I had purple coneflowers this summer that never turned purple. Many of the flowers were green. What causes this?
There is a disease called aster yellows that may be affect coneflowers and many other species. Several years ago, I learned from Extension agent Bob Ary that the condition, which is an infection of a phytoplasma spread by leafhoppers, can cause a variety of symptoms: green flowers, stunting, yellowing, abnormal shoots, tiny leaves that emerge from the seed heads.
In most cases, a plant infected with aster yellows will eventually die, but even if the plant lives, there is the chance that the condition could spread to other plants by any insect that feeds on the plant.
Aster yellows can’t be cured, and it’s not practical to try to control leafhoppers, Ary said. Garden experts say that the disease is sporadic enough that it may only affect a few plants in a bed. When you remove the plant, it’s also a good idea to remove nearby weeds that may be secondary sources of the disease.
Garden events in Middle Tennessee
Sept. 7 – Beekeeping 101, backyard beekeeping basics, 10 a.m. – noon at WarnerParkNatureCenter. This adult-level class is led by Vera Vollbrecht, Melissa Donahue, and Dganit Eldar. Call to register, 352-6299.
Sept. 17 – Perennial Plant Society meets at Cheekwood in Botanic Hall, speaker is landscape designer Marty DeHart on “Problem Area Perennials.” Refreshments at 6:30, meeting at 7, open to the public.
Sept. 21 – Oct. 31: Cheekwood Harvest Fall Festival includes scarecrows along the garden paths, a pumpkin patch, guided garden tours and nearly 5,000 autumn-hued chrysanthemums in the Robertson Ellis Color Garden, planted specifically for Cheekwood Harvest. The full schedule is at www.cheekwood.org
Sept. 21 and 22: The Tennessee Gesneriad Society annual show and sale at Cheekwood in Botanic Hall. There will be many rare and unusual plants on display as well as for sale. Hours on Saturday September 21 are 9:30a.m.-4:30p.m., and on Sunday September 22 are 11:00a.m.-4:30 p.m. For more info, call Julie at 615-364-8459.
Sept. 26: Middle Tennessee Hosta Society meets at Cheekwood in the Potter Room; speaker is David Bates of Bates Nursery on shrubs that tolerate shade for use in hosta gardens. The meeting is at 6:30 and is open to the public.
Sept. 28: Welcoming Fall Wildflower Hike at ShelbyBottomsNatureCenter. A short naturalist-led hike for all ages, 10 – 11 a.m. Call (862-8539) or email (email@example.com) to register.
At WarnerParkNatureCenter, Deb Beazley leads adults on a stroll through a meadow to enjoy the fall wildflowers, 9 – 11 a.m. Call 352-6299 to register.