Arborvitae Help!

by Mark Stare
(Bel Air, MD)

Arborvitae showing brown patches

Arborvitae showing brown patches

Last year we removed over grown 20 year old Leylands. They were blocking the sun completely from our back yard. Had the soil tested and it was fine. Planted Arborvitae in the same spot. They sprouted new buds this spring so I put the weed block mesh down and mulched. Since then we have gotten brown spots.

I have been watering twice a week about 5 gallons per tree each time.

How do I fix this and get my plants healthy again?

Comments for Arborvitae Help!

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Jul 14, 2020
 When you say...
by: Jacki Cammidge, Certified Horticulturist

When you say, the soil was fine, what does that mean? Lots of nutrients? Good pH? What exactly were you testing for?

Leyland cypress are known for cypress root rot. They don't live very long any more, so the days of old established leylands are gone. Arborvitae (Thuja) are not related, so generally, they don't get the same diseases.

This issue looks to me like some kind of root problem, but different. I'm wondering what you purchased; ball and burlap? In a wire basket? Field dug? In pots? I think it might be worth sacrificing one of them (maybe at the end of the row) and seeing what's going on with the roots. Are the roots tangled around each other, or spreading out?

Fortunately, it looks like it's not too late to do something, but the question is, what? What's the best treatment, or not?

I might just trim off the worst looking brown patches, give supportive care (continue watering, carefully, no fertilizer) and see what happens.

What is your water source? Is it a deep well, by chance? There are certain kinds of minerals that don't benefit plants. I prefer rainwater, which is cleaner. Is your water very cold? This can be an issue as well.

Also, are you watering from overhead? This can cause browning as the sunlight on the water can burn the leaves. Drip irrigation is best.

This type of browning can also occur in cold, dry winds, so if that sounds like it's what happened in the winter, you may have to wrap the trees in the winter. Personally, if a plant doesn't survive in my garden, out it goes.

Sometimes these kinds of issues resolve themselves as the plants get established.
Jul 14, 2020
 More help
by: Mark

Jacki Thank you that was helpful. Soil was tested for PH. Was told it was acceptable. Wasn’t given a specific number.
They were potted from a nursery. We bought them online and they shipped in a protected box in the pot.
I did use the Jobe spikes for his year. Per the directions two per tree.
Thank you again

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