What's Growing Out of My Echinacea?

If a coneflower starts growing a tiny green coneflower out of the middle of its own flower, that’s not a quirk — it’s probably aster yellows, and it’s worth a closer look.

Here’s one I hope you never have to use. If you grow Echinacea long enough, you may eventually look at one of your flowers and think something has gone very wrong. The cone may start growing little green structures. Petals can turn green. The flower can become distorted. Sometimes it almost looks as though another flower is trying to grow out of the original flower.

Don’t ignore that. Your Echinacea may have aster yellows.

You’ll sometimes hear aster yellows described casually as a virus because it behaves somewhat like one. Technically, it isn’t.

Aster yellows is caused by a phytoplasma, a microscopic bacteria-like pathogen that lives inside a plant’s vascular tissue. It can’t crawl from one Echinacea to another. It needs transportation.

And that’s where a tiny insect comes into the story.

Leafhoppers feed by piercing plants and sucking sap. If a leafhopper feeds on a plant infected with aster yellows, it can acquire the phytoplasma. When that insect later feeds on a healthy susceptible plant, it can introduce the pathogen into that plant.

So you can have two Echinacea sitting beside one another and only one develops the disease. The leafhopper is essentially the delivery system.

And Echinacea isn’t the only plant susceptible. Aster yellows has an enormous host range that includes many members of the daisy family as well as plants outside it.

This is where Echinacea makes aster yellows relatively easy to notice. The flowers can become bizarre. Look for:

• ✓ Green petals where colored petals should be
• ✓ Distorted or stunted flowers
• ✓ Green leafy growth emerging from the cone
• ✓ Clusters of abnormal shoots
• ✓ Yellowing or unusually pale foliage
• ✓ Flowers that increasingly look less like an Echinacea

That green growth coming out of the cone is one of the classic things that should get your attention. Extension specialists note that malformed flowers are often the first obvious symptom people notice on Echinacea.

There’s a complication. Eriophyid mites can cause distorted Echinacea flowers too.

Mite damage tends to produce abnormal growth on the flower head, and at first glance it can look a lot like aster yellows. Herbicide injury can also twist and distort plants.

One useful distinction is that classic aster yellows often creates strange leafy, flower-within-a-flower growth, and symptoms tend to get progressively worse rather than disappear on the next flowers.

If you’re uncertain, take pictures and ask your local Extension office or garden center before destroying a prized plant.

Unfortunately, this isn’t something you spray. You can’t fertilize the plant out of it. You can’t prune the affected flower off and eliminate the infection. Once the phytoplasma is inside the plant, the entire plant is infected.

The recommended solution is to dig it up and remove it. Don’t put an infected plant into your compost pile; dispose of it with the trash. Removing infected plants also removes a source from which additional leafhoppers could acquire the pathogen.

The good news is that the organism doesn’t persist in the soil, so discovering aster yellows doesn’t mean that spot in your perennial garden is permanently contaminated.

And it definitely doesn’t mean you should stop growing Echinacea. It’s still one of my favorite perennials.

Just remember what a normal coneflower is supposed to look like. If one starts growing what looks like a tiny green Echinacea out of the middle of another Echinacea, take a closer look.

Reference: Purdue University Extension · University of Minnesota Extension, Aster Yellows · Schlegel Greenhouse production notes