How to Control Budworms on Geraniums


A budworm, also referred to as a tobacco budworm or a geranium budworm, causes damage to a geranium in several ways. According to Colorado State University, a budworm creates tunnels in the stems of the geranium, eats away at the leaves and flowers, along with the ovaries and buds. Control budworms to prevent further plant damage. Most budworms, however, are resistant to pesticides, so use an all-natural approach when controlling them.

Moderately Easy


Things You’ll Need
  • Bacillus thuringiensis var. kurstaki (Btk)
  • Long clothing
  • Gloves
  • Goggles
  • Mask
  • Water
  • Garden sprayer
    1. Select the strain Bacillus thuringiensis var. kurstaki (Btk) to use on your geraniums. Not all strains of Bacillus thuringiensis are effective against budworms. For example, some strains only kill mosquito larvae. Btk is a bacteria that grows on decaying matter in soil. When the budworms ingest the Btk, endotoxin is released in their digestive systems. This poisons the budworms and they die. You can purchase Btk at your local garden center.
    2. Read the product label and follow all of the recommended safety precautions. According to Purdue University, it is a good idea to wear long clothing, gloves, goggles and a mask when handling Btk even though the product is deemed safe.
    3. Mix the Btk with water if you bought it as a concentrate. Follow the specific product instructions, but most likely you will need 3 to 4 tsp. of the concentrate per gallon of water. Do the mixing in a garden sprayer.
    4. Spray the geraniums with the Btk late in the day, only when the budworms are in the caterpillar stage. Spray the geranium well and make sure you spray inside the flower petals, as budworms like to hide there.
    5. Repeat two weeks later to kill the remaining budworms.

Tips & Warnings

  • Do not apply Btk on a windy day as drifting may occur.

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