Why it's important to find organic solutions

Often we react to seeing weeds or pests by immediately applying chemicals, or even apply chemicals as prevention.

Exposure to pesticides has been linked to a long list of diseases and health problems: Parkinson’s, infertility, cancer, birth defects, encephalitis, and lymphoma, just to name a few. Another problem is that the law does not require companies to test lawn pesticides with the same standards as pesticides used on commercially-grown food. Many of these contact hidden "inert ingredients" that have never been tested for possible harm.

In addition to the harm they can do to us humans, pesticides contaminate the air, water, soil, plants, and animals around us. For example, many studies have proven that pesticides harm honeybees, butterflies, ladybugs (which eat lots of other pests), and fish, and that lawn chemicals seep into the water table.

Besides that, they can be expensive!

Learning to combat pests without chemicals is a great way to help your health and that of your neighbours and the environment.

Pests are actually a normal part of every garden. They come and go with the seasons without really causing too much drama. In healthy gardens, they are kept in check by birds, frogs and lizards as well as beneficial predatory and parasitic insects.

But keeping plants in good shape is crucial, because weak, sick and stressed plants are more prone to attack. Cultural practices like crop rotation and companion planting further reduce the risk of attack.

Traps and barriers can be used to protect vulnerable plants such as seedlings. As a last resort make organic sprays to cure particular outbreaks. Look on olive trees, citrus or passionfruit vines and you'll probably find black scale. These sucking insects gather on leaves and stems and can quickly build up to the point where they stunt plant growth.

Scales shoot a sweet substance called honeydew. Ants literally farm the scale to feed on the honeydew. They'll pick them up and they'll move them all over the tree. Honeydew also leads to sooty mould, a black dusty fungus that grows over the leaves and stems. Controlling the scale will also get rid of the sooty mould.

If you only have a small amount of scale, scrape it off with a fingernail or toothbrush. Larger infestations can be controlled by spraying with an oil to suffocate them.

Make the oil spray by blending two cups of vegetable oil with one cup of pure liquid soap, and mix it until it turns white. Dilute one tablespoon of the emulsion to one litre of water and spray all affected areas thoroughly. Do this during mild weather, because if it's hot it may burn the plant’s leaves.

Mealy bug is another common sucking insect that's around at the moment. Mealy bugs like sheltered conditions and are commonly found on plants under patios, in glass and shade houses as well as indoor plants. Being sap suckers, they cause the leaves to wilt and distort. They also produce honeydew, which leads to sooty mould fungus, also farmed by ants. The big ones can just be squashed with your fingers, but dab the little ones with methylated spirits. This dissolves the waxy coating, which causes them to dehydrate and die.

Citrus leaf miner is a common pest during summer and autumn affecting all citrus. The larvae tunnels in the leaf, forming a squiggly silvery window pattern. When it's fully grown, it curls the edges of the leaf together and pupates to emerge as a small moth about five millimetres in length. The moth is only active at night, so it's rarely seen and its lifecycle may take as little as three weeks. The leaves often become severely distorted, which can stunt growth and reduce yield, but rarely kill a tree. Damage is normally on new sappy growth and can be controlled by cutting off and destroying the damaged parts. Citrus leaf miner like warm weather, so fertilise citrus at the end of autumn and in early winter so the new growth won't be attacked. During warm weather, you can also protect new growth by spraying with an oil spray, similar to that for scale.

Slugs and snails are common garden pests and can cause damage, particularly to young seedlings, but it's surprisingly easy to keep numbers down. Set some beer traps. Just half fill a jar with beer and lay on its side, where slugs and snails are likely to strike. They will be attracted to it. They'll crawl in there for a drink, get drunk, and die. It's also a good idea to lay traps in cool, damp places where snails hide. If you can't stand to waste beer, try coffee spray. This is an idea borrowed from Jerry Coleby-Williams, and it works a treat. One part really strong espresso coffee to 10 parts water, and spray the seedlings and surrounding soil thoroughly. The slugs and snails cross, it absorb the caffeine and die. You have to reapply after rain or irrigation.

Some natural sprays can be harmful. For example, pyrethrum is actually quite poisonous until it breaks down. Chilli and garlic spray, used to control aphids, can be painful if it gets in your eyes. Always label containers, even if they're harmless, and keep out of reach of children. Remember, even natural sprays should only be used as a last resort, because they can also harm beneficial insects, some of which help keep pest insects under control.

with thanks to ABC's Gardening Australia