Pest control in the garden with Annette McFarlane - video transcript

This page is a transcript of the Pest control in the garden with Annette McFarlane video on Brisbane City Council's YouTube channel. The video is 12 minutes and 17 seconds long.


>> ANNETTE:  Hello I'm Annette McFarlane. Today I'm here to talk about pest control in the garden.

We all know that pest control is a matter of balance. We have to put up with a few chewed leaves. Frankly, I am happy to have chewed leaves if it gives me butterflies in the garden.  If I have circular patches taken out of my rose leaves, I know I have the wonderful leaf cutter bee. But in terms of other pests, I am not so generous.

It is important however to recognize that a lot of pest and disease problems we have in the garden we actually cause ourselves. That's because we haven't done something that we should have done; perhaps have not watered or fertilized. Or perhaps we have overdone things. For example, too much nitrogen on the garden or being a bit careless with fertilizer application can mean that we get more aphids. They love that really soft growth. So it is a question of balance. But there are some simple things that you can do to make sure that your garden is balanced and you don't have too many big outbreaks of pest problems.

When it comes to fruit trees, one simple thing you can do is cover the trees themselves once the fruit has set. You can buy exclusion netting to put over after the fruit after fruit set to protect it from a whole range of pest. Pests like the dreaded fruit piercing/sucking moth or fruit fly that attack our fruit. Fruit piercing/sucking moths attack the fruit at night, causing the fruit to drop prematurely from the tree. You know you have fruit fly if you open up the fruit and it is full of those terrible maggots. If you don't want to go to the expense of exclusion netting, you can also net curtains that you might be able to get from a second hand store.  

If it's not possible to cover the entire tree, then a technique that I like to use is simply to bag individual fruit. This is perfect for capsicum, tomatoes and things like that. Put a paper bag (brown paper bag or white glassine bag*) over the fruit.  Secure it with a peg. That’s it, all done. It is surprising how long these bags last; even if we get rainfall the bags still survive. They are cheap, easy and you just need to bag the fruit that you really want to keep. Let's move on to some other issues in the garden that are easy to control.

This is my really productive lemon, but it's suffering at the moment from some damage on the leaves caused by the leaf miner moth. This moth flies around at night. It lays eggs in the new growth and causes leaf distortions. This plant is not too badly affected, but it looks a little bit ugly. I could just trim these leaves off (which is probably what I will do) or I could spray with an oil spray. (See oil spray below). In general the damage is cosmetic - it's not too much of a worry on an established plant like this.

While I'm looking at the plant, I will check to see if there any citrus gall wasps. There doesn't appear to be many swellings, but if you find that you get swellings on the stems (particularly on the new growth), citrus gall wasp has been active. Prune them off before the wasps emerge (end of June in Queensland).

There are times when we have pest outbreaks that we need to control. You don't necessarily have to rush off to the shops. You often have simple things at home in the cupboard or in the shed. I will go through a few of them now. We are putting the recipes of all of these preparations on the transcript, so if you need to check any details, please do so, before you try and make the products up. (See recipe summary below)

One thing you might have available is garlic. You can use fresh cloves of garlic or if you happen to have a jar of garlic paste, that is quite suitable as well. Garlic is used as a repellent. You need to put it on before the pests are active. You might know from experience that a particular plant that you have, or a crop that you grow in the vegetable garden tends to get pests. So you may know from experience that it's a good idea to put a repellent spray on. Garlic has antiseptic properties as well, but really it is the repellent quality that gardeners admire. Use garlic spray on roses.

You need the equivalent of about three cloves of garlic or about a tablespoon of a paste; one tablespoon of vegetable oil; soap and water. Soak the garlic in the oil overnight. Basically you're making garlic-infused oil. Strain the oil and add to a litre of water with a teaspoon of soap (grated or liquid). Spray it fresh because that's when it's going to be at its most potent. Some gardener say this works effectively for them in repelling aphids, ants, scale and other soft-bodied insects. It is something you could try.  

If you find that the garlic preparation isn't doing the job, you can move on to something stronger and that's where a chilli spray comes in. (see recipe summary below) Chilli sprays are both an irritant to an insect and also a stomach poison if they consume them. You can use chillies that you've grown yourself. Put them in a blender with water and then strain that concentrate or you can simply use ground, dried chili. You can even cheat. If you've got some really hot sauce like Tabasco in the fridge, you can use that as well. You need the equivalent of about a tablespoon of ground chilli or Tabasco sauce; two litres of  water and again you need that teaspoon of liquid soap or grated soap (dissolved in little warm water). Combine the ingredients in the two litres of water and apply straight away.

With all of these sprays, I try not to store them because they will deteriorate over time. Also, with a chilli spray in particular, there's always a risk in leaving it around. You want to really make sure that people don't mistake it for something else and be careful yourself when you're applying it in the garden. Chilli is an irritant, so you don't want to get it in your eyes; on your hands or on your skin. Make sure that you take appropriate precautions.  

