Description
Essential Oils for the Home & Garden
If you are trying to limit your exposure to toxic and synthetic chemicals in your garden and home essential oils can be valuable tools. They are well-known for their wellness virtues for humans, and can also be precious allies to protect your plants naturally and ecologically.
These oils have been used for thousands of years for their medicinal and cosmetic benefits, and their power lies in the hundreds of chemical constituents they contain. Whether you are trying to chase away garden pests from your vegetable or flower garden, protect your plants against diseases, or simply to improve their overall health, we can use these natural defences to our advantage in both our home and garden, using products you can store in your medicine chest. How cool is that!
Tagetes Essential Oil
Tagetes is commonly called Khakibos is South Africa. This essential oil is native to the temperate grasslands of southern South America, and is extracted from the flowers. It offers a unique and delightful aroma that is fresh and herbaceous with powerful notes of green apple and a subtle floral undertone. It is aromatically strong with complex notes that are interesting to blend with. The essential oil is known for its insect repellent qualities and its ability to help with various skin conditions.
In the Garden
Khakibos essential oil is widely utilized as a biochemical Pesticide and Repellent. It also possesses Fungicidal, Antiviral, and Antimicrobicidal properties.
The active insecticidal properties in Tagetes minuta oil come from its rich terpene profile, which includes compounds like ocimenone, tagetone, and limonene. The efficacy of the essential oil has been demonstrated against a wide range of pests, including stored-grain insects, field crop pests, and livestock ectoparasites.
Tagetes minuta is registered by the United States Environmental Protection Agency as a biochemical pesticide. It is applied to both food and non-food crops to manage soft-bodied pests like; Aphids, Thrips, Mites, Whiteflies, Mealybugs, and Scales.
It is officially classified as an active ingredient in Insecticides and Acaricides used to control Mites, Whiteflies, Aphids, Mealybugs, Scale Insects, Thrips, Psylla, Ticks, Fleas and Mosquitoes.
Red Spider Mites
Because the essential oil is highly acaricidal, it actively repels and kills plant-damaging mites, including Red Spider Mites.
Cabbage Aphid (Brevicoryne brassicae)
The cabbage aphid occurs widely in South Africa. It is considered a major agricultural pest known for attacking crops of the Brassicaceae family, including cabbage, cauliflower, broccoli, and canola. The aphids are easily identified by their characteristic grey-green, waxy appearance and generally form dense colonies on the leaves of the host plants, inflicting severe damage to crops through direct feeding and stunting plant growth, and by acting as vectors for various plant viruses. While active throughout much of the year, their populations tend to peak during the summer and autumn months.
Stored Grain Pests
The essential oil is also reported to have significant Fumigation and Contact Activity against stored grain insect pests like beetles from the genus Callosobruchus. In South Africa, the two most common and damaging species found in this genus are the Cowpea Weevil, and the Pulse Beetle or Bean Weevil.
The Cowpea Weevil (Callosobruchus maculatus) is a dominant pest across the African continent and is frequently found infesting stored crops like cowpeas and lentils in South African households and farms. The Pulse Beetle or Bean Weevil (Callosobruchus rhodesianus) is widely distributed across Central and southern Africa and is known to cause severe post-harvest losses by infesting several varieties of legumes. These beetles are highly adaptable and thrive wherever host crops are grown and stored.
The Rice Weevil (Sitophilus oryzae) is a stored product pest which attacks seeds of several crops, including wheat, rice, and maize.
Red Flour Beetle (Tribolium castaneum) is a highly common cosmopolitan pest found across the country’s warmer and subtropical regions, thriving in households, pantries, and grain storage facilities. Locally, it is widely referred to as the rust-red flour beetle and is known as a major secondary pest of stored agricultural products, including wheat flour, maize, millet, and other cereals.
As a Nematicide
Khakibos essential oil is also highly regarded as a Nematicide, repelling or killing crop-destroying roundworms. In South Africa, microscopic roundworms known as plant-parasitic nematodes are a devastating threat to crop production.
Species like the Root-knot (Meloidogyne spp.) and Lesion (Pratylenchus spp.) nematodes attack root systems, often causing stunted growth, leaf discoloration, and yield losses of up to 50%.
Applying a Nematicide
The most common method for small-scale farming and gardening is drenching the soil by blending the oil with an eco-friendly surfactant or emulsifier like liquid soap to make it water-soluble. This emulsion is mixed thoroughly into water and applied as a heavy soil drench directly around the root zones of targeted crop seedlings.
Exact dosages are hard to for gardeners and small scale farmers, so mix as you would for the garden spray described below and test dosages first.
Soil Bio-Fumigation Using the Raw Material Alternative
If you are a small scale farmer and are looking for a low-cost, traditional alternative to purchasing essential oils to use as a nematicide, farmers often use the plant itself to generate the oil directly in the soil.
