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.

Melting Ice Sheets on Greens

Dr. Kevin W. Frank, Michigan State University

Andrew Hollman, Dr. Brian Horgan, & Sam Bauer, University of Minnesota

When given lemons make lemonade.  When given an ice sheet, conduct an ice melt study.  On January 31 at the Hancock Turfgrass Research Center (HTRC) at MSU we conducted an ice melting study in cooperation with Dr. Brian Horgan, Andrew Hollman, and Sam Bauer from the University of Minnesota.  We tested 20 products for their ability to melt ice.  Conditions during our treatment window which began at approximately 11 am and concluded at 5:30 pm had temperatures hovering around 25 °F and constant cloud cover.  The treatments can be broken down into three general categories:

Standard Chemcials/Salts (all application rates 28 lbs./1000 ft.²)

1. Calcium chloride

2. Sodium chloride

3. Potassium chloride

4. Magnesium chloride

‘Safer’ ice melt products (all application rates 28 lbs./1000 ft.²)

5. Calcium magnesium acetate (CMA)

6. Sodium acetate (NAAC)

7. Enviro Melt (carbonyl diamide/urea)

8. Safe Paws (modified amide/glycol admixture)

9. Paw Thaw (CMA and fertilizer)

10. Tenderfoot Ice Melter (urea and DeFrost)

11. Ammonium sulfate. 

Solar Absorption Products (dark colored)

12. Milorganite greens grade (56 lbs./1000 ft.²)

13. Sustane greens grade (40 lbs./1000 ft.²)

14. Top Cut biosolids SGN 90 (53 lbs./1000 ft.²)

15. Top Cut SGN 200 (53 lbs./1000 ft.²⁾

16. Top Cut + DeFrost SGN 200 (53 lbs./1000 ft.²)

17. BioDac + DeFrost SGN 200 (47 lbs./1000 ft.²)

18. BioDac + DeFrost + Colorant SGN200 (47 lbs./1000 ft.²)

19. Eon 75 humic acid (47 lbs./1000 ft.²)

20. Black sand (100 lbs./1000 ft.²)

Treatments on ice sheet at MSU.

We recorded surface ice temperatures prior to treatment application and at intervals following applications using an infrared temperature sensor.  We rated ice melt based on observation of standing water on the plots on a scale from 1-5 with 1 = no visible melt, and 5 = visible standing water. 

Surface temperatures prior to treatment application were very similar to air temperatures 25-26 °F.  One hour after treatment application the treatments were separated into two groups, the standard salts and safer ice melt products vs. the solar absorption products.  The solar absorption products with their dark coloration had surface ice temperatures of 35-37 °F whereas the salts and safer treatments had surface ice temperatures of 27-31 °F.  Treatments were still significantly different at 4.5 hours after treatment application although the temperatures for the solar absorption products declined to 30-32 °F, most likely due to the sun setting. 

There were also differences in visible melt from the treatments.  The following treatments produced the most visible melt: Milorganite, Sustane, Top Cut biosolids SGN 90, Eon 75 humic acid, and black sand.  The standard salts and safer ice melt treatments produced very little visible ice melt.  

Solar absorption products had the greatest melting.

The standard salts were the only treatments we observed that were able to penetrate through the 2 inch ice sheet so they could be effective in facilitating gas exchange with the surface but of course there is the risk of turf burning from the salt properties of these treatments.  

Calcium chloride melted holes all the way to the turf surface.

Overall, even though temperatures were below freezing and cloud cover persisted the solar absorption treatments were effective at melting the ice surface but were unable to melt to the surface given our 2 inch ice sheet. We are planning to replicate this trial again this coming week at both MSU and Minnesota when temperatures are forecast to be above freezing.  We will also be assessing turfgrass phytotoxicity from the treatments this spring. 

Helping the Melt

Next week most areas of Michigan are forecast to have temperatures above freezing and possibly into the mid 40’s in combination with rain.  Many superintendents have been attempting to clear greens down to the ice layer to facilitate melting.  Keep in mind that if this melt occurs there is going to be a tremendous amount of water that will be moving off greens.  Ensuring the water can exit the greens will be critical to try and prevent water backing up onto the green and refreezing if temperatures drop below freezing at night.  Ultimately Mother Nature is going to dictate whether or not our Poa annua putting greens have survived the ice sheet and the pending melting and freezing in the next month.    

What Lies Beneath: Ice?

Dr. Kevin W. Frank

Associate Professor & Extension Turfgrass Specialist

Michigan State University

Some might remember 'What Lies Beneath' as the title of a horror movie but currently ice is a real life potential horror for golf course superintendents worried about winterkill. 

Weather Scenario

The winter of 2013-2014 will be remembered for many years to come. The first significant event was the ice storm of Dec. 21-22 that knocked out power for thousands and coated everything, included exposed turf, with a perfect coating of ice. 

