Pale, Sickly Marigold - Ask Extension
Hello,
A French marigold has turned pale yellow-green. Some leaves are yellow, turning brown at the tips. Most others have gray-white splotches. Do...
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Pale, Sickly Marigold #801950
Asked July 19, 2022, 8:34 AM EDT
Hello,
A French marigold has turned pale yellow-green. Some leaves are yellow, turning brown at the tips. Most others have gray-white splotches. Don’t have a hand lens, so can’t offer more detail, though they don’t look like mildew. Plant looked good seventy-two hours earlier* Flowers were healthy looking twelve hours ago. Plants are crowded. Soil is heavy with a lot of clay. Any suggestions?
*I’m tending the garden at my niece’s house and get over there 2-3 times/week.
Thanks for your help!
Tim Voss
Hennepin County Minnesota
Expert Response
Thank you for writing.
Several things appear to be happening at once.
The flower photograph is overexposed but looks like aster yellows https://www.thespruce.com/how-to-identify-aster-yellows-4781045 I could do better with a better picture.
The leaves look sunscalded.
Those white dots could be a sign of over watering (edema) which floods cells and then explodes them.
It is possible that there are pests too but I would need a close up of the stems and of the underside of leaves.
Several things appear to be happening at once.
The flower photograph is overexposed but looks like aster yellows https://www.thespruce.com/how-to-identify-aster-yellows-4781045 I could do better with a better picture.
The leaves look sunscalded.
Those white dots could be a sign of over watering (edema) which floods cells and then explodes them.
It is possible that there are pests too but I would need a close up of the stems and of the underside of leaves.
Hello, Steve,
Thanks for your quick response. Here are some, hopefully, better photos of representative leaves.
Here’s a better photo of the plant. It’s much paler than the other marigolds. You suggested aster yellows. I did some online research and haven’t found any photos of aster yellows that match this. No deformed leaves or flowers, at least not yet. To be safe, I pulled the plant last night and burned it. The roots were poorly developed compared to the very bushy marigold they supported. Perhaps a symptom of overwatering? (Didn’t think to take a photo.)
Thanks, again, for your help.
Tim Voss
Hi Tim,
The cluster of thickened, twisty petals on the top of the marigolds in the first picture gave me concern. Here is a picture of aster yellows in marigolds https://www.britannica.com/science/aster-yellows This seems to be present in your plants but there are so many variants of marigolds that I cannot say for certain.
The leaves are sun scalded (brown). Edema (white spots are still seen). Edema is different that mildew. https://www.rhs.org.uk/problems/oedema
https://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/pests-and-problems/environmental/oedema.aspx
Clay soil can be difficult to work with. The nearest, cheapest answer is in the compost pile. https://extension.oregonstate.edu/news/theres-no-break-people-who-garden-clay#:~:text=Bark%2C%20sawdust%2C%20manure%2C%20leaf,inches%20of%20your%20garden%20beds.
You may be seeing rootrot in this plant. https://homeguides.sfgate.com/problems-marigolds-39424.html
My best guess is still a multi-cause problem. Too much water, plant (roots, leaves, and stem weakens), yellows moves in. But even if you take out the aster yellows, soil amendments might be the answer. A one time major piece of work would be raised garden beds which would drain into the clay underneath.
The cluster of thickened, twisty petals on the top of the marigolds in the first picture gave me concern. Here is a picture of aster yellows in marigolds https://www.britannica.com/science/aster-yellows This seems to be present in your plants but there are so many variants of marigolds that I cannot say for certain.
The leaves are sun scalded (brown). Edema (white spots are still seen). Edema is different that mildew. https://www.rhs.org.uk/problems/oedema
https://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/pests-and-problems/environmental/oedema.aspx
Clay soil can be difficult to work with. The nearest, cheapest answer is in the compost pile. https://extension.oregonstate.edu/news/theres-no-break-people-who-garden-clay#:~:text=Bark%2C%20sawdust%2C%20manure%2C%20leaf,inches%20of%20your%20garden%20beds.
You may be seeing rootrot in this plant. https://homeguides.sfgate.com/problems-marigolds-39424.html
My best guess is still a multi-cause problem. Too much water, plant (roots, leaves, and stem weakens), yellows moves in. But even if you take out the aster yellows, soil amendments might be the answer. A one time major piece of work would be raised garden beds which would drain into the clay underneath.
I expect you’re right about aster yellows. Root rot is pretty likely, too. It mostly comes down to clay. These are all excellent suggestions and links. Thank you! I started digging compost in last Spring. But raised beds are the best long term answer. It’s gonna be a project!
All best,
Tim
Best of luck to you.
