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Weed & Disease > Disease Exam > Flashcards

Disease Exam Flashcards

1
Q

Plant disease

A

anything that prevents a plant from performing to its maximum potential

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2
Q

Abiotic

A

Caused by conditions external to the plant, not living agents

Cannot spread from plant to plant but are common

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3
Q

Example of abiotic disease

A

nutritional diseases, soil compaction, salt injury, ice, and sun scorch

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4
Q

Biotic Disease

A

Caused by living organisms called plant pathogens

Pathogens can spread from plant to plant and may infect all types of plant tissue including leaves, stems, crowns, roots, tubers, fruit, seeds, and vascular tissues

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5
Q

List 6 types of Plant Pathogens

A
  1. Fungi/Fungal-like organism
  2. Bacteria
  3. Phytoplasmas
  4. Viruses
  5. Nematodes (animal kingdom)
  6. Parasitic Plants
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6
Q

Sign

A

visible portions of a disease-causing organisms

Ex: When you look at powdery mildew, you’re looking at a parasitic fungal disease organism itself

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7
Q

Symptoms

A

The visible effect of disease on the plant.

May include a detectable change in color, shape, or function of the plant as it responds to the pathogen.

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8
Q

Chlorosis (Define)

List two types (Define)

A

A loss of normal plant color

Interveinal: yellowing of leaf tissue between veins

Halo: ring of chlorosis around lesions

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9
Q

Necrosis (define)

List 3 types

A

Dead tissue

Dieback, Lesion, Canker

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10
Q

Necrosis: Dieback

A

whole sections of plant dies

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11
Q

Necrosis: Lesion

A

contained region of tissue that has suffered damage

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12
Q

Necrosis: Canker

A

sunken, swollen, cracked lesion. Used to describe lesions on trunks and branches of woody plants.

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13
Q

Mosaic

A

caused by VIRUS

characterized by yellow flecking and spotting

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14
Q

Ringspot

A

caused by VIRUS

a type of mosaic, but lesions exist as halos around green tissue

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15
Q

Stippling

A

Spot pattern of damaged, chlorotic leaf tissue

*Usually caused by ABIOTIC factors or sucking/piercing insects

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16
Q

Scorch

A

Large necrotic lesions usually caused by bacterial infections or by abiotic factors

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17
Q

Wilt

A

when the above-ground portions of the plant are not getting enough water because the vascular tissue is compromised BIOTIC AND ABIOTIC

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18
Q

Rot

A

Decay of roots or fruit.

Usually caused by fungi and bacteria

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19
Q

Gall

A

Masses of undifferentiated cells. Caused by bacteria and nematodes. Female of nematode lives inside gall. SYMPTOM

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20
Q

Cyst

A

caused by nematodes (2 types). Female nematode is the cyst SIGN

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21
Q

Blight

A

A rapid and complete chlorosis, browning, then death of plant tissues such as leaves, branches, twigs, or floral organs.

Many diseases that primarily exhibit this symptom are called blights.

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22
Q

3 Parts of disease triangle

A

Pathogen, Environment, Host

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23
Q

Fungi

A

Organism is made of cells called hyphae. Masses of hypha is called a mycelium

Multicellular eukaryotes

Heterotrophic: absorptive nutrition

Cell wall made of chitin

Reproduction: spores (sexual or asexual)

24
Q

2 Types of Fungi Sexual Reproduction

A

Heterothallic: can reproduce only with another individual of opposite mating type

Homothallic: can reproduce with another individual or itself

25
Q

Another name for spores

A

conidia (produced by conifiophores)

26
Q

Environmental factors for fungi

A

Temperature: Warm, Cool, Disease is favored by conditions that provide it with an advantage over the host

Moisture: most fungi require water to INFECT about 90%

27
Q

Fungi: Biotroph

A

Leach nutrients off living plant

Infection is specialized through mechanical insertion or through natural openings

growth intercellular

28
Q

Fungi: Necrotroph

A

Eats and kills everything

Host cells killed rapidly with toxins and enzymes -pathogen kills host first then feeds

Infection occurs at wounds or natural opening

Growth is inter- and intracellular

29
Q

Fungi: Hyperplasia

A

fungi makes plant create more cells than it needs

30
Q

Fungi: Hypertrophy

A

tissue malformation of one cell “smut”

31
Q

Bacteria

A

Prokaryote

The most primitive of life and very small organism

Known as prokaryote because of lack of membrane-bound organelles

A single circular chromosome
Can contain from several to hundred of accessory DNA segments, called plasmids

Many navigate by chemotaxis (opposite chemicals attracting)

