An investigation into the extracellular enzymes produced by Dothistroma pini and their relation to pathogenicity : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Biochemistry.
The aim of this chapter is to provide a background against which the pathogenic action of Dothistroma pini can he discussed. Plant Diseases. There are three principal groups of organisms implicated as causal agents of diseases in planto; fungi, bacteria and viruses. These pathogens cause diseases which in general can be divided into three kinds: necrosis, hypertrophy and hypoplasia. Necrosis Necrotic diseases can be general or local in nature. General necrosis is called rotting or decay and is usually caused by fungi or bacteria. An example is Rhizoctonia disease of sugar beet. Local necrosis is more limited in its extent. Examples are leaf spots, fruit spots, anthracnoses and certain types of cankers e.g. the leaf spot of maize caused by Cochliobolus carbonum and red band blight of pines caused by Dothistroma pini. Hypertrophy. [FROM INTRODUCTION]