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Near where I live there is a stand of Eastern White Pines that are all about 100 feet tall.

Last year one of the trees was struck by lightning and severely damaged, partially collapsing. The top of the tree that was struck fractured off.

I notice that the two trees that were on either side of it now appear to be dead. All their needles from top to bottom are brown.

Is it possible that lightning somehow killed these trees by electrocution without physically destroying or damaging them in any visible way?

I would note that these trees are very closely connected. The part that was struck was actually coupled to one of the trees and grew out of the same root. That half (the half of the tree that was struck) is completely dead and has insect borings in it. The third tree, even though it is not visibly conjoined to the other seems to share roots with it somehow because its base is right next to the base of the other.

Also, I would mention that both trees have a strange wet spot near their bases. The wetness appears to be water and in both cases covers about half of the circumference of the trunk and is about 3-4 feet in height.

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  • Can you add a photo showing the wet spots?
    – Bamboo
    Sep 5 at 15:19
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Obviously, electric currents generate heat and that is the primary cause of damage in a lightening strike.

If we consider can electrical currents damage a plant by means other than their heating effect, the answer is "yes". Whilst not possessing a nervous system, plant cells can generate action potentials (by creating a difference in ion concentrations across cell walls). They can use them for signalling and cellular control. Externally applied electrical currents can disrupt these action potentials and interfere with the normal function of the cells. I have observed that leaves touching electric fences in my field eventually die, although the rest of the plant remains unharmed.

In the case of your lightning strike, I am doubtful that what you have observed is due to anything other than the heating effect. It is mostly likely that current flowed down into the roots of the tree that was struck and then into the roots of neighbouring plants (they are likely to be more conductive than the surrounding soil) causing them to heat up - it only needs to get them hot enough to kill the cells (around 60°C). It's not necessary to turn the water into steam to kill the plant.

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My answer is "maybe". One unknown variable is the energy in a particular lightening strike. There are southern pines in this area, typically 100ft tall. A few years ago a pine near the street was hit by lightening; the bark was exploded full height by steam pressure from about 1/4 of the circumference.( I noticed it the day after as there were chunks of bark in the street). But more interesting , there was about a five foot long, several inch deep trench over to the buried cast iron sewer pipe. I expect this was caused again by steam caused by the lightening power flow. I think that is evidence that lightening can cause damage underground in the immediate area of the struck tree.

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