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BSAAS > CRP001 (CONCEPTS OF PLANT DISEASES) > Flashcards

CRP001 (CONCEPTS OF PLANT DISEASES) Flashcards

1
Q

Structures of the pathogen found associated with the infected plant

A

Signs

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2
Q

Actual evidence or proof of the presence of a pathogenic agent

A

Signs

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3
Q

the suspected pathogen must always be present in the plant when diseases occur

A

Association

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4
Q

PROOF OF PATHOGENICITY also called

A

Koch’s postulate

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5
Q

causal organism must be isolated and grown in pure culture

A

Isolation

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6
Q

the pure culture must be introduced to a healthy susceptible host to
produce the symptoms and signs of the disease

A

Inoculation

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7
Q

the suspected causal organism must be re-isolated in pure culture from
the inoculated plant and must be identical to the original organism

A

Re-isolation

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8
Q

Enumerate the Classification of Plant Diseases (4)

A
  • According to the affected plant organ
  • According to the symptom
  • According to the type of affected plants
  • According to type of pathogen that cause disease
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9
Q

The more common non-parasitic causes of disease in plants are: (13)

A
  1. extremely high temperatures
  2. excessively low temperatures
  3. lack of oxygen
  4. unfavorable soil moisture relations
  5. nutrient deficiencies
  6. nutrient excesses
  7. mineral toxicities
  8. air pollutants
  9. toxicity of pesticides
  10. improper agricultural practices
  11. adverse meteorological conditions
  12. naturally occurring toxic chemicals
  13. too much or too little light
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10
Q

Abiotic stress or injury (4)

A
  1. Non-living
  2. Not spread from diseased to healthy plants
  3. Non-infectious
  4. Knowledge of environmental factors before and during disease occurrence necessary for
    correct diagnosis
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11
Q

PARASITIC AGENTS OF PLANT DISEASES (7)

A
  • Viruses and Viroids (subcellular entities)
  • Bacteria and phytoplasmas (prokaryotes)
  • Fungi and fungal-like protists
  • Nematodes
  • Parasitic flowering plants
  • Protozoa
  • Others
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12
Q

Ultramicroscopic obligate parasites made up of nucleic acid and a protein coat.

A

Virus

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13
Q

Virus:
The infectious part

A

Nucleic acid core (RNA or DNA)

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14
Q
  • Provide a protective sheath for the nucleic acid
  • Facilitate the movement of virus from cell to cell
  • For transmission of viruses by vectors
A

Protein coat

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15
Q

What are the functions of the protein coat?

A
  • Provide a protective sheath for the nucleic acid
  • Facilitate the movement of virus from cell to cell
  • For transmission of viruses by vectors
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16
Q

Stable entities of low molecular weight RNA that can infect plant cells

A

Viroids

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17
Q

They are much smaller than viruses and lack a protein sheath.

A

Viroids

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18
Q

Shape of virus particle

A
  • Spherical
  • Bacilliform
  • Cylindrical
  • Bullet-shaped
  • Elongate rod-shaped
  • Flexible filaments
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19
Q

viruses that attacks bacteria

A

Bacteriophages

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20
Q

associated with an autonomous virus before it can cause infection or be
replicated in the host plant

A

Satellite virus

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21
Q

Transmission and Spread of Viruses (8)

A
  • Mechanical means
  • By grafting
  • By nematodes (as vectors)
  • By certain soil-borne fungi (as vectors)
  • By insects (as vectors)
  • Through infected seeds
  • Through infected vegetative planting materials
  • Mites
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22
Q

if the insect transmits the virus within seconds or minute after acquisition

A

Non-persistent

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23
Q

Types of Virus transmission (4)

A
  1. Non-persistent
  2. Persistent
  3. Stylet-borne
  4. Circulation
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24
Q

viruses that adhere to and are borne on the stylet of an insect that feeds on an infected plant

A

Stylet-borne

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25
Q

if the insect transmits the virus only after a latent period has elapsed after acquisition
and the vector remains capable of transmission for many days

A

Persistent

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26
Q

viruses that are swallowed by an insect passed through the blood and are returned to
the salivary glands before they can be transmitted by an insect

A

Circulation

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27
Q

Symptoms Caused by Virus

A
  • Range from no symptoms to death of plants
  • Local lesions
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28
Q

Systemic symptoms

A
  • Mosaic
  • Ringspot
  • Excessive branching (Witches’ broom)
  • Vein clearing
  • Color Breaking
  • Stunting
  • Chlorosis
  • Leaf curling
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29
Q

are generally stunted and yield less produce of usually poor quality

A

Virus-infected plants

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30
Q

If the plant is symptomless because of unfavorable environmental conditions, the symptoms
are said to be ______

A

masked

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31
Q

If no symptoms appear irrespective of the environment, then the infected plant is a
__________________

A

Symptomless carrier

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32
Q

are helpful to the bacteria in carrying the determinants for drug resistance, phage
resistance, UV resistance, survival in secondary habitats and for pathogenesis

A

Plasmids

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33
Q

Some bacteria have a ________ which is used for movement

A

Flagella

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34
Q

Characteristics of Plant Pathogenic Bacteria (5)

A
  • Mostly rod-shaped
  • Mostly aerobic
  • Mostly flagellated
  • Mostly Gram-negative
  • Mostly non-spore forming
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35
Q

Symptoms Caused by Bacteria (6)

A
  • Leaf Spot
  • Soft Rot
  • Blight
  • Gall
  • Canker
  • Wilting
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36
Q

are prokaryotic microorganisms similar to bacteria, they have no cell walls

A

Mollicutes

37
Q

Mollicutes are resistant to ___________

A

Penicillin

38
Q

is a specialized propagative body which may be formed asexually by arising from
modified mycelial portions or sexually through the fusion of unlike celled (gametes)

A

Spore

39
Q

The fungal plant pathogen’s primary stored carbohydrate is ________

A

Glycogen

40
Q

The mycelium may have ______ or _____ or may be continuous (__________).

