My two-year-old coneflowers (Echinacea) are wilting and dying. They make many flowers, then they wilt and the leaves turn brown. The whole plant seems to die, stem by stem. What can I do? Nothing else in my perennial bed seems harmed.
Answer: Coneflowers are generally easy to grow and free of pests, but there are some diseases that attack them when conditions are right. The symptoms you describe suggest sclerotinia stem and root rot, also sometimes called crown rot. It is caused by the fungus Sclerotinia sclerotiorum.
This disease can present itself while the plants are still small or during bloom. It can originate in the soil and form black areas on the roots and plant crown after the plant dies. It can also reach the plant through the air, in which case it causes stem blotches, wilting and dieback. Flower heads may droop. Digging up one of the plants to examine the roots should help you diagnose the problem. A small, weak or broken root system also points to a fungal problem.
This disease is most likely to occur in damp conditions. If your area has received more rain than usual this year or it has been very humid, this fungal disease is most likely the problem. Also, echinacea are drought-tolerant plants that don’t require or prefer a lot of watering. If you are watering consistently to meet the needs of the other, undamaged plants in the bed, you might want to consider growing your coneflowers elsewhere.
You should work with your county extension agent, Master Gardener group or a trusted nurseryperson to confirm that sclerotinia is the problem, and they’ll be able to recommend action, which may include applying a fungicide.