Dogwood Disease Identification - Ask Extension
Hello - I planted several varieties of Cornus Florida last spring (2022) and all seemed to be establishing well by the end of the season. However, a f...
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Dogwood Disease Identification #833219
Asked June 01, 2023, 3:47 PM EDT
Hello - I planted several varieties of Cornus Florida last spring (2022) and all seemed to be establishing well by the end of the season. However, a few of them are showing browning on the leaf tips, even as they continue to appear vigorous and otherwise healthy. Photos attached.
I noticed a slight amount of this browning in a couple of them late last season and was concerned about Anthracnose, so I began applying fungicide to every tree at budbreak this spring. I began with myclobutanil and then rotated in chlorothalonil and propiconazole spraying every 7-10 days.
The browning started a few weeks after I began the fungicide rotation so I'm wondering if this is even a fungal pathogen or something else. I have 4 regular white Cornus Floridas that have no symptoms, and 1 Cornus Kousa that is also not symptomatic. It is the Cherokee Brave and Cherokee Princess varieties that seem to be most affected. The Cherokee Princess is shown in the attached photo. Finally, all are planted in areas that receive a few hours of direct sun and filtered sun the rest of the day. I have been watering twice weekly during this dry May.
I would appreciate any help you can provide to identify this issue.
Thanks!
Greg Kellogg
Livingston County Michigan
Expert Response
Hi Greg,
This looks like leaf scorch, which is likely a symptom of the hot, dry weather we've had.
https://s3.wp.wsu.edu/uploads/sites/2071/2013/12/Leaf-Scorch-of-Dogwood.pdf
If the leaves continue to turn brown and fall off, or if they develop brown spots on the leaves other than at the tip, it could be a sign of something else. Please reach out if that occurs.
For now, please be sure the dogwoods were planted and mulched (if applicable) properly to avoid root stress. Mulch should not touch the trunk of the shrubs, rather, rake it back 2" from the trunk to avoid stem rot.
Because just the two varieties are affected, it could be there were adapted to a cooler, moist environment?
If this worsens, or if you have questions, please feel free to reach out.
Thank you,
-Julie
This looks like leaf scorch, which is likely a symptom of the hot, dry weather we've had.
https://s3.wp.wsu.edu/uploads/sites/2071/2013/12/Leaf-Scorch-of-Dogwood.pdf
If the leaves continue to turn brown and fall off, or if they develop brown spots on the leaves other than at the tip, it could be a sign of something else. Please reach out if that occurs.
For now, please be sure the dogwoods were planted and mulched (if applicable) properly to avoid root stress. Mulch should not touch the trunk of the shrubs, rather, rake it back 2" from the trunk to avoid stem rot.
Because just the two varieties are affected, it could be there were adapted to a cooler, moist environment?
If this worsens, or if you have questions, please feel free to reach out.
Thank you,
-Julie
Hi Julie -
I have read about leaf scorch but thought I had been watering enough to prevent that. I've been giving each of them about a gallon twice per week, but with temps this hot maybe they need more? All of them are mulched appropriately with no mulch touching the trunk.
That said, I was still wondering if it could be leaf scorch since the browning does not match the patterns I've seen in photos of various fungal diseases (and we've certainly not had the cool wet weather conducive to disease). I will give them a bit more water while it's this hot, and then monitor for changes in symptoms and reach back out if they worsen.
Thanks so much for your help with all of my tree problems! I like to think I know how to plant and site trees but our property is heavily wooded and wet (in normal years anyway) which makes it a challenge to ward off disease.
By the way, the young white pine I asked about with browning needles has now shed most of them and appears to be stable, and the new growth is incredibly vigorous so I may be out of the woods on that one. Also, the bark borers in my Scots Pine stand did not touch any of the trees I sprayed so I think that helped too!
Thanks again,
Greg Kellogg
Thanks, for the update, Greg! I recognized your name!!
We have some white pines with yellowing needles here locally. Sent some pictures into the diagnostic lab, and they thought environmental factors could have played a part, including a wet fall last year. Glad yours is doing better and that he yellowing has subsided.
Also good news on the scots pine!
On the dogwood, the browning tips just are not indicative of any fungal diseases, which is a good thing. Despite water, the hot temps are likely the major factor in causing the scorch. So, keep watering and monitoring. And do let me know if anything changes for the worse!
Thanks, Greg,
-Julie
We have some white pines with yellowing needles here locally. Sent some pictures into the diagnostic lab, and they thought environmental factors could have played a part, including a wet fall last year. Glad yours is doing better and that he yellowing has subsided.
Also good news on the scots pine!
On the dogwood, the browning tips just are not indicative of any fungal diseases, which is a good thing. Despite water, the hot temps are likely the major factor in causing the scorch. So, keep watering and monitoring. And do let me know if anything changes for the worse!
Thanks, Greg,
-Julie
