wrapping trunks of young fruit and nut trees
What is the best way to wrap and protect the trunks of young fruit and nut trees?
It really depends on what the purpose of wrapping them is. One of these articles may help you:
If you're looking to protect them from deer, this article may help you: https://www.gardeningknowhow.com/plant-problems/pests/deer/how-to-protect-trees-from-deer.htm
If the bark is showing signs of distress, that may or may not be normal for that type of tree, and you'll need to identify the issue in order to treat it appropriately.
If you wrap any trunk for winter, you'll want to remove the wrap in the spring.
If your intention is to provide protection from sunscald, this article may help you (and gives specific tips for fruit trees): https://www.gardeningknowhow.com/plant-problems/environmental/sunscald-on-plants.htm
For the nut trees, select the type of tree from the category list here, for information specific to the type of nut tree you are growing: https://www.gardeningknowhow.com/edible/nut-trees/