Recipes for Alternative Pesticides

While organic growers prefer to use no pesticides, there are times when it is a choice between no crop or using some form of poison. Some of these, such as Bacillus thuringiensis, are specific to a particular organism and harmless to man and pets. Many are very toxic and should be used with caution. The reason these latter materials have found favour with organic growers is that they break down to non-toxic materials in the garden. Until they have broken down, exercise caution with these materials.

Borax

Where ants and cockroaches are a problem, mix equal parts of borax and icing sugar. Place in shallow containers in the cupboards where these pests are a problem. This material is very poisonous, so take precautions to keep away from children.

Bordeaux Mixture

This is the copper spray used to prevent fungal disease of fruit trees and also blight in potatoes. It must be used fresh.

Dissolve 100 gm of copper sulphate (bluestone) in 5 l of water overnight.

Mix 140 gm of slaked lime in 5 l of water and add to the copper sulphate solution. Stir vigorously and use straight away. Agitate during use.

Bracken

Useful aphis killer. Toxic to most insects.

Steep 25 gm dried bracken fronds in 1 l of water for 24 hours. Strain and use 1 ml per litre.

Bug Juice

In the October 1976 the Rodale Organic Gardening and Farming magazine reported the use of 'bug juice' by a commercial farmer. He reported a cost saving of $5,000 per annum on his chemical bills and that after three years no further applications were required.

I kg of insects will treat 30 Ha.

Liquefy the bugs (slugs, caterpillars etc.) in a blender with about 1/3 the volume of water. Strain and use 4-5 ml per 100 l water.

Fermenting slugs after killing them with dry sugar also works. The dehydrated slugs are put in a container of water in a warm place for a few days, strained, diluted and sprinkled around the garden.

Various theories abound as to why this works: natural pathogens, attraction of predators, confusion of insect communication systems (they rely a lot on pheremones which are detected by smell).

Chamomile

This medicinal herb is used to control fungal diseases, especially mildews. Use the generic recipe under Herbs.

Coriander

A 2% emulsion of Oil of Coriander is an effective control for red spider mites. To make an emulsion, use a little soft soap (potassium soap, 'Clensel', 'Safers' etc) in the water.

Dipel

This is the brand name of Bacillus thuringiensis. In some places it is also available as 'Thuricide'. It is the dehydrated bacterium mixed with a little of the toxin (a stomach poison) that you are purchasing, plus a filler if it is a home gardeners pack. It is specific to caterpillars and completely harmless to other living things. It is expensive and can be made to go further quite cheaply. Mix a little of the powder in lukewarm milk and allow to stand for 24 hours. The bacteria multiply and a little of the mixture can be used to start a new batch. The effectiveness will probably decline over time, necessitating the start of a new batch from the pure culture.

Remember that Dipel, being a living organism, prefers cool, moist conditions in the garden to work best.

Derris (Rotenone)

This is a longer lasting insecticide than most organic sprays. It lasts for 48 hours rather than 24. It kills fish as well as most insects (including predators), so use it with care.

25 gm derris powder

50 gm potassium soap

10 l water

Dissolve soap in half of the water and derris in the other half. Combine the two solutions and use.

Garlic

This is used as an insecticide and fungal control.

100 gm minced garlic

10 ml mineral oil

500 ml water

50 ml soft soap

Soak the garlic in the mineral oil for 2 days. Add the water and soap. Strain and store in a glass container. Use a 1% solution (1 part concentrate to 99 parts water).

Herbal Sprays

Many herbs can be used as insecticides and insect repellants. The formula to use is to just cover the fresh herbs with boiling water. Steep for 30 minutes. Strain and dilute with an equal quantity of water. As the potency of the herbs will vary depending on seasonal and other conditions, exact recipes are not possible. The addition of soft soap as a wetting agent will increase the effectiveness of these materials.

Wormwood, southernwood, tansy, chamomile, rhubarb leaves, ragwort, potato leaves and lantana are all worth trying.

Milk

Mosaic virus disease can be controlled with milk. Smokers should dip their fingers in milk before handling tomatoes and cucumbers.

Use equal parts of whole milk and water as a spray.

Rat Poison

A very effective rat poison, until the rats learn to exercise caution, which they invariably do, is as follows:

1 part cement

1 part flour

a few jelly crystals

The cement sets in their stomachs preventing further feeding. Another reputed sure-fire rat killer is Coca Cola. The rats bloat and die.

Slug and Snail Baits

The green slug baits contain metaldehyde. This material breaks down to water and carbon dioxide, but until it does, is very toxic and attractive to dogs, cats and birds. The ingredients are bran and metaldehyde, so they fall to pieces quite readily in the rain. A more effective formula is:

1 part metaldehyde

1 part limil

1 part cement

3 parts bran

This mixture lasts for a very long time indeed. Put the baits underneath boards, rocks etc. where the slugs hide at night.

Soap

Soap solution is an effective aphid killer. The best to use is potassium soap, also known as soft soap. Being a liquid, it is easier to dissolve. Two commonly available brands from most nurseries are 'Clensel' and 'Safers'. Use 100 ml per 2.5 l of water.

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Jonathan Sturm 2003 - 2011

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