Pl Sc 380 to midterm 1

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Pl Sc 380 to midterm 1
2015-09-29 15:38:02
plant science
plant pathology
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  1. Phytopathology
    study of plant diseases/suffering
  2. 3 main areas of study in plant pathology
    etiology, epidemiology, control/management
  3. "Father of Botany"?
    • Theophrastus 
    • wrote Enquiry to Plants and On the Causes of Plants
  4. Festival held in ancient Rome to appease the god of rust?
  5. Patron Saint of Ergotism?
    St. Anthony
  6. Women accused as being witches during the Salem witch trials often had what disease?
  7. Establisher of "germ theory" and disprover of "spontaneous generation"?
    Louis Pasteur
  8. Two big historical events involving plant pathology?
    Irish Potato Famine (potato late blight) and the Bengal Famine (brown spot of rice)
  9. Disease
    Any deviation from normal state of the plant from abiotic or biotic factors
  10. Injury
    Random event, occurs swiftly (can be predisposition for disease)
  11. Symptom
    A host reaction, an external reaction of plant as a result of disease
  12. Sign
    Pathogen, part of a pathogen in/on a host
  13. Non-infectious diseases
    Caused by abiotic factors, non-transmissible
  14. Infectious diseases
    Caused by biotic factors, transmissible
  15. Parasites
    Organism that is partially or completely dependent on another organism (host) for its substience, grows and multiplies at expense of host
  16. Pathogens
    a biological agent responsible for inciting disease
  17. Pathogenicity
    capacity to insite disease
  18. Biotrophs
    obligate parasites (grow and reproduce only on living host and difficult or impossible to culture)
  19. Necrotrophs
    Organisms that cause death of host tissues as they grow through them (can be cultured)
  20. Non-obligate parasites
    Can live on dead or living host
  21. Facultative parasites
    Live most of the time on dead organic materials but can sometimes become parasites (weak parasites)
  22. Saphrophytes
    • Organisms that are able to live on dead materials (can't be on living cells) 
    • like moulds
  23. Facultative Saphrophytes
    most of the time are parasites, no living host around then they can continue to live as a saphrophyte for a while (not forever)
  24. Lesion
    a localized diseased area or wound
  25. Pustule
    An eruption of the epidermis caused by spores moving to the surface of the tissues
  26. The disease triangle
    virulent pathogen - susceptible host - favorable environment
  27. Other complexities that may accompany the disease triangle?
    • vector
    • alternate host (to complete cycle)
    • complex of pathogens
    • human activities
  28. The disease pyramid
    virulent pathogen - susceptible host - favorable environment - TIME
  29. Different systems of classification of plant diseases
    • according to symptoms
    • according to plant organ affected
    • according to type of plant affected
    • storage diseases, post-harvest diseases
  30. Inoculum
    any structure(s) produced by pathogen and involved in infection process (ex. spores, mycelium, etc)
  31. Primary (initial) inoculum
    inoculum responsible for initiating disease cycle
  32. Secondary inoculum
    inoculum that originates from infections caused by primary inoculum and responsible for additional infection
  33. Sources of inoculum
    • plant debris, volunteers, alternative hosts
    • also seed, tubers, transplants, cuttings, etc
    • outside sources
  34. Disease cycle
    chain of events involved in disease development; includes all the stages of host infection and pathogen development and reproduction
  35. Monocyclic disease
    • simple interest diseases
    • only one disease cycle per season (no secondary inoculum producted)
    • soil borne, systemic
  36. Polycyclic disease
    • compound interest diseases
    • more than one disease cycle per season (both primary and secondary inoculum produced)
    • most diseases
  37. Etiology
    Causes of plant disease
  38. Biotic agents
    Infectious or transmissible, more gradual
  39. Abiotic agents
    Non-infectious or non-transmissible, very distinguishable border
  40. Examples of abiotic causes of plant disease
    • Unfavourable temperature
    • Water relations
    • Unfavourable soil pH
    • Nutrient deficiencies
    • Air pollutants
    • Herbicides
  41. Examples of biotic causes of plant disease
    • Fungi + fungal-like organisms
    • Viruses and viroids
    • Bacteria
    • Phytoplasmas
    • Nematodes
    • Parasitic higher plants
  42. Two main groups of fungal-like organisms
    • Kingdom Protozoa
    • Kingdom Chromista
  43. Kingdom: Protozoa
    contains many microorganisms and fungal-like organisms
  44. Kingdom: Protozoa
    Phylum: Myxomycota
    Produce a plasmodium or plasmodium-like structure
  45. Kingdom: Protozoa
    Phylum: Myxomycota
    Class: Myxomycetes
    • the slime moulds 
    • body=amorphous plasmodium
  46. Amoeboid
    slimy mass of cytoplasm with many nuclei
  47. Spore
    propogative unit carrying out dispersal/survival function, does not contain a pre-formed embryo
  48. Syngamy
    • union of two gametes to form a zygot
    • involves plasmogamy and karyogamy
  49. Kingdom: Protozoa
    Phylum: Plasmodiophoromycota
    Class: ?
