How To Use Organic Pesticides
Using environmentally sustainable sprays, traps and deterrents to control insect pests and diseases is good garden practice.
There are a range of safe, simple, organic remedies that target specific problems only and that are not toxic to the soil, the plants, or the people who will eat the harvest.
Regularly hand-pick insects off plants and squash them.
A strong jet of water deters many insects, including aphids. Spray under leaves to control red spider mite populations in hot, dry conditions.
Sticky card traps consist of coloured waterproof cards coated with a sticky non-drying glue. Different colours attract different kinds of pests.
Plant a crop of French marigolds (Tagetes), then turn the plants into the soil when flowering. This will help to control nematodes.
Tea tree oil is used in effective broad-spectrum fungicide sprays, as are the essential oils of oregano, thyme and lavender.
Weeding by hand is safest between crop plants, so mulch beeds to help suppress weeds.
Place used coffee grounds around seedlings as a barrier to slugs and snails, as many commercial slug pellets are toxic to pets and children.
Beer traps are also very effective against snails and slugs while thin copper banding around garden beds delivers a deterrent electric shock to snails and slugs.
1. Milk spray
Very effective against powdery mildew. To make it, dilute 1 part full-cream milk or whey in 10 parts water.
2. Insecticidal soap spray
Sold under the name NatraSoap, this spray is high in fatty acids and is sprayed directly onto soft-bodied insects, including aphids, mealy bugs, scale insects and white flies. This causes the insects to die by dehydration.
3. Activated bicarbonate soda spray
Sold under names like Eco-Rose or EcoCarb, this spray can be used on fungal problems such as powdery mildew.
4. Natural sprays
These sprays include garlic, chilli, horseradish, elder leaf, rhubarb leaf, nettle, chamomile and casuarina (she oak) leaf. Casuarina spray is high in silica; use to control fungal diseases such as mildew and anthracnose.
5. Molasses spray
This spray can be used as a soil drench on curl beetle larvae and caterpillar infestations, and at double this concentration as a nematode drench. To make it, dissolve 1 tablespoon of molasses and a few drops of soft soap in 1 litre of water.