Physiology, Plant Stress, Winter Injury

Mitigation of Anoxia under Ice and Impermeable Covers on Annual Bluegrass Putting Greens (2010)
Darrell K. Tompkins, Philippe Rochette, and James B. Ross

Winter damage to annual bluegrass putting greens caused by a lack of oxygen under ice or impermeable winter covers is an important problem in cold climates.  The objective of this trial was to evaluate various covering systems that would maintain oxygen levels and, in turn, prevent damage associated with anoxia (lack of oxygen).  White impermeable winter covers, some with an insulating air layer of either Enkamat or bubble wrap, were compared against ice cover and no ice (snow only) treatments.  A ventilation system that could replenish oxygen under the impermeable covers was also evaluated.  Following installation of the various covering systems, an ice layer was established in order to induce a condition of anoxia.  Once the ice layer was established, gas samples were collected on 15 day intervals from under the covers in order to determine oxygen and carbon dioxide concentrations.

In this trial, oxygen concentrations under the various treatments remained constant for the first 75 days.  However by day 90, there was a significant reduction in oxygen for the ice only and the ice, impermeable cover (no air layer) treatments.  Values for the ice, impermeable cover treatments that had an air layer were better than the no air layer, but significantly lower than the no ice (snow only) treatment.  Air replenishment did not appear to have an impact on oxygen concentration.

Carbon dioxide levels were lowest for the no ice (snow only) treatment.  On day 90, the highest carbon dioxide levels were for the ice only and ice, impermeable cover (no air layer) treatments.  There seemed to be some improvement in carbon dioxide levels that had the insulating materials.

With regards to survivability the ice only treatment was dead in both years of the study.  Otherwise, there were no significant differences between the other treatments when considering relative hardiness levels and these treatments survived completely.

Evaluation of Ventilation Systems under Winter Covers on Annual Bluegrass Greens (2009)
Darryl Asher¹ and Jim Ross^2
1The Glendale Golf and Country Club, ²Prairie Turfgrass Research Centre

Winter damage to annual bluegrass (Poa annua L.) golf course putting greens often occurs in the cold climates of North America.  The Glendale Golf and Country Club is a well established club in Edmonton, Alberta and has a history of winter injury on their putting greens that was caused by anoxia (a complete lack of oxygen).  The objective of this study was to evaluate various ventilation systems under impermeable winter covers that would prevent gas concentration fluctuations that could result in injury due to anoxia.  Three different ventilation systems were compared with a non-ventilated system and were installed in early November prior to permanent snow cover.  Gas concentrations and temperature were monitored on a weekly basis throughout the winter.  Once permanent snow cover occurred, gas concentrations began to fluctuate.  Those greens that had the ‘roof turbine vents’ system had the least gas concentration fluctuations on each of the rating dates.  The ‘vent tube matrix’ system also was also superior to those greens that had ‘exhaust vents only’ or ‘no vents’.  Although the survivability of the putting greens was excellent under all ventilation systems, it was expected that those greens that had the greatest fluctuation in gas concentrations would be the first to suffer damage from anoxic conditions.

Survivability of Annual Bluegrass under Impermeable Winter Covers - The Glendale Study (2008)
Darryl Asher¹ and Jim Ross^2
1The Glendale Golf and Country Club, ²Prairie Turfgrass Research Centre

The Glendale Golf and Country Club is a well established club in Edmonton, Alberta that has a history of winter injury on their annual bluegrass putting greens.  The objective of this study was to develop a cover system that would prevent winter injury to the putting greens at Glendale.  A secondary goal was to establish a monitoring system that would quantify temperature and gas concentrations under this cover system.  This report is the third and final year of this study.

A passive ventilation system was compared with an active ventilation system on the putting greens in order to assess their effectiveness in preventing winter injury from anoxia.  Covering systems were installed in early November prior to permanent snow cover.  Gas concentrations and temperature were monitored on a weekly basis throughout the winter.  In addition, organic matter and soil physical properties were assessed and compared with gas concentrations to determine if there was a relationship.

Duration of snow cover was approximately 120 days for year one and two of this study. In year three, snow cover duration was 150 days and snow depth was much greater than the two previous years. This depth of snow provided sufficient insulation during periods of extreme cold. On one occasion at a local golf course, an extremely cold day (-35^oC) occurred in early winter prior to permanent snow cover. At that time, the insulation that was provided by the covering system was sufficient to prevent injury from cold temperatures.