    Order: Plasmodiophorales
    • Endoparasitic slime moulds
    • obligate parasites
    • plasmodia produced within cells of roots and stems of plants
  50. Kingdom: Protozoa
    Phylum: ?
    Order: Plasmodiophorales
    • Produce zoosporangia that give rise to zoospores in early summer
    • Plasmodia produce resting spores -> zoospores in following season
  51. Hyperplasia
    Number of cells increase (like cancer)
  52. Hypertrophy
    Cell size increases
  53. Plasmodiophora brassicae
    • Root parasite, cause of clubroot of crucifers
    • forms galls on roots
  54. Management of clubroot
    • well-drained soil
    • use healthy transplants
    • sanitation
    • crop rotation
    • resistent cultivars
    • fungicides
    • bait crops
  55. Spongospora subterranea
    • cause of powdery scab of potato
    • hypertropy 
    • cosmetic infection
    • vector of moptop virus
  56. Management of powdery scab of potato
    • crop rotations
    • disease-free seed
    • crop in porous and well-drained soils
    • chemical treatments not usually effective
  57. Polymyxa graminis
    • common parasite of the roots of cereals
    • no significant damage to roots
    • vector of soilborne wheat mosaic and barley yellow mosaic viruses
  58. Kingdom: Chromista
    • Unicellular/multicellular, filimentous or colonial organisms
    • contain brown algae, diatoms, oomycetes
  59. Oomycetes/Phylum: Oomycota
    • Produce coenocytic hyphae
    • 2 kinds of spores: zoospores and oospores
  60. Zoospores
    asexual and biflagellate
  61. Oospores
    • Sexual, produced through two morphologically dissimilar gametes
    • Thick walls
  62. Oogonium
    female cell (multinucleiate)
  63. Antheridium
    male cell (one nucleus)
  64. Plasmogamy
    fusion of two mycelia
  65. Karyogamy
    fusion of two nuclei
  66. Kingdom: Chromista
    Genus: Pythium
    • facultative parasite
    • causes dampening-off of seedlings, seed decay, root rots
  67. Dampening off
    a disease that causes collapse or dent of seedlings before or after emergence
  68. Management of Pythium diseases
    • Greenhouse -> soil sterilization
    • Fungicides at moderate disease pressure
    • Good soil drainage
    • seeding depth
    • seeding time
  69. Pythophthora infestans
    • potato famine in Ireland (1840s)
    • Two mating types, A1 and A2: pathogen variability through sexual recombination
    • Re-emerging disease
  70. Heterothallism
    fungi producing compatible male and female gametes on physiologically distinct mycellia (ex. not self-fertile)
  71. Homothallism
    Fungi producing compatible male and female gametes on same mycellium (ex. self-fertilizing)
  72. Management of late blight of potatoes
    • use disease-free seed (certified)
    • spray recommended fungicides according to recommended calandar
    • use adequate spacing
    • store in cold, dry location to prevent progress of infection during storage
  73. Albugo candida
    causes white rust of crucifers
  74. Stagheads
    • infection of flower buds and growing tips results in swelling, forming large deformed structures that contain oospores
    • happens with white rust of crucifers
  75. sporangiophore
    • a specialized branch bearing one or more sporangia 
    • a stalk of sporangium
  76. Sorus
    a cluster or mass or spores or sporangia
  77. Management of white rust
    • crop rotation (3yrs)
    • resistance
    • clean seed
    • control volunteers
    • often occurs as a complex with downy mildew
  78. Peronospora parasitica
    • cause of downy mildew of canola and mustard
    • when seen on plant you see chlorosis and downy layer of sporangia underneath leaf
  79. Plasmopora viticola
    • cause of downy mildew on grape
    • important in the history of disease control (first fungicide was for this->Bordeaux mixture)