What's wrong with these arborvitaes? Help!

[garyacker]

We have 10 large arborvitae shrubs which have done well for many years as a hedge along our fence. Early this year they all started showing damage on the bottom third of the tree, what at first appeared to be deer damage. However, where the trees are damaged, there is protection from deer with netting, and are not accessible.

I would like some opinions on what's happening and what can I do!

(BTW We have another group of arborvitae the same size, which are perfectly fine.)

 

[Marck]

Greetings, welcome to the Forums.

That is an interesting pattern of necrosis or defoliation. Are you seeing bitten branch stubs suggesting that something chewed off the young branches? Are these Emerald Green Arborvitae (Thuja occidentalis 'Smaragd')?

 

[garyacker]

Yes I believe they are the Emerald green variety. I don’t see evidence of branches being eaten and also this happened quite quickly just the last 2-3 weeks

 

[Marck]

Wow, that's a lot of brown-out in just a few weeks. Does it seem to be moving up the trees or did it all appear at once and then stop?

Thuja occidentalis 'Smaragd' is considered hardy to USDA Zone 2 so weather doesn't seem likely to be playing a role.

 

[garyacker]

So it appeared quickly but I don’t think it’s spreading up the tree but I haven’t actually measured to confirm. I took some more close ups.

Do you think these photos show deer damage? I just can't see how they could access with all the netting around the area.

I would really value opinions on the cause, and more importantly, what should I do now to try to salvage these.

 

[Marck]

In the photos in Post#5 there is evidence of stems being entirely chewed off. This could be the work of smaller mammals (rodents, lagomorphs).
It might also be possible that hungry White-tailed Deer (Odocoileus virginianus) could press up against or reach around the netting to access some stems.

 

[DirtMechanic]

That horizontal line tree to tree is a pretty strong clue something acted upon them rather than inside out. I was going for an errant spray pattern\chemical burn until the deer theory got advanced. That line is machine perfect so I had to look again. Did this happen after the netting went up? Does that netting have a chemical smell in the hot sun? Are you a friendly neighbor?

 

[Mike Allen]

Could be a conifer mite infection. Remove all damaged material. Spray/treat as best you can the remaining tree and the possible contaminated soil area. Sadly, the future looks dim.

 

[garyacker]

As far as chemical burn, the only

That horizontal line tree to tree is a pretty strong clue something acted upon them rather than inside out. I was going for an errant spray pattern\chemical burn until the deer theory got advanced. That line is machine perfect so I had to look again. Did this happen after the netting went up? Does that netting have a chemical smell in the hot sun? Are you a friendly neighbor?

Yes this did happen after the netting went up.

hmmm.. I did use a deer repellent granular at the base of each tree. It was the "Liquid Fence" brand but the ingredients are egg solids, garlic, sodium lauryl sulfate, thyme oil, and diatomaceous earth, nothing that would appear harmful.

Definitely not the neighbor.