Penn State University has distributed information from fruit specialist Jim Schupp regarding how to asses fruit tree health following the recent freezing weather: Peach Bud Survival – Compare the number of live buds to the number a fruiting lateral should carry based on the target yield per acre 
- To get a good estimate, examine about 150 to 200 flower buds per variety per block.
- Collect one strong fruiting lateral (pencil thick and 24 to 32 inches long) from each of two sides of 5 representative trees per block.
- Bring the fruiting laterals into a heated building, place them in buckets of water, and allow them to warm up.
- Count and record the total number of flowers and unopened buds on a branch.
- Examine the ovule in the center of each flower, and count the number that are healthy.
- Compare this number per fruiting lateral to your desired crop load. If, for example, you have 12 live flower buds on a fruiting lateral that should carry 3 peaches at harvest, then you have four times as many live flower buds as are required for a full crop.
More info can be found at: http://extension.psu.edu/plants/tree-fruit/news/2014/grab-some-buds