How to make white oil for an organic insecticide

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White OilWhite OilOrganic gardeners are always on the lookout for a good general-purpose insecticide, and if it is simple to make at home, it’s all the better. This white oil recipe is safe, very economical, and you can make up small batches as you require them, eliminating a build-up of pesticides in your cupboard which you often never use again, and then have to figure out how to dispose of safely. It is easy to use, efficiently kills soft bodied insects on contact, has only two ingredients, and can be made in minutes!

Commercially produced oils used for managing pests on plants are most often called “horticultural oils.” Horticultural oils are derived from petroleum sources, and are sometimes called “mineral oil,” “narrow range oil,” or “superior oil.” Other oils produced to control pests may also be made from plants, such as canola, neem, or cottonseed oil.

Do not spray oil sprays when beneficial insects are activeDo not spray oil sprays when beneficial insects are activeThe advantages of using white oil for pest control is it is low in toxicity to humans, wildlife and pets, yet effective. Since oils are only active for a short time, they do not affect beneficial garden insects like: ladybugs, parasitic wasps, honey bees, etc. unless they are exposed to the direct spray. Oils also evaporate quickly and do not generally contaminate the soil or groundwater sources. They are also considered one of the few classes of pesticides to which insects and mites have not developed resistance. Repeating applications as soon as pests are noticed will effectively protect your plants.

Oils have different effects on insects and work in several ways: by coating the insects and suffocating them; acting as a poison by interacting with the fatty acids in the insect and/or interfering with their normal metabolism, or by disrupting how the insect feeds.

Oil will control various chewing and sucking insects and their eggs, on deciduous ornamental shrubs like roses and dormant fruit trees, as well as on evergreens like citrus. It is commonly used against mites like red spider mite and bryobia mite, aphids, whiteflies, thrips, citrus leaf miners, caterpillar eggs, leafhoppers and mealybugs; and is especially good on scale insects, including: red, purple, mussel, pernicious and soft brown scale. Oils can also be used against powdery mildew because its fungal strands grow on the surfaces of the leaves of susceptible plants.

Roses and deciduous fruit trees are only sprayed with white oil when dormant in winter, usually after they have been pruned, to control pests such as scale. The first winter application is usually carried out after pruning and a second application just before bud burst occurs. Proper timing is critical for success when using oils. When spraying dormant plants the oils should be applied just before the leaves or flowers show signs of breaking dormancy; that is, before "bud break." If sprayed too early, and before the insects are actively respiring, the oils will be less effective.

Citrus should be sprayed when the fruits are about the size of a walnut and again about 2 months before harvesting. To control citrus leaf miner, spraying is done when a new flush of growth occurs, and the application is repeated every 5 to 14 days. Do not use oils on citrus trees in late autumn or winter, as this can sometimes cause increased susceptibility to winter injury, wait until after winter hardening has occurred before spraying.

With vegetables, to control mites, aphids and greenhouse whitefly, spraying is done when pests first appear, with repeated applications. The withholding period for edibles with commercially produced petroleum oils is 1 day before harvest. Plant based oils are safe for use on vegetables with no withholding period, so you can spray and eat on the same day, just wash thoroughly before eating as you normally would.

Oils can control insects like scale on indoor pot plantsOils can control insects like scale on indoor pot plantsOils can also be used on indoor plants to control scale insects, mealy bugs and spider mites, but remember some indoor plants such as maidenhair ferns are more sensitive to leaf damage, so it is recommended to test on a small area of foliage before using.

Winter or early spring spraying with oil plays a key role in controlling insects organically because during these months the natural enemies of most pests are less active, making it the ideal time for populations like scale to breed - so be on the lookout constantly and spray immediately. Also, during the cooler months there is less chance of plant damage.

Garden insects thrive in protected, shielded areas of the garden and also love hiding in secluded spots on plants, like under the leaves, and are therefore not always easily detected unless you really look for them. For this reason infestations are often high before gardeners even notice them, making them even more difficult to control, and why most insect infestations are only noticed when winter and early spring pruning is done, so use these cooler months to spray both your evergreen and deciduous plants to control various insects.

With the trend back to natural pest control methods, we’ve seen an increased interest in the use of vegetable-based oils for pest control in recent years. However, gardeners have been using oils for about 200 years, and they are considered one of the most useful pesticides available for managing pests on woody ornamentals and fruit trees, as well as on herbaceous flowers and vegetables.

CAUTION:

Although oils can be used throughout the year, to minimize the risk of plant injury when using white oil, spray in the cool of the morning or late afternoon. Avoid treating when temperatures are below 5°C or above 28°C, or when the relative humidity is above 90 percent.

