Arborvitae - Ask Extension
Just seeing some severe discoloration in my arborvitae. I assumed it was because of lack of water but wanted to see if it was potentially something e...
Knowledgebase
Arborvitae #880724
Asked August 08, 2024, 2:45 PM EDT
Just seeing some severe discoloration in my arborvitae. I assumed it was because of lack of water but wanted to see if it was potentially something else? Is the discolored tree still viable and able to be saved?
Prince George's County Maryland
Expert Response
No, the plant pictured cannot be saved, unfortunately. Once conifers (needled evergreens) like arborvitae discolor, becoming a sickly yellow-olive-green or any shade of brown (excepting varieties that change color in winter, which is not applicable in this case), they are a lost cause and cannot recover. What originally caused the damage is hard to determine once it's this advanced, and conifers are notorious for not showing obvious indications of drought stress until it's too late and foliage dies off after the fact. Frustratingly, both over-watering and under-watering can cause similar-looking symptoms.
Was the planting irrigated periodically during the drought? If not, then perhaps this was due to roots getting too dry, or drought stress attracting a secondary issue like a fungal canker infection or wood-boring insects that caused too much damage to the main trunk. If it was being irrigated, perhaps the soil didn't drain well enough or watering was taking place too often, as arborvitae don't have a good tolerance for wet soils or those low on oxygen (due to wetness or heavy compaction).
The plant in the foreground is definitely dead/dying, but a couple behind it also look suspect for dieback, as they appear to be a yellower green color characteristic of decline. (The plant immediately behind this one, and another a couple plants down the row.)
Current rain aside, if you feel the soil around six inches deep next to the roots and it has become somewhat dry to the touch at that depth, then a thorough watering is probably needed. If damp when checked, though, watering can wait. How long the recent rains last will be hard to predict (it depends in part on soil type and drainage), but if the rest of autumn trends dry again, the plants will need occasional irrigation to make sure they're in good health going into winter.
Miri
Was the planting irrigated periodically during the drought? If not, then perhaps this was due to roots getting too dry, or drought stress attracting a secondary issue like a fungal canker infection or wood-boring insects that caused too much damage to the main trunk. If it was being irrigated, perhaps the soil didn't drain well enough or watering was taking place too often, as arborvitae don't have a good tolerance for wet soils or those low on oxygen (due to wetness or heavy compaction).
The plant in the foreground is definitely dead/dying, but a couple behind it also look suspect for dieback, as they appear to be a yellower green color characteristic of decline. (The plant immediately behind this one, and another a couple plants down the row.)
Current rain aside, if you feel the soil around six inches deep next to the roots and it has become somewhat dry to the touch at that depth, then a thorough watering is probably needed. If damp when checked, though, watering can wait. How long the recent rains last will be hard to predict (it depends in part on soil type and drainage), but if the rest of autumn trends dry again, the plants will need occasional irrigation to make sure they're in good health going into winter.
Miri
Hello,
As always, thank you for the information. Would you replant arborvitae in the same space or would you recommend a different variety potentially? We have dealt with bagworms and fungal issues with these 3-4 trees before.
Thanks,
Mara
Hello Mara,
You could replant with arborvitae if you want, as it's hard to guess as to why the current plant(s) failed. If the soil drains well, can be watered during drought, and receives full sun, then the location should be fine for growing arborvitae. If poorly drained, then certain other evergreens (though it's a limited list) may tolerate wetter soil, and if it skews dry or is unable to be regularly monitored for watering needs during drought, that a different group of evergreens (primarily junipers) would be better-suited to the conditions. Unfortunately, bagworms can consume a wide variety of evergreens (plus some deciduous plants as well), so few alternative plants would be immune to their impacts if they continue to be a problem. Fungal issues with arborvitae tend to be root-related with regards to root rot in poor drainage or if over-watered, and less so with above-ground branch or foliage infections, as can happen more often with deciduous plants. In our experience, dieback on conifers like arborvitae is often tied to root health.
Miri
You could replant with arborvitae if you want, as it's hard to guess as to why the current plant(s) failed. If the soil drains well, can be watered during drought, and receives full sun, then the location should be fine for growing arborvitae. If poorly drained, then certain other evergreens (though it's a limited list) may tolerate wetter soil, and if it skews dry or is unable to be regularly monitored for watering needs during drought, that a different group of evergreens (primarily junipers) would be better-suited to the conditions. Unfortunately, bagworms can consume a wide variety of evergreens (plus some deciduous plants as well), so few alternative plants would be immune to their impacts if they continue to be a problem. Fungal issues with arborvitae tend to be root-related with regards to root rot in poor drainage or if over-watered, and less so with above-ground branch or foliage infections, as can happen more often with deciduous plants. In our experience, dieback on conifers like arborvitae is often tied to root health.
Miri
