If you've recently planted a new tree, especially a younger specimen, and it receives daily full-sun exposure, you'll want to consider ways to protect it from possible sun scalding. Bark is the natural defense against the sun, but most new trees (younger then 2) won't have established enough bark to protect it from the sun, especially during long periods of exposure. Wrapping or painting tree trunks is one of the most effective and cost efficient ways of protecting the trunk while the bark on the young tree is still forming. As the tree grows, the "skin" of the trunk gradually forms bark which insulates better against the sun. At the same time, the canopy of the tree becomes wider and blocks the sun from reaching the trunk of the tree. Once these have occurred, it isn't necessary to wrap or paint. This usually takes 2 to 3 years for most trees.
If you keep the canopy of your existing trees trimmed high enough that the sun hits the trunk, we recommend wrapping during the summer months. Any light colored cloth material or light colored, water based latex paint will suffice. For best results, use professional tree wrap, available at Big Tex Nurseries.