Viburnum brown spot? - Ask Extension
Can you confirm that this is some kind of fungus and suggest a remedy? I’ve had it for about 3 weeks, bought from a great local nursery.
Knowledgebase
Viburnum brown spot? #753074
Asked May 31, 2021, 1:42 PM EDT
Can you confirm that this is some kind of fungus and suggest a remedy? I’ve had it for about 3 weeks, bought from a great local nursery.
Multnomah County Oregon
Expert Response
Emily,
Please provide a bit of history to help me understand what has happened so far:
- What size containers were the plants in at purchase;
- How soon did you plant them;
- How did you prepare the planting holes -- e.g.: compost; good soil; potting mix; fertilizer; "stones in the hole for drainage;" or?
- How do you water the shrubs? e.g.: sprinkler; hand-held hose; drip system; soaker hose?
- How often do you water?
Please send at least one more image, a well-focused, full-size view of the shrubs and their surroundings.
I look forward to receiving your reply.
Please provide a bit of history to help me understand what has happened so far:
- What size containers were the plants in at purchase;
- How soon did you plant them;
- How did you prepare the planting holes -- e.g.: compost; good soil; potting mix; fertilizer; "stones in the hole for drainage;" or?
- How do you water the shrubs? e.g.: sprinkler; hand-held hose; drip system; soaker hose?
- How often do you water?
Please send at least one more image, a well-focused, full-size view of the shrubs and their surroundings.
I look forward to receiving your reply.
IT was a half gallon pot that I planted either same day or the next morning. I had been using a sprinkler until a few days ago when I laid soaker hoses.
I used cardboard and mulch to prepare the area last summer along with leaves from my nearby oak that I raked over last fall. I did not add any fertilizer. It was fairy rootbound, I loosened it up a bit with my hori hori and watered it at the base after planting. I typically water when the top inch or so dries out. 
Thank you for the update, Emily.
I suspect the dark marks on the leaves are due to direct sunlight during the recent heat. In other words, it's a mild case of sun scorch during which time the leaves on the sunny side of the plant overheated enough that some of the chlorophyll died, just enough to reveal the underlying anthocyanins (dark reds). The marks will remain until the leaves drop of their own accord.
Consider rigging temporary shade a foot or more above the plant to protect it for the duration of the current heat wave. (Then, too, it's important to realize that you may need to replace the shade protection during late summer.)
For at least the rest of the summer, it's important that the soaker hose runs across the top of the original rootball. Even then, you will need to hand water the root zone. With the current high temperatures, the rootball will dry very rapidly, such that the shrub may need supplemental water every day.
I suspect the dark marks on the leaves are due to direct sunlight during the recent heat. In other words, it's a mild case of sun scorch during which time the leaves on the sunny side of the plant overheated enough that some of the chlorophyll died, just enough to reveal the underlying anthocyanins (dark reds). The marks will remain until the leaves drop of their own accord.
Consider rigging temporary shade a foot or more above the plant to protect it for the duration of the current heat wave. (Then, too, it's important to realize that you may need to replace the shade protection during late summer.)
For at least the rest of the summer, it's important that the soaker hose runs across the top of the original rootball. Even then, you will need to hand water the root zone. With the current high temperatures, the rootball will dry very rapidly, such that the shrub may need supplemental water every day.
If you have additional questions, please ask in a reply to this email.
Thank you so much! I sincerely appreciate you folks providing this service!
Emily
You're welcome!
Enjoy your growing landscape and garden.
Enjoy your growing landscape and garden.
