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.
6. Horticultural oil
Sold under names such as Eco-Oil and PestOil, this horticultural oil is based on light plant oils, which smother insect pests. Direct contact is required. Do not spray when temperatures are over 32°C. Use on citrus leaf miner, whitefly, scale, mealy bugs, aphids, leafhoppers, bronze orange bugs and spined citrus bugs. Never spray within a month of using a sulphur-based spray.
7. Mineral oils
Apply these oils to fruit trees and grapevines before buds burst in spring to control scale insects, aphids, mites and leaf rollers.
8. Neem oil
Marketed under names such as Eco Neem, neem oil controls powdery mildew, aphids and mealy bugs.
9. Pyrethrum products
These products have broadspectrum activity against pest insects but are also very toxic to beneficial bees and parasitic wasps. Spray late in the day after bees have retired.
10. Horticultural glue
Marketed under names such as Tanglefoot and Trappit, this sticky glue is derived from natural plant resins, waxes and oils. It is applied to paper banding around tree trunks to trap codling moths, procession caterpillars and ants.