/14. 

As of May 29, 2014, only the nitrogen fertilization and mowing height regimens have been implemented  long enough to notice any treatment differences. The most striking contrast is between the fertilizer rates. Rates of 0.05, 0.10, and 0.15 lb N/1000 ft² are sprayed (initiated Sept. 2013) weekly. The photographs below reveal that the plots receiving 0.10 lb N/1000 ft² and 0.15 lb N/1000 ft² of fertilizer are much farther along than the plots receiving 0.05 lb N per week. The differences between the two higher rates are currently harder to differentiate, but the highest (0.15 lb N/1000 ft²) rate did seem to grow in significantly faster initially than either of the other two rates. The warm air and soil temperatures during the past couple of weeks have given most of the 0.10 lb N/1000 ft² plots a chance to catch up to the highest rate, but the lowest rate plots still have significantly less coverage than the others.

Pure Distinction 5/25/14. Darker green areas are 0.10 & 0.15 lb N/1000 ft² rates and thin areas are the 0.05 lb N/1000 ft² rate.

Mowing was initiated last fall and resumed this year on April 30, 2014 yielded minimal clippings until the second week in May due to cold soil and air temperatures. Half of the plots were originally being mowed at 0.200” and the other half at 0.150”, with each height being reduced by 0.05” each week until a height of 0.125” is reached. Mowing heights are currently at 0.190” and 0.140”. Plots being mowed at the lower height are growing in more densely than areas at the higher cut, even though they look similar from a standing distance due to longer, more lateral growing leaves on the higher cut turf (see Figures 4-7).

Mowing Height Differences. 5/29/14.  Plot on the right (above the 1) is mowed at 0.140” and the plot on the left (above the 2) is mowed at 0.190”. Both plots fertilized at 0.150 lb N/10000 ft². They look very similar from above, but upon closer inspection the lower mowing height (the plot on the right) has more leaf density than the higher height (plot on the left).

Mowing height 0.190”. 5/30/14. Notice there are quite a few areas where the leaves are sprawling outward instead of standing up.

          

Mowing height 0.140” 5/30/14. When compared to the higher mowing cuts the grass blades are more upright and less sprawling.

The verticutting regimen was initiated on May 28, 2014. At the time this post was written, the cutting was too new to see any differences between plots. The PGR applications will began  the week of June 1, 2014.

Multiple Factor Photo. 5/26/14. Plots below the number 2’s are mowed at 0.190” and plots below the number 1 (second from the right) are mowed at 0.140”. Fertilizer rates are as follows from left to right: 0.05 lb N/1000 ft², 0.05 lb N/1000 ft², 0.15 lb N/1000 ft², 0.10 lb N/1000 ft². 

Winterkill Recovery: Slow and Steady

Dr. Kevin W. Frank
Michigan State University

Unfortunately the recovery from winterkill seems to be following the common saying of slow and steady wins the race.  The recent temperature spike in the last several days has certainly helped the recovery but the forecast is a roller coaster with highs ranging from 50 to 70 and even whispers of a possible frost event before the end of the week.  Statewide temperature ranks provided from NOAA National Climatic Data Center indicate the period of February-April to be among the coldest on record for Michigan.  Temperature ranks for Michigan in April were classified as near normal but based on data from the last 120 years I would suggest it was closer to the below average rank.  In April Michigan’s temperature rank was 46, indicating that of the 120 years of data 45 years had cooler temperatures and 74 had warmer temperatures.  In a typical year where winterkill reestablishment wasn’t an issue these temperatures probably wouldn’t have been much of an issue but this year it was definitely not ideal for establishing turf on putting greens.   

NCDC Statewide Temperature Ranks Feb-April 2014.

NCDC Statewide Temperature Ranks April 2014.

Still Assessing Life and Death

In the April 17 blog post (http://msuturf.blogspot.com/2014/04/winterkill-and-recovery-update.html) the picture of ‘the different colors of winterkill’ was presented which was taken on April 7.  At that time I was attempting to assess survival of Poa annua displaying different colors. 

The different colors of winterkill, April 7, 2014.

The picture below was taken on May 13.  As the picture indicates the areas of Poa annua that I thought might survive did survive and have now filled in with living, breathing Poa annua.  Unfortunately the areas that I thought were dead still appear dead.  In some of these severely damaged areas of Poa annua we are observing some recovery but it’s doubtful that without seeding creeping bentgrass into these areas recovery will be sufficient. 

The different colors of winterkill, May 13, 2014.

