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Introduction to Plant Pathology
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Introduction to Plant Pathology
Introduction to Plant Pathology
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1
Question
What is the etymological origin and literal definition of plant pathology?
Page 1
Answer
The term comes from the Greek words 'pathos' meaning suffering and 'logos' meaning to study, translating to the study of the suffering plant.
2
Question
What are the four primary characteristics that define a plant disease?
Page 1
Answer
A plant disease is a malfunctioning process that results in suffering, is generally harmful or detrimental, produces symptoms (histological or morphological), and is caused by an agent.
3
Question
How does plant pathology function as both a science and an art?
Page 1
Answer
As a science, it investigates the characteristics, causes, and control of diseases. As an art, it applies this scientific knowledge to diagnose, assess, forecast, and manage plant health.
4
Question
What are the six vital plant processes that can be affected by disease?
Page 1
Answer
Root absorption, uptake of water and minerals, photosynthesis, respiration, transport of photosynthates, and reproduction.
5
Question
What is the ultimate objective of plant pathology according to the material?
Page 1
Answer
The objective is to control or manage diseases to increase food production and maintain the quantity and quality of fresh commodities until they reach the consumer.
6
Question
How did Heinrich Anton de Bary define the cause of rust and smut diseases?
Page 3
Answer
De Bary asserted that fungi associated with rust and smut diseases are the cause, rather than the effect, of these diseases.
7
Question
What is the significance of Thomas Jonathan Burrill's research from 1878 to 1883?
Page 3
Answer
Burrill demonstrated that bacteria can cause plant disease by collecting sap from apple and pear twigs infected with blight, observing bacteria under the microscope, and successfully re-producing blight symptoms in healthy plants.
8
Question
What are the two reproductive stages of a fungus and their general purposes?
Page 6
Answer
The asexual stage (anamorph) produces conidia for rapid dispersal without genetic recombination. The sexual stage (teleomorph) produces sexual spores in fruiting bodies for survival and genetic variation.
9
Question
How do hypoplastic and hyperplastic symptoms differ in their effect on host cell numbers?
Page 7
Answer
Hypoplastic symptoms involve a decrease in cell number or failure of differentiation, leading to stunting or mosaic. Hyperplastic symptoms involve an increase in cell number, leading to root galls, fasciation, or nodules.
10
Question
What are the components of the 'Disease Triangle' required for a disease to occur?
Page 6
Answer
A susceptible host, a virulent pathogen, and a favorable environment.
11
Question
What defines the 'asymptomatic' or 'symptomless carrier' state?
Page 5
Answer
A host that does not show symptoms irrespective of the environment. It may harbor the pathogen, such as endophytic fungi, and can remain infectious despite showing no outward signs.
12
Question
How do obligate and facultative parasites differ in their survival requirements?
Page 5
Answer
An obligate parasite attacks only living tissues and requires a living host to survive. A facultative parasite is ordinarily a saprophyte that can also function as a parasite when given the opportunity.
13
Question
What is the difference between signs and symptoms in plant disease diagnosis?
Page 6
Answer
A symptom is the manifestation or expression of the plant itself resulting from a disease. A sign is the pathogen or a part of the pathogen found on the host plant.
14
Question
What are the common symptoms of ozone damage in plants?
Page 10
Answer
Ozone causes stippling, mottling, chlorosis of leaves, premature defoliation, and stunting.
15
Question
How do Mollicutes, such as Phytoplasmas, differ from typical bacteria in cell structure?
Page 12
Answer
Mollicutes are prokaryotic but lack cell walls, possessing only a 9-12nm thick plasma membrane, which makes them pleomorphic and sensitive to osmotic changes.
16
Question
What is the causal agent of Coconut lethal yellowing (rag kadang kadang)?
Page 13
Answer
Candidatus phytoplasma palmae
17
Question
What is the vector of Coconut lethal yellowing?
Page 13
Answer
Haplaxius crudus
18
Question
What is the first symptom of Coconut lethal yellowing?
Page 13
Answer
Premature drop of coconut fruit
19
Question
What are subsequent symptoms of Coconut lethal yellowing after fruit drop?
Page 13
Answer
Blackening of the flower, then severe chlorosis of leaflet, mild stunting
20
Question
How does 'ang kadang kadang' variant differ from standard Coconut lethal yellowing?
Page 13
Answer
Severe stunting, walay yellowing, walay blackening of the flower
21
Question
What causes Lime stubborn or Lime witch's broom?
Page 13
Answer
Candidatus phytoplasma aurantifolia, vector Circulifer tenellus
22
Question
What are symptoms of Citrus stubborn disease?
Page 13
Answer
Very small fruit, yellowing, leaf mottling, reduced fruit size, no canker, Witch's broom
23
Question
What is the causal agent and vector of Citrus stubborn?
Page 13
Answer
Spiroplasma citri, vector Circulifer tenellus
24
Question
What causes Corn stunt disease?
Page 13
Answer
Candidatus phytoplasma maize or Spiroplasma kunkelii, vector Dalbulus maidis
25
Question
What are symptoms of Corn stunt?
Page 13
Answer
Reddening of leaves, abnormal formation of tassel, reduced ears, severe stunting
26
Question
List the management strategies for diseases caused by Mollicutes.
Page 13
Answer
1. Use resistant cultivars or hybrids. 2. Proper control of insect vectors. 3. Use of mollicute-free planting materials. 4. Eradication of alternative hosts. 5. Use of tetracycline antibiotic. 6. Sanitation.
27
Question
Why is tetracycline used in Mollicutes management?
Page 13
Answer
Eradication of alternative hosts and antibiotic treatment target the wall-less pathogens effectively.
28
Question
What are Fastidious Vascular Bacteria (FVB) also called?
Page 13
Answer
Rickettsia-like organisms (RLO)
29
Question
Can FVB be grown on simple culture media without host cells?
Page 13
Answer
No, cannot be grown on simple culture media in the absence of host cells
30
Question
What are the three types of fastidious bacteria mentioned?
Page 13
Answer
1. Fastidious phloem-limited bacteria. 2. Citrus plants affected with greening disease. 3. Fastidious xylem-limited bacteria