Failing coneflowers - Ask Extension
Can you tell me what is wrong with my white coneflowers, which are failing.
The leaves are turning brown, the flowers stems are drooping.
This is af...
Knowledgebase
Failing coneflowers #871619
Asked June 04, 2024, 8:53 PM EDT
Can you tell me what is wrong with my white coneflowers, which are failing.
The leaves are turning brown, the flowers stems are drooping.
This is affecting six of the twelve plants.
They are planted on the south side of my house and this is their third year in this spot. No problem last year.
I also saw boxelder bugs on the plants.
Franklin County Ohio
Expert Response
Hello,
It looks to me like your coneflowers may have herbicide damage. Has herbicide been applied in the area recently that could have drifted? Another possibility is if a bleach solution was used to wash any nearby structure such as a deck or siding. If the plants were hit by any overspray, this could be causing the symptoms you are seeing. Since your plants look more affected on the top than the bottom, this is another indication of herbicide damage.
There are leaf fungi that can infect coneflower, but these symptoms typically start with purple splotches on the leaves at the base of the plant. As far as I can tell from your photos, the basal leaves look pretty healthy.
Another disease that can affect coneflower is asters yellow. This disease causes yellowing (chlorosis) of the leaves and malformation of the flowers. I don’t see any symptoms of chlorosis in the leaves and the flowers look like they’re developing normally. It’s sometimes hard to see the symptoms in the flowers until they are more fully developed, so I would advise watching for more symptoms. This article from Ohio State extension has information on and photos of asters yellow on coneflower. These photos also show symptoms appearing on lower leaves before upper leaves.
Box elder bugs feed primarily on box elder or other trees in the maple family, so I do not believe they are the cause of the damage on your coneflowers.
If you would like further assistance, you may wish to contact your local extension office.
It looks to me like your coneflowers may have herbicide damage. Has herbicide been applied in the area recently that could have drifted? Another possibility is if a bleach solution was used to wash any nearby structure such as a deck or siding. If the plants were hit by any overspray, this could be causing the symptoms you are seeing. Since your plants look more affected on the top than the bottom, this is another indication of herbicide damage.
There are leaf fungi that can infect coneflower, but these symptoms typically start with purple splotches on the leaves at the base of the plant. As far as I can tell from your photos, the basal leaves look pretty healthy.
Another disease that can affect coneflower is asters yellow. This disease causes yellowing (chlorosis) of the leaves and malformation of the flowers. I don’t see any symptoms of chlorosis in the leaves and the flowers look like they’re developing normally. It’s sometimes hard to see the symptoms in the flowers until they are more fully developed, so I would advise watching for more symptoms. This article from Ohio State extension has information on and photos of asters yellow on coneflower. These photos also show symptoms appearing on lower leaves before upper leaves.
Box elder bugs feed primarily on box elder or other trees in the maple family, so I do not believe they are the cause of the damage on your coneflowers.
If you would like further assistance, you may wish to contact your local extension office.
