Biological Control · Insect · Pest · Pest Control

Pest Control: Biological control; organic & green recipes

My philosophy on pest control:

  • Effective – preferably works with the first treatment
  • Environmental and people friendly – do not want to kill off all the helpers in the garden and certainly do not want to poison myself or wait for two weeks for the chemicals to degrade before harvesting
  • Cheap and sustainable – made from easy to find, cheap products and the chemicals are not long lasting in the environment

So here I will list homemade remedies for all pests big and small, which have been tested and are now trusted…

The dishwashing soap I use is good ol’ Sunlight liquid and the white spirit vinegar is the Boston (5% vinegar solution) brand. I always have my spray on a fine mist to ‘fumigate’ the plants until they are shiny wet (not necessarily soaking, but it won’t affect the plants adversely).

Spray the plants and the ground surrounding the plant, as the little buggers (aphids especially) jump off or sit on the ground until it is safe to attack the plant again. I would not recommend spraying toads or frogs accidentally as their skins are very sensitive, it won’t kill them, but they won’t appreciate the rash either lol.

  • 1tsp = 5ml

WhiteFly Spray

WhiteFly (Aleyrodidae)
WhiteFly (Aleyrodidae)

This is a reliable white fly killer on the first treatment. For heavily infested plants, spray till soaked, for follow up or deterrent treatment, spray lightly. Works wonders for infested tomatoes and persimmons.

  • 1L of water
  • 1tsp of dishwashing soap
  • 1tsp of white spirit vinegar

Preferably do not exceed the amount of soap or vinegar, as it may burn ‘finer’ plants (such as comfrey). The concoction does not harm any other ‘higher’ insects, such as bees, mantids, spiders or beneficial flies.

Aphid Spray

Common Rose Aphid (Macrosiphon rosae)
Common Rose Aphid (Macrosiphon rosae)

This is a once-off killer of green, red and black aphids (still testing it on the woolly aphids). Aphids I always spray till the buggers are drowning. Works like a charm on ornamental flowers and strawberries.

  • 1L of water
  • 1tsp of dishwashing soap
  • 1tsp of white spirit vinegar
  • 1tsp of homemade citrus-peel tea

You must add the citrus, as that is the main thing that kills the aphids. Can also be used on whiteflies if the solution is already made up. The citrus tea is made by adding three chopped peels of oranges (or other citrus, I would recommend two if you used lemon) to enough hot water to cover the peels. Leave overnight, pour the liquid into a glass jar (microwave the liquid in the glass jar without the lid for 5sec – just to kill any bacteria or fungi that survived the hot water) and store in the fridge (keeps for up to a month!). Again no harm to any other insect.

Woolly Lemon Pests

Woolly lemon pests ants honeydew
Woolly lemon pests (aphids or scale)

I tried to research which pests this is exactly but there is a woolly aphid, woolly white-fly and a woolly scale that all look similar and feed on lemons. Apparently this is a widespread and common problem on most citrus, especially during winter. Here you can choose from two recipes that I have, but the main thing is to catch this before it overwhelms the lemon plant else you will be spraying the buggers the whole day. Aim for the bottom of the leaves and you will likely have to treat again in about a weeks time.

Option 1: Bicarb recipe

  • 1 L of water
  • 1 tbsp of bicarbonate of soda (baking soda)
  • 1 tsp of dishwashing soap
  • This will settle on top of the fluff and dries them out! Does not harm any higher insects.

Option 2: White oil concentrate, complementary of Gardening Australia

  • 2 cups of vegetable oil (sunflower for instance)
  • 1/2 cup of dishwashing liquid
  • Mix well to make a concentrate that can store for a few months. To use this add:
  • 2 tbsp of white oil concentrate
  • 1 L of water

Cover the insects with by misting/spraying it on. This will smother them, also works for regular scale on citrus and other pests as well! Do not apply in hot weather as it may cause burn on plants (apply in the cooler afternoon or shade). Alternatively, scrub plants with a brush and soapy water!

Powdery Mildew Spray

Powdery Mildew
Powdery Mildew Spots

It is very easy to spot powdery mildew on your Cucurbits (squash, watermelon, zucchini and cucumbers). Small coin-sized white powdery spots on the leaves, sometimes on the stems, are noticed in late summer or when the plants have been wet/moist for extended periods of time. Fungi are more of a pain to get rid of than insects, 2-3 treatments of the solution should do the trick, can also be used preventatively. For heavily infected plants – spray until soaked, for a few spots, spray until shiny. I tested the solution on the powdery mildew on the carrot leaves: it does not kill off the fungus as with the cucurbits, but it prevents the spread and lessens the growth rate of the mildew – which already assists with carrot growth, else just remove the infected leaves.

