Mountain Ash problem #700463 - Ask Extension


Mountain Ash problem #700463

Asked July 13, 2020, 8:31 PM EDT

We planted a nursery-grown 9-ft mountain ash last fall on our Lake Superior property. It seemed very healthy this spring and early summer and bloomed beautifully. A couple of days ago we noticed that most leaves had suddenly become brown, especially around the edges. We also found insect activity. Another smaller mountain ash about 15 feet away, transplanted last fall from another spot on our property, seems fine (although it did not bloom). We have been watering both regularly. These trees are planted in an area behind a sea wall we had replaced last summer. The planting area was disturbed, and a foot of gravel now helps drainage behind the wall, but we added much soil before replanting this area. Previously, several mountain ash had thrived in this spot. Let us know if you have any idea what may be wrong with this tree and if there is anything we can do to help it.

Cook County Minnesota

Expert Response

Based upon your comments, we believe the tree might be suffering from transplant shock. Leaf scorch, (brown edges) is a common symptom.

The following bulletin discusses transplant shock, what causes it and how to minimize it to get plants off to a good start. (Especially note paragraph three as it pertains to your tree.)

We can't identify the caterpillar.  Unless there are many causing defoliation, it's probably not affecting the tree's health.

Bob Bystrom Replied July 14, 2020, 4:12 PM EDT

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