Call walls made of peptidoglycan

32
Q

3 Different types of bacteria

A

Bacilli (rod-shaped)
Cocci (spherical)
Spirilla (spiraled)

33
Q

Bacteria Reproduction

A

Sexual and Asexual
Asexual: Binary Fission
Sexual: transformation and conjugation (picking and sharing DNA fragments)

34
Q

Plasmid

A

circular segment of accessory DNA

35
Q

Bacterial Leaf Spots

A

Typical leaf spots caused by bacteria appear as water-soaked brown to black lesions often outlined with a yellow halo

Necrotic spots can be angular “V” shape

36
Q

Symptoms of bacteria

A 
leaf spots 
bacterial leaf scorch
bacterial blights
bacterial wilts
Rot and galls
37
Q

Virus

A

Open system

DNA or RNA wrapped in protein coat called capsid

Vector-borne

Protein coat intersects with cell membrane and virus is absorbed

Genetic material is incorporated into host genome

Need a living host cell in order to reproduce

38
Q

Virus Symptoms

A

Mosaic
Ringspot
Rosette
Discoloration

39
Q

Oomycetes

A

Water molds: use water as transport method

Primarily parasites of vascular tissue

Kingdom: Chromista

40
Q

Oomycetes Reproduction

A

Sporangium: Zoospores
Oogonium (female) and antheridium (male)

Oospores (reproductive organ)

41
Q

Symptoms of Oomycetes

A

Root rot
Blight
Canker

42
Q

Nematodes

A

Most numerous multicellular organisms on Earth

Multicellular with a “tube in a tube” body structure

Feed through a stylet, the feeding strategies vary

43
Q

Life cycle of Nematodes

A

6 Stages of Growth: egg, 4 juvenile stages, and an adult phase

Nematodes can go from egg to egg-laying in 21 days

Males are long and slender
Females, after mating, fuse their mouth parts to the root tissue, swell with eggs, and burst from the pressure of the developing eggs

44
Q

Signs and symptoms of nematodes

A

patches or spots
galls
cyst

45
Q

Disease cycles

A

The chain of events involved in the disease development includes inoculation, penetration, infection, penetration, infection, incubation, reproduction, and survival.

46
Q

1st stage of disease cycle

A

Inoculation: the introduction of the plant pathogen to the host.

47
Q

2nd stage of disease cycle

A

Penetration: wound sites and natural plant openings, such as stomata and hydathodes, facilitate the entrance of some plant pathogens

48
Q

3rd stage of disease cycle

A

Infection: pathogens invades the plant tissue and establishes a parasitic relationship between itself and the plant

49
Q

4th stage of disease cycle

A

Incubation: once inside the plant, pathogens may undergo an incubation period and remain latent for a period before initiating disease

50
Q

5th stage of disease cycle

A

Reproduction: plant pathogens can reproduce sexually and asexually. It is dependent on the pathogen

51
Q

6th stage of disease cycle

A

Survival: Plant pathogens have evolved so they can survive prolonged periods of unfavorable weather conditions.

52
Q

Nitrogen Deficiency

A

Utilization: key element in every biological molecule, especially chlorophyll

Symptoms: chlorosis in the older leaves, leaf drop

N is mobile (older parts of plant)

Looks like: viruses, root rots, early stages of wilt, downy mildew

53
Q

Potassium Deficiency

A

Utilization: chilling tolerance, disease tolerance, enzyme cofactor

Symptoms: stunting, darkening of leaves, scorching of leaf margins, leaf cupping, chlorosis, necrosis

K is mobile (older parts of plant)

Looks like: viruses, bacterial leaf scorch, root rots

54
Q

Magnesium Deficiency

A

Utilization: integral in chlorophyll molecule, enzyme cofactors

Symptoms: interveinal chlorosis beginning in old leaves

Mg is mobile (older parts of plant)

Looks like herbicide damage, viruses, powdery mildews, downy mildews

55
Q

Iron Deficiency

A

Utilization: Enzyme cofactor, crucial in chlorophyll production, transport other elements

Symptoms: Chlorosis beginning in the youngest leaves, stunting

Iron is immobile (younger parts of plant)

Looks like: root rot, sulfur deficiency, early stages of wilt

56
Q

Calcium Deficiency

A

Utilization: structural component of cell wall, chemical gradients, enzyme cofactor

Symptoms: leaf cuppings, margin burn, distorted growth, aborted flowers and fruit

Ca is mobile (older parts of plant)

Looks like: viruses, soft rot, root rots, bacterial leaf spot

Weed & Disease (3 decks)

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