Summer storms bring the crackle of lightning and the rolling boom of thunder. If it’s coastal Georgia in summer, watch for those 3 p.m. thundershowers.
Sometimes the lightning strikes trees. Many times, the strike may not harm the tree at all. Sometimes the strike will explode a tree into toothpicks.
Lightning can do almost anything or nothing. How much injury a tree suffers from a strike depends on the nutrition of the tree, the growth phase it is in at the time, the weather and the strength of the discharge.
What to do after a strike depends on tree species and the severity of injury to the tree. You ask, "Gee, Don, what does that mean to me?"
It means there is no single answer to cover what to do after a lightning strike to a tree. There are some general guidelines that usually apply and things you can watch for. So think of this as a "what every homeowner should know about lightning-struck trees primer."
First, if the strike didn’t blow out all the electronics in your home, enjoy your good luck. Second, if the tree has broken or collapsed limbs and branches hanging in it, you will probably want to have those removed soon, unless you can keep people and pets out of the area for the next month. If it is safe to approach the tree, look for the course of the strike. If the trunk is split by the strike, removal is probably indicated. If the bark has been blown off half way around the tree at any point, the tree will likely die.
If it is a pine tree, start checking it at least weekly for beetle injury, even if the tree shows no outward sign of the strike. The two things to look for are the accumulation of fine sawdust at the base of the tree and spots of resin eruption from the trunk. If you see either of these, it is important to remove the tree and at least get the trunk horizontal on the ground as quickly as possible. It is better to have the trunk removed from the site altogether so it does not become a source for the beetles to launch attacks on nearby healthy pines. The decision on pines is fairly straightforward.
Hardwoods, and especially live oak, present a more complicated assessment. It is better to wait 30 days before doing any pruning on lightning-struck hardwoods, as it will take about that long for everything that was killed to show the extent of injury. Lightning strikes that traveled along the outside of the barks and did not discharge into the tree are the most survivable.
Next, a strike that gouged a thin strip of bark and maybe a little wood as well is the next level down in survivability. Strikes that blow off bark but not wood are less survivable. Strikes that split trunk-wood are generally fatal to the tree due to the loss of structural integrity.
As with pines, watch for fine sawdust accumulation at the base of hardwood trees. If beetles are in the tree, it is probably beyond saving. Injured trees give off fragrances that the bugs react to like dinner bells. They generally do not attack healthy trees. Ambrosia beetles in a tree are a good indicator that the tree is too far gone to save. Don’t waste money trying to save a tree that is already dead.