with Deryn Thorpe

Organic poison-free solutions to pests and diseases

I don’t like using poisons in the garden and try to tackle pest and disease problems the old fashioned way.

This usually means picking off or squashing the bad bugs like aphids that eat our plants and waiting for the natural predator insects like lady birds to arrive.

As a last resort I will spray with a homemade solution made from chilli and garlic but even organic sprays should be the last line of defence as you are disrupting the natural balance in the garden and the sprays indiscriminately kill both the good and bad bugs.

However, plant diseases are very different and it is best to take action as soon as possible to stop fungal problems. If you let them get a hold it is very difficult to get control using organic methods and you may have to buy a commercial fungicide.

When the weather is warm and damp fungal problems abound in the garden, often showing up as a pretty dusting of white on the leaves of susceptible plants

The white frosting is spores of the powdery mildew fungus and another common fungus shows up as red-brown coloured spore or a bright yellow spore, which is called rust.

Chilli & garlic spray

8 finely sliced chillies
4 crushed gloves of garlic
1 tablespoon soap flakes
1 litre of boiling water
Combine in a glass jar and set aside for 24 hours. Strain, pour into a spray bottle and use within 2 weeks

If you are vigilant you can recognise early warning signs – a puckering or crinkling of the leaves and it is then time to take immediate action as most organic controls work best if used as prevention.

Fungus draws on the moisture and nutrients within the leaves and causes leaf yellowing, leaf drop and distorted flowers and fruits. It is more common in shade and areas with poor air flow.

New spores are released during the day and carried on the wind to infect new plants and at night, when temperatures drop and the humidity increases, the spores germinate on wet leaves.

Some of the worst plants for mildew are some species of roses, members of the cucurbit family like cucumbers, zucchini, choko and pumpkin, lilac, grapevines, begonia and hydrangea.

Myrtle rust is prevalent on the east coast of Australia and appears as bright yellow spores and affects 150 species in the myrtle family including Eucalyptus. Other rust tends to be host specific and attacks a wide range of plants including roses, hollyhocks, chrysanthemum, fuchsia, pelargonium and beans.

My first remedy for mildew is a fungicide spray I make up using one part milk to ten parts water. Both the top and underside of the leaf and the stems need to be thoroughly sprayed with the mix.

An alternative is a solution made from bicarbonate of soda. Add two teaspoons to a litre of water and a drop of either vegetable oil or horticultural oil which helps the mixture stick to the leaf. The bicarb makes the leaf alkaline which inhibits the germination of fungal spores and it also helps with rust and black spot on roses.

Infected leaves should be destroyed by being placed in the rubbish bin and not put into the compost.

The best organic solution for rust is sulfur which is available as either a powder or wettable solution. Do not use it when the temperature is over 32 degrees as the plant will burn.

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