Generally, as oxygen levels decreased carbon dioxide levels increased.  This was attributable to activity of plants and microbes.  These gas concentrations did not begin to change until there was snow on top of the winter covers.  When comparing the three years, carbon dioxide concentrations were higher and oxygen was lower in year three of this study.  This was attributed to the long duration and deeper snow cover.

The two insulating materials that were used, closed-cell foam and bubble wrap, had minimal effect on gas concentration changes. Temperatures that were above freezing produced greater gas concentration changes than did temperatures below freezing. When considering the two ventilation systems, the passive system was more effective than was the active system. In year two, it appeared that when organic matter reached a certain threshold that gas concentration fluctuations were more rapid. However, in year three there did not appear to be a relationship between organic matter and gas concentration fluctuations.

At Greywolf, there were greater fluctuations in gas concentrations early in the winter. It was thought that an early deep snow cover may have caused frozen greens to thaw from underneath. These warmer temperatures used more oxygen and produced more carbon dioxide. These early conditions did not have a negative impact on the survivability of the greens.

The monitoring system that was used effectively quantified temperatures and gas concentrations and could be used to establish critical thresholds as to when damage would occur. As damage never occurred we were not able to establish these critical thresholds.

Survivability of Annual Bluegrass under Impermeable Winter Covers - The Glendale Study 2008
Darryl Asher, Todd Paquette and Jim Ross

Introduction

Previous research conducted at the Prairie Turfgrass Research Centre (Olds, Alberta, Canada) showed that there was a rapid loss of relative hardiness of annual bluegrass plants between 45 and 60 days under continual ice cover (Tompkins, Ross and Moroz, 2004), while plants in non-iced conditions lost hardiness very slowly. The fact that air cannot be replenished under ice cover, or an impermeable covering of any sort, was thought to be a factor contributing to the injury. Research conducted in Quebec found that under an impermeable cover oxygen was depleted and carbon dioxide increased (Rochette et al, 2006). This increase was attributed to use by the plants and to low temperature microbes. When oxygen is completely depleted, the condition is known as anoxia.

In earlier research, Beard (1965) had similar results and found that injury to annual bluegrass occurred 75 days after continual ice cover. However, it seems that creeping bentgrass is affected much less and in our research was still alive after 120 days of continual ice cover. Other researchers found that differential sensitivity to conditions of anoxia was common amongst various plant species (Bertrand et al, 2001).

So what happens to annual bluegrass between 45 and 60 days when air cannot be replenished?

It seems that under conditions of anoxia a rapid depletion of stored foods occurs. We know that these stored foods act as an anti-freeze agent for plants so when they are completely depleted the plants have lost their ability to resist freezing. And, of course, once they freeze irreversible cell damage occurs and plants die

At this point, we think that when oxygen is fully depleted rapid utilization of food reserves occurs, which in turn causes a rapid loss of hardiness (between 45 and 60 days). Once food reserves are depleted, the plant begins to utilize energy that is provided by a process called, glycolysis. However, the energy produced is not sufficient to sustain the plant. This deficit also leads to the induction of fermentation metabolism and to an increase in the production of potentially phytotoxic metabolites such as ethanol, lactic acid and carbon dioxide (Rochette et al, 2009).

So it appears that injury results from either a toxic build-up of these gases or from a complete depletion of food reserves. In the Quebec study, high levels of carbon dioxide did not produce mortality, so that may be an indication that the depletion of food reserves is the reason for the injury.

Mitigation of Anoxia under Ice and Impermeable Covers on Annual Bluegrass Putting Greens (2008)
Darrell K. Tompkins, Philippe Rochette, and James B. Ross

Summary

Winter damage to annual bluegrass putting greens caused by a lack of oxygen under ice or impermeable winter covers is an important problem in cold climates. The objective of this trial was to evaluate various covering systems that would increase oxygen levels and, in turn, prevent damage associated with anoxia (lack of oxygen). Impermeable winter covers, some with an insulating air layer, were compared against ice cover and snow cover only treatments. Additional treatments to examine air replenishment under the covers were also evaluated.

