Tufted flower parts that rise rosette-like from coneflower cones are produced by the Coneflower Rosette Mite. The mite is an eriophyid (family Eriophyidae) that has yet to be taxonomically categorized, so it has no scientific name or approved common name. However, the mite is generally referred to as the Coneflower Rosette Mite based on the damage that it causes to coneflowers.
The mites live inside the developing flower buds and suck nutrients from the base of the flowers. As a result, green to reddish-green elongated rosette-like tufts of stunted and distorted flower parts will sprout from the tops or sides of the cones of coneflowers.
The damage caused by the rosette mite is not only unsightly; it can also seriously reduce seed production and thus natural re-seeding. Sanitation is key to managing the mite. Cutting and destroying flower heads deformed by mite activity will reduce mite populations.