Tall fescue encased in ice.

Most turf areas were covered with snow prior to the icing event and as the rain percolated through the snow it formed a very porous, crusty ice-snow layer.  This type of ice-snow layer is not a concern for turfgrass as it is porous and allows for gas exchange from the turf/soil interface to the atmosphere.

  

Two inch porous snow-ice layer + 1 in. snow on top.

Five days after the ice storm (Dec. 27) temperatures at the Hancock Turfgrass Research Center (HTRC) warmed to 38 °F and were accompanied by 0.15 in. of rain. On Dec. 28 and 29 temperatures were above 40 °F.  The warm temperatures resulted in melting and I believe this is when the first ice layer formed.  On Dec. 30 temperatures dropped and we all learned what a Polar Vortex meant as day time high temperatures were in the single digits and nighttime lows were well below 0 °F.  The Vortex combined with a foot or more of snow closed MSU for Jan. 6 and 7 but by Friday Jan. 10 the HTRC recorded a daytime high temperature of 38 °F and by Jan. 13 the high temperature was 44 °F.  This resulted in another melting event and another ice forming event as temperatures in the day melted snow and nighttime temperatures refroze any remaining water.   Some superintendents that were clearing snow from putting greens throughout the winter may have been successful at removing any ice that existed or formed during these melts.  However, depending on available labor and equipment many superintendents are not able to constantly remove snow during the winter so ice formation is inevitable. Since the melting ended on Jan. 13-14 the temperatures have been well below the point where any further melting would occur.  Not every green at the HTRC is covered in ice but at least one poorly draining Poa annua putting green is now covered in a 1-2 inch ice sheet.  I believe this ice sheet initially formed during the Dec. 28-29 melt so as of today (Jan. 29) the Poa has been under ice for 31 days.   

Two inch ice sheet on Poa annua green at HTRC.

Ice Sheets

In Michigan especially for Poa annua greens, crown hydration and subsequent refreezing are often the primary culprits of winterkill. However, this year ice sheets are a cause for concern.  In the 1960’s James B Beard conducted research at MSU on survival of creeping bentgrass and Poa annua under ice sheets.  Creeping bentgrass survived 120 days of ice cover without significant injury while annual bluegrass was killed somewhere between 75 and 90 days of ice cover. More recently Darrell Tompkins conducted research at the Prairie Turfgrass Research Center in Canada that suggested Poa annua greens could be damaged in as few as 45 days under ice.  The primary cause of death to turfgrass under ice sheets is most likely from toxic gas accumulation under the ice sheet from soil and turfgrass respiration.  The day estimates for turf survival are just that, estimates, use them as a guide but know that they are not absolutes.

Remove Ice?

Whether or not to attempt ice removal is a difficult decision for golf course superintendents.  The decision to remove ice can be based on several factors including: turf sampling, duration of ice cover, current and future temperatures, ability to remove water following melting from the green, and labor.

1. Sampling – Bob Vavrek from the USGA recently posted a great YouTube video http://tinyurl.com/k9mbfjc on how to sample greens under ice to assess survival.  An important point that Bob makes is that there is variability in sampling and just because your sample comes out alive doesn’t mean all areas on the green will survive – same can be said if your sample is dead.   

2. Duration of ice cover – as discussed in the previous section, estimates of days of ice cover causing death vary from 45-90 for Poa annua and 120 days for creeping bentgrass.  At this point I’m less concerned for creeping bentgrass surfaces as I’d expect significant melting before we reach a 120 day threshold as this would be well into April.  Poa annua is less certain as at the HTRC we will approach 45 days under ice cover by mid-February.  Check your calendar and start counting. 

 

Ice sheet at HTRC, 31 days and counting.

3. Temperatures – our 10 day forecast does not look good for trying to remove ice as day time high temperatures are forecast in the teens to low 20's with nighttime lows in the single digits.  Part of the concern with removing ice is exposing the turf to cold air temperatures after being insulated with snow and ice since mid-December.  In the past, some superintendents have removed ice and then recovered the greens with snow to provide insulation against cold temperatures. 

4. Physical ice removal – physical ice removal includes practices to fracture the ice with impact (hammers, chisels, aerifiers, slicers) and then remove the fractured ice sheet with shovels, tractors, or skid steers.  I recommend avoiding direct impact with tools such as hammers to less impact concentrated equipment such as slicers and aerifiers.  There’s always some risk associated with impact related ice removal but the alternative of leaving ice in place and rolling the dice on survival is also risky. 

 

Damage from a hammer used to crack ice.

5. Melting ice – there are many different products that have been used to melt ice including black sand, dark colored natural organic fertilizers, and synthetic fertilizers.  The key to any melting strategy is to be able to remove the water from the green following melting so it doesn’t refreeze and form another ice sheet. We will be testing products to melt ice at the HTRC in cooperation with researchers from the Univ. of Minnesota in the coming weeks.     