Reestablishment and Opening Greens for Play

Temporary greens are still in play on many golf courses and as expected the pressure to play greens is only increasing. Many golf courses had planned or hoped to open severely damaged greens that had to be reseeded by June 1.  Although every course differs in how quickly they are recovering the June 1 date now appears somewhat unrealistic for the most severely damaged greens.  One of the most common questions is how soon can we play the greens?  My typical response is that when we establish greens (which is essentially what we’re doing) we don’t go from seed to play in 45 days, which is approximately what a June 1 target date would mean. 

 

Many severely damaged greens are still not ready for play.

My suggestion is to assess each green individually and open greens as soon as you determine they are ready for play.  Of course the logistics and pressure of making these decisions can be immense as golfers may ‘suggest’ that you open a series of consecutive greens to allow for consecutive playing of holes and/or facilitating posting 9 hole scores for handicap purposes.  The concern with trafficking newly seeded greens too soon is that the turf will lose density and the greens will essentially go backwards in terms of turf cover.  Ultimately this could lead to turf thinning and loss that by July and August may result in golfers playing on a mix of bare soil, algae, and moss.

Winterkill and Recovery Update

Dr. Kevin W. Frank, Dr. J.M. Vargas, Jr., and Dr. Trey Rogers
Michigan State University

In the last couple weeks the extent of winterkill to Poa annua putting greens throughout mid to southeast Michigan has become evident.  On many greens we have observed several different colors of turf as winter receded and spring slowly arrived.  Generally the Poa annua that retained green color did of course survive and in many locations is now actively growing.  Poa annua that was brownish in color has slowly started to recover and our hope is that most of these areas will fill back in as temperatures and soil temperatures continue to warm.  The Poa that was white or dark gray to black does unfortunately appear to be dead.  Scratching at the turf or taking samples from these areas you may find some and I emphasize some, turf that has survived but to get these areas back in play will require seeding and/or sodding, and limiting traffic.

The different colors of winterkill.

Temporary Greens

One of the most common questions we have answered recently is if temporary greens are necessary.  Damaged putting greens will recover faster if temporary greens are used.  Traffic on Poa annua that is trying to recover or on newly seeded creeping bentgrass will lengthen the time for reestablishment and may even kill the new seedlings.  It is difficult to set a date for when damaged greens can be opened for play as Mother Nature reminded us again with snow and low temps this week that she is still in control.

Winterkill to Tees, Fairways, and Rough

Generally the damage to tees and fairways was not as severe as the damage to putting greens.  However perennial ryegrass, which is often used on driving range tees in Michigan, also suffered winterkill.  The good news with perennial ryegrass is due to its rapid germination and emergence; time for reestablishment should be shorter.     

Perennial ryegrass fairway test plot at HTRC sustained significant damage.

The rough on many golf courses was also damaged from snow mold activity.  Whereas greens, tees, and fairways are typically sprayed with snow mold fungicides to protect the turf, the rough typically not sprayed.  The rough will generally recover from any snow mold damage and in most situations won’t require any reseeding but limiting cart traffic in these areas is advised to allow recovery. 

Rough damaged by snow mold will recover but restricting traffic will help.

Reestablishment

Efforts to reestablish and recover winterkilled turfgrass are already underway on golf courses.  Many damaged greens have already been interseeded with creeping bentgrass and many more will be seeded in the coming days.  Sod from nursery greens on golf courses is also being used to patch small areas of dead turf. 

Surviving Poa annua emerging in verticut channels.

Spreading the Winterkill Message

In the last couple weeks I have conducted several radio interviews discussing winterkill on golf courses with the goal of explaining the issue and preaching patience from golfers.  One of the most recent was for the Greening of the Great Lakes radio segments that will air throughout the state this weekend.  You can listen to the interview by following this link (the audio is near the bottom of the article) http://goo.gl/93psbi

Winterkill 2014: What to do now

Dr. J.M. Vargas, Jr., Dr Kevin W. Frank, and Dr. Trey Rogers
Michigan State University

Winterkill 2014

In the last week as additional snowmelt has revealed the turf, it is now obvious that injury has occurred to annual bluegrass (Poa annua) in Michigan.  Most of the damage appears to be from ice cover that trapped toxic gases under the ice, which covered the greens for more than 45 days.  Many putting greens were under ice for 70 or more days.  In addition to ice cover, damage may also have been caused by crown hydration freeze injury, desiccation, and low temperature kill.  The questions now are primarily related to reestablishment.  Decisions would be easier if we could accurately predict the weather, but forecasts tend to lack accuracy and reliability.  If a warm spring occurs, interseeding the damaged areas with creeping bentgrass will work well. However, if a cold spring occurs, which many are predicting, it will take the interseeded areas considerable time to fill in with dense turf.  Sodding completely dead areas especially if you have an annual bluegrass nursery green may be a better option.  If you purchase sod, make sure your putting green root zone is compatible with the purchased sod root zone. However, if a nursery green is not available then seeding with creeping bentgrass is the only realistic option.   

