Why are my asters dying?
The asters in my garden bed are slowly dying from the ground up. The first year I planted them they were fine. Last year they started, what looked like, rotting and it smelled badly. I attributed it to all the rain. Same thing has happened again this year. They come in strong in the spring and then part way through summer they die. Any idea what is going on? Pictures are from a couple weeks ago and it has gotten worse.
We see some white at the base of the plants in the second photo. Also, dying from the bottom-up is an indicator. This looks like Southern blight. https://extension.umd.edu/hgic/topics/southern-blight
The leaves are high stippled (the light dots) from sucking insects. We suspect thrips: https://extension.umd.edu/hgic/topics/thrips-flowers
They can also get spider mites: https://extension.umd.edu/hgic/topics/spider-mites-flowers-and-groundcovers
And chrysanthemum lacebugs. Look under the leaves for these.
Be sure to avoid over-watering asters, which are full sun plants and like it on the dry (not dead-dry) side. Also, never have mulch piled on or touching any plants. Keep it back a few inches.
Thanks for this information, Ellen! What is the best way to control and get rid of the blight? Should I remove all plants in the bed and plant something else?
Read the link above about blight carefully. You can choose to let the plants struggle on. If you remove them, you might as well remove the infected soil, too.
Sorry, I should have mentioned that the link in the original response is no good. Takes me to a page that says "Content Not Found". Can you try sending the link again?
Here is the link https://extension.umd.edu/hgic/topics/southern-blight