Mature Arborvitaes dying

Asked September 24, 2019, 8:43 AM EDT

Monroe County Extension office submitting question on behalf of a resident.... "We have a line of mature green arborvitae 15-20 feet tall. In the last few years , we have had to remove a few of the arborvitae because they have browned, lost leaves and died. These arborvitae are a haven for hundreds of birds over the years and we do not want to lose anymore. One local nursery said maybe bag worm but no signs of that and another nursery confirmed that it is not bag worm. Looking on your MSU site, one of your articles said the browning and dropping of leaves or twigs at the end of the branches is not normal and could kill the entire branch. We do have this happening again. We are concerned now about losing the next arborvitae in our line as it seems stressed more than the others. I don’t know if there could be a disease going down the line killing each one or what it could be , please advise. We would like to have an expert examine our arborvitae before we lose another one. This spring we bought a 5 foot arborvitae replacement but are concerned we will keep losing these arborvitae without a diagnosis and treatment. I’ve explored the MSU extension website for information and help as far as I could. I hope the MSU extension office will help us resolve this issue. Thank you for your consideration and attention." -Sharon McNeil

Monroe County Michigan

1 Response

Hello Sharon,

While MSU doesn’t have any on site services for homeowners, you can hire a certified arborist, a professional who has taken training in care, diseases, pests and passed certification tests. He/she will come on site and give a complete diagnosis and a plant care plan. Find certified arborists by zip code here—-

What you can do yourself- Check soil moisture down 8-12 inches and keep the arborvitae watered at the base, keeping leaves dry. Mulch with shredded bark or wood chips around the base, and do not let the mulch touch the trunks.

The most important thing is to keep evergreens ( all trees actually) watered during dry times from spring through late October until the ground freezes. Evergreens never really go dormant and must have water stored in their roots for the winter.

Correctly planting your new shrubs is important to success. Here is the Tree Owners Manual which explains correct planting, mulching and care. It applies to arborvitae, too.

If you have any questions on this, please write us again. Thank you.