PESTS & DISEASES

Chemicals, even organically acceptable ones, can cause more damage than we realize. Contact killers can often hit non-pest species, while treatments designed to combat fungal problems can be washed into the soil, damaging worms and other soil-dwellers. The best technique is to deal with problems early on, thus avoiding the need for chemical treatments.

Chemical pesticides have no place in organic gardening. Organic gardeners have many insecticides at their disposal. Some are derived from plants, such as pyrethrum and neem. Some of the best insect killers are simply refined soaps or oils. And others more subtly pit one kind of organism against the pest. The bacterial insecticides Bacillus thuringensis ("Bt" for short), and milky spore are examples.

Often these pesticides are chosen for exactly the opposite reason that people choose other kinds of insecticides. Instead of being broad-spectrum and long-lasting, organic pesticides may attack just one type of insect and break down quickly after use. Organic gardeners know there are good insects as well as bad in the garden (bees, for example), and usually know enough about bugs to zap just the culprit and not the passer-by.

Don't rely on just one method of pest control, as the best results come from using a range of techniques. Traps and barriers, naturally resistant varieties, biological controls and plant rotation are just some of the ways to keep pests at bay. Vigilance is crucial. By checking your plants often, you'll spot problems in the early stages when they are easier to deal with. Often you can allow nature's armory of natural predators to work for you. Also, it pays to take good care of your soil, because healthy soil will produce strong plants that tolerate some pest attack.

There are several ways to combat diseases naturally. Always change the position of your vegetable crops each year. By doing this, you'll avoid a build-up of soil-borne problems. Keep plants growing steadily by never letting them go short of water. Dry roots lead to stressed plants that are ready to succumb to any disease. Keeping the soil well-composted will help suppress many diseases as well.

Organic gardens are vital havens for wildlife. Grow a range of plants providing food and shelter and see how quickly the creatures arrive. Aim to attract as wide a range of wildlife as possible, because greater diversity will produce better balance, allowing natural predators to keep pests under control.

Weed Control - Once again, the key is to aim for a balance. If weeds are likely to compete with your plants for nutrients, they should be controlled. So-called organic herbicides don't exist, so other methods must be used:

• Keep bare soil covered as weeds will seed in any open space. In ornamental areas, use ground cover plants or a mulch to smother weeds. Mulch around vegetables with leaf-mould or hay.
• During winter grow a green manure, such as clover, where you have no crop cover. As well as keeping down weeds, it stores nutrients in its roots. These are returned to the soil when it is uprooted and dug in during spring.
• Hoe off weeds as soon as they appear. All the green waste can be added to the compost heap where any minerals and other nutrients they have absorbed during their short growing time will be recycled for the benefit of your garden plants.
• On hard surfaces, use a flame-weeder to burst and kill plants' cells. Done regularly, it will keep annual weeds in check and weaken perennial weeds.