Coreopsis 'Moonbeam' Powdery Mildew and Mystery Flower Holes

Your container 'Moonbeam' coreopsis has white powder on leaves (powdery mildew) and holes in yellow flowers. You don't see aphids. Two separate issues.

Powdery Mildew: Cultural Control

• White powder = fungal spores. Favors humidity, crowding, dry roots + wet leaves.
• Incureable but manageable: Remove worst leaves. Water soil only. Thin nearby plants. Full sun.
• Don't compost diseased foliage.

Flower Holes: Likely Not Aphids

• Aphids = visible (green/yellow/brown/white beads on stems/buds). You'd see them.
• Holes in petals = caterpillars, earwigs, beetles, or slugs (night feeders).
• Check at night with flashlight.

Organic Controls

• Jalapeño spray: 2 hot peppers + 1 cup water, blend, strain, + 1 tsp Dawn. Spray affected areas. Repels chewers.
• Ladybugs: Buy small pack; release at dusk. Eat aphids, not chewers.
• Diatomaceous earth: Dust around base for slugs/earwigs.
• Bt (Bacillus thuringiensis): For caterpillars only.

Container Advantage

Move pot to optimal sun/air flow. Isolate from other plants. Easier to monitor.

Mildew is cosmetic; chewers reduce bloom. Target the chewers; manage the mildew.