Exam 1 Flashcards

(46 cards)

1
Q

disease

A

abnormal functioning of an organism

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2
Q

characteristics of disease

A

-injurious (causes harm to plant)
-progressive

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3
Q

plant disease triangle

A

-susceptible plant
-pathogen capable of disease
-favorable environment

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4
Q

symptoms

A

expression of disease by a plant as a response to activities of a pathogen

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5
Q

biotic agents

A

living agents including pathogens

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6
Q

abiotic agents

A

non living agents

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7
Q

pathogens

A

organisms that cause disease in living host
-include fungi, virus, bacteria, nematodes

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8
Q

infectious

A

transmitted from 1 plant to another

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9
Q

pathogen signs

A

pathogen structures or products on or in diseased plants

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10
Q

fungi signs

A

spores and fruiting bodies

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11
Q

bacteria signs

A

bacterial ooze

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12
Q

virus signs

A

inclusion bodies

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13
Q

nematode signs

A

can be extracted from the roots or soil

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14
Q

host range

A

set of species in which pathogen can cause disease

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15
Q

abiotic agents

A

-non infectious
-could be damage from herbicide, fertilizer, heat/cold
-symptoms all the same on all plant species in area
-no pathogen signs

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16
Q

environmental factors

A

-recent temps
-rainfall or irrigation
-light or shade
-soil characteristics, like ph or soil type
-fertilizers, herbicides, fungicides, etc
-presence of other organisms

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17
Q

saprophytes

A

organisms that obtain their nutrients from dead organic matter

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18
Q

biotrophs

A

-obligate parasites
-have narrow host range
-cannot grow as saprophytes
-attack healthy host tissue at any stage
-kill host cells slowly
-penetrate directly via natural openings
-mildews, rusts, virus, nematodes

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19
Q

necrotrophs

A

-bacterial fungi
-have wide host range
-can grow as saprophytes
-attack young, weak, or senescent tissues
-kill host cells rapidly by producing toxins or enzymes
-penetrate through wounds or natural openings
-anthracnose, cankers, fruit rot, leaf spots and blights, root rot, vascular wilt

20
Q

hemibiotrophs

A

-live part of cycle in living tissue and then kill plant and continue to live in dead tissue
-ex. Phytophora infestans

21
Q

stages in disease cycle

A

inoculation
penetration
infection
growth and reproduction
dispersal of pathogen
survival of pathogen

22
Q

inoculation

A

-primary inoculum: initiates infection (first step in disease cycle)
-secondary inoculum: 2nd set of inoculation that occurs at later stage of disease cycle

23
Q

penetration

A

-direct penetration: pathogen creates entry point using structures (appressoria and haustoria (teeth))
-penetration through wounds
-through natural openings (stomata, lenticels, hydathodes)

24
Q

infection

A

-establishment of pathogen within host cells to obtain nutrients
-infection courts: where infection starts
-successful infection will produce symptoms
-incubation period: time interval between inoculation and appearance of symptoms

25
growth and reproduction
-pathogen grows and multiplies in infected host -fungi: spores -virus: replicate within cell -nematodes: eggs
26
dispersal of pathogen
-wind, rain, people, animals, insects, machinery -spores of fungus can be dispersed through all methods
27
plant pathology
study of what causes plant disease, why they occur, and how to control them
28
ergotism
poisoning from ergot alkaloids
29
ergot alkaloids
mycotoxins produced by fungus claviceps
30
ergot symptoms
-presence of sclerotia instead of grains, produces ergot alkaloids that causes ergotism in humans -caused by claviceps fungus -host is rye
31
coffee rust
-fungus hemilela vastatix -affects arabica and robusta coffee -lesions on leaves which affects photosynthesis -severe defoliation can kill trees
32
underdevelopment
-stunting of plants, leaves -shortened internodes -inadequate chlorophyll production -caused by many types of pathogens
33
overdevelopment
-overgrowth of leaf tissue causes thickening or distortion -galls form on all plant parts, caused by many pathogens -in roots: nematodes -on stem: bacteria
34
fungal leaf spots
-tissue necrosis -usually round, not vein limited -may have alternating zones of light/dark tissue -sporulation or mycelia may be evident
35
bacterial leaf spots
-tissue necrosis -often dark and water soaked -often vein limited, giving angular shape -bacterial flow observed under microscope
36
fruit rots
--tissue necrosis -firm or soft and watery -colors vary -fungal sporulation may be present -fungal and bacteria causes
37
cankers
-tissue necrosis -localized necrotic lesions -sunken or swollen or both -mainly caused by fungi and bacteria -can be caused by mechanical injury
38
root rots
-tissue necrosis -root lesions -darkening and softening of roots -yellowing of foliage and stunting of plants -fungal and bacterial causes
39
blight
-tissue necrosis -rapid and complete chlorosis, browning and then death of plant tissues -fungal and bacterial causes
40
damping off
-tissue necrosis -rapid death of seedlings and cuttings -stem infected at soil line, seedling topples -caused mainly by fungus
41
wilting
-response to disruption of transport of water in plant due to invasion of xylem or roots by phloem -mainly fungal and bacterial causes
42
mosaic
-caused by virus -irregular patches of discolored tissue -often with distortion to tissue
43
ringspot
-on leaves and fruit -distinct ring shaped lesions, often in concentric zones -caused by viruses
44
abiotic causes of change in appearance
-chemical damage and nutritional deficiencies
45
symptom variability
-diseased plants may have more than one problem (and more than one pathogen) -pathogens have varying levels of virulence -environmental conditions can affect symptoms -host genetics and physiology can affect symptoms (resistant, tolerant, or susceptible)
46
fungal signs (more in depth)
-shape of fruiting body aids in fungal identification -tissue location may help differentiate between species