Strong, healthy plants are far less likely to fall victim to infection and infestation than weak, unhealthy ones. Always start off by purchasing plants that look vigorous and healthy, with no signs of dieback, abnormally coloured leaves or poor root development. You may also want to consider buying disease-resistant cultivars.

Always try to grow plants in the right conditions, taking into account the soil type, texture and pH, the amount of sunlight, and risk of exposure to frost or wind. A plant grown in an environment suited to its needs will have a much better chance of fighting off any problems than one that is already struggling to cope with poor environmental conditions.

Plant spacing is another important consideration; crowded conditions will not only mean that plants will have to compete for nutrients, air, water and light, but the close, humid surroundings will also encourage fungal disease.

If a plant has been badly damaged by disease or pests, it may be best to destroy it, particularly if there is a chance that it might infect other healthy plants.