Do not spray when plants are in flower, avoid treating drought-stressed plants, and do not spray with oils in autumn as this can cause winter damage to evergreens. If spraying in winter do so on a warm day, because in freezing temperatures the emulsion doesn’t hold together properly, and coverage is uneven. 

When spraying evergreens with oils, always ensure that the plant foliage is dry, and remember that because oils have a low residual activity, they must be sprayed directly onto the insect or mite, so ensure that you cover all plant surfaces and especially the undersides of leaves and stems where pests can hide. Avoid large spray droplet sizes by using a good garden pressure sprayer with an adjustable nozzle. Also, remember, it is never very effective to spray on a windy day, or in the heat of the day.

Please spray responsibly, even if you are using organic products. Never spray if you notice bees or other beneficial insects on or near the infected plants; and only spray the infested plants, not everything in sight! 

IMPORTANT NOTE:  

Although generally considered safe, oils can injure susceptible plant species. Symptoms of plant injury (phytotoxicity) may be acute or chronic, and can include leaf scorching and browning, defoliation and stunted growth. Phytotoxicity in plants usually occurs in those that are overly sensitive to chemicals, and soft-leaves plants like lettuce and hairy-leaved plants are generally sensitive to oils. Do not spray oils directly onto sensitive flower heads to prevent oil spotting. Stressed plants are also more prone to sensitivity than those that are well watered and healthy.

Injury can occur when tank mixed chemicals are applied in hot weather or when an adjuvant (sticker) or solvent is added to the tank mixture.

Do not combine oils with sulphur or sulphur-containing sprays such as lime sulphur as they can react with oils to form substances toxic to plants. Also, do not use horticultural oils within 30 days of a sulphur application because elemental sulphur can persist for long periods.

Some plants most commonly listed as being oil sensitive include: Azalea, Carnation, Fuchsia, Hibiscus, Impatiens, Photinia, Cryptomeria, Juniper, Japanese Holly, and actively growing Roses.

Before applying and spraying your plants with ANY TYPE of spray ALWAYS test the spray on a small area of the plant and wait for 24 hours to see if the plant is susceptible to spray damage.

With oil testing you can mix up a small batch and test all the plants you believe you could potentially use the oil on in the future. To remember which leaves or small branches you have sprayed, tie a small piece of red wool onto the branch, or anything that will indicate where the plants were sprayed and check-up 24 hours later. This is where a gardener’s journal comes in most handy. Take notes on the day of spraying: the date, the temperatures, and if applicable the humidity. Name the plants tested and the results – this will come in handy in the future because you are likely to forget.

If you are growing produce on a larger scale or in tunnels, commercially produced horticultural oils would be the most effective to use in the heat of summer, because by the additional processes of filtration, distillation and dewaxing, manufacturers produced the very light and highly purified petroleum-based horticultural oils available today, and these oils can be used in all seasons of the year and do not cause leaf burn if used according to directions. Because summer oils won’t control all stages of insect growth, regular monitoring, early detection of infestations, and spraying immediately is vital to control them.

White Oil IngredientsWhite Oil IngredientsWhite Oil Recipe:

This simple recipe is made up of: one part dishwashing detergent to two parts vegetable oil. Adjust the amounts to suit your needs.

While some recipes call for specific types of oil such as sunflower or canola oil, you can use any vegetable oil. Any dishwashing liquid like ‘Sunlight” will do, as long as it does not contain bleach.

Combine the dishwashing detergent and cooking oil in a jar or a bottle with a tightly fitting lid.  Secure, shake vigorously, and before you know it, the oil and dish soap will have combined to become a whitish, creamy mixture. Using a blender stick will work even quicker. To ensure that your oil is truly emulsified, leave it overnight, and if it separates, you will need to blitz it again.  If, after much shaking the mixture still does not emulsify, add more detergent until it does.

This concentrated white oil insecticide needs to be diluted, using 2 tablespoons per litre of water. Agitate the mixture well before and during spraying. You can store the concentrate for several months in a sealed container placed in a cool place. Be sure to label it identifying it as a pesticide - you don’t want someone accidentally using it as a dinner ingredient!

TOXICITY:

Environmental impact of any garden product can be broken down into the categories of toxicity, soil mobility, persistence and bioaccumulation potential.

If we compare the toxicity of the natural and synthetic petroleum oils, we see some differences. In general, they’re both classed as low in toxicity to animals, birds, bees and fish, but moderately toxic to earthworms and some other aquatic organisms such as molluscs.

If we have a closer look at human toxicity, we see that the petroleum oils do present a higher toxicity hazard in terms of chronic toxicity hazard in the areas of reproductive and developmental toxicity.