Oxygen content under the various treatments remained constant for the first 75 days of the trial. However by day 90, there was a significant reduction in oxygen levels for the ice only and the ice, impermeable cover, no air layer treatments. In addition, the ice only treatment was significantly lower than the ice, impermeable cover, no air layer treatment. Air replenishment did not appear to have an impact on oxygen concentration.

Carbon dioxide levels were lowest for the no ice, no cover treatment. On day 90, the highest levels were for the ice, snow cover only and ice, impermeable cover, no air layer treatments. There seemed to be some improvement in carbon dioxide levels with the Enkamat and bubble wrap treatments.

Ice, snow cover only treatments were dead in both years of the study.

As data for turf quality and relative hardiness levels were not yet completed for this trial, it is preliminary in nature.

Strategies for Removing Ice from Annual Bluegrass Golf Greens (2005)
D.K. Tompkins, J.B. Ross and M.A. Anderson

Summary

Ice cover on annual bluegrass (Poa annua L.) putting greens often causes damage in the cold climates of North America during long winters. The objective of this study was to evaluate various ice removal strategies for use on annual bluegrass putting greens. In addition, the various products were evaluated for turf injury (damage caused by the product). An initial screening study was conducted in order to choose the best treatments for the field study. Selection of treatments was based on effectiveness and turf injury caused by the products.

Results of the five separate field tests showed that there was ice removal was not improved with the use of covering materials. As far as the individual treatments were concerned, the Landscape and Alaskan ice melters had the greatest effect on reducing ice hardness, increasing ice melt and reducing the ice bond. The methanol was not as effective as either of the granular ice melters in the three tested parameters. The radiant heat producing materials, black sand and Milorganite, appeared to be more effective when light intensities were greater in the late winter study. It also appeared that full sun improved their performance.

This field trial was conducted over a three year period to attempt to determine turf injury as a result of the various products. Turf injury was measured as percent area damage. There were no differences in turf injury when considering the covering materials. On one occasion Alaskan Ice Melter caused greater injury than any of the other treatments. Landscape Ice Melter also had significantly more injury than the other treatments. Methanol, Milorganite and black sand had injury that was similar to the untreated control.

Relative hardiness levels were measured in year three to determine whether the different ice melting strategies negatively impacted hardiness levels. The early winter test of year three showed that there were no differences in relative hardiness levels and the plant grew on normally after the freeze test, which might indicate that there was no damage from the treatments.

Survivability of Annual Bluegrass under Impermeable Winter Covers - The Glendale Study (2004)
Darryl Asher, Todd Paquette and Jim Ross

Previous research conducted at the Prairie Turfgrass Research Centre (Olds, Alberta, Canada) showed that there was a rapid loss of relative hardiness of annual bluegrass plants between 45 and 60 days under continual ice cover (Tompkins, Ross and Moroz, 2004), while plants in non-iced conditions lost hardiness very slowly.  The fact that air cannot be replenished under ice cover, or an impermeable covering of any sort, was thought to be a factor contributing to the injury.  Research conducted in Quebec found that under an impermeable cover oxygen was depleted and carbon dioxide increased (Rochette et al, 2006).  This increase was attributed to use by the plants and to low temperature microbes.  When oxygen is completely depleted, the condition is known as anoxia.

In earlier research, Beard (1965) had similar results and found that injury to annual bluegrass occurred 75 days after continual ice cover.  However, it seems that creeping bentgrass is affected much less and in our research was still alive after 120 days of continual ice cover.  Other researchers found that differential sensitivity to conditions of anoxia was common amongst various plant species (Bertrand et al, 2001).

So what happens to annual bluegrass between 45 and 60 days when air cannot be replenished?

It seems that under conditions of anoxia a rapid depletion of stored foods occurs.  We know that these stored foods act as an anti-freeze agent for plants so when they are completely depleted the plants have lost their ability to resist freezing.  And, of course, once they freeze irreversible cell damage occurs and plants die.

At this point, we think that when oxygen is fully depleted rapid utilization of food reserves occurs, which in turn causes a rapid loss of hardiness (between 45 and 60 days).  Once food reserves are depleted, the plant begins to utilize energy that is provided by a process called, glycolysis.  However, the energy produced is not sufficient to sustain the plant.  This deficit also leads to the induction of fermentation metabolism and to an increase in the production of potentially phytotoxic metabolites such as ethanol, lactic acid and carbon dioxide (Rochette et al, 2009).

