Herbicide Damage: Horticultural spray oil

categories: Common Problems Herbicide Damage

revision date: 2022-11-02 09:51

Needle browning and loss on spruce from horticultural oil damage.
Needle browning and loss on spruce from horticultural oil damage
Photo by: R. Maleike

Biology

Horticultural spray oils may be applied to plants for control of various diseases, insects and mites. However, if oils are applied when temperatures are below 50 degrees F or above 85 degrees F, plant tissues may be damaged. In addition, oils should not be applied within 2 to 4 weeks of sulfur applications, or necrotic (dead) foliage may result. Symptoms may include chlorotic spots, general leaf chlorosis or yellowing, or leaf browning or loss. Horticultural oils also may remove the bluish color from blue spruces and other blue-needled conifers. Some plants with known potential for oil damage include palms, ferns, and some broadleaf evergreens.

Management Options

Use Integrated Pest Management (IPM) for successful plant problem management.

Non-chemical Management

Select non-chemical management options as your first choice!

  • Do not apply horticultural spray oils during freezing weather.
  • Carefully read all label instructions and precautions prior to purchasing and applying horticultural spray oils.

Chemical Management

IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.

Carefully read all label instructions prior to using horticultural spray oils.

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