My parents have 3 ash trees in their yard. They are 4-5 yrs. old, and all have splits in the bark. But only on the larger limbs and trunk. Some are 2-3 feet long, and 1/4" -1/2" wide. The leaves show no distress, and growth seems fine. What could this be?

Hi Ed, could have been damaged during planting. or could be frost cracks. not much can be done now. at least they appear healthy. water during drought and mulch and let them regrow as best they can.