Aster yellows is a phytoplasma, a minute organism smaller
than bacteria, that infects many weeds, vegetables, and
flowers such as aster, Chrysanthemum, cosmos, gladiolus,
Marguerite daisy, marigold, nasturtium, primrose, sunflower,
and vinca. Aster yellows is vectored by several species
of leafhoppers. Flower parts develop into leaflike structures
and are yellow or green and dwarfed. Clusters or tufts of
spindly, yellow upright shoots commonly develop around the
base of infected plants, often on one side of the plant.
Corms or tubers can mature early, be undersized, or have
stunted roots if they are infected during the current season.
When corms or tubers infected during the previous season
are grown, they develop many thin, weak, yellowish leaves,
distorted flower spikes, and green blossoms.
Plant pathogen-free plants and use good sanitation.
Don’t plant near weeds that may host leafhoppers. Remove
and destroy infected plants. Remove nearby weeds and control
Flower parts develop into green, stunted growth.