Safe Pest Control - Step 1 and 2

What to do about food garden pests if you don’t want to use chemical pesticides? This series of blog posts discusses pest control strategies that result in healthy produce without leaving harmful chemical residues.

But first, what are the problems with chemical pesticides?

• Our health: Fruits and vegetables treated with chemical pesticides often contain chemical residues and there have been many examples of these residues being responsible for damage to human health.  Often these chemical residues break down very slowly and remain active in the soil, so they may affect crops long after you have forgotten you ever used the pesticide.

• The health of our environment: Chemical pesticides may kill your target pest, but many of them also kill other life forms in your garden. Pest control chemicals that do this are called broad-spectrum pesticides. They may even kill beneficial insects and other organisms that were in the process of destroying your target pest. The result of your action may be a short-term success, but a long-term increased vulnerability to the target pest because you have killed its predators.

Ladybirds not only look cute, but are also beneficial insects because they eat aphids

And organic pesticides don’t cause these problems?

Many people think that anything organic is automatically fine, but this is definitely not the case. A perfect example is nicotine. For centuries this extract from the tobacco plant has been used by farmers to kill sucking insects, such as aphids. It is an organic pesticide because it is not chemically modified to do the job, but it is no better for human health than artificial chemical alternatives.


So what pesticides are safe?

Australian Certified Organic (see ACO) is Australia’s largest organisation for certification of organic produce. ACO has spent many years finding answers to this question. Australian farms that want to be recognised as ‘certified organic’ need to comply with standards regarding farm methods and materials that lead to safe produce without any harm to the environment.

Click on ACO’s Australian Certified Organic Standard 2013 if you like to know more about approved practices on certified organic farms.

The approaches to pest control discussed on this blog are in line with the Australian Certified Organic Standard 2013.

Six steps for safe pest control

Best-practice pest-control for food-gardeners is not complicated and involves the following steps (in this order):

1. Make your food garden as healthy as possible 
2. Don’t please your pests 
3. Keep them out 
4. Catch and remove 
5. Is further action needed? 
6. Use a low-impact pesticide 

Step 1 and 2 are discussed below.  Step 3 and 4 are discussed here and Step 5 and 6 are discussed here.

I would like to thank Margaret W, Jan R and Marg M for proofreading and commenting on my drafts of this series and for the additional information they provided.


Step 1 - Make your food garden as healthy as possible

Ever been in the situation where everyone at work caught a cold, but you didn’t? That may have been because you were more rested, less stressed and ate better than your colleagues, resulting in a stronger immune system.

The first line of defence against food garden pests is to make sure that your plants are strong and healthy. If that is the case, a garden pest that sweeps through your area may cause less damage to your plants or may not be able to establish itself.

Be aware what each vegetable or fruit variety needs and provide that as best as you can.

Focus on

• Making and using good compost (see Making Compost – part 1 and Making Compost part 2 )

• Providing sufficient water and mulching (see Improving your Irrigation and Automating your Irrigation )

• Providing sufficient space for each plant.

• Creating friable healthy soil (see And now improve your soil biology and Soils ain’t Soils )

• Rotating your crops (see The Importance of Rotating Crops )

• Planting amongst your fruit and vegetables flowers to attract insects and birds.

• Foliar feeding: once a week spray your vegetables, berries and fruit trees with diluted seaweed extract (for example Seasol) or diluted fish emulsion (for example PowerFeed).

If you do all these things, you have in place a perfect first line of defence against food garden pests.

Step 2 - Don’t please your pests

Get to know your pests.  Find out what conditions particular pests thrive in and then make sure not to provide those conditions.  For example:

• Mildew loves humid environments, especially when leaves remain wet for a while. Peas often get mildew. So do not irrigate your peas from above in the evening, because wet leaves, that remain wet overnight, are loved by mildew.  Instead, water pea plants at ground level early in the morning.

Peas affected by Mildew

• Aphids love capsicum plants that are kept in humid conditions without much air movement. Last year I had capsicum plants in my hothouse throughout summer and had a real problem with aphids. This year I started my capsicums in the hothouse in the cool months, then put them outside in a sunny spot subject to winds. I don’t have many aphids on my capsicums this summer.

• Viruses, malevolent microbes and soil-bound diseases, love it when you put plants of the same variety in the same spot for more than one season. After one season put new soil in pots and rotate your crops around your garden, so you don't give pests the opportunity to establish themselves.

• Aphids, Cabbage White Butterfly and Cabbage Moth love brassicas. Most people grow their brassicas over summer and thereby provide wonderful host plants for caterpillars of the Cabbage White Butterfly and Cabbage Moth, and aphids. Consider growing brassicas over winter when these pests are not around. The result may be a slightly smaller crop (because temperatures are down), but produce may be completely unaffected by pests.

Caterpillars of this cute little butterfly are ferocious eaters 

• Consider using varieties of food plants that are less susceptible to pests. Examples are heirloom tomato varieties Tommy Toe and Sweet Bite. Many sources claim they have good disease resistance.

This series of blog posts on Safe Pest Control continues with Step 3 & 4 here.