So it appears that injury results from either a toxic build-up of these gases or from a complete depletion of food reserves.  In the Quebec study, high levels of carbon dioxide did not produce mortality, so that may be an indication that the depletion of food reserves is the reason for the injury.

Survivability of Annual Bluegrass under Impermeable Winter Covers (2004) - The Glendale Study
Darryl Asher¹, Todd Paquette¹ and Jim Ross^2
1The Glendale Golf and Country Club, ²Prairie Turfgrass Research Centre

The Glendale Golf and Country Club is a well established club in Edmonton, Alberta that has a history of winter injury on their annual bluegrass putting greens.  The objectives of this study were to develop a cover system that would prevent winter injury and to develop a system to monitor temperature and gas concentrations under this cover system.  A passive ventilation system was compared with an active ventilation system on the putting greens in order to assess their effectiveness in preventing winter injury from anoxia.  Covering systems were installed in early November prior to permanent snow cover.  Gas concentrations and temperature were monitored on a weekly basis throughout the winter.  In addition, organic matter and soil physical properties were assessed and compared with gas concentrations to determine if there was a relationship.

Weather conditions were not considered severe for either winter of this study and the insulation that was provided by the covering system was sufficient to prevent injury from cold temperatures.  Generally, as oxygen levels decreased carbon dioxide levels increased.  This was attributable to activity of plants and microbes.  When comparing the two years, carbon dioxide concentrations were similar while oxygen was somewhat lower in year two.  These gas concentrations did not begin to change until there was snow on top of the winter covers.  The two insulating materials that were used had minimal effect on gas concentration changes.  Temperatures that were above freezing had greater gas concentration changes than did temperatures below freezing.  It appeared that when organic matter reached a certain threshold that gas concentration fluctuations were more rapid.  When considering the two ventilation systems, the passive system was more effective than was the active system.

The monitoring system that was used effectively quantified temperatures and gas concentrations and has the potential to establish critical thresholds as to when damage would occur.

The Effect of the Plant Growth Regulator Primo on Winter Hardiness Levels (2004)
J.B. Ross, M.A. Anderson and D.K. Tompkins

Summary
Ice Injury

Turfgrass growth under winter covers in early winter and spring is thought to be a problem for overwintering putting green turf in cold climates. Considerable growth reduction in the spring under a winter cover was observed following a single fall application of Primo MAXX at an Alberta golf course. As a result, this trail was established in order to determine the effect of the growth regulator, Primo MAXX, on fall hardening and spring dehardening of annual bluegrass (Poa annua).

An initial pilot study was conducted during the winter of 2003-04 where a single application of Primo Maxx was applied at three different rates in the late fall to an annual bluegrass (Petersen’s creeping bluegrass) putting green located at the Prairie Turfgrass Research Centre in Olds, Alberta. Individual treatments were then subjected to various dehardening temperatures for various periods of time. After a freeze test, plants were re-grown and their relative hardiness levels were assessed. Due to an equipment failure during the secondary hardening stage results of the trial were inconclusive.

In year two of the study there were also no significant treatment differences when evaluating fall relative hardiness levels. Application rates and timing of Primo MAXX were evaluated in this study. For all treatments, the LT50 values for the plants were -19oC.

Spring hardiness levels will also be determined in order to evaluate the product for its effect on slowing the loss of hardiness as a result of temperature increases in the spring.

Strategies for Removing Ice from Annual Bluegrass Golf Greens (2004)
D.K. Tompkins, J.B. Ross and M.A. Anderson

Summary

Ice cover on annual bluegrass (Poa annua L.) putting greens often causes damage in the cold climates of North America during long winters. The objective of this study was to evaluate various ice removal strategies for use on annual bluegrass putting greens. In addition, the various products were evaluated for their phytotoxicity (damage caused by the product) to the turf. An initial screening study was conducted in order to choose the best treatments for the field study. Selection of treatments was based on effectiveness (efficacy) and phytotoxicity of the products. Results of the three separate field tests showed that there was no benefit to covering the turf. As far as the individual treatments were concerned, the Landscape and Alaskan ice melters and the methanol softened the ice more than the other treatments. The two granular ice melters melted the ice the best and were best at reducing the bond between the ice and the turf surface. However, in year one these two products also produced some toxicity, while the other treatments did not.

