Though there are many beneficial insects and other wildlife that help control insect pests in the garden, this article will focus on natural chemical controls.
Garlic and Onion (alliums)
Garlic is effective against a wide range of diseases and insects at different stages in their life cycle (egg, larvae, adult). This includes ants, aphids, army worms, caterpillars, Colorado beetle, diamondback moth, pulse beetle, whitefly, wireworm, false codling moth, imported cabbage worm, khapra beetle, mice, mites, moles, Mexican bean beetle, peach borers and termites as well as fungi and bacteria. Nematodes can also be controlled by drenching the soil with garlic liquid.
Garlic Spray: Blend 100 grams of grated and crushed garlic cloves, 0.5 litres of water and 10 grams of soap (Use potash based soft soap that is used for washing dishes and not the modern washing powders that contain caustic soda which will harm plants). Mix well. Strain the mixture through a fine cloth. Dilute the solution in 5 litres of water. Adding onion would also be effective.
A botanical pesticide made from an extract of the plant Azadirachta indica. It is not harmful to mammals or beneficial insects. Neem oil repels harmful insects like white flies, gnats, aphids, mites, and weevils, as well as strengthening the crops against rust, scab, mildew, and blight and it also functions as a fungicide. Neem oil makes the plants it touches taste bitter, so pests won’t eat them, as a “contact” insecticide. Azadirachtin also interrupts insects’ transitions between different stages of metamorphosis, such as growing from larvae to pupae. It prevents insects from developing a hardened exoskeleton. When the chemical gets absorbed through the roots of crops, it functions as a “systemic insecticide.” That means crops don’t need to be constantly re-sprayed. Here is a product you might want to consider..Green Light Sales #07824 24OZ Neem Oil
The capsaicin in hot peppers acts as a repellent to a variety of different insects and may kill many soft bodied insects on contact. I have traditionally put habanera peppers in a blender and then strained to make an effective spray. However, there are products on the market that use a wax to allow the treatment to not wear/wash off as easily.
Derived from the root of tropical and sub-tropical plants of the genus Derris. Rotenone acts as a broad-spectrum natural insecticide that poisons both on contact and by ingestion. Rotenone is typically used as a dust or spray, and while non-toxic to plants, it is highly toxic to fish and moderately toxic to warm-blooded mammals. Rotenone breaks down rapidly in sunlight so is generally less damaging to beneficial insect species than are synthetic pesticides. While most rotenone formulations are only moderately toxic to mammals, including us, some concentrated, liquid formulations are highly toxic. Rotenone is available as a powder (dust) and concentrated liquid, sometimes in combination with other insecticides. Here is a product you might want to consider..Bonide 757 4Lb Rotenone Dust or..Bonide Rotenon/Pyretherin 8 oz.
Derived from the Dalmatian chrysanthemum and is used in dust or liquid suspension form. In large concentrations, it acts as a natural insecticide by attacking an insect’s central nervous system. Pyrethrum in small concentrations may not be toxic to insects, but it retains the ability to repel insects. Pyrethrum is toxic to fish, but less toxic to mammals than synthetic pesticides. It is biodegradable and breaks down easily with exposure to light. You might want to consider this; Pyrethrum Powder – 7 oz or this; X-Clude Pyrethrum Aerosol 20 oz.
Botanical insecticide. Pure nicotine is a tobacco extract highly toxic to warm-blooded animals. The insecticide usually is marketed as a 40% liquid concentrate of nicotine sulfate, which is diluted in water and applied as a spray. Dusts can irritate the skin and are not normally available for garden use. Nicotine is used primarily for piercing sucking-insects such as aphids, whitefiles, leaf hoppers and thrips. Nicotine is more effective when applied during warm weather. It degrades quickly, so can be used on many food plants nearing harvest. It is registered for use on a wide range of vegetable and fruit crops. I would not use it near tomatoes (or members of the nightshade family) for fear of the tobacco mosaic virus.
Liquid dishwashing detergent, such as Ivory, (or Ivory Snow liquid laundry detergent) with water to a 1-2% solution that can be sprayed to cover plants has been found effective at controlling insects. Penetrates the outer shells of soft bodied insect pests and causes dehydration and death within hours. Can be used indoors or outdoors to kill aphids, mealybugs, spider mites, and whiteflies. Can be used up to the day of harvest. Does not kill beneficial insects such as ladybugs, praying mantis and others. Take care to not overdue it as overuse may be damaging to some plants. Here is a product that you might want to consider – Safer’s Insecticidal Soap: 500mL Concentrate
Worm castings and tea
It has been known for some time that certain insects will not cross an area with worm castings and the substance that causes this repulsion is chitinase. This substance is of sufficient concentration in worm castings and tea to function as an effective control for insects. Also, for disease control, the beneficial microbe population can increase exponentially in compost tea, and these microbes help to control the “bad guys.” A liquid foliar spray can be made from castings for topical control, but chitinase and other substances can be taken up systemically from the castings into the plant such that insects are deterred. Other pathogens are also discouraged with this approach and its just another reason to practice vermiculture and worm composting! Here is a good article on compost tea. If you don’t plan to produce your own castings, here is a product that you might want to consider; FREE SHIPPING – Nature’s Big Bud Worm Castings Premium 100% Organic Liquid Plant Food Tea Fertilizer 1 Gallon
A Natural Insecticide Recipe:
- 1 bulb of garlic
- 1 small onion
- 1 tablespoon cayenne (red) pepper
- 2 tablespoons liquid soap
- 1 quart water
It should be noted that most natural insecticides are only modestly effective (especially the “food” based ones) and that a major outbreak may not be contained by these measures.