  • 1L of water
  • 1tsp of dishwashing soap
  • 1tsp of bicarbonate of soda (baking soda)
  • 1/2 tsp of sulphur

The solution does not harm any insects. The sulphur is optional, but it does give the solution an extra kick. Simply add the sulphur (usually sold as “flowers of sulphur” at your local pharmacist or chemist) it won’t dissolve in the water, so just shake it before spraying on the plant to get an even distribution on the leaves.

Eggplant Rust

Eggplant rust, Puccinia substriata Pearl Millet Rust
Eggplant rust, Puccinia substriata Pearl Millet Rust

Eggplants get rust during spring, especially if it has been raining often. The look like orange blisters when viewed from the top of the leaf. On the underside you will see the growing structure of the fungus. They belong to the Basidiomycota division or the ‘True Fungi’, which include the cap fungi/mushrooms. The make aeciospores on the surface of the leaf, this is those orange round structures on the underside of the leaf after the tissue has burst open. Rust is treated with sulphide compounds and lavender/rosemary have antifungal properties, so I use an interesting mixture of sulphur powered and lavender tea.

For the lavender tea:

  • 1 Cup of fresh chopped lavender leaves and two rosemary sprigs of ~15cm
  • 600ml of water (will give ~500ml of tea given evaporation )
  • Now you can go get yourself some ‘Flowers of Sulphur’ from the chemist or pharmacists. This is really cheap and easy to find.

So use a dripper to soak the eggplant rust spot with lavender tea and then dust with sulphur using a paint brush. This will make a sulphur-caked spot, which should be fairly rigid and not easily dislodged, but just re-apply if it falls off. This will kill the rust.

If you do not have lavender leaves to make your tea, you can use the sulphur on its own by making a paste with sulphur and water, then spreading it on the spot. The sulphur will inhibit the fungus from growing or maturing its reproductive structures, if you keep its growth suppressed it will die at some point as it has come to the end of its ‘life cycle’. Lavender on its own does not affect the rust, it is the combination that finally kills the rust.

Do not use lavender flowers for the tea, as the active antifungal agent of lavender is found in the leaves and the fresher the lavender tea, the more viable the antifungal agent.

This recipe does not harm any animals or plants.

Please note that the smell of sulphur is hard to wash from your hands, some gloves can be used to apply the treatment to plants.

Red Spider Mite Spray

Severe red spider mite infestation
Severe red spider mite infestation

Had a little red spider mite infestation on my eggplant and a massive infestation on my potatoes at one point. So I used the powdery mildew spray (minus the sulphur) to get rid of the colony. The bicarbonate of soda hardens on the spider mite’s webbing and dries it out making in curl and break! Didn’t think it would work so well, just sprayed them with the powdery mildew spray out of frustration as I had the solution already made up. So just to recap the recipe:

  • 1L of water
  • 1tsp of dishwashing soap
  • 1tsp of bicarbonate of soda (baking soda)

The solution does not harm any ‘higher’ insects.

Scale insects

Australian Bug, Fluted Scale, Cottony Cushion Scale (Icerya purchasi)

There is only one solution when it comes to these critters and that is to get yourself armed with a butter knife and go to town popping them off the plant. Because of their biology (attached to the plant and protected by a shield-like plate) you can’t get chemicals in there to kill them, except chemical systemic pesticides that are transported in the plant’s phloem (water and nutrient channels) that is tapped into by these insects. I did try such a chemical previously, but within two seasons they became resistant to it – so just scrape them off then! Alternatively, get a bucket of soapy water and a brush (one that will not harm the plant). Scrub the buggers right off! Works well for hardwoods, such citrus and brush cherries!

From an old episode of Gardening Australia, a recipe to control scale:

White oil concentrate:

  • 2 cups of vegetable oil (sunflower for instance)
  • 1/2 cup of dishwashing liquid
  • Mix well to make a concentrate that can store for a few months. To use this add:
  • 2 tbsp of white oil concentrate
  • 1 L of water

Spray on all insects, the oil will smother them. Might require repeat application in about a week. Do not apply in hot weather as it may cause burn on plants (apply in the cooler afternoon or shade).


