In Casper Wyoming this year they are losing most of their trees. The temperature dropped from the 7o's to below freezing very quickly. Most of the trees had their leaves and flowering and then it froze. Apparently with the sap in them it affected them too much and they are dying. We have had a problem here in Oklahoma I have noticed with the red bud trees. We had a similar situation here. The red bud leaves turn yellow on trees. I wonder if it will kill the trees.