Herbal pesticides are used by organic growers in order to treat a particular organism that harms the crops and could possibly harm man and pets. A good example of such organisms that attack crops is bacillus thuringensis. Most of these herbal pesticides are toxic and caution should be exercised when using them. The reason why organic farmers used these herbal pesticides is that they do not leave toxic residues in the garden, unlike their conventional pesticide counterparts. Caution must be exercised until the herbal pesticides have broken down.
The following herbal pesticides are found effective in countering organisms:
Borax. To prepare mix equal parts of borax and icing sugar. Place in shallow containers in places where ants and cockroaches reside. These herbal pesticides are very poisonous.
Bordeaux Mixture. To prepare, dissolve 100 gm of copper sulfate (bluestone) in 5 liters of water overnight. Mix 140 gm of slaked lime in 5 liters of water and add to the copper sulfate solution. Stir vigorously and use fresh right away. Agitate during use. These herbal pesticides are used to prevent fungal disease of fruit trees and blight in potatoes.
Bracken. Kills aphids and toxic to most insects. To prepare, steep 25 gm dried bracken fronds in 1 liter of water for 24 hours. Strain and use 1 ml per liter.
Bug juice. To prepare herbal pesticides, liquefy the bugs (slugs, caterpillars, and others) in a blender with 1/3 volume of water. Strain and use 4-5 ml per 100 liters of water.
You can also ferment slugs after killing them with dry sugar. Put them in a container of water in a warm place for a few days, strain and dilute and sprinkle in the garden.
Coriander. To prepare herbal pesticides, 2% emulsion of Oil of Coriander. To make an emulsion, use soft soap (potassium soap, etc.) in water
Derris (rotenone). This can kill most insects as well as fish so use with caution. To prepare, 25 gm derris powder, 50 gm potassium soap, 10 liters water. Dissolve soap in half of the water and dissolve debris in the remaining half. Combine the two then use.
Garlic. These herbal pesticides are used as insecticides and as fungal control. To prepare, 100 gm minced garlic, 10 ml mineral oil, 500 ml water, and 50 ml soft soap. Soak garlic in mineral oil for 2 days. Add water and soap. Strain and store in a glass container. Use 1% concentrate and 99% water.
Rat poison. Use coca-cola. Another recipe: 1 part cement, 1 part flour, and few jelly crystals. The cement in the stomachs prevents further feeding.