How to Get Rid of Black Spots on the Leaves of Gardenia Shrubs

Black spots on gardenia leaves are caused by sooty mold fungus. This fungus develops on the excrement of insects that feed on gardenia plants. When the insects feed on the sap of the plant, they produce excrement rich in sugars that fungus thrive on. This excrement is often referred to as honeydew. The fungus and excrement can be washed off but the only way to prevent it from coming back is to remove the insects causing it. The types of insects that feed on gardenia shrubs include white flies, mealybugs, aphids and scales.

Insecticidal soap
Dishwashing liquid
Fungicide
Vegetable oil
Cotton swabs
3 jalapeno peppers
3 cloves of garlic
Neem oil
Fish oil

Instructions

- 1
  Spray the plant with water. A strong spray of water will wash the mold off the plant along with the insects causing it. Use cool or lukewarm water to avoid scalding the plant.
- 2
  Spray the leaves with insecticidal soap. Mix one teaspoon of insecticidal soap with one gallon of water and spray both sides of the leaves thoroughly.
- 3
  Make a mixture of four ounces of dishwashing liquid with one gallon of water to ward off insects. Spray the leaves with the mixture and then rinse the leaves with water. Wait 15 minutes and repeat the process.
- 4
  Spray the plant with fungicide after washing off the mold. Fungicide will kill any remaining fungus on the leaves and prevent it from growing back. Fill a spray bottle with a commercially-made fungicide and spray both sides of the leaves.
- 5
  Make a mixture of one tablespoon of dish washing liquid and one cup of vegetable oil to remove aphids. Add two teaspoons of the mixture to one gallon of water. Spray the leaves with the mixture and then rinse the leaves with water. Wait 15 minutes and repeat the process.
- 6
  Remove white flies and mealybugs manually. Dip a cotton swab in a mixture of water and vinegar and swab each mealybug.
- 7
  Wash the leaves with dishwashing liquid and water. This will remove any insects on the leaves and wash off the honeydew causing the black spots.
- 8
  Make a spicy jalapeno and garlic mixture to get rid of aphids. Blend three jalapeno peppers, three cloves of garlic and one quart of water. Strain the mixture and spray it on the leaves.
- 9
  Avoid using general broad-spectrum insecticides. These chemicals kill all insects, even insects that are beneficial to plants, such as ladybugs.
- 10
  Spray the plant with neem oil to control white flies and aphids. Mix one teaspoon of neem oil with one quart of water in a spray bottle and spray it directly on the leaves.
- 11
  Spray the plant with fish oil to control scales and mealybugs. Mix one teaspoon of fish oil with one quart of water in a spray bottle and spray it directly on the leaves.

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