Wisconsin Pesticide Applicator Test 100% Correct

Define plant disease and what causes disease. - Answer Plant disease is any harmful change in the physiology and/or structure of a plant caused by the continuous irritation of a primary causal agent (pathogen). List examples of plant pathogens. - Answer 1. Fungi 2. Oomycetes 3. Nematodes 4. Bacteria 5. Viruses 6. Phytoplasmas 7. Viroids How is fungi spread? - Answer Wind, rain splash, or insect vectors How is Oomycetes spread? - Answer Wind, rain splash, Transfer of infested soil (for example on equipment tires) How is Bacteria spread? - Answer Rain splash, insect vectors, and on tools How is Phytoplasmas spread? - Answer Only by insect vectors (principally leafhoppers) How are Viruses spread? - Answer Insect vectors, mechanical transmission (rubbing of infected leaf onto another leaf by equipment), some are seed borne, vegetative propagation. How are Viroids spread? - Answer mechanical transmission, vegetative propagation How are Nematodes spread? - Answer Transfer of infested soil (for example on equipment tires), in infested planting stock What are four prerequisites for plant disease to occur? - Answer 1. A pathogen population capable of causing the disease. 2. A host that is susceptible to infection by that pathogen population. 3. Environmental conditions that favor disease development. 4. Sufficient time for disease to actually develop. What are clues that help you determine whether a problem is caused by an abiotic agent (non living thing) or a pathogen (living thing)? - Answer Caused by an abiotic agent if... 1. The problem appears suddenly 2. The problem is in a uniform pattern 3. More than one plant species is affected