BASIC CONCEPTS IN PLANT PATHOLOGY
Prepared by John R. Hartman, Extension Plant Pathologist Adapted from Master Gardener materials - University of Kentucky, University of Georgia and Virginia Tech Edited by Gail Ruhl, Purdue University INTRODUCTION Plant diseases in the landscape and garden are very important and can be a significant source of frustration and loss to the gardener. There are about 30,000 diseases of economic importance in the U.S. Plant pathology is the study of the biotic and abiotic agents that cause disease in plants; of the mechanisms by which these causal agents induce disease in pants and of the methods of preventing or controlling disease and reducing the damage caused. PLANT DISEASES IN HISTORY Certain diseases have …ver más…

Knowing how a pathogen obtains nourishment is important to understanding the disease process and developing control strategies. Most microbial pathogens are primarily parasites, but some are mainly saprophytes and can sometimes cause disease. Saprophytes usually feed on non-living organic matter. Most microbial pathogens have some saprophytic abilities, which are important in survival and in the disease process. Pathogens with saprophytic ability can be cultured away from their host plant. Some pathogens can only grow in nature on their live host, (e.g. powdery mildew and rust fungi) and are called obligate parasites. Obligate parasites feed and reproduce on living plant material. CONDITIONS NECESSARY FOR DISEASE In order for disease to occur, three conditions must be met. First it is necessary to have a susceptible host plant. Each species of plant can be infected by only some pathogens. The plant must also be in a stage of development susceptible to infection by the disease agent. The second requirement is the presence of an active pathogen. If there is no pathogen present, there can be no disease. Also, the pathogen must be in a stage of development conducive to infecting or affecting the host plant. The third condition is an environment suitable for the pathogen to cause disease of the plant.

SUSCEPTIBLE HOST DISEASE

VIRULENT PATHOGEN