Turfgrass Science

Last year’s heat and drought and this year’s late spring have added extra stress to lawns.

With buds finally starting to bloom on trees in the southern part of Minnesota and ice still stubbornly floating around on lakes in the north, it’s a good time to take stock of a strange year of weather and its effect on our lawns and vegetation.

To rehash the recent weather history that many of us may be trying to repress, we had an exceedingly wet and warm spring in 2012, followed by a summer and fall of extreme heat and certifiable drought. That took a toll on grass and trees—not to mention crops—all around the state.

And while we cut into the moisture deficit with a rather snowy winter, that winter only recently (mostly) released its grip on the landscape. And that landscape includes a lot of struggling vegetation.

A narrow window for recovery

According to Sam Bauer, turfgrass expert with University of Minnesota Extension, many people saw their grass wither and even die heading into the winter, especially if they didn’t provide extra irrigation in the fall.

A photo taken of a driving range in Hastings, MN after 10 inches of snow on May 2nd

To make matters worse, the painfully long winter has shortened the natural recovery period for grasses, when the root system develops enough to withstand the stresses of summer heat.

Normally, that window begins toward the end of April and lasts till early June. But this year we were still getting snow at the end of April en route to a monthly total of 17.6 inches—the snowiest month of the entire winter.

“Essentially, our window for recovery this spring is shortened, what with the cool temperatures we’ve had and the third snowiest April,” Bauer says. “Our recovery period is not much more than a month.”

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2012-13 has been a year for the record books with extreme heat and droughts across the state in the summer and a winter that never seemed to end. Consider: 

-       April 20th record cold, 21°F (previous record 26°F in 1888)

-       Average date for first 60°F occurrence is March 29th.   We reached 60 on April           26.

-       3rd snowiest April on record (17.6 inches)

-       April was the snowiest month of the 2012-13 winter

We do not see a uniform pattern of winter injury across MN. Low lying areas that accumulated ice experienced death, as did annual bluegrass (Poa) that was covered with ice for an extended period. Poa can survive 60 days under ice and bentgrass can last 90+ days under ice. Most golf courses are a mixed stand of grasses, which is why you don’t see complete death or a course that experiences no problems.

Especially hard hit was perennial ryegrass. You can see this in your collars, fairways, tee boxes and driving ranges. Perennial ryegrass has the lowest cold tolerance of the grasses we grow in MN. We use it because it germinates rapidly and has moderate wear tolerance. We don’t recommend its’ use because of winter.

One more item we observed on a few golf courses was some sort of chemical burn to fairways from fall-applied fungicides. In the fall, fungicides are sprayed to golf courses (tees, greens and fariways) to protect the plants from snow molds. We are not sure why or all the specifics yet, but we have seen golf course fairways with turf that is noticeably burned from chemicals sprayed last fall. We are working with manufacturers and scientists to determine what happened.

For those with significant turf death, expect this year to be about growing grass to make sure it is mature going into winter. For those with small random spots of dead turf, expect GUR and reduced pinning locations while the turf recovers and seedlings mature. Regardless, be supportive of your superintendent’s efforts to give you the best playing conditions possible.

For those of you who are wondering when to put your preemergent summer annual grassy weed herbicides down, NOW IS THE TIME. Soil temperatures are near 55 degrees in the upper profile and crabgrass will be germinating at 60 degrees. Any preemergent applications made after crabgrass has germinated will be ineffective. This application can be combined with fertility for increased density and spring turf greenup. Be sure to apply at the correct rate as directed by the herbicide and fertilizer label.

What a difference a year can make.  We certainly didn’t expect to be writing this report in the end of April while looking at snow on the ground across the state.  Now compare this to last spring, with golf courses opening in mid-March, and it gives us a little perspective on the influences that Mother Nature can dish out from season to season.  This winter has certainly gone on long enough, but the end is near (let’s hope).  We rewrote the record books last summer and fall with heat and drought extremes across the state, and this winter broke some records of its own.  How about these new Twin Cities records:  

-          Coldest April 20^th  ever: record cold 21 degrees (previous 26 degrees, 1888)

-          Average date for first 60 degree occurrence is March 29^th (we still haven’t hit 60 degrees!)

