Home Remedies — Alternatives to Insecticides and Fungicides (Green Pages) [Montréal Botanical Garden]

Home Remedies for Insect Pests and Diseases

Caution

These recipes for home-made pesticides (for domestic use) are given for information purposes only. The Montréal Botanical Garden does not guarantee their effectiveness.

The Montréal Botanical Garden recommends extreme caution when preparing, handling, using and storing any pesticides, including home-made ones. Some products can be hazardous even if they are « natural ».

Wear protective gloves, goggles and clothing. When preparing, applying and storing home remedies, it is best to use tools (containers, spray bottles, etc.) reserved for this purpose. Mark all home remedy storage containers clearly and keep them out of reach of children.

Before treating an entire plant, test the mixture on a few leaves and wait 24 to 48 hours to see if there are any signs of phytotoxicity (discoloured, stained, wilted, dried or dropping leaves). If so, do not treat the plant.

Avoid treating plants on windy days, in full sun or during a heat wave or dry spell.

These recipes are not selective and may destroy both useful and harmful organisms.

Home remedies for insect pests (insects, mites)

Insecticidal soap

Dissolve 5 ml (1 tsp) of liquid dish soap in 1 litre (4 cups) of water. Spray on plants infested with spider mites, whiteflies, aphids or thrips.

NB: Insecticidal soap is not a preventative. It acts on contact, which means that it must touch the insect pest in order to be effective.

Garlic-based insecticide

Place a clove of garlic in a blender and add 500 ml (2 cups) of water. Blend until smooth. Pour the liquid into a container, cover and let sit for 24 hours. Filter through cheese cloth or a strainer. Dilute with 4 litres (12 cups) of water and add one or two drops of insecticidal soap to make the mixture adhere to plant leaves. Spray on plants infested with spider mites, whiteflies, aphids or thrips.

NB: Garlic-based insecticide is not a preventative. It acts on contact, which means that it must touch the insect pest in order to be effective.

Ref.: Hodgson, Larry. Le potager. Saint-Constant : Éditions Broquet, 2007, 160 p.

Home remedies for fungal diseases

Baking soda solution

Dissolve 5 ml (1 tsp) of baking soda in 1 litre (4 cups) of water and add a few drops of liquid dish soap to make the mixture adhere to plant leaves. Spray on as a preventative against powdery mildew, rust and blackspot. Repeat every 7 to 14 days or after a rain.

Horsetail decoction

Fill a pot with fresh horsetail and cover it with water. Bring to the boil and let simmer for 45 to 60 minutes. Let cool and strain. Dilute the mixture with 9 times as much water. Add 2 ml (1/2 tsp) of insecticidal soap per litre of diluted extract. Spray it on as a preventative, every two weeks, against powdery mildew, downy mildew and rust. Apply every other day to plants that are already showing symptoms.

NB: If the decoction is prepared with dried horsetail, use only half the suggested amount.

Ref. : Michaud, Lili. Le jardinage éconologique : Quand économie rime avec écologie, Sainte-Foy : Éd. MultiMondes, 2004, 178 p.

Chamomile flower infusion

Steep 7 g of dried chamomile flowers (about 5 Tbsp) in 1 litre (4 cups) of boiling water. Cool the infusion and spray it on seedlings to prevent or control damping off.

Ref.: Gagnon, Yves. La culture écologique des plantes légumières, 2nd edition, Saint-Didace : Éd. Colloïdales, 2004, 296 p.

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