Cottony Scale on Roses in Miami: Organic Control Strategy

Understanding Cottony Scale

Cottony cushion scale (Icerya purchasi) appears as white, fluffy egg sacs on stems. Crawlers (mobile nymphs) spread to new growth. Hosing off only removes visible sacs—crawlers remain.

Organic Treatment Protocol

1. Insecticidal soap: Thorough coverage, repeat weekly × 3. Targets crawlers.
2. Horticultural oil: Suffocates all stages. Apply in cooler hours; avoid bloom.
3. Pyrethrin or neem oil: If soap/oil fail. Botanical, short residual.

Sources

• Gardens Alive (gardens-alive.com)
• Planet Natural (planetnatural.com)
• Local independent garden centers.

Cultural Practices

• Prune heavily infested canes.
• Control ants (they farm scale for honeydew).
• Encourage predators: lady beetles, lacewings, parasitic wasps (Rodolia cardinalis).

Persistence Is Key

Scale has overlapping generations in warm climates. Monitor monthly; treat at first sign of crawlers.