Programs
The Garden
Organic Pest Control
All pesticides are toxic to some degree. The following
hints should assist you in dealing with garden pests organically,
without the use of harmful pesticides.
Use your judgement and test some suggestions on a small
problem area first before going ahead on a larger scale.
Where the use of water is suggested you should keep in mind
water conservation measures and any water use restrictions
that may apply.
Aphids
Ants frequently nurture plant pests such as aphids, scale
insects, mealy bugs, feeding on their sweet honeydew. Sticky
barriers made of non-drying organic glues can be used to
protect trees and other ornamental plants, such as roses
from ants.
If the infestation is slight you can squash them between
your thumb and your finger.
Or use a high-pressure jet of water to hose them off the
plants.
Alternatively, plant onions, garlic or nasturtiums beneath
plants prone to aphid attack to deter this pest.
As a last resort use a soap spray, a eucalyptus oil spray
or a vegetable oil spray. Or dab with cotton wool soaked
in methylated spirits.
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Caterpillars
Hand pick them off and squash them.
Or, lightly dust them with flour or white pepper.
Or, use a weak clay or hot water spray.
Or, use Dipel.
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Mites and other tiny insects
For indoor plants, simply wipe the leaves with a soapy
cloth.
Outside in the garden, blast them off the foliage and stems
with a high-pressure jet of water.
Use an old toothbrush to remove those clinging too tightly
to be hosed off.
Or, use a soap, milk, clay or pyrethrum spray.
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Scale
Cut away badly affected foliage or scrub scale insects
gently from twigs using a soft brush and soapy water.
Use a soap, vegetable oil, eucalyptus oil or clay spray
to smother this pest.
You can also use white oil to kill scale. White oil has
a relatively short residual life, as well as low impact
on beneficial insects.
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Snails and slugs
Snail baits mostly consist of powders or pellets, which
contain metaldehyde or methiocarb and are spread on garden
beds. It is not known how metaldehyde works but methiocarb
acts like all carbamates to interfere with the transmission
of nerve impulses.
Snail baits are a hazard to pets, animals and birds and
a safer alternative such as the one listed below should
be considered.
A slug trap consists of a dish sunk level with the ground
baited with equal parts of stale beer and sweetened water.
This will trap the snails and slugs.
Physical barriers to deter slugs can be made using soot,lime,sawdust,
grit, eggshells or wood ash to protect seedlings. The grit
will stick to the snail’s slimy surface and deter it.
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Homemade Organic
Sprays
Organic sprays break down more rapidly than chemical pesticides.
But please remember that although many sprays are made with
“natural ingredients” they may never the less
be toxic to humans and garden friendly creatures, as well
as the organisms you seek to control.
You should always wear protective clothing, a facemask,
long sleeves and gloves when applying sprays such as pyrethrum,
wormwood and Dipel. Also label and store organic sprays
as carefully as you would other chemicals. Keep them away
from children and pets.
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Baking soda (bicarb soda) spray
This spray prevents fungal spores from establishing themselves
and developing on your plants. It is effective in treating
any mould or mildew problem on grape or passion fruit vines.
Simply combine 1 teaspoon of bicarb soda with a few drops
of liquid soap, then dissolve in 2 litres of water. The
soap helps the spray stick to the leaf surface. During times
of greatest risk (high temperature and humidity) spray twice
weekly with this solution.
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Chamomile spray
This easy to make spray acts against powdery mildew, rust,
stem rot, brown spot, brown rot, leaf spot and other fungal
diseases. It is the gentlest fungicide possible.
Simply make a pot of ordinary chamomile tea, and then leave
it to brew for 10 minutes. Cool, then spray every few days.
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Clay spray
This spray suffocates creatures such as mites, thrips,
caterpillars and aphids, however, remember that useful creatures
such as ladybird larvae will be affected as well, so restrict
your spraying to creatures you can actually identify. The
spray has no residual effect, so it can be reapplied every
few days.
Using pure clay, dilute the clay with sufficient water
to make a spray.
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Dipel spray
This is a commercial product containing bacterium Bacillus
thuringienis. It is an example of biological control, being
largely non-toxic to animals. Lethal effects are not passed
on down the food chain to birds or any other predator.
Dipel spray needs to be reapplied about every seven days,
as the bacterial spores are destroyed by sunlight. It is
effective against moth and butterfly caterpillars, which
readily inject it, resulting in paralysis of their digestive
tract.
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Eucalyptus oil spray
Eucalyptus oil, like many essential oils, kills scale insects,
aphids, earwigs, slugs, slaters, whiteflies, mites and many
other pests. It is a non-residual spray, best applied around
seedlings and at the base of plants.
To make the spray, combine 1 teaspoon of eucalyptus oil
with 500 ml of soapy water. Generally speaking a solution
of about 2% eucalyptus oil in water is considered a good
general-purpose insect spray. You can repeat the spray every
three days.
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Garlic spray
To make a safe, general garlic spray, soak 85 grams of
chopped garlic in 2 tablespoons (40ml) mineral oil (paraffin
oil) for 24 hours. Dissolve 7 grams of soap in 600ml of
water. Slowly add the soap to the garlic and stir well.
Strain the liquid through a fine gauze and store in a china
or glass container (not metal). Dilute 1 part mixture to
50 parts water for general use. Label the container. Good
against aphids, caterpillars, flies and snails.
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Hot water spray
Many soft-bodied insects are killed by a simple spray of
hot water (between 45 degrees Celsius and 55 degrees Celsius).
This will not harm most foliage.
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Milk spray
Milk is lethal to red spider mites and mildew. A milk spray
can be used on plants such as zucchinis, lettuces, cucumbers
and tomatoes.
To prepare your milk spray, mix equal parts milk and water.
The spray needs to be repeated every few days.
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Soap spray
A soap spray will kill caterpillars, thrips, scale insects,
mites, whiteflies and aphids. It does this by paralysing
its victim, which then eventually dies of starvation. By
killing aphids and scale insects, soap spray also controls
sooty mould.
For this spray start off with soft soap, that is, soap
that is neither a detergent nor contains caustic soda. Mix
together soap and water until you have a frothy milky solution.
Allow the spray to dry on the leaves, then rinse the leaves
clean the following day. Spray every 2-3 days for two weeks.
If your plants are drought or heat stressed, or weakened
in any way, use a more dilute solution.
Commercial pesticides, herbicides, soil sterilants and
fungicides can pose an unnecessary danger to your family
and the environment. There is almost always an alternative
to using these products.
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References:
- Dadd, D L (1997). Home Safe Home. Jeremy P. Tarcher/Putman,
New York, USA.
- Stewart, R (2002). Robin Stewart’s Chemical
Free Home. Black Inc. Melbourne, Victoria
- Total Environment Centre (1996). A-Z of Chemicals
in the Home. National Library of Australia.
Disclaimer:
Zero Waste SA shall not accept responsibility for injury,
loss, or damage occasioned to any person acting or refraining
from action as a result of material in this information
sheet, whether or not such injury, loss, damage is in any
way due to a negligent act or omission, breach of duty or
default in the part of Zero Waste SA or the Government of
South Australia.
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