Controlling Geranium Budworms with Bt

The Pest: Geranium (Tobacco) Budworm

Caterpillars eat buds before they open. Standard sprays often fail once worms enter buds.

Effective Treatment: Bacillus thuringiensis (Bt)

• Pathogen paralyzes budworms; they stop eating and starve.
• Apply as spray or dust in late afternoon/evening or overcast (UV degrades Bt).
• Timing critical: apply when eggs hatch, before worms enter buds.
• Available via mail-order/organic suppliers; may not be in local garden centers.

Supplemental Measures

• Remove dried buds/flowers harboring worms.
• Pyrethrin or carbaryl sprays work only at hatch stage.
• Corn earworm same treatment.

Safety

Bt low risk to humans; may cause skin/eye irritation or allergy. Wear protection.