Cutworm, Noctuidae species
Cutworm, Noctuidae species

These are dark green and brown caterpillars of moths. The larvae live in the soil and at night they sever young plants and seedlings at the ground level. The moment you notice cut-off plants or ‘felled’ seedlings dig 20cm around the plant 1-2 cm into the ground and you will most likely find the culprit. Also treat the ground with wood ash (potash or potassium) to solve the problem and this also provides essential nutrient for the plants as well.

Beetle/Chafer deterrent spray

Rose Chafer, Large Wattle Chafer (Hypopholis sommeri)

I have had a request to come up with a control for those pesky brown beetles (Hypopholis sp., the Rose Chafer & Sparrmannia sp., the Woolly Chafer) that eat your rose bushes, fruit trees and various vegetables at night.

  • 1L of water
  • 1tsp of dishwashing soap
  • 1tsp of concentrated tea

The concentrated tea is made by adding 10 tea bags to 600ml of boiled water (to compensate for evaporation, to end up with ~500ml, just a nice amount to add in a jar). Leave the tea to steep overnight, strain and put in a jar or container. Store in the fridge. The tea contains tannis (tannic acid), which is unpalatable to insects, so it should prevent the beetles from feeding. I have not tested this recipe, as I do not have a problem with these beetles (touchwood!). Therefore, you can increase the amount of tblsps of tea (not soap) you add to the water until the beetles stop feeding, increase the tblsp by twofold (2, 4, 6 ect). The spray won’t harm other insects, only taste bad to those that eat it. Spray once a week and every time after rainfall. That should do the trick – Good Luck!

Bird deterrent

Balckeyed bulbul Pycnonotus tricolor Snowmanradio Derek Keats
Balckeyed bulbul, Pycnonotus tricolor, Snowmanradio Derek Keats

The best is a cat, but if you are short on one of those you can use any reflective surface, such as tinfoil, old CDs and mirrors will do. You can make a wind or sun chime out of the reflective pieces. Birds do not like silver or red light being reflected into their sensitive eyes – there are scientific studies on this, watched a whole documentary on reflective red and silver rotating pyramids that are used in strawberry fields and on buildings to deter birds. I use CDs and little plastic windmills – those that kids play with – works wonders as they are colourful and squeak when they turn in the wind. Put a few colourful and reflective ones about the veggie patch to keep hungry birds away.

Cat deterrent

Cat (Felis domestica) Eye ear tail
Cat, Felis domestica

The irony – the cats keep the birds out of the garden, now to keep the cats from trampling and snoozing on seedlings or even worse making a litter box out of the garden. I do not want to use ‘Get-off’ sprays as I do want my kitties come home again… Physical barriers are the only solution. You can use trellises or large hole plastic netting and place it gentle over the seedlings (if you can suspend it mid-air by resting it on supports that is even better!).

Stuff that doesn’t work

Aphids, Whitefly, Red Spider Mites: Any garlic or onion based solution does not deter these pests. Rather ‘live’ onions and garlic repel pests – I hypothesise that the agent, which deters the pests is only active in the living plants, which is not entirely impossible – plant one onion/garlic for every 2 x 2m plot and one per pot (additional to whatever is already in the pot – tomato, eggplant etc.). The onions/garlic does not deter each and every pest, but it seems to reduce the frequency of their visits. Onions planted near herbs increase their essential oil content, another bonus.

Any pesticide based on mixing garlic and chillies I do not recommend, as it burns the plants and working out proper concentrations for these mixtures is difficult. I also do not recommend using food (milk for powdery mildew, fruits for fruit fly traps) as deterrent sprays, rather eat your food. It just doesn’t make sense or feel right to me to use food as deterrents.

Cat deterrent: Camphor barrier around the garden. I observed one of my cats sniffing the camphor directly, did not seem offended by it and subsequently walked into the veggy patch.

Also note that pest control through organic pesticides forms part of a holistic IPM (Integrated Pest Management), which includes diverse crop planting, crop rotations, the use of green manures, organic fertilisers (from wormeries & comfrey) and the recruitment of beneficial insects (as biological control) in order to control pest populations and increase crop production. – Pest profiles on all of the above-mentioned pests are soon to follow!


32 thoughts on “Pest Control: Biological control; organic & green recipes

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s