Weed whacker damage to trees
Unfortunately, there is nothing you can do to remedy the damage that is already done. We do not recommend putting any type of sealant on the wounds. That can actually be counterproductive because it can hold in excess moisture and lead to rot and other problems. I recommend that you create a mulched area around the trees to protect them from further mower injury. Please refer to our page about mulch for information on the correct placement and depth. Do not place the mulch directly against the trunk. https://extension.umd.edu/hgic/topics/mulch
If you would like to have an arborist do an assessment of the trees, you can find a certified arborist near you using this website from the International Society of Arboriculture, https://www.treesaregood.org/
Also, I wanted to ask if we may have permission to use your photos for teaching purposes. We would not use your name or any other identifying information. Your photos illustrate a clear example of "how not to treat a tree" when it comes to lawn mowing, which can be instructive to others so they can avoid this type of problem.