As you walk around your garden, something catches your eye: a flower or plant you don’t remember planting. Misshapen flower heads and petals and unusual growth are tell-tale signs of aster yellows, a disease that affects over 300 plants.
Weird-looking echinacea thanks to an aster yellows infection.
What is ‘aster yellows’?
Aster yellows is a serious disease that affects mainly plants in (but not limited to) the Asteraceae family. The disease gets its name from the yellow-ish hue of infected plants; it causes chlorosis, a yellowing of the body or the leaves while the veins remain green.
How can you tell if a plant has aster yellows?
Aster yellows can present as unusually colored and shaped petals, flower heads growing out of flower heads, stunted growth, and distorted leaves.
While the flower heads growing out of flower heads can be created by genetic modification on purpose (e.g., Echinacea purpurea x ‘Doubledecker’), the abnormalities brought on by aster yellows aren’t wanted nor are they pretty.
This coneflower does not have aster yellows.
Don’t get aster yellows confused with the coneflower rosette mite, which causes abnormal growth only in the flower head and can be controlled by removal of just the flowerhead.
Eerie hue, stunted growth—aster yellows was here.
How does it spread?
It’s spread mainly by aster leafhoppers that are infected with phytoplasma, a bacteria-like pathogen. When the leafhopper feeds on an infected plant, it sucks in the phytoplasma.
A swallowtail perched on healthy purple-pink coneflowers.
What should I do if my plants have aster yellows?
There is no treatment or cure, unfortunately. The weather, which you can’t control, plays a part in the spread of the disease. Physical barriers between plants can stop the leafhoppers but can be awkward or unsightly in the home garden. You may not need to pull all of them.