Winterkill damage on a Poa annua putting green.

Interseeding Greens

The areas to be seeded on greens should be vertically mowed and if possible aerified, then seeded and lightly top dressed. The seed should be applied to the greens following aerification and then vertically mowed in an attempt to move the seed into the verticut slits. Another option would be to apply the seed to the greens and then run a spiker over the greens to push the seed into the soil. The aerification, verticuting and spiking should also stimulate some of the annual bluegrass seed reservoir in the soil to germinate as well.  A fertilizer with phosphorus should be applied at the time of seeding to encourage germination followed by light sand topdressing and rolling.  Research conducted on turfgrass reestablishment following winterkill at MSU indicates regular applications of fertilizer containing phosphorus results in faster establishment than nitrogen applications alone.  Foliar feeding is the preferred method of fertilizing since the cool soil temperatures and the limited root systems of the newly germinated seedling are not conducive to nutrient up take.  On ”warm” windy days, frequent light irrigation cycles will be necessary to keep the surface of the greens moist during the germination process and the earlier seedling stage.  Mowing heights should be raised to .150 in. and then gradually brought down to more normal mowing heights.  Based on our research mowing can begin 8-10 days after germination (covers will speed this up).  Do not be afraid to mow frequently in the beginning, as it helps the new seedlings establish.

Prepping a seedbed in a dead green.

Covers and diseases

If covers are available, they should be used on severely damaged greens. This will increase temperatures, especially on warm sunny days, and speed up the recovery process. Cotton grow covers can be cut into smaller pieces and used on greens that have small damaged areas allowing the green to remain in play. If covers are used on greens with major damage, temporary greens will have to be established.  Once sufficient establishment has occurred, the covers can be removed during the day to allow play to occur on the greens. At night the greens should be covered to retain the heat of the day and to further encourage as much growth as possible.  Microdochium patch fungicides should be applied to prevent this disease from developing, especially if covers are used. The QoI or dicarboximide fungicides would be good choices for management of this disease.

Covering greens may be critical for speeding reestablishment.

Ice and Poa Survival Update

Dr. Kevin W. Frank and Dr. J.M. Vargas, Jr.

The winter of 2013-2014 will be remembered for many years to come.  The ice storm of Dec. 21-22 knocked out power for thousands and coated everything, included exposed turf, in ice.  Following the ice storm there was a brief warm-up Dec. 28-29 immediately followed by a Polar Vortex, a blizzard, and then another brief warm-up from Jan. 10-13.  The weather events resulted in thick ice sheets forming on many putting greens with the most severe conditions appearing to be from the Lansing area eastward.

Ice from a putting green.

The primary cause of death to turfgrass under ice sheets is from oxygen depletion and toxic gas accumulation from soil microbial respiration.  The warmer the soil is when the ice forms the faster the oxygen is depleted by the microbes and the sooner toxic anaerobic gases like butanol and ethyl butyrate will form.  These gases are what superintendents often refer to as the smell of death and unfortunately many, including myself, have experienced this smell in the last week.  The day estimates for Poa annua survival under ice range from 45 to 90 days and for creeping bentgrass from 90 to 120 days.  Currently many putting greens have been covered in ice for greater than 60 days.  We have sampled Poa annua under a 2 inch ice sheet at the Hancock Turfgrass Research Center at MSU weekly for the last three weeks.  Last weeks samples from 58 days under ice (5 days after sampling) show that ½ of the plugs sampled appear to be dead but we will continue to monitor and sample.  Some superintendents have started reporting similar results in the last week.

Poa annua samples, 58 days under ice, 5 days after sampling.

Many superintendents have been active in trying to clear snow and remove ice throughout the winter but it has been a nearly impossible process due to frequent snowfall and very cold temperatures that make melting or physically removing ice very difficult.  This might be the winter that Mother Nature dictates turf life and death no matter what actions were taken by superintendents.  Unfortunately winter is not over and the upcoming warm temperatures and melt that will arrive can be just as calamitous especially to Poa annua greens.  Poa annua loses its cold temperature hardy proteins and begins to take up water quickly as temperatures warm.  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.  The damage resulting from freeze/thaw cycles is typically referred to as crown hydration injury.  Despite efforts to squeegee water from low spots on greens it is difficult to remove all the water and completely prevent crown hydration injury.  It has already been a very taxing winter and unfortunately spring doesn't look like it will be any easier.  We will continue to update the situation as spring arrives.