Emerald Green Arborvitae

[StLouis]

We have approximately 20 Emerald Green Arborvitae evergreens (Thuja occidentalis "Smaragd") as a border between ourselves and our neighbors.* Ten of these plants are approximately 5 years old, and the other 10 were just planted 1.5 years ago.* The ones planted 5 years ago really thrived and did great, showing a lot of new growth this past summer and the new ones seemed to be settling in fine (We only had a slight problem with those planted in moderate/heavy shade).** It appears as if overnight they started browing from the inside out and are really started to look like they might die.* We checked for spider mights, but saw nothing, and we just fertilized and put new mulch down a month or two ago.* Does anyone know what is happening?* I would really hate to loose these plants, we have put so much time and money into them and they are just starting to give us the privacy we were wanting.*

[Newt]

Hi StLouis,

You do say they are browning from the inside out, but is it from the bottom up too?* Often some environmental change can cause sudden problems.* You mention that you fertilized and mulched about two months ago.* Did the problem start after that?* If so, they could be suffering from fertilizer burn or there is too much mulch piled against the trunks.* The mulch should not touch the trunks. Some browning and shedding of older interior needles is common, especially in fall.

Here's some other possibilities.* Take a look and see if anything fits.
http://www.agf.gov.bc.ca/cropprot/cedar.htm
http://www.agr.gc.ca/pfra/shelterbelt/evergreen_e.htm

Cercosporidium Blight could be another cause if the browning is from the bottom up.* Leyland cypress is also effected by this, so take a look here.
http://www.doacs.state.fl.us/pi/enpp...circ/pp397.pdf

Were these planted with burlap on the rootball?* If so, check to see if the burlap or twine has turned to a blue or green color by digging down gently.* Sometimes burlap and twine are treated with copper sulfate.*

Newt

[StLouis]

The trees are browning all over from inside out, not from down up.* I will check the root ball this afternoon.* The browning didn't start until last week, at the earliest.* One tree started looking bad and then all of sudden all of them turned, almost overnight.* Could this be from fertilizer burn?* My husband applied it and it is possible it was put close to/touching the trunk.** I checked out the site regarding cercosporidium Blight and it doesn't look like the same thing.

[Newt]

It could just be the normal shedding, but best to check the other items I mentioned first.* Btw, have you had a sudden change in the weather?

Newt

[StLouis]

I asked my husband about burlap on the root ball, and he said he removed it before planting.* We were having an Indian Summer for awhile, was back into the 90s for several days last week, so we were wondering if it could just be a lack of water?* We slowed down the watering schedule because the weather was cooler.* I guess we can just do what we can and hope for the best.* How do we deal with fertilizer burn if that is the case?

[Newt]

Glad your hubby removed the burlap.* Have your hubby check this site to see if he may have planted them too deep and mulched properly.
http://www.ext.nodak.edu/extpubs/pla...ees/f1147w.htm
http://www.treesaregood.com/treecare/mulching.aspx

Just because it gets cooler doesn't mean that the soil won't dry out.* Winter winds can also cause drying of the foilage.* If the ground isn't frozen in winter, there's no snow cover and no rain, you will need to water - especially in the first year.
http://cals.arizona.edu/pubs/water/az1298/
http://www.watersaver.org/pdfs/FALL_..._FOR_TREES.pdf

Maybe these will help.
http://www.treegator.com/
http://www.engineeredwatering.com/Ooze_Tube.htm


The best way to deal with fertilizer burn is to flush the area with water to rinse away as much of the chemicals as possible.* I'm guessing you used a synthetic fertilizer and not an organic one.* Organics rarely burn plants.* Best to topdress with an inch of compost in spring.* Just move the mulch aside, add the compost and put the mulch back.*

You should find this site helpful with info on Arborvitae.
http://www.aboutarborvitae.com/

Newt