Diseased black eyed susans - Ask Extension
Hello,
Last year was year 2 for my black eyed Susans and they spread rapidly, but with all of the rain last summer they quickly became diseased with...
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Diseased black eyed susans #865878
Asked April 25, 2024, 1:08 PM EDT
Hello,
Last year was year 2 for my black eyed Susans and they spread rapidly, but with all of the rain last summer they quickly became diseased with powdery mildew and attacked by pests. I cleared out the black eyed Susans last fall rather than leaving the dead foliage over winter since the plants were diseased. This year the black eyed Susans have started to come back, but I noticed that they are already diseased and being attacked by pests. I am going to pull the diseased ones, but is there any hope for new seedlings that might pop up? Is there something I can do to prevent them from being diseased? Or is it an issue with the soil or the seeds themselves that can’t be resolved? Thanks in advance!
Anne Arundel County Maryland
Expert Response
Hopefully, you see this sooner rather than later because we don't think that you need to pull all of your plants.
The disease that you are seeing on the leaves is called Powdery Mildew which is very common here and tends to pop up when weather conditions are just right. You can just pinch out the worst affected leaves and put them in the trash.
Here is our page on it:
https://extension.umd.edu/resource/powdery-mildew-disease-flowers/
All diseases tend to be worse when leaves stay wet for longer periods of time, so make sure the plants are in as much sun as they like and also spread them out or prune them so they are not crowded and have more airflow around them.
The bugs you see are aphids, and they are not of great concern. They are soft-bodied sucking insects that can multiply quickly, but if you wait a bit beneficial insects insects like lady beetles arrive (especially if you don't use pesticides in your yard) and can knock their numbers down. They are also eaten by other insects and birds. If you have more than you can tolerate you can also put on gloves and squish them or wash them off with a hose.
See here:
https://extension.umd.edu/resource/aphids-flowers/
Christine
The disease that you are seeing on the leaves is called Powdery Mildew which is very common here and tends to pop up when weather conditions are just right. You can just pinch out the worst affected leaves and put them in the trash.
Here is our page on it:
https://extension.umd.edu/resource/powdery-mildew-disease-flowers/
All diseases tend to be worse when leaves stay wet for longer periods of time, so make sure the plants are in as much sun as they like and also spread them out or prune them so they are not crowded and have more airflow around them.
The bugs you see are aphids, and they are not of great concern. They are soft-bodied sucking insects that can multiply quickly, but if you wait a bit beneficial insects insects like lady beetles arrive (especially if you don't use pesticides in your yard) and can knock their numbers down. They are also eaten by other insects and birds. If you have more than you can tolerate you can also put on gloves and squish them or wash them off with a hose.
See here:
https://extension.umd.edu/resource/aphids-flowers/
Christine
Thank you so much, this is helpful! You’re not too late, I haven’t pulled anything yet. All of my blackeyed Susans succumbed to powdery mildew last summer so I was demoralized to see it reappearing again this early in the season — but I will try pinching off the diseased leaves and hope for the best!
Have a nice weekend,
Ann
