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Horticultural oil

Horticultural oil is a complex mixture of hydrocarbons containing traces of nitrogen and sulfur-linked compounds that is used to control plant pests. It is an acceptable alternative to control pests in organic farming (Olkowski; et.al., 1995: pp. 54, 84-87, 252). However, horticultural oil usage is poorly understood since the product labels give little information on the content.

Types of horticultural oil

  • Dormant oil - used for woody plants during the dormant season. Dormant oil now refers to the time of application rather than to any characteristic type of oil.

  • Mineral oil - any oil found in the rock strata of the earth. The white mineral oil is the tasteless petroleum used for pharmaceuticals or medicinal purposes.

  • To control powdery mildew, add 3 tbsp of kerosene to 1 gallon of water containing 1/2 tsp of detergent soap. Mix well and stir or shake constantly your extract container while in the process of application.

  • Narrow-range oil - highly refined that has a narrow range of distillation.

  • Petroleum oil - synonymous to horticultural oil and a more common term of reference.

  • Spray oil - designed to be mixed with water and applied to plants as a spray for pest control.

  • Summer oil/Foliar oil - used on plants when foliage is present.

  • Supreme oil - highly refined and distilled oil.

  • Vegetable oil - derived from the seeds of some oil seed crop.

  • To control powdery mildew, add 3 tbsp of oil to 1 gallon of water containing 1/2 tsp of detergent soap. Mix well and stir or shake constantly your extract container while in the process of application.

  • Botanical plant oil - derived from parts of the plant known to have insecticidal properties.
    1. Botanical plant/vegetable oil
    2. Garlic oil spray
    3. Chinaberry oil spray
    4. Citrus oil
    5. Custard apple seed oil extract
    6. Garlic oil spray
    7. Neem oil spray
    8. Pongam oil spray

    Pests controlled

    1. Aphids
    2. Corn earworm
    3. Fall armyworm
    4. Leafminers
    5. Leafrollers
    6. Mealybugs
    7. Spider mites
    8. Scales
    9. Whiteflies
    10. Fungal diseases
    11. Algae growing on fruit and fruit trees

    Precautions when using horticultural oil

    (Smith-Fiola, 1997)

  • Do not apply on sensitive plants and avoid drift onto them.
  • Do not apply on drought-stressed plants. Plants that are under-stress may be damaged.
  • Do not apply during freezing weather or when humidity is above 90% for longer than 36 hours.
  • Do not apply when plant foliage is wet or when rain is expected.
  • Do not spray during shoot elongation and when buds are fully-opened.
  • Do not apply in combination with sulfur or sulfur-containing pesticides.
  • Do not use spray tank that previously contained a sulfur-based fungicide.
  • Do not mix oil with fungicide and do not spray oil within 2 weeks after fungicide treatment.
  • Standard procedures for the preparation and application of homemade extracts

    1. Read and follow the label instructions carefully. Ask for assistance from your local agriculturist office when using horticulture oil for the first time.
    2. Spray in the early morning or late afternoon.
    3. Use utensils for the extract preparation that are not use for your food preparation and for drinking and cooking water containers. Clean properly all the utensils every time after using them.
    4. Do not have a direct contact with the crude extract while in the process of the preparation and during the application.
    5. Make sure that you place the extract out of reach of children and house pets while leaving it overnight.
    6. Harvest all the mature and ripe fruits before extract application.
    7. Always test the extract formulation on a few infected plants first before going into large scale spraying. When adding soap as an emulsifier, use a potash-based one.
    8. Wear protective clothing while applying the extract.
    9. Wash your hands after handling the extract.

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