Download Homework #332 Plant Pathology - Colorado State University

Colorado Master Gardenersm Program
Colorado Gardener Certificate Training
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Homework #332
Plant Pathology
Answer the following questions
1. What is the difference between a sign and symptom?
A symptom is the plant’s response to a causal agent whereas a sign is the actual
organism.
2. Explain the disease triangle.
The vertices of the triangle are host, causal agent, environment and time. Without one
of these vertices present in the system, disease will not occur.
3. What is the difference between biotic and abiotic causal agents?
Biotic causal agents are infectious, transmissible and display a random symptomatic
pattern. Abiotic causal agents are non-infectious, non-transmissible, and display a
uniform symptomatic pattern.
4. Leaf spots are a symptom of only fungal infection not bacterial infection. T or F False
5. Weed control could help suppress disease control in the garden. T or F True
6. How are viruses transmitted?
Viruses are transmitted by insects, nematodes, pruning tools, and vegetative
propagation.
7. How can some abiotic disorders relate to improper water management?
Overwatering and underwatering cause root death.
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8. Chemical injury to plants can be caused by what?
Chemical injury to plants can be caused by fertilizers, pesticides, or de-icing salts and
other products.
9. What abiotic disease symptoms mimic biotic disease symptoms?
Chemical injury may mimic eriophyid mites, viruses and/or phytoplasmas. Weather
induced injury may mimic bacterial or fungal infections, and/or borer activity.
10. What is the first step in the diagnostic process?
Identify the plant
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