South Dakota

“I have a little bit of a question; hope you guys can clear something up for me.

“In my grove, I have about 40 ash trees. When they were planted in ‘89, the person, of course, was thinking the closer, the better. Well, now, after all the years, they are huge. The problem I have is that I think when they were growing they should have done some easy pruning on them so they would not have three or four leaders on each tree. Now they are about 40 feet tall and are all smashed together. They can only grow up and have no room to branch out. So, what I have started to do is cut all of the leaders down to one per tree, if that makes any sense. What I am thinking is by doing this, I will encourage them to branch out.

“They are planted maybe 10 to 12 feet apart. Would I be better off cutting every other one out and removing the leaders on the ones that are left?”


“By the way it sounds, it sounds like you topped them, more or less. Call a tree care company out to do the work. In most situations, don’t top.”

South Dakota

“I have no idea what you are talking about. Could you let me know what this term means? Does it mean cutting the top back like you would do to an apple tree.”


“Whatever you do, don’t take any more than about 20 percent of the live foliage out in one year. The rule of thumb for pruning is remove dead, diseased, damaged, crossing and competing first. If you are under 20 percent, then you can prune for aesthetics or space.

“I would hate to see you cause damage to the tree. You may even create hazards if you get it wrong. I hope you don’t create liability issues for yourself. Also, be careful working at [that] height. A decent climbing arborist has all the tools and the techniques to work for the benefit of the trees and their owners.”


“White ash (Fraxinus Americana) has a mostly upright form. This meaning, most of the time, one trunk from the bottom and then it starts to branch out in the top. A white ash more than likely will have multiple leaders in the top, it’s just the way they grow. This tree can, and normally does, grow to 50 to 80 feet with a similar spread.

“Green ash (Fraxinus Pennsylvanica)  are normally planted as ornamentals. They grow more of a spreading form. They normally branch out at the bottom into several leads. One thing about green ash is they grow very fast in a wide variety of sites—they do well as street trees. They can grow as big as 60 feet tall (I’ve never seen it); tallest I have ever seen was around 35 to 40 feet.

“I will warn [you], it is very difficult to tell the difference between the two. A good book to help you with this would be ‘Manual of Woody Landscape Plants.’

“Another consideration for hiring an arborist is they will know if emerald ash borer (EAB) is in your area. EAB destroys ash. If it is in your area and you stress your trees too much, you might invite them to a feast on all of your ash trees.”

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