A

Cross walls; septa; coenocytic

41
Q

Septate mycelia may be (3)

A

uninucleate or binucleate or multinucleate

42
Q

Each branch of a mycelium is called _____

A

Hypha

43
Q

Mycelial growth occurs at the ___________

A

Hyphal tips

44
Q

a specialized propagative body which may be formed asexually by arising from
modified mycelial portions or sexually through the fusion of unlike celled (gametes)

A

Spore

45
Q

The only member of Kingdom Fungi that form motile cells (zoospores or gametes)

A

Chytridiomycota

46
Q

sexual spores (Ascospores) formed within a sac known as ascus

A

Sac fungus

47
Q

Produce non-motile asexual spores in sporangia

A

Zygomycota

48
Q

Sexual reproduction is through an ascogonium (female spore) fertilized by an
antheridium or spermatium, a minute male spore

A

Ascomycota

49
Q

the sexual or perfect stage

A

Teleomorph

50
Q

the asexual or imperfect stage

A

Anamorph

51
Q

Club and mushroom fungi

A

Basidiomycota

52
Q

are thread-like unsegmented worms
which are usually elongated and cylindrical in shape

A

Nematodes

53
Q

feed from the outside and only the stylet enters the plant cells

A

Ectoparasites

54
Q

feed by burying the front part of the body into the host cells while the
posterior portion is outside the host

A

Semiendoparasites

55
Q

the entire nematode body enters the plant cells while it feeds

A

Endoparasites

56
Q

move from one part of the plant to another portion of the host or move from
the plant to the soil and back.

A

Migratory

57
Q

attach themselves to the roots or burrow into the root

A

Sedentary

58
Q

any part of the pathogen that can initiate disease

A

Inoculum

59
Q

completed when the pathogen has passed through the initial cell wall or
entered the intercellular areas so that the pathogen is within the plant

A

Penetration

60
Q

the deposition of inoculum unto or into an infection court

A

Inoculation

61
Q

if the pathogen plays no active part in entering the host
plant

A

Passive Penetration

62
Q

The pathogen directly participates as when the fungal spore
germinates, form a germ tube, an appressorium for attachment, and penetrates
through the intact host surface by forming an infection hypha or penetration
peg

A

Active Penetration

63
Q

Occurs when the pathogen has become established in the
plant tissues and obtains nutrients from the host

A

Infection

64
Q

Is the growth or movement of the pathogen through the host tissues

A

Colonization

65
Q

the time from inoculation to the production of visible symptoms

A

Incubation

66
Q

after the symptoms has advanced, signs or pathogen structures are usually formed on
the colonized surface of the host

A

Dissemination

67
Q
  • Survival phase
  • Weakest link in the disease cycle
  • Pathogen population is at its lowest
  • Target for most control strategies
  • The pathogen has therefore to tide over adverse conditions or survive until conditions
    become once more favorable for pathogenesis.
A

Saprogenesis phase

68
Q

One disease cycle in one crop growing season or one year

A

Monocyclic disease

69
Q

2-30 disease cycles in one cropping season or one year

A

Polycyclic disease

70
Q

is the study of disease development in plant populations

A

Epidemiology

71
Q

refers to epidemics of plant diseases

A

Epiphytotic

72
Q

is one that is native or indigenous to a particular place

A

Endemic disease

73
Q

one which had been introduced from some other area

A

Exotic disease

74
Q

one of worldwide or widespread occurrence throughout a continent
or a region

A

Pandemic disease

75
Q

are those that occur at irregular interval

A

Sporadic disease

76
Q

Fundamental principles for plant disease controlwere first classified by Whetzel (1929)

A
  1. Exclusion
  2. Eradication
  3. Protection
  4. Immunization
77
Q

is the prevention of a “new pathogen” from being introduced into a locality where it is currently unknown.

A

Exclusion

78
Q

Further advances in plant pathology led to development of newer methods. The National
Academy of Science (1968) has added two more principles.

A
  1. Avoidance
  2. Therapy
79
Q

involves removal, elimination, or destruction of a pathogen from an area in which it is
established to reduce disease threat

A

Eradication

80
Q

Involves the prevention of infection by putting a chemical barrier (protectant spray or dust)
between the pathogen and the suscept

A

Protection

81
Q

involves modifying certain physiological or physical features of the host so that
it can repel infection, as in the breeding for disease resistance

A

Immunization or Host Plant Resistance

82
Q

This involves avoiding disease by planting at time when, or in areas where inocula is absent
or ineffective due to environmental conditions

A

Avoidance

83
Q

is the treatment of infected host plant, which is attempted in case of economically important
horticulture plants

A

Therapy

84
Q

the use of chemicals to inactivate the pathogen

A

Chemotherapy

85
Q

sometimes used to inactivate or inhibit virus development in infected plant
tissues so that newly developing tissue may be obtained which is free of pathogen

A

Heat

86
Q

involves the exposure of diseased plants or parts of them to hot
water or high air temperatures for different periods of time.

A

Thermotheraphy

87
Q

defined epidemics
as
an
increase
in
disease incidence within the plant population with time

A

Vander Plank (1963)

88
Q
A

BSAAS (5 decks)

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