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Aster Yellows (Misshapen Coneflowers)

Green petals, misshapen flowers, twisted, and distorted leaves that turn yellow or red and tufts of white hairy roots on carrots are symptoms of aster yellows.

This disease attacks nearly 300 plants including coneflowers, Rudbeckias, coreopsis, marigolds, and other members of the aster family.  Lettuce, carrots, and potatoes are just a few of the susceptible vegetables.  Aster leafhoppers are the carriers of the phytoplasma (bacterium-like organism) that causes this disease and these symptoms. The leafhopper feeds on an infected plant, ingests some of the disease organism, and injects it into the next plant it feeds upon.

Though the disease is usually not fatal removing infected plants reduces the source of disease.  This includes infected weeds like dandelions.

Removing infested plants and using insecticidal soap to control the leafhoppers that carry the disease may help reduce its spread.

A bit more information:  Though infected plants usually don’t die this disease can overwinter in the crowns of perennial plants and serve as a source of infection the following year.  And keep in mind controlling leafhoppers can be difficult since they are constantly moving in and out of the garden. 

Upcoming Appearances


Jan. 26, 2022
Gardening for Wildlife
(webinar)

Jan. 29, 2022
WCBA's Home Building &
Remodeling Expo

West Bend, WI
(in-person event)

Feb. 2, 2022
Small Space Gardening
(webinar)

Feb. 11-13, 2022
PBS Wisconsin
Garden & Landscape EXPO

Madison, WI
(in-person event)

Feb. 18-20, 2022
NARI Milwaukee
Spring Home Improvement Show

Milwaukee, WI
(in-person event)

Feb. 23, 2022
Dahlias - Proven Performers!
(webinar)

March 1, 2022
Michigan Green Industry Assn.
Annual Tradeshow & Convention

Novi, MI
(in-person event)

March 5-6, 2022
​​​​​​​Maryland Home & Garden Show
Lutherville-Timonium, MD
(in-person event)

​​​​​​​March 26-27, 2022
​​​​​​​REALTORS Home & Garden Show
West Allis, WI
(in-person event)

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