PCA - Plant Pathogens Latest Version Graded A+

PCA - Plant Pathogens Latest Version Graded A+ Plant Disease Definition Abnormal physiological processes caused by a causal pathogen Economic significance of plant diseases Losses of yield, crops, inputs, land Pathogen Causal agent of disease Signs of disease Structures of the pathogen Symptoms of disease Plant response to pathogen infection Abiotic factors of plant disease Air pollution, temperature, nutrients Biotic factors of plant disease Living organisms (fungi, bacteria, viruses) Obligate parasite unable to grow outside of a living host Facultative saprophyte prefers living organic matter as a source of nutrition but can adapt to the use of dead organic matter under certain conditions Facultative parasite A pathogen that prefers dead inorganic material, but can also obtain nourishment from living organic material Biotroph Any parasite that cannot survive in a dead host and therefore keeps it alive Necrotroph Parasite that kills host cells Koch's Postulates series of guidelines used to identify the microorganism that causes a specific disease Three components of disease triangle Causal agent, environment, host Role of each component of disease triangle All three must be present for disease to occur. Environment must favor causal agent. Host must favor causal agent. How humans impact each component of disease triangle Manipulate the environment, host- plant resistance, preventative/suppressive/erradicative pesticides Impact of epidemic when one component of disease triangle does not come into contact with the other two components Slows epidemic to a halt. Disease spread needs all three components interacting Management strategy to break environment component Alter planting dates, remove alternative hosts, alter harvest Management strategy to break host component Alternate crop, host-plant resistance Management strategy to break causal agent component Pesticide applications How can knowledge of plant disease triangle be used in diagnosis? Can rule out different pathogens based on host and environment.