Khakibos is grown densely as a cover crop, and before it goes to seed, the entire crop is chopped up and ploughed directly into the soil. As the plant tissues break down, they release nematicidal essential oils and compounds like alpha-terthienyl naturally into the surrounding earth, effectively fumigating the plot.
Livestock & Pet Care
Khakibos essential oil effectively kills or repels a wide range of agricultural, household, and livestock arthropod pests. Due to its broad bioactivity against Ticks, Fleas and Mites, the oil is often formulated into natural livestock care and animal-repellent sprays.
Ticks and Parasites
The oil is highly effective against livestock ectoparasites, particularly ticks. Research shows it repels and causes ticks such as the Large, Coarse Bont-legged Tick (Hyalomma rufipes) to drop off host bodies.
These ticks are widespread in South Africa, except in Lesotho, the eastern Free State, the coastal areas of KwaZulu-Natal, and the coastal and adjoining inland regions of the Western Cape.
They thrive in dry, semi-arid, and savannah environments, and are known to be the primary vector for the Crimean-Congo hemorrhagic fever virus, and can transmit Rickettsia conorii (the agent for boutonneuse fever) to humans.
For specific anti-tick properties, you can review the scientific findings detailed in the Onderstepoort Journal of Veterinary Research Studies.
Mosquitoes
Khakibos essential oil acts as a powerful spatial repellent against host-seeking female mosquitoes, and research has shown the essential oil to be an effective, environmentally friendly larvicide for curbing mosquito swarms.
The compound E-ocimenone exhibited strong larvicidal activity when tested on the mosquito larvae of the Yellow Fever Mosquito, (Aedes aegypti). This mosquito is widespread in subtropical regions across the eastern parts of South Africa and populations are highly prevalent in urban and coastal centres along the KwaZulu-Natal coastline and the Eastern Cape. The mosquitoes thrive by breeding in small, stagnant pools of water, in containers such as tin cans, roof gutters, and water storage vessels. While Aedes aegypti is the primary vector for diseases like dengue, Zika, chikungunya, and yellow fever, South Africa does not currently have local, widespread transmission of these viruses. The risk remains tied to imported cases from infected travellers returning from endemic areas.
Khakibos essential oil also proved effective against Malaria vectors like the Summer Malaria Mosquito (Anopheles arabiensis). This mosquito is the primary and most widespread malaria-carrying mosquito in South Africa’s three malaria-endemic provinces. In KwaZulu-Natal it is particularly prevalent in the northern areas like Jozini. It is widespread in the Lowveld regions, and is present across the eastern and lower-lying regions of Limpopo. Because Anopheles arabiensis is highly adaptable and feeds or rests both indoors and outdoors, it has proven uniquely difficult to eradicate using traditional indoor methods alone.
As a Fungicide
Tagetes minuta essential oil is actively researched and utilized as a botanical fungicide. It is rich in secondary metabolites like terpenes and thiophenes, which have been shown to strongly inhibit the growth of common pathogenic fungi, such as Fusarium and Aspergillus species. Because of these microbicidal properties, it serves as a powerful biopesticide and a natural alternative to synthetic fungicides.
Studies demonstrate that the essential oil provides significant antifungal activity against plant pathogens, helping manage seedling and tree diseases.
Post-Harvest Preservation:
The oil’s volatile compounds prevent fungal decay, making it a viable, eco-friendly agent for preserving stored grains and food products.
Garden Spray
Mix 10-20 drops of the essential oil in 1 Litre of water with an emulsifier. Shake well, and regularly while spraying down the foliage of plants or surfaces.
Post-Harvest Protection
Fumigation
The essential oil can be introduced to sealed storage containers to deter pests and affect adult development without impacting the germination rate of legumes or cereal.
Protection
Add a few drops of pure oil to porous clay pucks or sachets and place them inside sealed storage containers. The released fumes safely repel beetles without diminishing seed viability or germination rates.
The Cotton Wool Method listed below is also effective in pantries and small storage spaces.
In the Home
Tagetes essential oil is native to the temperate grasslands of southern South America, and is extracted from the flowers. It is also grown commercially in South Africa, France and North America for its essential oil.
The oil offers a surprisingly unique and delightful aroma that is fresh and herbaceous with powerful notes of green apple and a subtle floral undertone. Its strong aroma and strong, complex notes make it interesting to blend with.
The essential oil is known for its insect repellent qualities and its ability to help with various skin conditions.
If diffused the essential oil is a great repellent for a wide variety of insects. The vapour also acts as an antiseptic in a room.
- Add a few drops to a diffuser to create a peaceful, meditative atmosphere.
- Dilute with carrier oil for use in massages or skincare applications.
- Combine with Epsom salts and other relaxing oils for a deeply calming bath soak.
How to Use Essential Oils for Pest Control
When it comes to organic gardening, prevention is better than cure, and spraying crops regularly with essential oils to prevent insect infestation and disease is the most effective method. This will not only chase pests away, but also make your garden smell great!
Always use pure essential oils, and because they are so potent, always dilute them first.
