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Tuesday, January 27, 2015

Tree Trunk Damage Best Left Alone

Q. I have a beautiful 10 foot tall oak that has provided privacy with it's wonderful light green, very dense foliage. I enclosed a picture of a rapidly expanding bark rot-looking area that seems to be circling the trunk and moving upward at the same time. Can this be stopped, cured, or is it life threatening to the tree?
Damage to trunk of oak from reader

A. From your picture, which I posted on my blog, this damaged area of the trunk near the ground seems to be on the mend. You can see the bark “rolling” in over the wound. Allow for the tree trunk to heal on its own. Pull away any rock or wood mulch touching the trunk and make sure irrigation is not too frequent.
Tree tissue rolling over large wound

From the looks of the damage, this was a “traumatic” event and not a disease. After damage like this the living layer around the damage forms a “compartment” that isolates the damage and heals over and around the wound. This reaction is normal to a healthy plant after an injury that is a one-time event and not getting worse.

At first it looked like collar rot, a disease, that was developing but I don’t think so. Just to be on the safe side, pull any gravel or would surface mulch away from the trunk a distance of 12 inches and keep the trunk as dry as possible.

If there is irrigation water applied close to the trunk, then move the source of the water a distance of 18 to 24 inches away from the trunk. When you are watering, avoid daily or every other day irrigations which might keep the soil wet.

Deliver the water the tree needs for several days all at once, not a little bit every day. Judging from the size of your tree this might be around 20 gallons at a time.

Trees of this size should receive water from drip emitters in at least four different locations under the tree canopy. If you are delivering 20 gallons and you have four emitters then they need to run long enough for each of them to deliver 5 gallons each.

In winter, irrigate about once every 7 to 10 days or possibly longer if you can determine the soil still has moisture. In summer time you might water once or possibly twice a week if you have several inches of mulch laying on the soil surface. 

1 comment:

  1. Thank you Robert. I am very late reading my e-mail and was pleasantly surprised to see my tree photo and your explanation in the paper. I thought it was rot because an earlier and higher damaged area healed. I think you are correct, because the drip system that is completely underground was probably set in a small circle when DR Horton planted the small tree. I also may be the culprit, as I hand water small surface root plants surrounding the tree, and frequently splash water on the trunk during the summer months. I will adhere to your watering advice because I feel that the issue could be exacerbated by the lack of sunshine from the west because of the boulder, a towering Shoe String Acacia from the south, and it being 5 feet from the house on the West side.

    Again Thanks.