problem with coneflowers

Question: Hi - I have a bunch of coneflowers in my yard (Towson, MD) and a lot of them have black petals and others have weird things growing out of the seed heads. I'm wondering how to address this. 

And if I need to remove the plants, should I just cut down so there's a few inches left, or do I need to pull them out by the root? I'm not sure if the black petals are related to the weird growths and if they should be treated the same or differently. I'm also worried about the surrounding plants (liatris, butterfly bush, milk weed) and don't want them to get sick. Thank you so much!

responder: Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied August 13, 2024, 9:28 AM EDT
response: The plants pictured in images 2 and 3 unfortunately have the classic symptoms of Aster Yellows, a disease that is incurable and not treatable. The entire plant in those cases should be removed and disposed of. The plant in the first image is not showing symptoms of a serious problem, and could simply have drought stress damage, petal damage from passing insect chewing (nothing that needs intervention), or possibly some degree of Coneflower Rosette Mite injury, which similarly does not need treating (especially given the plant's value to pollinators and birds).  Aster Yellows can be fairly commonplace, and avoiding the disease entirely is not really possible. If symptoms appear on other plants, they can be removed as soon as they are discovered, but symptomless plants can be left alone and just monitored for changes.  Miri

responder: The Question Asker Replied August 13, 2024, 10:08 AM EDT
response: Thank you, Miri, for your fast and thorough reply! I really appreciate it! Kris On Tue, Aug 13, 2024 at 9:28 AM Ask Extension <<personal data hidden>> wrote:

responder: Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied August 13, 2024, 10:24 AM EDT
response: You're welcome!

responder: The Question Asker Replied August 14, 2024, 3:45 PM EDT
response: Hi - I have another question. I've removed the flowers with asters yellow (see pink circle area in photo), and I'm wondering if/when I can plant something new there. Is the spot contaminated for a certain amount of time?  Thanks so much! KrisOn Tue, Aug 13, 2024 at 10:24 AM Ask Extension <<personal data hidden>> wrote:

responder: Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied August 15, 2024, 10:10 AM EDT
response: The soil will not be contaminated, as the Aster Yellows pathogen is transmitted by a certain type of leafhopper insect that does not enter the soil during its life cycle, and the pathogen needs to stay in a living host to survive. While the pathogen does potentially have a wide host plant range, it's not often practical to avoid all of the possible hosts when replanting, so use whatever species you'd like that works well for those site conditions. If you want to be cautious, the plant we see showing symptoms the most often (suggesting it's infected more often than other plants) is Coneflower (Echinacea) and occasionally other members of the aster/daisy family (Asteraceae), so another species might be good to try. For example, Agastache foeniculum might be a nice addition for a pollinator garden, or beebalm (Monarda didyma, punctata, or fistulosa).  Miri

responder: The Question Asker Replied August 15, 2024, 1:02 PM EDT
response: Thank you so much - you are awesome! What a wonderful resource.  On Thu, Aug 15, 2024 at 10:10 AM Ask Extension <<personal data hidden>> wrote:

responder: Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied August 15, 2024, 1:27 PM EDT
response: You're welcome!