Plant diseases

Why is My Echinacea Turning Green?

First the disease affects echinacea’s cone, causing green growth to appear. Photo: pamsenglishcottagegarden.blogspot.com

Yes, there are a few plants with green flowers: green roses, green zinnias, green glads, green echinaceas, etc. These plants are hybrids developed for their unusual color. But if a plant you choose for flowers of another color suddenly starts producing green flowers, the chances are pretty good it is suffering from a disease: aster yellows.

Aster yellows is a very common in the wild, found especially in goldenrods, asters and other wildflowers, and is caused by the aster yellow phytoplasma (AYP), a bizarre entity closely related to bacteria, but behaving like a virus. Notably, once a plant is infected, no treatment can cure it. 

Leafhoppers transport aster yellows from one plant to another. Photo: http://www.gardeners.com

Aster yellows are transmitted by leafhoppers: by piercing plant tissues, they inject the phytoplasma which then extends gradually throughout the plant, affecting its growth and gradually weakening it.

Over time, the entire flower turns green and often begins to produce satellite flowers. Photo: http://www.missouribotanicalgarden.org

The first symptom in many plants is the greening of the flowers. This is called phyllody, the abnormal development of floral parts into leafy structures. In the case of echinaceas, a kind of green growth starts to form on the cone in the flower’s center. Over time, the cone produces small satellite flowers that are completely green. Weird … and really not too wonderful!

The only treatment for aster yellows is to destroy the plant. If left alive, the disease will gradually spread to neighboring plants, including echinaceas, asters, carrots, cosmos, strawberries, daisies, marigolds, zinnias. More than 300 other plants in 84 different plant families are known to be infected by this disease.

This is a case where a quick strike solves a ton of future problems: yank the infected plant out at the first sign of symptoms and you can prevent the disease from spreading to your other garden plants.

Article originally published on September 27, 2014. 

Larry Hodgson is one of Canada’s best-known garden communicators. He has notably been editor-in-chief of HousePlant Magazine, Fleurs, Plantes et Jardins, À Fleur de Pot and Houseplant Forum magazines and is currently the garden correspondent for Le Soleil and radio garden commentator for CKIA-FM Radio. He has written for many garden publications in both the United States and Canada, including Canadian Gardening, Harrowsmith, Horticulture, Fine Gardening and Organic Gardening. He also speaks frequently to horticultural groups throughout Canada and the U.S. His book credits include The Garden Lover’s Guide to Canada, Complete Guide to Houseplants, Making the Most of Shade, Perennials for Every Purpose, Annuals for Every Purpose, and Houseplants for Dummies, as well as nearly 60 other titles in English and French. He is a past president of the Garden Writers Association (now Garden Communicators International) and the winner of the prestigious 2006 Garden Media Promoter Award offered by the Perennial Plant Association. He resides in Quebec City, Quebec, Canada.

7 comments on “Why is My Echinacea Turning Green?

  1. Thank you for this learning moment because I’d never heard of this.

  2. I had not heard of this in many years. I remember others talking about it in the late 1980s, probably because it had just been a problem for field grown cut flowers on the Central Coast.

  3. How do you know that the first picture is not a coneflower with Eriophyid mites? How can you tell?
    Thanks!

    • Largely because I trust the source of the photo. The main difference is that you can cure a plant of mites (i.e. cutting it down to zero in the fall) and it will grow back “normal” the next season. It won’t with aster yellows.

  4. Thanks for this – I had this exact problem this spring and the flowers looked exactly like that. I wasn’t sure whether to pull them until I found this.

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