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Monday, April 10, 2017

Limb Damaged. Will It Survive?

Q. Can you tell me if this tree will survive and what I need to do we have three purple plums and do not want to loose. 


A. Judith. Let me tell you what I think happened and then I will explain whether it will survive or not. This tree appears to be the purple leaf Plum. I see some branches coming from this large limb on the upper surface of it. Perhaps the started growing about three years ago?

There is damage to at least one side of this limb. My guess is that this damage faces the South or West. I am guessing that several years ago this limb received sunburn damage to this side. Shortly after this damage or possibly even before this damage, boring insects or borers entered this limb. The female borer is a small beetle about 3/8 inch long and she deposits her eggs close to these damaged areas.
This borer damage started as sunburn to the trunk of this ash tree.

The young from these eggs burrow into the limb where they feed on the soft, juicy, sweet tissue just under the bark. This feeding causes the limb to die in a larger area usually only near this sunburned area. Areas not in direct sunlight, like the top and bottom of the limbs, are usually not damaged.
Borer damage to ornamental plum again for the same reason, it started with the sun damage and then progressed to insect damage.

I cannot tell how much damage this limb has without a closer look but I am guessing it is not bad enough to remove unless there is extensive dying of the smaller limbs attached to it. You can apply an insecticide around the base of the tree called Bayer Advanced Tree and Shrub Protect and feed which will kill the boring insects inside the limb and protect the tree for as long as 12 months. This may give the tree enough time for recovery to begin.

A word of caution: the active ingredient in this insecticide has been implicated in honeybee decline but not proven. There is evidence both pro and con. But it is best to apply this after the tree has finished flowering.

Make sure the tree has enough water so that it is not getting water stressed. This means make sure there are enough drip emitters or they are large enough to support the tree. This tree probably needs somewhere around 30 gallons each time it's watered. Watering once to twice a week is enough. Around May, that will change to two three times per week. This tree grows best if the top of the soil under its canopy is covered in 3 to 4 inches of wood chip mulch, not rock mulch.

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