Using natural pest control in the garden can be good for you and the planet. But, sometimes, finding chemical-free ways to deal with common Australian garden pest insects can be tricky. With some clever planting and a few organic pest control remedies, a healthy, green garden that is resistant to pests is possible.
What Is Organic Pest Control?
Much like standard pest management methods, organic pest control consists of:
- Repelling pests and preventing diseases before they can cause damage
- Killing pests and destroying diseases once they're detected
Conventional vs. Organic Pest Control
The difference is that conventional methods rely on synthetic chemicals which are often toxic to humans, beneficial insects like bees, and the environment. Alternatively, organic pest control relies on natural methods of controlling pests, including physical controls and natural chemicals that are safe for the environment. Whether you're trying to control pests and diseases in your vegetable garden, on citrus trees or another type of fruit tree, on ornamental plants or even around indoor plants, you can control pests naturally without having to resort to toxic, synthetic sprays using organic or natural pest control.
Natural Pest Control Practices
Natural control for common garden pest insects that thrive in Australia usually involves using several control methods, rather than turning to a poison straight away. You can for instance:
- Check your vegetable, fruit, and ornamental plants early in the morning (paying particular attention to the undersides of leaves), squash any pest insects before they can eat your plants, and make a note of insect pests and larvae that will need follow-up organic pest control.
- Watch for fungi and fungal diseases, like black spot (Diplocarpon rosae), which attacks ornamental plants like roses but can spread to other plants.
- Introduce some beneficial predatory insects to eat the pest insects that want to destroy your garden.
- Experiment with companion planting, a natural pest control method that uses one plant to protect another.
- Use organic pest control including natural pesticides, lures, and traps to repel or kill pests and insects naturally.
Good Soil Plays a Role in Natural Pest Control
Many gardeners don't realise that having healthy soil is part of natural pest control because healthy plants are less vulnerable to insect pests and diseases. A rich, healthy soil also supports beneficial nematodes which attack dreaded root knot nematode pests.
To build healthy soil in your garden:
- Regularly add organic matter like compost, vermicast (worm poo), and worm juice (the liquid from a worm farm) to your soil. It will retain more moisture, provide nutrients, and feed the beneficial microorganisms you need for your garden to flourish.
- Avoid tilling your soil, as this destroys soil structure, making it harder for plants to spread their roots and 'breathe'.
- Plant a variety of green manure crops, such as peas, broad beans, lucerne, or mustard, then cut them back at ground level before they flower and use the plant matter as mulch. This will help keep your soil healthy by providing valuable nutrients and lots of organic matter. Some will even keep pests and diseases at bay more directly by fumigating the soil. For example, a mustard green manure can prevent early blight from decimating your tomato and potato crops.
Natural Controls for Every Pest
Codling moth in your apples, fruit fly on your peaches, aphids on your roses, and cabbage moth and white butterfly destroying your vegetables - these are the stuff of a gardener's nightmares. Don't panic. You can control all of these plant pests naturally without using synthetic pesticides that affect your soil, plants, fruit, or the environment.
Companion Planting for Natural Pest Control
Some of the 'good guys' or beneficial insects of natural pest control are:
- Ladybug larvae, which feed on aphids
- Ground beetles, which eat ground-dwelling pests
- Parasitic wasps, which feed on caterpillars and grubs
- Common spiders, which eat grasshoppers
- The lovely lacewing, which feeds on a wide variety of pest insects including aphids, caterpillars, mealybugs and scale insects
These garden heroes will thrive in a garden that includes thyme, rosemary, mint, dill, daisies, camomile, coriander, and Queen Anne's lace (which is also disliked by grasshoppers and locusts). If you interplant these (and other companion plants that are known to be effective in Australian gardening conditions) among the plants you want to protect, you can attract a persistent population of beneficial insects to kill some pesky pests, and you can confuse and repel others. For instance, marigolds deter nematodes and beetles.
Lures and Traps
You can also use lures and traps to control various pests.
Make Fruit Fly Traps
To stop fruit flies eating your soft fruit, make a natural fruit fly trap. You will need:
- Citrus peel
- Soft drink bottle
- String for hanging
To make the traps:
- Put a spoon of Vegemite, a spoon of sugar, and some citrus peel in an old soft drink bottle.
- Fill the bottle to just under halfway with water and cut a couple of small holes further up to let fruit fly in.
- Shake well, then hang the open bottle near your fruit trees for organic fruit fly control.
Control Hibiscus Beetle
To control hibiscus beetle naturally, you will need:
- Empty ice cream container
To make the traps:
- Fill an ice cream container with soapy water.
- Leave it at the bottom of your hibiscus tree. The beetles will drown.
Get Rid of Whiteflies and Mealybugs
Whiteflies, which are closely related to aphids and mealybugs, love new growth in your garden. To get rid of whitefly naturally, you will need:
- Spray bottle
- Vegetable oil
- Fill a spray bottle with water and add some soap. If fighting mealybugs, add vegetable oil as well.
- Spray plants.
Rid Your Garden of Earwig Infestations
Earwigs love vegetable gardens, especially silverbeet and parsley. To make traps, you will need:
- Plastic container with lid
- Scissors or sharp knife
- Vegetable oil
To make the traps:
- Punch holes in the plastic container lid using scissors or a sharp knife.
- Add vegetable oil to the container and put the lid on. Leave in your garden.
Protect Against Australian Plague Locusts
After rainfall, cover plants with exclusion fabric to protect against Australian plague locusts. Birds, including chickens, love to eat these pests as well as earwigs, so plant shrubs, like grevillea, that attract native birds, or keep chickens for eggs.
There are about 6,000 varieties of thrips, a pest that can make your leaves look white or mottled, the fruit or petals go brown, or even the flower buds fall off. Control thrips with a store-bought insecticidal soap.
Other Natural Ways to Repel and Kill Pests
Use pest control methods with other natural practices.
Just like improving soil health, crop rotation is a preventive practice used by gardeners who value natural pest control. It's a simple idea - don't plant the same type of veggie crop in the same plot every season, to break the disease life cycle of a pest insect. Follow a simple rotation plan.
Use Microbial Biopesticides
To kill insect pest larvae, or leaf eating caterpillars when they are small, Bacillus thuringiensis, a very useful species of bacteria, is one of a range of microbial biopesticides which, once eaten, causes the pest to stop eating and, soon, die. Be aware that it can be harmful to butterfly larvae.
Add Diatomaceous Earth
Diatomaceous Earth is fossilised algae which dries out the body of pests who come into contact with it. It gets rid of aphids, mites (like spider mite), thrips, ants, slugs, every kind of snail, fruit flies, maggots, grubs, and cucumber beetles in the garden naturally.
Treat Fungus With Milk or Neem Oil
For fungal diseases, mix one part milk and 10 parts water and spray on plants. Or treat with Neem oil, which can also be used to control leaf miners, mealybugs, whiteflies and caterpillars. You'll get the best results if you treat your garden once a week.
Vinegar can be used to control pests such as aphids, caterpillars, or stink bugs. Mix one part vinegar to three parts water, add a little dishwashing liquid, and spray regularly on vegetables and fruit.
Pyrethrin, made from chrysanthemums, can be used to kill flying insects and ground pests like grubs.
A Clean, Green, Natural Garden
Use a variety of natural pest control methods, and you will reap the rewards in the form of chemical-free produce, healthy ornamental plants and a cleaner environment. Knowing what insect pests or diseases are attacking your garden will also help you decide on the best, toxin-free ways to treat them.