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Natural Pest Control

No organic or inorganic pest control can be substituted for basic housekeeping rules. Keeping your garden healthy is the single biggest factor that will benefit your garden and keep it disease and pest free. Moving towards organic practices is not a quick overnight fix, but rewards will come from being patient.

  • Check your garden regularly, especially your vegetable garden. Watch out for insects and diseases so you can remove and/or destroy them by hand before they overwhelm the plant.
  • Keep the garden weed free as this not only stops the weeds from taking up valuable nutrients, it also removes places for pests and diseases to flourish.
  • Keep your garden soil well fed with compost to encourage earthworms to add valuable nutrients to the soil.
  • Pruning infected or diseased wood on ornamental shrubs and removing them from the garden will limit the chance of pests or disease.
  • Remove weak or sickly plants from the vegetable garden.
  • Remove and destroy leaves that show signs of disease.
  • Ensure that plants are well fetilised and watered.
  • Practice crop rotation in your vegetable garden; this can help to break a disease cycle.
  • When choosing bulbs or tubers, only purchase or plant healthy ones; avoid examples if they feel soft.
  • Remove old or unproductive trees from your orchard.
  • Remove infected or diseased fruit from the ground around your trees, this interrupts the life cycle of the bugs in the fruit that will complete their life cycle by re-infecting your trees.

Homemade pesticides are easy and cheap to make. They are not a new practice but, as with any spray, they come with a few words of caution.

  • Make a sample batch first and trial.
  • Use the same sensible precautions that you would with chemical varieties.
  • Use pure ingredients, especially where soap is concerned.
  • Measure the ingredients accurately as unbalanced natural sprays can cause damage as well as chemical versions.
  • Apply at the suggested rates, as they can cause damage if over sprayed.
  • Organic sprays work on the contact theory: if the spray does not touch the bug, then it won’t kill them.
  • Avoid using any sprays when bees are around, as all sprays can be toxic to them.
  • Any oil-based spray used on a hot day can cause burning of the foliage, so wait for a cooler, cloudy day.
  • All pesticides will kill beneficial bugs as well as un-wanted ones, so use them wisely.
  • The material and containers you use for mixing your sprays must be used only for this purpose.
  • Keep all sprays out of the reach of children.

Kitchen recipes.

Aphids are particularly fond of new growth and are a real nuisance. They will “suck” onto foliage and can rapidly take hold in the garden.

Chili and onion spray:
  • Chop up 1 kg of onions and a handful of chilies.
  • Place ingredients in a large bowl.
  • Combine with 500ml of boiling water and half a cup of liquid soap.
  • Leave to stand for 24 hours.
  • Strain off the liquid and throw the onions into the compost bin.
  • Dilute with the solution with water so that it makes up to 20 litres.
  • Label the mixture and store in a cool and dark place.
  • Apply to your plants every 10 - 14 days.

Scales attach themselves to the plant and suck out the plants juices. They are easily controlled when smothered with an oil spray. Make sure you get in to the nooks and crevices for complete control.

Oil spray:
  • 200ml of fish oil.
  • 200ml of mineral oil.
  • 1 cup of detergent.
  • Mix together.
  • Store in a cool dark place and label.
  • To use dilute 1 tablespoon to 1 liter of water.
  • Use every 10 - 14 days.

Whitefly collect in ‘clouds’ that are noticeable when disturbed; the spray you use here can also be used on caterpillars.

Garlic spray:
  • Chop 100g of garlic; add 2 tablespoons of mineral oil and soak for 48 hours.
  • Add 500ml of water and 30g of pure soap.
  • Filter the mix.
  • Store in a plastic container, in a cool, dark place.
  • As always, label clearly.
  • To use, dilute 3 tablespoons to 1 litre of water.
  • Use every 10 - 14 days.

Codlin moths pupate in the ground and then they make their way up into your trees. To interrupt this life cycle use barrier traps.

  • Smear a stocking, paper, cardboard or cotton in Vaseline and tie around the lower part of the tree trunk forming a band. These bands will trap the insect larvae and prevent them from reaching the fruit; they will also hibernate in these bands.
  • Remove and burn the bands regularly.
If you are concerned about pesticides on your fruit and vegetables try this mixture to help remove residue – 2 tbsp vinegar to 1 liter of water soak for 5 minutes and then rinse thoroughly

Store-bought sprays.

There has always been a debate on the use of natural insecticides versus the use of chemical options. The problem with chemical sprays is that the chemical residues stay in the soil and on your produce for long periods of time. Now, more than ever, there is more focus on eco-friendly options for the home gardener:

  • Pyrethrum spray is a natural insecticide derived from pyrethrum flowers. It can be used on fruit, vegetables and ornamentals. Pyrethrum sprays have a withholding period of 24 hours but can be harmful to bees.
  • Kiwicare No Caterpillars spray is an organic-certified caterpillar spray that uses a naturally occurring bacterium widely recognised in organic gardening. Effective against leaf roller caterpillars, white butterfly, tomato fruit worm and looper caterpillars. It can be used on fruit, vegetables, vines and flowers. It can also be used in conjunction with a liquid feed and is certified “bio-gro” with no withholding period.
  • Tui Eco Oil is a blend of oils including tea tree and eucalyptus that will control scale, mites, whitefly and leaf miner and their eggs by smothering them. The oils also make the surface of the leaf slippery, making it difficult for the insect to hold on. This product has no with withholding period, so it is perfect for the vegetable garden and can also be used on citrus, indoor plants, roses, flowers and fruit trees.
  • Yates Conqueror Oil is a mineral-based oil that has been around for many years. It works as a contact spray and smothers the insect and is especially useful on fruit trees, grapes and roses when they are dormant. It can be added to other sprays to increase their stickability.
  • Lures are another safer way to control pests. These sticky traps will capture the insect and prevent them from breeding. These pheromone traps are particularly effective when used to control codlin moth as they can be reused and one trap is enough to protect up to five trees.
  • Tui Quash Snail Bait is a bran-based pellet with added iron. When digested by slugs and snails, it acts as a powerful stomach poison. Unlike other slug and snail baits, it doesn’t contain poison and the iron is safe for the garden, so will not harm microorganisms, worms or your pets. Pellets need to be on the soil around the plants to protect them. Apply by using a scoop or old spoon (reserve for this purpose). Put a few pellets around the plant that needs protection.
  • Sticky traps are very low-tech but very effective. Simply hang them from branches or stakes and bugs become attracted to the colour and then get stuck on the trap. You can aid the trap by giving the plant a shake when passing; this will disturb the bugs and cause them to swarm into the traps.
  • Companion planting we covered in our September issue. Try planting marigold through your garden as a natural pest deterrent and they have the added benefit of using up the space that weeds can grow in.