With the extremes in weather that we’ve had, you may not have been in the landscape long enough to tally any cold injury to landscape trees and shrubs. No worries, for cold injury only becomes easier to spot over time, as tissue death is realized.
Ordinarily, cold injury occurs when plants are “triggered” to grow prematurely, as a result of an out of season warm spell during the winter months. In this scenario, plant sap flows upward and cell water content increases. In the event of a freeze, respective cellular water freezes and therefore ruptures cellular walls, resulting in cold injury.
However, the weather this winter has remained consistently cold. So the scenario above has not occurred, at least not yet.
Still, cold damage is manifesting with some ornamentals within the landscape. Examples of plants that have exhibited cold injury include Wax Myrtle and Tobira Pittosporum. Unexpectedly, several Japanese Hollies have displayed cold injury as well.
A pretty good article on Winter Protection is at http://pubs.caes.uga.edu/caespubs/pubcd/c872/c872.htm , if you are concerned.