Golfdom, June 2014

stresses such as crown hydration and anoxia Consequently preparing for winter injury should be considered a year long process that encompasses a number of diferent cultural practices to promote turfgrass health GettinG winter ready Winter hardiness of turfgrasses is achieved through the process of cold acclimation which is induced by decreases in temperature and light during the fall During this period of time turfgrass plants undergo physiological and metabolic changes that allow them to become more tolerant to winter stresses Te process of cold acclimation is inf luenced by plant genetics such as the species or cultivar in combination with environmental conditions such as temperature and moisture Along with cold acclimation temperature fuctuations during winter and early spring months deacclimation can also infuence the winter injury potential of the turfgrass Largely cold acclimation capacity and resistance to early cold deacclimation is controlled by genetics however there is potential to increase both of these factors through management strategies to ultimately reduce overall winter injury Because of the high degree of species variability that exists on putting greens turfgrass species becomes the major factor infuencing winter injury For example creeping bentgrass has excellent winter hardiness compared to annual bluegrass Research has shown that diferences in winter injury potential between these two species is associated with enhanced cold acclimation capacity of creeping bentgrass along with increased susceptibility of annual bluegrass to early cold deacclimation Tompkins et al 2000 2004 Hofman et al 2014 Terefore one strategy to minimize winter damage would be to promote creeping bentgrass and reduce annual bluegrass PHOtO 2 populations In some situations this may not be an option In addition creeping bentgrass may still be susceptible to winter injury depending on both plant and environmental factors Consequently management of annual bluegrass creeping bentgrass golf greens should focus on promoting healthy turfgrass plants throughout the year while minimizing conditions that favor the potential for winter injury So lets look at a few of the major winter stresses along with management strategies to prepare greens for winter ice ice baby Crown hydration and damage from ice cover are two of the most devastating causes of winter injury on putting greens every year Crown hydration occurs when temperatures increase causing plants to absorb water and results in winter injury if Meltdown followed by subfreezing temperatures As a consequence cells rupture due to the formation of ice crystals and this is lethal for the plant Damage may also be associated with ice formation outside of cells causing water to move out of the cells and can cause severe dehydration and or death of the turfgrass Ice cover can also be a contributor to crown hydration as ice melts and then refreezes In addition non porous ice can cause anoxia and or buildup of toxic gases mainly CO 2 and has been shown to be more injurious to annual bluegrass compared to creeping bentgrass Tompkins et al 2000 2004 studied the impact of ice encasement ice cover and snow cover on annual bluegrass in a growth chamber and in the feld Annual bluegrass plants did not survive 90 days of ice encasement in Continued on page 32 June 2014 Golfdom 31 Golfdom com photo by Sam bauer Sod cutters are useful in opening up channels for water flow off putting surfaces prior to winter Water will often back up at the green collar interface therefore extending these channels through the collar and into the green can be important