Unfortunately, pests and diseases can affect most crops at some stage during their life. By ensuring your crops grow well in good soil and aren't stressed by a lack of water and nutrients means they are less likely to be attacked. Some problems are specific to each crop, others will affect many types of vegetables. For instance slugs, aphids and whitefly will affect most crops.
Control varies from problem to problem, but identifying a problem quickly and dealing with it immediately will help prevent the problem reaching epidemic proportions; this can lead to a reduction in yield, weak plants, inedible crops or even the death of the whole plant.
Crop rotation helps prevent the build-up of soil-borne pests and diseases. Covering the plants with horticultural fleece (before the pest attacks!) will prevent the insect pests from reaching the plants. It's important to ensure the edges of the fleece are buried in the soil to prevent insect access and that the fleece is loosely held over the plants so that it can move with them as they. grow. This is now how many growers produce carrot fly-free carrots and cabbage rootfly-free brassicas.
In extreme case you will have to resort to using a pesticide. If you don't like using chemicals then try Bio Organic Pest Control which is based on oil seed rape and is safe to use on all crops. In all cases, prevention is better than cure!