-          3^rd snowiest April on record (17.6 inches)

-          April was the snowiest month of the 2012/13 winter

Climatologists are calling it the winter of ice, and that just about sums it up.  The majority of our ice accumulation across the state occurred around the first part of January, if not earlier.  Parts of northern Minnesota and western Wisconsin had ice cover for the longest duration, starting around the middle of December.  Winter injury from ice cover can be attributed to anoxia (or suffocation) and/or buildup of toxic gases because turf is still respiring in a dormant state.  For respiration to occur, the turf needs oxygen, and an impermeable layer of ice prevents oxygen from getting to the plant.  Additionally, ice encasement over a turfgrass area causes the buildup of toxic gases released by plant and microbial respiration.  Generally we see annual bluegrass death occurring after 60+ days of ice cover, while creeping bentgrass and other species can tolerate 90+ days of cover. 

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A quick update for those of you planning to submit soil tests this spring.  Effective April 15th, the University of Minnesota Soil Testing Laboratory has new forms and prices for conducting a soil test.  The new price for a Regular Test is $17.00.  This is a very reasonable price for testing pH, phosphorus, potassium, organic matter, and soil texture.  If you have old forms, please throw them out.  New forms can be downloaded from their website here: New Soil Testing Form 

For more information on the services offered at the soil testing laboratory, please follow this link: http://soiltest.cfans.umn.edu/

This video was shot with a GoPro camera taking 2 photos per second. The photo size was so big that I had to reduce the video quality just to get it to upload, but it gives you the idea of how the single replication treatments were applied.

On Thursday, March 21st, Andrew Hollman cleared off the snow on two putting greens at the TROE Center to evaluate treatments that had the best potential to melt ice. The treatments were applied to either native soil ‘V8′ creeping bentgrass, or USGA ‘Vesper’ velvet bentgrass (some poa). The initial snow blowing of the areas took place on March 14th, but with excessive blowing snow, the areas filled back in over a weeks time. This is simply an investigation into which products will speed up the ice melting process. There were 12 treatments in the trial, including: control (nothing), ice removal, black sand, green sand, 6-2-0 organic, 10-2-10 organic, granular humate, urea 1# gr, urea 1# lq, calcium cloride, black dye, green paint.

Results- the ice thickness during the trial was not desirable and it did have some significant honeycombing. I would have rather seen thick clear ice. Even so, I was able to get a pretty good idea of which treatments performed the best. In general, the black granular substances melted ice the quickest, approximately 2 days faster than the control. Green sand, black pond dye, and green paint were second best, probably a day faster than the control. I was surprised that 1# of urea really didn’t speed up the melting process much. The CaCl treatment was just too light to really show the potential, I was nervous about burning some turf so I didn’t put it on heavy.

Based on the results from this investigation, I really think black sand is a great product of choice for this application. The rate we used was 3 tons per acre, which is a fairly normal topdressing rate.

Another point to mention is that snow removal was the most important step in this process. If you’re getting to the 90 day date of turf being under ice cover, a snow clearing process is a great tool in your arsenal. There are many superintendents completing this task right now, if they haven’t already. While the ice melting treatments sped up the ice removal process, initially all of your effort should be placed on removing the snow.

Andrew Hollman snow blowing the native green on March 14th, 2013

Ice melting treatments immediately after application on March 21st, 2013

Ice melting treatments on March 24th, 2013. Notice that all plots, even the control, are completely clear of ice. Also compare this to the 6-8″ of snow and ice surrounding the plots.

Are you ready for spring or still enjoying the winter?  Either way, it’s time to start thinking about home lawn care again.  Last fall we were stressing the importance of maintaining moisture levels in your lawn amidst one of the worst droughts in Minnesota’s history.  In case you’ve forgotten, the months of August through November alone saw an eight inch precipitation deficit in the Twin Cities area.  This translates to approximately 70% below average precipitation for the fall period.  Many other areas of the state, mainly northwestern and southern Minnesota, were in a much worse situation.

Web link: http://climate.umn.edu/doc/journal/drought_2013.htm

Currently, 70 percent of Minnesota is in Extreme Drought or Severe Drought according to the University of Minnesota Climatology Working Group (Spoden, 2013).  Fortunately, total precipitation for 2013 is so far above average.  The climatology map on the left shows precipitation departures from normal for the first of the year until now.  The northwest region of the state has received as much as 2 inches of precipitation above normal.  Question: will this help to replenish soil moisture levels?  The simple answer is, well, not exactly. 

