Tear like features on willow limbs

[Dave Mackay]

We have some mature willows with tear like features on some of the main stems, it looks like lighting strikes about 8- 10 feet long but they are height up and don't reach the ground. There are about 15 trees in a row spread over 300 yards. Has anyone any idea what would cause this and what problems are associated with this 

Edited January 23, 2020 by Dave Mackay

[Alinicoll]

They look like strip cankers. Whats the soil like? Drought stress can cause this.

[Dave Mackay]

The trees are on the edge of a path but next to a meadow which was dry last summer up until late September when it flooded. It's a high footfall area, so I am concerned about what damage this may have caused to the trees.  Any advice ?

Thanks Dave