Yellow Aster and powdery mildew - Ask Extension
1. Some of my coneflowers have yellow aster issues. Do I need to dig up the root of the infected plants? Do I need to dig up the healthy looking conef...
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Yellow Aster and powdery mildew #885199
Asked September 13, 2024, 7:00 PM EDT
1. Some of my coneflowers have yellow aster issues. Do I need to dig up the root of the infected plants? Do I need to dig up the healthy looking coneflowers as well as the infected ones?
2. My bee balm has powdery mildew? Do I need to dig it up or will it be ok for next year?
Otter Tail County Minnesota
Expert Response
Aster yellows affects all parts of infected plants, so include the roots when removing them.
Plants that haven't been affected can remain.
https://extension.umn.edu/plant-diseases/aster-yellows
Some bee balm cultivars are mildew resistant, but most are not.
The amount of mildew varies from year to year. It isn't necessary to dig up affected plants, but removing all affected leaves and stems this fall may reduce the extent of disease next year.
If the plants are crowded, it might help to divide them to allow good air circulation.
https://www.chicagobotanic.org/downloads/planteval_notes/no12_monarda.pdf
Plants that haven't been affected can remain.
https://extension.umn.edu/plant-diseases/aster-yellows
Some bee balm cultivars are mildew resistant, but most are not.
The amount of mildew varies from year to year. It isn't necessary to dig up affected plants, but removing all affected leaves and stems this fall may reduce the extent of disease next year.
If the plants are crowded, it might help to divide them to allow good air circulation.
https://www.chicagobotanic.org/downloads/planteval_notes/no12_monarda.pdf
