Diseases

Abstract

A disease is something that causes impairment to the normal functioning of a plant. Diseases can be caused by another living organism (biotic) or caused by something in the non-living part of the environment (abiotic). As with pests, diseases are important in plantation forestry only when the impairment they cause is sufficient to threaten the viability of the plantation. Whilst chemical control of diseases is often possible, as with pest control it is considered more desirable to use an ‘integrated disease management system’ based around the natural circumstances of the disease. Fungal diseases are the most common in plantation forests and a number of examples from around the world are described, together with the control measures developed to deal with them. Other biotic diseases are caused by bacteria, viruses, insects, mites, nematodes or even some other plants. These are rare in plantation forests and are discussed only briefly. Abiotic agents of plant disease include air or soil pollution, high or freezing temperatures, pesticides, drought, salt, poor soil aeration, nutrient deficiency or mechanical damage; these too are less common in plantation forests and are also discussed only briefly.