Plum Transplant Shock and Dieback ..Or is it?

Readers plum tree with dieback

Q. Attached are some photos of my semi-dwarf plum we just planted in September.  The left side of the tree seems to be dying.  The leaves are all browning.  We have it on a drip system along with a few other trees and shrubs which are all doing fine.  We water about 15 minutes each day. I sent these photos to the nursery and they said it’s transplant shock and it should be fine.  What is your opinion? 

A. After seeing your pictures I do not believe it is just transplant shock. Trees that large, when transplanted, go through a lot of shock which is true. It is always best to buy the smallest container size possible as it will catch up and surpass a larger tree due to a lesser degree of “transplant shock”.

            Transplant shock is when a plant has to “reorganize” and “renew” its root system as it leaves a container in a protected environment like a nursery and is put into a different, usually harsher environment.  Up to and from an

            The root system grows differently in a container than it does in the ground. When growing in a container, roots gather where there is the best water/air/nutrient environment; usually at the bottom and sides of the container.

First of all this is not my picture. I borrowed it from
Washington State University
(https://sharepoint.cahnrs.wsu.edu/blogs/urbanhort/archive
/2011/03/23/plant-containers-does-size-really-matter.aspx)
but it does demonstrate how roots grow in containers nicely.

            Once in the ground, the best environment for roots shifts and is nearer the soil surface. This results in a “reorganization” of the roots as it adjusts to this totally new soil environment. During this shift new roots grow near the soil surface and older roots deeper in the soil die resulting in “transplant shock”. The degree of transplant shock results from the condition of the plant going into the ground as well as how it was handled at planting time.

            Now on to your tree and how it was handled at planting. Hopefully you dug the hole three to five times wider than the container. It did not have to be deep, just deep enough for the roots to be planted below the soil level.

            Next, hopefully, you amended the soil going into the hole with lots of compost and a starter fertilizer to mix in the backfill. The plant should be planted the same depth as it was in the container, no deeper and staked to keep the roots immobilized.

            In one picture you sent the tree appears to be planted fairly deeply but it is hard to gauge from a picture. If planted too deeply it can kill or damage the tree.

            Next the tree must be staked to prevent movement in the wind during the first complete growing season. Sometimes on larger trees that have more severe “transplant shock” it may require a second season. The stake should prevent the movement of the roots in the soil, not necessarily top movement. This is extremely important on container trees especially older container trees.

            I don’t think 15 minutes is enough time for irrigation unless during that 15 minutes you are giving the tree at least ten or maybe 15 gallons each time.

            Thirdly, every day watering is not necessary and may cause a problem similar to what you are seeing. Every day watering is fine in containers but once in the soil there is alot more soil available to hold water so every other day or even every three days is probably adequate during the summer. Planting in the fall you probably will get by watering twice a week.

            Lastly, the tree will do much better with a thick layer of mulch around the tree extending about three feet from the trunk in all directions but keeping the mulch six inches away from the trunk to prevent the trunk from rotting.