Wear Tolerant Grasses for Use on Sports Fields in a Cold Climate (2003)
D.K. Tompkins, M.A. Anderson and J.B. Ross

Summary

This trial was established in order to determine the wear and cold tolerance of various grasses for use on sports fields in the Prairie Provinces of Canada. An initial screening of 48 different grasses to determine their cold tolerance was conducted in a controlled environment during the winter of 2002-03. From this 21 grasses were chosen for the field study component of this trial. In addition, Poa supina, a Poa supina and Touchdown Kentucky bluegrass mix, and the City of Calgary standard sports field mix were added to the treatment list. Cultivars of perennial ryegrass and tall fescue established more rapidly than did the Kentucky bluegrass cultivars, the Poa supina, the Poa supina/Kentucky bluegrass mix and the City of Calgary standard sports field mix. The perennial ryegrass cultivars that established most quickly were Fiesta 3 and Pick RC2, while Grande and SR8600 tall fescue were equal to the two perennial ryegrasses. On the second rating date, Touchdown Kentucky bluegrass, all four perennial ryegrasses and all six tall fescue were the top rated grasses for establishment.

The Effect of the Plant Growth Regulator Primo on Winter Hardiness Levels (2003)
J.B. Ross, M.A. Anderson and D.K. Tompkins

Summary

Considerable growth reduction in the spring under a putting green winter cover was observed at an Alberta golf course, which prompted the development of this trial. As a result, the objective was to determine the effect of the growth regulator, Primo MAXX, on fall hardening and spring dehardening of annual bluegrass (Poa annua).

Control of Winter Injury Caused by Ice Cover on Annual Bluegrass and Creeping Bentgrass (2000)
D.K. Tompkins, J.B. Ross and D.L. Moroz

Summary

A lab study compared the effect of ice cover and ice encasement with a control treatment (no ice) on annual bluegrass (Poa annua) and creeping bentgrass (Agrostis palustris) plants. Generally, snow covered plants maintained cold hardiness much longer than plants that were ice encased. Cold hardiness levels for the ice covered plants were intermediate between the other two treatments. This effect was much more pronounced for annual bluegrass than for creeping bentgrass. For annual bluegrass, after 60 days, cold hardiness levels were: -180 C for snow covered plants, -100 C for ice covered plants and -20 C for ice encased plants. By 90 days, ice encased plants were dead. By 120 days, the ice covered plants were dead. For creeping bentgrass, the same trend occurred, but the loss of cold hardiness was greatly delayed. Therefore, at 150 days the snow covered plants had a cold hardiness level of -20 C compared to -180 C for the ice encased plants.

A related field study compared the effects of: snow cover, snow removed in February, ice cover and ice removed in February for annual bluegrass and creeping bentgrass plants. Annual bluegrass plants that had been ice covered had very little cold hardiness after 60 days and were dead by 5 days. Creeping bentgrass plants in all treatments could tolerate temperatures below -280 C after 90 days.

Evaluation of Winter Covers for Prevention of Freezing Injury on Putting Greens (2000)
J.B. Ross

Summary

This trial was initiated to determine the insulating value of various winter covers and whether there was an effect on spring colour and plant hardiness levels.

Four golf green winter covers were compared against an uncovered control. The four covers were: Evergreen permeable cover, Typarâ permeable cover, RPEâ Type 4 impermeable cover and an impermeable insulated turf blanket. Covers of 12 foot by 24 foot dimensions were installed on greens at four golf courses throughout Alberta.

Temperatures were collected twice a month from November to the end of February and then three times per week in March and April to determine the effect of the covers on temperatures at the crown level of the plants. Colour rating and plants hardiness levels were also conducted in April.

The insulated turf blanket showed the least fluctuations in temperatures while the RPEâ Type 4 cover showed the greatest heating. The insulated turf blanket and the RPEâ Type 4 cover had the highest colour ratings.

There was the greatest retention of hardiness levels under the insulated turf blanket when measured on April 10. The RPEâ Type 4 cover had the least amount of hardiness. Hardiness levels were measured for the Innisfail site only.