What are my options in Pest Control? How do I know what is best?
There are 3 main types: systemic, contact, and biological.
Systemic insecticides work by being absorbed by the plant's roots or leaf system, and killing insects that come into contact with the plant. This will work for difficult pest, such as the grubs of vine weevils which are hidden in the soil, and scale insects which protect themselves from above with scaly cover.
Contact insecticides must be sprayed directly on to the insects to be effective. Most organic insecticides work this way, but they generally kill all insects, even beneficial ones, such as hoverflies and ladybirds. Try to remove them before spraying the infected plant.
Biological control is used by commercial growers in their glasshouses; this means natural predators are introduced to eat the pest population. Although not all are suitable for the amateur gardener, they can be used in conservatories for dealing with pests such as the whitefly. Hope this gives you a little more insight into the pest control world.
Happy gardening!