Coneflower blossom problem - Ask Extension
One of our coneflower plants has an interesting problem--green growths forming at the top of the blossoms. I will attach two photos. I've researched...
Knowledgebase
Coneflower blossom problem #674786
Asked August 09, 2020, 6:49 PM EDT
One of our coneflower plants has an interesting problem--green growths forming at the top of the blossoms. I will attach two photos. I've researched online and the best I can come up with is that the plant has an infestation of coneflower rosette eriophyid mites. Online wisdom suggests cutting off the affected blossoms to reduce the number of mites, but otherwise there seems to be no consensus about what to do. My questions: 1. Does this look like coneflower rosette eriophyid mite damage? 2. Deadheading the only reasonable response? In advance, thank you for your help. Bob Nixon, Clarksville ###
Howard County Maryland
Expert Response
Hi - These appear to be symptoms of Aster Yellows, a virus-like pathogen which affects daisy-family plants such as these along with many other garden plants and weeds. It is transmitted by sap-sucking insects called leafhoppers. Leafhoppers are common garden pests but their control is quite difficult, especially on plants such as these that have good wildlife value (and therefore should not be treated with insecticide).
Aster Yellows is not curable and will eventually kill a plant. The affected plants (roots included) need to be removed and disposed of (do not compost).
The pathogen is not in the soil itself, so you can replant safely, though there is a risk new plants will contract the same pathogen if they are vulnerable species and are feed upon by infected leafhoppers. To reduce this risk, make sure the area is weed-free and be vigilant for symptoms appearing in any nearby plants, removing them as needed if they do manifest.
These pages provide more information on this disease and a few look-alike conditions:
https://extension.umd.edu/hgic/topics/aster-yellows
https://bygl.osu.edu/index.php/node/1634
https://wimastergardener.org/files/2015/12/aster_yellows.pdf
Christa
Aster Yellows is not curable and will eventually kill a plant. The affected plants (roots included) need to be removed and disposed of (do not compost).
The pathogen is not in the soil itself, so you can replant safely, though there is a risk new plants will contract the same pathogen if they are vulnerable species and are feed upon by infected leafhoppers. To reduce this risk, make sure the area is weed-free and be vigilant for symptoms appearing in any nearby plants, removing them as needed if they do manifest.
These pages provide more information on this disease and a few look-alike conditions:
https://extension.umd.edu/hgic/topics/aster-yellows
https://bygl.osu.edu/index.php/node/1634
https://wimastergardener.org/files/2015/12/aster_yellows.pdf
Christa
