Coneflowers, or Echinacea, are native wildflowers of North America. These reliable, hardy flowers have also become a popular addition to gardens. Coneflowers grow from hardiness zone 3 to 8, and some varieties will tolerate zones 9 and 10. Little maintenance is required for these plants; just keep them in well-drained soil. Blooms will arrive all summer long from lush, coarse foliage. Purple and pink hues are most common, but they also grow in yellows and oranges. If your blooms are deformed, your coneflowers have probably been affected by a disease or mite, as it is unlikely for it to be an innately unhealthy plant. Find out what is affecting your coneflowers so you can take proper action.
Aster yellows is the most common cause of deformed coneflower blooms. Petals may be scarce, wilted or develop growths. Many affected blooms are discolored with a large green center; you may see leaves within the bud. Foliage will become smaller and wilted. It will also turn yellow, keeping green veins. This is a very unattractive disease.
Aster yellows is actually a virus derived from a phytoplasma. Small insects suck the sap and contract the disease forever. It becomes prominent in salivary glands in a matter of weeks. Aster leafhoppers are the most common carriers to coneflowers. The disease is transported when the insect feeds on any part of the coneflowers. The virus is then injected into the plant. The coneflower may show symptoms in as little as a week or as long as six weeks. Unfortunately, you will have to remove these plants; there is no treatment.
Eriophyid mites are tiny, pink, plant-feeding organisms. Pines are this mite’s favorite food, but they also have an appetite for coneflowers. These mites aren’t visible with the naked eye, but they will cause deformities and bulges in the plant material. Eriophyid mites live inside the plant and will feed on blooms from the inside out. Blooms will become discolored; petals curl and twist. The twisting and irregularities in shape of foliage is the biggest clue to the microscopical mites. Little plant hairs may also begin to develop. For management, remove affected plant parts. Spray will discourage the mite’s return.
Common stalk borers attack a myriad of plant species, including coneflowers. These are larvae of borer moths. Moths lay eggs in grass and weeds that may be near plants. When the eggs hatch, the larvae search for food and shelter. If your coneflowers are closest, they will fall victim to the larvae. These creatures will work their way up through the stem of your coneflowers, tunneling tiny holes until they reach the top. This causes immature and deformed flowers. There may be a complete absence of blooms. Depending on the damage, your plants may recover after the larvae leave in a month or two. Keep the lawn trimmed to prevent these.