Roots Growing Along the Stems of Cosmos and Zinnias
I've raised cosmos and zinnias and have a problem with the roots growing out all along the stems of these plants. Sometimes, these roots become very large and unsightly by mid to late summer. What causes this and how can I prevent it?
These adventitious roots may be a symptom of aster yellows. This disease is caused by a phytoplasm transferred from sick to healthy plants by the aster leafhopper. This disease affects about 300 species of plants including cosmos, zinnias, aster, marigold, petunia, lettuce, carrots, beets and onions. In addition to the adventitious roots the plants may have yellow, bronze, and twisted new shoot or flower growth. The most severe symptoms are seen in late July and August and don't let up until frost. The only way to control the disease is remove infected plants and kill the leafhoppers to stop the spread of the disease. You may want to grow less susceptible plants like Nicotiana (flowering tobacco), geraniums, Salvia, cockscomb (Celosia), Impatiens, Portulaca (moss rose) and Verbena.
Related
Article
Article
Upcoming Live Events
& Webinars
March 22, 23, 29, 30, 2025
REALTORS Home & Garden Show
West Allis, WI
March 26, 2025
FREE WEBINAR:
Succession Planting & Crop Rotation
Register here
March 27, 2025
FREE WEBINAR:
Rain Garden Q & A
Register here
April 2, 2025
FREE WEBINAR:
Container Gardens for Sun & Shade
Register here
April 10, 2025
FREE WEBINAR:
Reinvigorate Your Rain Garden
Register here
April 12, 2025
Plant a Colorful & Edible Spring Garden
Pasquesi Home & Gardens
Lake Bluff, IL
April 26, 2025
Organic Gardening Basics
Ebert's Greenhouse Village
Ixonia, WI
May 3, 2025
Low-Maintenance Gardening
Merton, WI
Register here
May 7, 2025
FREE WEBINAR:
Vertical Gardening
Register here
May 10, 2025
Ask the Plant Doctor Q&A
Ebert's Greenhouse Village
Ixonia, WI
May 11, 2025
Ask the Plant Doctor Q&A
Ebert's Greenhouse Village
Ixonia, WI
May 15, 2025
FREE WEBINAR:
7 Steps to Managing Water on Your Property
Register here
May 17, 2025
Ask the Plant Doctor Q&A
Ebert's Greenhouse Village
Ixonia, WI
May 18, 2025
Ask the Plant Doctor Q&A
Ebert's Greenhouse Village
Ixonia, WI
June 4, 2025
FREE WEBINAR:
Attracting Hummingbirds
Register here
June 8, 2025
Selecting the Right Hydrangea
for Your Landscape
Ebert's Greenhouse Village
Ixonia, WI
WATCH ON-DEMAND WEBINARS
Learn More
Book an Appearance
