Ask a Master Gardener: Removing diseased echinaceas only solutionThis question has been answered by St. Louis County Master Gardeners, who have been trained by the University of Minnesota as horticultural educators. Question scan be submitted and more information found at www.extension.umn.edu/garden.
Q: The normally purple flowers on some of my Magnus coneflowers are totally green this year. What could be causing this?
A: You probably have aster yellows, which is a problem spread by leafhopper insects. It can affect many species of plants, including flowers, vegetables and weeds. Echinacea (coneflowers) have been hard hit this year.
Infected echinaceas might have tiny, distorted leaves, short stems, or unusual growths, but sometimes the most visible symptom is distorted green flowers. There is nothing you can do to help the plant once it is infected. You should remove and discard the plants to try to control the spread. More information can be found on our website and by following links to the July 16, 2012 “Yard and Garden News.”
Echinacea breeders have developed many green-flowered hybrid plants and echinacea are prolific self-seeders. If you have a green plant nearby it is possible, but not as likely, that what you are seeing is a seedling. Hybrids do not seed true, meaning that the flowers of seedlings will not be identical to the parent plant’s.