IT'S a tough question facing all gardeners when it comes to protecting plants from nasty pests and diseases.
Part of the answer depends on how much and what type of chemicals you'll allow bearing in mind factors such as children, pets and your own views.
Treatment then lies in first identifying what type of pest or disease you have then choosing the appropriate chemical.
Broadly speaking pests can be divided into either sucking or chewing types.
Chewers munch in our gardens and are mainly caterpillars, beetles and grasshoppers of various shapes and sizes.
Sucking insects are those that feed by sucking on plants. This is the largest group including aphids, thrips, lacewings, mites etc. These generally are more damaging to plants over the long term. Chemical control of insects works in a couple of ways.
■ Kills on contact e.g. fly and mosquito sprays and some garden insecticide. Problem is these aren't selective killing anything they contact. Generally not recommended in the garden.
■ Applied to the foliage so that insect ingests the chemical and it does its work. These are used on chewing insects.
■ Systemic control is a chemical that when sprayed onto the plant is absorbed into the plants internal system so that any pest that either chews or sucks is treated. Best for sucking types of insects.
■ Repellents work by making the plant unappetising to bugs. Examples are the organic sprays using things like garlic, chilli or soap dissolved in liquid. Great for organic gardening.
