ORGANIC MANAGEMENT OF PESTS AND DISEASE
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People sometimes ask me, "how do you deal with outbreaks of pests and disease in your garden?". This can be a tough question for me because I personally have not had to deal with very many outbreaks of pests and disease in my garden - I am not sure whether this is purely luck, or if it is evidence to the success of the preventative measures I have always taken in the garden.
SOIL HEALTH
The number one way to avoid pests and disease in the garden is to maintain healthy soil. Healthy soil grows healthy plants and healthy plants are much more adept at resisting pests and disease than weak, spindly or sluggish plants. See our page about maintaining healthy soils for more information.
BIODIVERSITY
Equally important to healthy soils, is maintaining diversity of species in the garden. If you have a diverse range of plants growing, and not too many of any one particular plant, your chances of pest outbreaks are much reduced. This diverse mix of plants needs to include flowers, usually a mix of wildflowers as well as vegetable plants flowering as part of the seed saving process. These flowers help to attract the beneficial insects which prey upon undesirables such as aphids and caterpillars. This is known as 'polyculture' and avoids many of the common problems encountered with mass scale monoculture cultivation of crops.
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OBSERVATION
One human-centric factor in dealing with pest problems is to not freak out over it - stay calm and be observant. Don't pull out the big guns just yet! The best solutions are usually those which work with the natural circumstances within the garden. Often, pests such as aphids will attack one or two of the weakest plants leaving many untouched. Yet if you remove those plants, then the aphids need to find a new home. Not to mention those aphids will be providing food for predatory insects in your garden, which will help to keep populations in check. This is the main reason why sprays - even organic sprays like those listed below - should only be used as a last resort.
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CROP ROTATION
Another critical aspect of preventing pests and disease in the back yard garden is crop rotation. By moving your crops around and not growing the same thing in the same spot year after year, you reduce the chances of soil-borne diseases such as club root or other root problems becoming well established in the soil. Often these diseases are crop specific, so if you deprive them of food by not growing that crop there for a season or a few seasons, the spores will eventually peter out.
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ALTERNATIVE / HOME MADE SPRAYS
Garlic
Effective against aphids, white butterfly, beanfly, leaf curl, brown rot, ants, spiders and caterpillars, but kills some useful predators too, so only use for severe infestations. To make a garlic spray, simply crush up a few cloves of garlic (3 to 10 or so depending how strong you want the spray) and soak them in a litre of water overnight. The next day, strain this liquid and dilute it down to 4 or 5 litres and add a few drops of natural dish soap. Apply with a pump sprayer. Chilli can be added to the concoction for extra kick.
Soapy water
Particularly good against aphids. Can be repeated as many times as you like. After spraying the affected plants, hose them down gently with clear water. Dissolve half a bar of plain soap or a few squirts natural dish soap in 5 litres of hot water. Stir well to make sure all the soap has dissolved. Cool before use.
Seaweed
Effective against mildew and acts as a feed too. Spray as a precaution whenever you think plants might be in danger, such as growing very close together and the weather is humid. Either leave the seaweed to soak in water for a fortnight or boil it up well-covered with water until the liquid begins to thicken. In either case, dilute it until the colour of palest sherry before using it.
Chamomile
Useful against mildew, fruit rot, rust and fungal diseases generally. Use at the first sign of trouble. Use fresh flowers, dried flowers or chamomile teabags. Cover with water, bring to the boil and hold it there for a minute or two before removing from the heat. Leave to cool, then strain and dilute with four times the amount of water.
Stinging nettles
Repels aphids, reduces mildew and is a good foliar feeding spray and liquid manure. Cut the tops off nettles and leave the roots to grow on. Cover stems and leaves in water and bring to the boil. Hold for about about 10 minutes. Cool and strain. Dilute to the colour of weak tea before use. The sludge can be tipped on the compost heap.
Onion
Effective against red spider mites. Cut up onions, skins and all, and leave covered with boiling water. Use well diluted. Instead, for a spray with more oomph, put the onions through the blender, add a garlic clove and a couple of chilli peppers, cover the mush with water, strain and dilute.
Chives
Useful for fungal problems on roses or cucurbits (squashes, courgettes, cucumbers). Spray regularly to prevent fungal problems developing. Pour 50ml of boiling water over a handful of fresh chives or 1 Tbsp of dried chives. Leave for an hour, then strain and store in a jar or bottle until needed. Use one part of chive liquid to two parts of water.
Elder leaf
A general insecticide and fungicide. Cover a quantity of leaves with water and bring to the boil. Simmer for 20 minutes. Don’t inhale the steam. Cool, strain and dilute until the colour is pale yellow before using.
Rhubarb leaf
Helps control aphids, thrips, whitefly and other pests. Best sprayed towards evening once bees have gone to sleep as contact with the spray may harm them, but it will soon break down. Only hose it off if there are a lot of dead insects you want to clean up. Rhubarb leaves are poisonous to people - don’t inhale the steam during preparation, only make enough spray to use in one go and never store it. Chop up the leaves, cover with water and boil up. Keep on a slow boil for about half an hour. Cool, strain and add the liquid to at least an equal amount of soapy water before use.
