Green Giant Thuja Problems

Asked June 8, 2020, 3:28 PM EDT

We planted a row of 20 Green Giant Thuja on the East side of the house in the Spring of 2017. This is in the country with an open field. They have been Green since then even thought the deer used some of these 4 foot trees for a rubbing post during the first winter. Now they are turning brown (but now dead). Some trunks are splitting and some branches show an open wound near the trunk. What is going on? What can I do?

Monroe County Michigan

1 Response

Thanks for the question. The tree looks pretty bad. The holes in the face of the injury are probably secondary to other problems with the tree. The giant would is older since it shows some significant healing. There seems to be some supports and perhaps a tie just above the big wound that looks like it has grown into the tree. Tree staking should be removes after the first year of transplanting. If the big wound is on the south side it could indicate the wound winter damage (frost cracking). This could weaken the tree and set it up for pests and disease. Water could also be an issue. The brown needles could also be winter injury (dessication). There also may be some branch cankers. There also seems to be no root flare indicating the tree was planted too deep. Overall, the tree seems stressed probably due to cultural issues and secondary pests and disease,
https://www.extension.purdue.edu/extmedia/id/id-477-w.pdf
https://www.purduelandscapereport.org/article/top-arborvitae-aggravations/
https://www.mortonarb.org/trees-plants/tree-plant-descriptions/giant-arborvitae
I hope this is helpful,