6. Labor – if you’re going to remove ice you need help.  Ice removal is not a 1-person job. If your golf course has 18 greens covered in ice even with several employees this is not a one day job. 

No Guarantees

Unfortunately there are no guarantees with respect to winterkill and whether or not ice is removed.  The days under ice cover for survival are estimates from research and conditions from course to course and even within the same course vary thereby effecting how long turf can survive under ice.  It’s already been a long hard winter and let’s all hope our turf survives so it’s not a long hard spring reestablishing grass. 

Grub Treatments with Nicotinoid Insecticides may Affect Bees

Dr. Dave Smitley

Department of Entomology

Michigan State University

There is a growing concern among entomologists and other agricultural scientists about the undesirable impacts of imidacloprid and other nicotinoid insecticides on the health of honey bee colonies, and native bees.  Nicotinoid insecticides are widely used on agricultural crops to control destructive insects.  They are also used on golf courses and home lawns to control white grubs and other turfgrass pests.  A recent study conducted in Kentucky by Dr. Dan Potter provides some useful information for how to avoid negative effects on bees that forage in treated lawns (http://www.plosone.org/article/info:doi%2F10.1371%2Fjournal.pone.0066375).  The results of this study can be summarized as follows:

1. Turf without any flowering weeds is not likely to be harmful to bees even immediately after a nicotinoid insecticide application because it is unlikely that bees will be present on the turfgrass.  Avoiding spray drift to surrounding flowering plants is advised.

2.  Applications of clothianidin (a nicotinoid insecticide used extensively on turfgrass) to turfgrass with clover in flower was harmful to bumble bee colonies foraging on the clover.   However, if the lawn was mowed just before or immediately after clothianidin was sprayed, so that there were no sprayed flowers present, there was no harmful effect on the bumble bee colonies.  Also, no harmful systemic effect was observed when the clover began to bloom again after clothianidin was applied, as long as the new flowers were not present when the lawn was sprayed.  In the discussion of these results Dr. Potter notes that more research is needed to address the long-term effects on bees throughout the growing season after the uptake and translocation of nicotinoid insecticides by clover and other flowering weeds.

 

White clover flowering in a low maintenance turf.

3. Chlorantraniliprole, a new turf insecticide with a different mode of action, did not have any harmful effects on the bumble bee colonies under any conditions. 

Considering recent research on the impact of imidacloprid on honey bees, and the results of the recent study summarized above, I recommend that if a lawn with weeds in flower needs to be treated for grubs, that the homeowner or lawn care professional mow the lawn immediately before spraying a nicotinoid insecticide, so that flowers are not present in the lawn at the time of application.  Please note this is approach is also in compliance with the precautionary statements on the pesticide labels which specify not to apply clothianidin, or other neonicotinoids, to blooming nectar-producing plants if bees are visiting the treatment area.  An alternative may be to use chlorantraniliprole which did not appear to be as harmful to bees in the Kentucky study.  Also, homeowners and lawn care professionals should follow three simple steps of MSU Smart Gardening to grow turf with a dense root system that is tolerant of grubs, so that no insecticide is needed:

1. Mow lawns at the highest cutting-height setting on your lawn mower

2. Use at least 2 lbs N per 1000 square feet per year

3. Water lawns during dry periods

Michigan Fertilizer Act Changes

Kevin W. Frank, Ph.D.
Michigan State University

On Jan. 1, 2012 phosphorus fertilizer applications to turfgrass in the state of Michigan were regulated according to Act 451 of 1994, Part 85 Fertilizers.  Basically the amendments to the fertilizer act restricted phosphorus fertilizer applications to turfgrass unless a soil test indicated need or for new establishment.  However, there were provisions that phosphorus fertilizer could be applied at 0.25 lbs. P/1000 sq. ft. if the source was a 'finished sewage sludge, organic manure, or a manipulated manure'.  This provision resulted in many questions and some confusion about which natural fertilizers fell within this category.  

On Tuesday, Nov. 5 Governor Snyder signed Public Act 151.  This Act made revisions to Act 451 and in particular to phosphorus applications to turfgrass.  The key addition was that the term 'natural fertilizer' was introduced into the language.  Natural fertilizer is defined as a substance composed only of natural organic, natural inorganic, or both types of fertilizer materials and natural fillers.  Public Act 151 has immediate effect, meaning today a person may apply biosolids, a natural fertilizer, or a manipulated manure to turf at a rate of not more than 0.25 lbs. P/1000 sq. ft./application.  The addition of the term natural fertilizer certainly expands the number of fertilizers containing phosphorus fertilizer that can be applied.  The key for the turf manager is understanding that the rate restriction of 0.25 lbs. P/1000 sq. ft./application is still in effect for these fertilizers so correct product calculations, calibration and application is critical to ensure applications don't exceed the 0.25 lb. P rate.