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In an era where we are encouraged to be more environmentally friendly, anyone with a garden has the opportunity to do their part for the environment, such as using less chemicals like herbicides, pesticides and man-made fertilisers. This entry will focus on a few suggestions to control some of the more common pests in your garden.
Aphids are small, sap-sucking insects. They attach themselves to the veins of young leaves and stems. With a sharp probe, they pierce the vein of the plant and suck the sap. They also produce a sticky by-product, which is sometimes the first sign that an infestation is present.
There are several methods that can be used to control aphids.
Natural soap washing-up liquid, mixed with water and sprayed onto the aphids is one method. Aphids breathe through their skin, so spraying them with a solution of washing-up liquid blocks the pores of the skin and they suffocate.
Natural predators of aphids include lacewings and ladybirds. If you have no lacewings or ladybirds in your garden, it's possible to buy packets of eggs via mail-order. The eggs are placed on the plant, near to where the infestation is. Both larvae and adults will consume many aphids in one day. By placing bug boxes around your garden, you are providing a winter shelter for lacewings and ladybirds.
Another way to rid your plants of aphids is to run your thumb and forefinger along the stems and leaves of plants and brush the aphids off. Do this gently, so as not to damage the plant. Once the aphids have been brushed off, they will not climb back onto the plant. Use this method every two days for one week and the aphids will be gone.
Hoverflies1 are always welcome visitors to the garden. Their larvae feed on many pests, primarily aphids and small caterpillars, and encouraging them to visit your garden is certainly worthwhile. Flowers which provide nectar and pollen will encourage these handy insects to breed. Hoverflies like flat, open flowers, such as feverfew and poached egg plant. They also like flowers rich in nectar, like hebes and golden rod.
Slugs can destroy a whole plant overnight and wreak havoc in the vegetable plot. During the day, they hide in damp, shady places and can be difficult to find. There are lots of methods to try and keep this pest from eating all of your crops and flowers. Some are successful, whereas others are not quite so effective.
Traps are quite effective, though they have their drawbacks. An old jamjar or the bottom of a plastic bottle can be used as a trap. Sink the trap into the ground up to the rim of the container. Half-fill the container with beer, lager or cider. Slugs will be drawn by the smell and slide into the trap, where they will drown. One drawback is that other beneficial insects will also be drawn to the traps. They will also have to be emptied and refilled regularly.
If you have pots or containers, copper tape can be used to help protect the plants. It is stuck around the container and gives the slug a small electric shock which deters them. However, it is only effective if the leaves of the plants do not trail down over the container or are not accessable via another plant.
Gravel, crushed egg shells, small nut shells, orange peel and salt have been used with little success. Salt should not be used around plants, as the build-up of salt in the soil will eventually kill the plants. It's worth remembering that a slug can crawl along the edge of a razor blade without harming itself.
Nematodes are an effective way to rid your garden of slugs. Microscopic parasites that feed on slugs, nematodes can be bought by mail order. They come in a sachet to which you add water and then apply to your garden. The treatment has to be repeated every six weeks between March and October to keep your garden virtually slug-free.
If you are lucky enough to have frogs, toads, hedgehogs or slow-worms living in your garden, you have the ideal slug-eaters. Encourage frogs into your garden by making a wildlife pond. Have a small pile of logs for them to hide under. An open compost heap is an ideal habitat for slow-worms, where they can burrow and shelter. Hedgehogs will also benefit from a compost heap. An old wooden crate, placed in a secluded, sheltered part of your garden and covered with dead leaves will make an ideal shelter for a hedgehog.
Both adults and grubs eat plants. The adults eat leaves and shoots, leaving holes in leaves.
Vine Weevil Control
The grubs do the most damage. They are found mostly in containers and potted plants, where the adult vine weevil lays its eggs into the soil. The grubs hatch and start eating the roots of any plant available. They are a very destructive pest, killing plants quickly. The grubs are easily recognised: they are almost white in colour, with a light brown head. The first sign of vine weevil grubs is a dead plant with no roots. There is only one organic control for this pest — a nematode that feeds on vine weevils. Watered into pots and containers, they will feed on the grubs.
Caterpillars come in many sizes, from little green ones to hairy ones to big fat ones. They are all designed for the same purpose: to eat as much as possible in a short time.
Caterpillars have many natural predators. Birds will take many to feed their chicks. Frogs and toads will also eat them, if they are within reach. Parasitic wasps will paralyse the caterpillar and then lay their eggs either inside or around the grub. The most effective way to deal with caterpillars on your plants is to pick them off and dispose of them. Also look out for the eggs, which appear in small clusters, or individually on the underside of leaves. The first sign of caterpillar damage is usually when the plants have been half-eaten.
Another natural control for caterpillars is an organism called Bacillus thuringiensis, which destroys the caterpillar from the inside.
In some cases, companion planting can be an effective deterrent to many pests. They can often be distracted from their favourite food source by plants with strong smells and/or large blooms that are nearby. These will either repel the pests with their odour or simply make the smells so confusing that they cannot locate your favourite plant! For example, marigolds not only look and smell nice, but will keep a whole range of bugs off your plants. Planting several marigolds in a greenhouse will help deter whitefly from your tomatoes and cucumbers. Onions or parsley planted near your carrots can likewise keep your crop bug-free.
It is well worth considering turning to organic methods of gardening. Not only will it benefit the environment, it will also bring lots of wildlife into your garden.
Methods of pest control involving the use of chemicals are discussed in the entry Pest Control in the Garden.