Troubleshooting
Threadleaf Tickseed 'Moonbeam' problems — and how to fix them
Threadleaf Tickseed 'Moonbeam' (Coreopsis verticillata) is generally forgiving once you match its basics, but a few issues come up again and again. Here is what each one looks like, why it happens, and the fix.
Powdery mildew
White coating on leaves during hot, humid summers; improve air circulation and maintain (but do not over-apply) soil moisture.
Floppy growth
Rich soils or too much shade cause stems to lean; grow in lean, well-drained soil in full sun.
Root rot
Consistently wet or waterlogged soils kill established plants; ensure free drainage.
Coreopsis spot (Septoria)
Small dark leaf spots appear during wet periods; remove affected foliage and improve air circulation.
Aster yellows
Phytoplasma disease causing distorted, yellowish growth; transmitted by leafhoppers — remove and destroy affected plants.
Prevent threadleaf tickseed 'moonbeam' problems before they start
Most threadleaf tickseed 'moonbeam' issues are care-mismatch, not bad luck. Dial in the basics:
Threadleaf Tickseed 'Moonbeam' problems — FAQ
Why is my threadleaf tickseed 'moonbeam' powdery mildew?
White coating on leaves during hot, humid summers; improve air circulation and maintain (but do not over-apply) soil moisture.
Why is my threadleaf tickseed 'moonbeam' floppy growth?
Rich soils or too much shade cause stems to lean; grow in lean, well-drained soil in full sun.
Why is my threadleaf tickseed 'moonbeam' root rot?
Consistently wet or waterlogged soils kill established plants; ensure free drainage.
Why is my threadleaf tickseed 'moonbeam' coreopsis spot (septoria)?
Small dark leaf spots appear during wet periods; remove affected foliage and improve air circulation.
Why is my threadleaf tickseed 'moonbeam' aster yellows?
Phytoplasma disease causing distorted, yellowish growth; transmitted by leafhoppers — remove and destroy affected plants.