How to dilute essential oils
One of the drawbacks of using essential oils in the garden is that the levels of terpenes and other constituents can vary greatly depending on the region where the plants are grown, genetics, climate and other seasonal factors. Therefore, maintaining consistency in the chemical profile of the oils is hard.
For example, Rosemary oil extracted from plants growing in two different regions of Italy will contain varying levels of α-pinene, ranging from 11% to 36%. Another study showed that essential oils extracted from different chemotypes of garden thyme did not have the same toxicity against the bean weevil.
This is the reason why, if you look for exact recipes for the oil you wish to use in the garden, you will find many different quantities of oil versus water used.
Another factor to take into account is the actual number of drops in a milliliter can vary greatly depending on the thickness of the liquid: Thicker liquids like essential oils produce larger drops, meaning it takes fewer drops to make 1mL. Different dropper bottles or droppers also have varying nozzle sizes, which changes the volume of a single drop.
In standard pharmaceutical measurements, 1 mL is equal to approximately 20 drops (meaning 1 drop is about 0.05 mL). Therefore, 10 drops are typically equal to about 0.5 mL.
This is why physicians do not rely on counting drops, as this can lead to incorrect dosing. Instead they use an oral syringe, a graduated measuring cup, or the specific dropper provided with the medicine.
CAUTION:
Because the actual number of drops in a millilitre can vary greatly depending on the thickness of the liquid and varying nozzle sizes, which changes the volume of a single drop, I recommend starting with the lowest recommended dosage. You can always increase it later.
Preventative Spraying
A general guideline when mixing sprays to deter insects, and for anti-fungus protection is to mix 4–8 drops of Essential Oil in 1 Litre of water with an emulsifier.
Garden Sprays
At certain times of the year various pests and diseases will be more prevalent, so for stronger protection dosages can be increased.
Generally you will find recommended dosages are between 10-20 drops per Litre of water.
Always Test Sprays First
Unless you apply very high doses of essential oils, they are perfectly safe to use in the garden. However, because the strengths of essential oils vary, to ensure they do not cause leaf burn, it’s important to always test your spray on a small, isolated area of the plant first. Wait at least 24 hours to check for damage before applying it everywhere.
A good method of remembering which leaves you tested your spray on is to tie string or ribbon onto the stems that have been sprayed.
Take Notes
Taking note of which plants were tested and the dosages used, will soon give you a good indication of the strengths your plants need for protection.
Mixing your spray
The Emulsifier:
Soap is essential as an emulsifier as essential oils do not mix with water and will float to the top, potentially burning your plants. A gentle liquid dish soap, pure liquid Castile or Black soap can be used.
Approximately one teaspoon of liquid soap emulsifier is used in one litre of water. Witch hazel, Vodka, or apple cider vinegar also emulsifies oil and water.
The Method:
In a small glass container, mix your essential oils with your emulsifier, then add some of the water and stir well. Warming the water helps with emulsification. Add the oil mix to the spray bottle with the rest of the warm water. Agitate well and also regularly whilst spraying.
Applying your Oils
Spraying in the middle of a hot, sunny day can cause leaf burn, so always apply the mixture in the cool of early morning or late afternoon. Remember to agitate the spray bottle well before use, and regularly while spraying. Ensure that you spray underneath the leaves where insects commonly hide.
During the cooler times of the day beneficial daytime pollinators are not that active. Never spray plants if you can see beneficial pollinators like bees around the plants. Even organic sprays can be abused in the garden, so as they say “everything in moderation”.
NOTE: The strength of the oils will evaporate, so reapply to plants after rain, every 2 weeks, or as needed.
Cotton Ball Method
To target specific insects in large numbers, like ant hills or rodent burrows, take some cotton balls and add a few drops of essential oils to them. Place the cotton ball right onto the ant hill, burrow or other insect grouping. This will cause them to relocate immediately. If that doesn’t work immediately you should repeat the process using a stronger solution.
You can also rub the oils onto any hard surfaces to create a long-lasting barrier.
Hanging Strips to Deter Pests
Add essential oils to a bowl of warm water and soak strips of pretty material or ribbon in the water before hanging onto the branches of fruit trees, or near edible gardens and ornamental shrubs.
Is there a waiting period before harvesting?
You should not eat vegetables and fruits immediately after spraying them with essential oils. These oils are highly concentrated and consuming them without a waiting period or proper cleaning can cause digestive upset, inflammation, or irritation of the mouth and oesophagus.
Essential oils degrade in sunlight and waiting 24 hours should be sufficient. Ensure that you always wash your food well and all will be fine.
Storing Essential Oil Mixes
Try to mix up only sufficient spray to use in a day, or within 24 hours of mixing. Once exposed to water and oxygen, oil-based garden sprays begin to separate, degrade, and lose their effectiveness.
If you do have any left-over, store it in a glass bottle in a cool, dark place, not in your plastic spray bottle, as essential oils break down quicker in plastic. Agitate well before using again.