Right now, soils are frozen.  Soil frost depths range from 0 up to 60 inches in Minnesota soils, and this takes time to thaw out in the spring.  This generally means that precipitation falling right now (frozen soil) does not get absorbed into the soil (or rootzone), but rather promotes the flooding that we experience every spring.  Even during slow spring thaws, the surface moisture melt will precede the defrosting of our soils, in which case most of the surface moisture will run off.  This means there is potential for spring flooding AND continuation of drought conditions.  Depending on your location in the state, you may need to consider preparing for flood or drought, possibly both. 

Flooded Lawns

Last spring we saw flooded lawns in many areas of the state.  Additionally, the floods near Duluth in June left many homeowners with silt covered turfgrass in need of repair.  If your home is in close proximity to any body of water, especially some of our main rivers like the Mississippi or the Minnesota, this may be nothing new to you.  However, it’s always good to be prepared for worse case scenario situations. 

A spring flooded lawn covered in silt and debris. Remedies for this situation would include removing the silt and debris, aerating, and interseeding. Photo: Randy Nelson

Consider these tips to help reduce the damage and recover from flooding:

• Sandbag high risk turf areas to reduce the extent of flooding and buildup of silt
• Remove all debris and silt from smothered turf areas as soon as possible
• Smothered turf should be aerated to allow the exchange of oxygen and encourage new growth
• Avoid planting perennial ryegrass, as it is generally less tolerant of flooding than other turfgrass species. 
• Consider completely renovating lawns that are not easily repaired

For more information on repairing spring flooded lawns, please see this Yard and Garden News Update from retired Extension Turfgrass Educator Bob Mugaas:

http://blog.lib.umn.edu/efans/ygnews/2010/04/repairing-spring-flooded-lawns-1.html

Drought Stressed Lawns

A lawn left to go dormant (possibly worse) last fall. Photo: Sam Bauer

It seems odd to be discussing both flooded and drought stressed lawns in the same article, but really this is the situation that we are potentially facing this spring.  Those of you that maintained sufficient soil moisture levels through supplemental irrigation last fall will be in a much better situation than those that chose to not water.  In many cases, even the slightest effort to provide your turfgrass with some moisture can pay big dividends.  We also discussed dormant seeding last fall, which can be great practice to improve the quality of your lawn the following spring.  If you failed to irrigate and/or dormant seed, unfortunately you might have a lot of work to do this spring.   

Proper irrigation practices will be critical to promote a healthy lawn this spring.  Consider these irrigation tips for drought stressed lawns:

• Irrigate during the early morning hours to reduce the leaf wetness period which is prolonged by night watering. Avoid daytime irrigation, which has the potential to evaporate quickly and be blown off target
• Water the SOIL, not the canopy
• Monitor daily soil moisture loss through evapotranspiration and replace only what is lost.  Follow this link for evapotranspiration values in your location:  http://www.soils.wisc.edu/uwex_agwx/sun_water/et_wimn
• Make seasonal adjustments to your irrigation system or watering schedule based on rainfall and temperature.  In general, spring and fall watering should be heavy and infrequent, and summer watering should be light and frequent
• Measure the depth of water put out by your irrigation system or sprinkler over a certain time period.  This will be important in determining how long to run your irrigation cycle

For more information on proper irrigation practices, please follow these links:

Home irrigation systems: http://www.turf.umn.edu/2012/07/is-your-home-irrigation-system-up-to-par/

Lawn watering practices: http://blog.lib.umn.edu/efans/ygnews/2011/05/post-12.html

Watering lawns and turf: http://www1.extension.umn.edu/garden/yard-garden/lawns/#watering

As always, call or email with questions: sjbauer@umn.edu or 763-767-3518

REFERENCES

Spoden, Greg. 2013. Drought Conditions: Update March 7, 2013. Minnesota Climatology Working Group. Online resource: http://climate.umn.edu/doc/journal/drought_2013.html

A special thank you to all the attendees of the 2013 School of Turfgrass Management at Gross National Golf Course in Minneapolis.  We had a very interactive group and it was great to get to know all of you during the three day session.

For those of you that missed it this year, next year’s School of Turfgrass Management will be held in Wisconsin, with a location to be determined.  If you would like to get on the email list, please feel free to contact us in the near future. 

Dr. Brian Horgan discussing Turfgrass Nutrition at the 2013 School of Turfgrass Management

The 2012 cultivar data is now posted on the cultivar evaluation page.  The cultivar evaluation data page also includes archived data back to 2007.  For additional cultivar data you can visit the National Turfgrass Evaluation Program website where you will find cultivar data from around the country.