It's easy to make your own oil based spray at home and it's totally safe. All you need is a little vegetable oil and liquid soap. Oil based sprays are very useful in controlling a wide range of insect pests in the garden.
Pests like scale, aphids, smooth skinned caterpillars, mites and even young grasshoppers suffocate when their bodies are covered with oil. You can even use oil sprays to deter the citrus leaf miner.
1. In a blender, combine 2 cups of vegetable oil with ½ cup of dishwashing liquid. Blend it up until it’s well mixed. This is your concentrate and can be stored in a jar. Be sure to label it and include the dilution rate on the label.
2. To prepare the concentrate for use, dilute 1 tablespoon in a litre of water, mix it well and spray the pest as well as both sides of the foliage thoroughly.
3. Always follow this dilution rate, because you can burn the foliage if it’s too strong and there are a few other rules; don’t apply it in hot weather and avoid using it on plants with hairy foliage as well as ferns, palms and cycads as this can also cause leaf burn.
4. Regular applications of this easy to make oil based spray will help protect your plants from many common pests found in the garden.
Another recipe from Peter Cundall is: One cup oil to half a cup of water.
Never use it on your trees in winter.