Make a New Year’s resolution to be more eco-friendly by creating your own natural fungal deterrents, insect repellents and traps
Mixing up your own insect sprays and fungal deterrents is an easy way to make your garden more eco-friendly. Although homemade sprays may need to be applied more frequently, they are produced from simple, organic or natural, non-chemical ingredients and degrade quickly so have less impact on the environment. They are also inexpensive and easy to make.
The recipes provided here are mainly for deterrents, which help to keep pest populations down rather than eliminating them, this in turn ensures that food remains available for beneficial predatory insects thus helping to maintain a natural balance in the garden.
RESPONSIBLE PEST CONTROL
When using repellents and deterrents, use only as much and as often as is necessary.
Some of these recipes make products that are non-selective, meaning they can kill beneficial insects like bees. As a result, use them where there are no beneficial insects present and then only target the affected portions of the plant.
Before using homemade sprays, test them on an inconspicuous part of the plant. Concentrations can vary from batch to batch; too strong a concentration can damage the leaves.
FRUIT FLY BAIT AND TRAP
Target: Fruit flies are small flies and wasp-like in the case of pumpkin fruit flies. When laying their eggs, they sting the flesh of immature fruits like peaches, apricots, apples, plums and nectarines as well as baby marrows, squashes and pumpkins; the resulting larva damage the fruit. A trail of sap hanging from a piece of fruit is an indication that it has been stung.
To make your trap: Remove the lid from a two-litre plastic cool drink bottle then cut off the top cone-shaped third. Place the bait in the base of the bottle; invert the cut-off third and slip it back into the base. Stretch a sheet of fairly thick plastic over the opening at the top and secure it with an elastic band. Heat a needle or paper clip over a candle and pierce the plastic, making holes large enough for fruit flies to fit through, but too small for beneficial insects like bees and wasps. Hang your trap near beds of baby marrow or pumpkins or among susceptible fruit trees as their fruit begins to swell; the fruit flies will be attracted by the smell of the bait.
Bait: Use apple cider vinegar, adding a few drops of canola or other cooking oil or dishwashing detergent to break the surface tension of the liquid. As an alternative, a few pieces of over-ripe fruit such as pineapple or banana also work well. Check the traps every one to two weeks and replace as necessary.
MILK SPRAY FOR POWDERY MILDEW
Researchers from Brazil discovered the benefits of milk as a fungicide in the mid-1980s. It is also thought to boost a plant’s immune system; some gardeners believe it is a deterrent to caterpillars, and if sprayed under the leaves, red spider mite.
Target: Mildew is a debilitating fungus which damages leaves, inhibiting food production. Susceptible plants include roses, cucumbers, marrows and pumpkins as well as ornamental flowers like dahlias and zinnias.
Recipe: Mix 1 cup skimmed milk with 9 cups water. Make up as required and apply twice weekly to the leaves as a preventative spray. This may also be effective on impatiens (Busy Lizzies).
Target: A wide range of insects like whiteflies, aphids, caterpillars and beetles. As it also affects beneficial insects, it’s best to spray in the evening when bees and predatory wasps are less active, targeting only the affected parts of the plant.
Recipe: Whizz together 2 garlic bulbs, 3 cups water and 2T canola oil in a blender; allow to steep in a sealed container overnight. Strain the mixture and add about 1t liquid detergent. To use, dilute 1T of the garlic mixture in 1 litre of water. Keep the unused portion in a sealed, labelled bottle in the fridge. Reapply at regular intervals as the effect wears off with time. Strong-smelling herbs like lavender or mint can also be added.
Where there is scale, or other pests which produce a honeydew, you will often find ants. One way to deter them is to grow strong smelling herbs and plants nearby, this includes mints, pennyroyal, rue, marigolds, wormwood or artemesia, tansy and khakibos. You can also add rue, marigolds, wormwood (artemisia) or tansy to your basic garlic spray. An alternative is to put out a bait of icing sugar and borax, which is a natural mineral.
Target: Mainly used for soft-bodied pests like aphids and caterpillars. As it is a broad-spectrum product it may affect beneficial insects, like bees and predatory wasps, thus it’s best to spray in the evenings when these are not active; this spray should be used with discretion and only to target specific pests.
Recipe: Chop 500g rhubarb leaves and add to 1 litre of water, bring to the boil in a container made from a non-porous material like enamel and then simmer for 20–30 minutes. Once cool, strain the liquid and add 1T dishwashing liquid. To use, dilute 1:100 with water. Spray in evenings as this mix breaks down in sunlight; it will keep in the fridge for two weeks.
Note: The oxalic acid in rhubarb leaves is poisonous so wear gloves during preparation. For the same reason, it’s essential to wait 48 hours before harvesting fruit or vegetables from any plants that you have sprayed.