Changes in Turfgrass Crown Membrane Fatty Acid Ratios in Response to Chemical Applications and Ice Stress within Annual Bluegrass Putting Green Species.

Annual bluegrass is susceptible to damage from winter conditions, particularly ice stresses. The objectives of this study were to evaluate the effects of various chemical treatments on plant regrowth, crown fatty acid ratios, and carbohydrate content under ice cover stress of annual bluegrass. Annual bluegrass field plots were treated in late summer through fall of 2015 and 2016 with: Civitas One, mefluidide, propiconazole, or trinexapac ethyl, in preparation for turf plants to undergo acclimation to winter conditions. Turfgrass plugs were then taken in late fall from each plot and transferred to an environmentally controlled low temperature growth chamber (-4^oC) where they underwent ice cover or no ice cover treatments. Turfgrass plugs were taken out of the low temperature growth chamber after 0, 20, 40, and 60 days for destructive sampling. One half of the plugs went towards fatty acid and carbohydrate analysis while the other half was subjected to a regrowth assay. Civitas treated plugs had the greatest amount of regrowth after ice and cold temperature treatments while trinexapac ethyl treated were no different from the untreated control in annual bluegrass. At 20 days under ice cover, fatty acids detected within annual bluegrass were linolenic acid (~10%), linoleic acid (~14%), oleic acid (~6%), stearic acid (~30%), palmitoleic acid (~6%), and palmitic acid (~30%). Plants that were treated with mefluidide, propiconazole, and Civitas  One had a greater percentage of polyunsaturated fatty acids, with linoleic acid being increased by ~50%  due to these chemical treatments, compared with trinexapac-ethyl and untreated samples. Results from this study suggest that by applying Civitas One, mefluidide, or propiconazole, ABG may be better able to survive winter conditions by altering the degree of polyunsaturated fatty acids in crown membrane tissue.