Adding soap is designed to make some of these products stick to plant and give better coverage over the leaves. You can also make a simple soap spray (see recipe summary below). Soap is a desiccant. It breaks down the exoskeleton or the waxy coating on the outside of an insect. You can use old-fashioned, pure, bar soap. I grate this on a fine grater. You'll find that it will dissolve quite readily in warm water and then you can expand it out by adding cold water. You can also use a really simple dishwashing liquid. Anything that is reasonably pure; doesn't have too many enzymes in it or is not meant to remove too much grease will be a perfect product for your soap spray.

Make up the soap spray as if washing an item of clothing. That is about the right strength to spray onto plants. Soap sprays are good for easy pests like aphids and they even work some caterpillars. You can use them on scale insects as well. Remember with all of these products, they are safe to use, but you do need to reapply them on a regular basis. It might be case of having to spray twice a week with a soap spray to bring a pest under control.

If the soap doesn't work for you, you can move on to something stronger. That's where we go to oil sprays (see recipe summary below). Soap sprays desiccate the insect; oil sprays suffocate them. You need to bring the oil in contact with the insect. You are going to need to make up a concentrate – half a litre of oil and half a cup soap. Dilute that down to one tablespoon per litre of water. This will store for a while, but again, I do like to make it up as fresh as I possibly can. Do not store at for long periods in the sprayer.

My favourite spray of all is molasses (see recipe summary below). Molasses is easy to buy from the supermarket, but it's much cheaper from a produce store. The best type to use is blackstrap molasses. That's the third stage in the sugar production process, so blackstrap molasses is very concentrated and it also has quite a lot of nutrition in it as well. It's really easy to make up.

You need one tablespoon of blackstrap molasses in a one litre of water. Again you'll need soap to make it stick. Use a teaspoon of liquid soap or grated soap. Spray onto your plants. It works magic on caterpillars eating everything in your garden. This is the spray that you need if you have cut worms that come up from the soil at the night and chew your seedlings off at ground level in your vegetable garden. It is also quite good for repelling possums. Don't store it for long periods of time because it will ferment in your sprayer. Your sprayer will get fatter and fatter as it ferments. Use it within a couple of days.

You can also make it up in a watering can and drench your soil if you find that you've got soil nematodes that are causing problems or any curl grub larvae (see recipe summary below). Curl grubs are larvae of beetles. They can eat the roots of your plants.  If you got those dreadful lily caterpillars that eat out your bulbs, then use the molasses drench on a regular basis.

We all have to share our gardens with insects and other wildlife, but if possums are making a mess of your garden, here's my suggestion. Buy a bag of carrots and put them out for the possum to eat. After all they have to eat something! Those plants that you really want to protect you should spray with oil of cloves (6 drops per litre of water). Do that every week or you can apply to fence lines or boundaries. You must do it every week to protect your plants from possums. But spare a thought for the possums and leave some plants for them to eat or provide an alternative food source.

So the balance in the garden is easy to achieve. Next time I'll be back to tell you how to deal with disease problems in your garden.

*Glassine bags used in the food service industry. They are made from glossy paper and are water and grease resistant.

Recipe summary

Soap spray

Mites; aphids; soft-bodied insects

  • Pure bar soap or soap flakes or liquid soap
  • Warm water

Combine soap with water to make a mix to the same strength you might use to wash cloves. Spray directly on insects. Re-spray as necessary. Soap sprays are desiccants.

Chilli spray

Caterpillars; ants; soft bodied insects

  • Fresh hot chillies (blended in water and strained) or 1 tablespoon ground chillies or tobasco sauce
  • 2 litres of water
  • 1 teaspoon liquid soap or 5 grams of soap flakes (dissolved in hot water)

Spray directly on plants where pests are active. Use immediately. Do not store. Take appropriate precautions to protect your eyes and skin from contact with the spray as burning may occur. Chilli is a stomach poison and irritant. Chilli powder sprinkled directly on the tops of potted plants also acts as a stomach poison and a deterrent to ants.

Oil spray 

Mites; scale; aphids; soft-bodied insects; citrus leaf miner

  • 500ml of vegetable oil
  • ½ cup dishwashing liquid or other pure liquid soap

Blend thoroughly and seal in a clean, clearly labelled jar. Dilute one tablespoon of this concentrate into one litre of water before spraying. Oil based mixtures suffocate mites, scale and other soft bodied insects. They help to repel leaf miner moths and some gardeners find them effective against small grasshoppers. Avoid using on plants with hairy leaves and during very hot weather.

Molasses spray

Caterpillars; soft-bodied insects; nematodes; cut worms; possums

  • 1 tablespoon black strap molasses
  • 1 litre warm water
  • 1 teaspoon liquid soap or 5 grams of soap flakes dissolved in hot water

Combine and spray regularly over the leaves of all plants attacked by caterpillars and other chewing pests. The molasses works by osmosis. Caterpillars stop eating and die a day or two after application.  Double the quantity of molasses to use as a soil drench against root knot nematodes and cut worms. Apply in the evening when cut worms move to the soil surface.

Oil of cloves 

Possum repellent

  • 6 drops Oil of Cloves
  • 1 litre water

Combine in a spray bottle and shake. Spray on plants (avoid soft leaves and vegetables) or around the area that you want to protect from the possums. Repeat every week. Provide an alternative food source for possums like carrots.


For more DIY pest control recipes see

Last updated: 29 April 2021
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