Aster Yellows- - Ask Extension
When I went out to deadhead my echinacea, I noticed I have one echinacea plant that is showing clear signs of aster yellows (brilliant green stunted p...
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Aster Yellows- #804761
Asked August 05, 2022, 11:00 AM EDT
When I went out to deadhead my echinacea, I noticed I have one echinacea plant that is showing clear signs of aster yellows (brilliant green stunted petals and multiple ‘heads’ sprouting out of one flower head). I will remove it tomorrow. What precautions should I take when pruning the other nearby echinacea? I assume I should clean the shears between plants, but don’t know what to use to clean the shears or if I should be cleaning them after each cut. I have about 20 echinacea plants in the area.
Also, could the aster yellows from echinacea also be spread to the nearby Black-eyed Susans (rudbeckia hirta)? They all look healthy. Should I take the same precautions with it?
Finally, if I am hoping to time the second bloom so it peaks around an event (wedding) do you have any suggestions as to when I dead head?
Thank you!!!
Montgomery County Maryland
Expert Response
It's hard to fully sterilize home pruning tools, since lab sterilization techniques are not achievable or practical at home. Ideally, the metal pruner blades would be dipped in alcohol and then flamed (like held in a Bunsen burner flame for several minutes) to kill any viral particles present. Lighter flames, for example, don't get hot enough, and attempting to use other sources of heat wouldn't be safe. Aster Yellows isn't technically a virus, but the virus-like organism responsible is lumped-in with these types of diseases.
Instead, just use either a disinfecting wipe or a several-minute dip in 70% rubbing alcohol to destroy what infectious particles you can; it won't be perfect, but it's probably better than nothing. Avoid using bleach because this can corrode and pit the metal, and those microscopic irregularities (along with those caused by general wear-and-tear) can harbor sap residues contaminated with infectious particles.
One of the primary vectors of Aster Yellows is a leafhopper, which sucks plant sap and transfers the contagion from one contaminated plant to a healthy plant, somewhat like needles can with infectious bodily fluids in people. Removing weeds in and around the garden will reduce the potential pool of plants harboring the pathogen for the leafhoppers to pick up, but isn't a foolproof solution since this insect can blow-in to our region from many miles away.
Black-eyed Susans and many other related (Aster family) and unrelated plant species can contract this disease. We frequently see Aster Yellows symptoms on Echinacea primarily, but the vulnerability of Black-eyed Susan is probably similar. That is not to say it will necessarily run amok in the garden, but do promptly remove any symptomatic plants since they will not recover. Cleaning pruners between every single cut or every single plant is certainly tedious and, while not harmful, probably not necessary between plants that currently look healthy.
If you're interested in learning more about Aster Yellows, these resources may be of use:
Unfortunately we don't have any suggestions to offer about the timing of dead-heading to promote rebloom by a certain date. By removing spent flowers and saving the plant energy from ripening those seeds, it can speed-up reblooming (and the plant may have enough energy to produce more flowers), but how long this process takes has too many environmental factors influencing it for us to make that prediction.
Miri
Instead, just use either a disinfecting wipe or a several-minute dip in 70% rubbing alcohol to destroy what infectious particles you can; it won't be perfect, but it's probably better than nothing. Avoid using bleach because this can corrode and pit the metal, and those microscopic irregularities (along with those caused by general wear-and-tear) can harbor sap residues contaminated with infectious particles.
One of the primary vectors of Aster Yellows is a leafhopper, which sucks plant sap and transfers the contagion from one contaminated plant to a healthy plant, somewhat like needles can with infectious bodily fluids in people. Removing weeds in and around the garden will reduce the potential pool of plants harboring the pathogen for the leafhoppers to pick up, but isn't a foolproof solution since this insect can blow-in to our region from many miles away.
Black-eyed Susans and many other related (Aster family) and unrelated plant species can contract this disease. We frequently see Aster Yellows symptoms on Echinacea primarily, but the vulnerability of Black-eyed Susan is probably similar. That is not to say it will necessarily run amok in the garden, but do promptly remove any symptomatic plants since they will not recover. Cleaning pruners between every single cut or every single plant is certainly tedious and, while not harmful, probably not necessary between plants that currently look healthy.
If you're interested in learning more about Aster Yellows, these resources may be of use:
- Aster Yellows article [PDF] - Wisconsin Master Gardeners
- Aster Yellows blog - Ohio State
- Aster Yellows page - Missouri Botanical Garden
Unfortunately we don't have any suggestions to offer about the timing of dead-heading to promote rebloom by a certain date. By removing spent flowers and saving the plant energy from ripening those seeds, it can speed-up reblooming (and the plant may have enough energy to produce more flowers), but how long this process takes has too many environmental factors influencing it for us to make that prediction.
Miri
