What's wrong with this Dogwood Tree - Ask Extension
Please look at the leaves and let me know what's wrong, and how to treat thee tree to reverse this problem.
Knowledgebase
What's wrong with this Dogwood Tree #807586
Asked August 22, 2022, 9:41 PM EDT
Please look at the leaves and let me know what's wrong, and how to treat thee tree to reverse this problem.
Baltimore County Maryland
Expert Response
The leaf damage looks like the phenomenon we call scorch, which is essentially just drought damage because something is interrupting the water flow from the roots up to the foliage. This could be the result of root damage, trunk damage, or injury to the branch bases wherever scorch is appearing.
This looks like a Kousa Dogwood (Cornus kousa), a non-native species planted for its improved pest and disease resistance compared to our native Flowering Dogwood (Cornus florida). We base this ID largely on the foliage that looks unafflicted with mildew or leaf spot, common ailments on native dogwoods by late summer, and on the appearance of its bark, which typically flakes off in chips or layers as Kousa dogwoods age. (Though this tree's bark flaking looks more excessive than average, which might be unrelated to the foliage stress and just a unique feature of this individual tree.)
There is no treatment except to irrigate the tree as needed, assuming it's not getting too much water or had any roots damaged by digging or compaction (like a vehicle driving onto the root zone). In that case, the tree would just need more time to recover, if it's capable of doing so by growing replacement roots. In the meantime, any branches that have defoliated or died can be trimmed off, especially any that never leafed-out this spring. Several infectious diseases and wood-boring insects target trees under stress, even if that stress isn't causing obvious symptoms yet. If a fungal canker or borer caused the dieback of select branches here, they may have arrived after the drought stress or other issues arose. If present in the tree now, they are not treatable with insecticides or fungicides, but won't necessarily spread to healthy trees nearby that are growing well.
Feel the soil about six inches deep in the tree's root zone and water well only when it becomes minimally moist to the touch at that depth. Watering more often risks over-saturating the roots and depriving them of oxygen, which can cause root death. Does a roof downspout empty nearby, or did any other drainage patterns in this part of the yard change in recent months? Was the structure that looks like a short retaining wall newly installed in the past few years?
Miri
This looks like a Kousa Dogwood (Cornus kousa), a non-native species planted for its improved pest and disease resistance compared to our native Flowering Dogwood (Cornus florida). We base this ID largely on the foliage that looks unafflicted with mildew or leaf spot, common ailments on native dogwoods by late summer, and on the appearance of its bark, which typically flakes off in chips or layers as Kousa dogwoods age. (Though this tree's bark flaking looks more excessive than average, which might be unrelated to the foliage stress and just a unique feature of this individual tree.)
There is no treatment except to irrigate the tree as needed, assuming it's not getting too much water or had any roots damaged by digging or compaction (like a vehicle driving onto the root zone). In that case, the tree would just need more time to recover, if it's capable of doing so by growing replacement roots. In the meantime, any branches that have defoliated or died can be trimmed off, especially any that never leafed-out this spring. Several infectious diseases and wood-boring insects target trees under stress, even if that stress isn't causing obvious symptoms yet. If a fungal canker or borer caused the dieback of select branches here, they may have arrived after the drought stress or other issues arose. If present in the tree now, they are not treatable with insecticides or fungicides, but won't necessarily spread to healthy trees nearby that are growing well.
Feel the soil about six inches deep in the tree's root zone and water well only when it becomes minimally moist to the touch at that depth. Watering more often risks over-saturating the roots and depriving them of oxygen, which can cause root death. Does a roof downspout empty nearby, or did any other drainage patterns in this part of the yard change in recent months? Was the structure that looks like a short retaining wall newly installed in the past few years?
Miri
Thank you
Steven
Steven
Miri
This tree is a Cornus Kousa which we planted in 2007. We checked the dirt around the tree for dryness. It didn't seem too dry but we have started watering the tree. As I started to trim the bad branches I noticed dark spots on the underside of the leaves. I wonder if this additional information may cause you to modify your diagnosis. I've also made sure the base of the tree is exposed and not covered by mulch.
Thank you
Hi Steven,
Thank you for the added information and photos. For now, we don't have any additional or different suggestions as to a diagnosis and don't recognize the source of the dark spotting underneath the leaves. This late in the season, even if it's caused by minor insect feeding activity or a low-grade leaf infection, it won't impact the overall health of the tree by itself, since leaf shed for autumn will begin in just a few weeks and the tree is already making internal tissue preparations for winter.
Miri
Thank you for the added information and photos. For now, we don't have any additional or different suggestions as to a diagnosis and don't recognize the source of the dark spotting underneath the leaves. This late in the season, even if it's caused by minor insect feeding activity or a low-grade leaf infection, it won't impact the overall health of the tree by itself, since leaf shed for autumn will begin in just a few weeks and the tree is already making internal tissue preparations for winter.
Miri
OK Thanks
Steven
Steven
