Exam 1 Flashcards
(46 cards)
disease
abnormal functioning of an organism
characteristics of disease
-injurious (causes harm to plant)
-progressive
plant disease triangle
-susceptible plant
-pathogen capable of disease
-favorable environment
symptoms
expression of disease by a plant as a response to activities of a pathogen
biotic agents
living agents including pathogens
abiotic agents
non living agents
pathogens
organisms that cause disease in living host
-include fungi, virus, bacteria, nematodes
infectious
transmitted from 1 plant to another
pathogen signs
pathogen structures or products on or in diseased plants
fungi signs
spores and fruiting bodies
bacteria signs
bacterial ooze
virus signs
inclusion bodies
nematode signs
can be extracted from the roots or soil
host range
set of species in which pathogen can cause disease
abiotic agents
-non infectious
-could be damage from herbicide, fertilizer, heat/cold
-symptoms all the same on all plant species in area
-no pathogen signs
environmental factors
-recent temps
-rainfall or irrigation
-light or shade
-soil characteristics, like ph or soil type
-fertilizers, herbicides, fungicides, etc
-presence of other organisms
saprophytes
organisms that obtain their nutrients from dead organic matter
biotrophs
-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
necrotrophs
-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
hemibiotrophs
-live part of cycle in living tissue and then kill plant and continue to live in dead tissue
-ex. Phytophora infestans
stages in disease cycle
inoculation
penetration
infection
growth and reproduction
dispersal of pathogen
survival of pathogen
inoculation
-primary inoculum: initiates infection (first step in disease cycle)
-secondary inoculum: 2nd set of inoculation that occurs at later stage of disease cycle
penetration
-direct penetration: pathogen creates entry point using structures (appressoria and haustoria (teeth))
-penetration through wounds
-through natural openings (stomata, lenticels, hydathodes)
infection
-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