test 1 pt.2 Flashcards
inoculum
any part of a pathogen that can initiate disease.
primary inoculum
survival form of pathogen that causes primary infection.
Secondary Inoculum
inoculum produced by pathogen and transmitted to host during the growing season.
inoculation
transfer of inoculum onto the host plant.
infection court
initial site of contact between pathogen and surface of host.
Penetration
getting inoculum into host tissue
direct penetration
through intact plant surfaces.
indirect penetration
through natural openings and wounds.
infection
establishment of pathogen within host.
invasion
pathogen invades other plant tissue beyond initial penitration
colonization
growth and reproduction of pathogen
incubation period
time period from infection to appearance of symptoms.
latent period
time from infection to production of secondary inoculum
polycyclic disease
disease whos pathogen possesses a secondary infection cycle.
monocyclic disease
lacks secondary infection cycle.
predisposition
when certain environmental conditions make a plant more vulnerable to disease.
What are the 6 stages of Disease
- Primary inoculum
- Dispersal
- infection court
- infection and colonization
- secondary inocuum
- pathogen survival
4 main mechanisms of inoculum dispersal
wind, water, on plant material or by vectors.
How can a pathogen survive if its seperated from its host?
it enters the survival stage
6 environmental Factors
- Temperature
- Moisture
- Light
- Wind
- Soil Nutrients
- Soil type and pH
Disease Management 4 parts.
Avoidance,Exclusion,Eradication,Protection
Avoidance
Plant when or where pathogen is not present.
Exclusion
Legal restrictions.
Eradication
removal of pathogens from infested soil and tools, and infected seeds or plants
Protection
cultural practices, chemical or biological treatments and genetic resistance.
Five major groups of plant pathogens
- Fungi 2.Bacteria 3.Nematodes 4.Viruses 5.Parasitic Seed Plants.
Plus: Protozoa
Fungi
Small thread like organisms composed of hyphae.
Cause 70% of plant disease, >10,000 fungus species cause plant disease.
Bacteria
Small-single celled organisms with cell walls.
prokaryotes, no nucleus. 100 species cause plant disease.
Nematodes
Unsegmented round worms, to small to be seen with the naked eye. 500 species attack plants.
viruses
1000 species cause disease, very small particles that consist of nucleic acid and a protein sheath.
Parasitic seed plants
Higher plants that produce seed, 2500 species parasitic,
Protozoa
not accepted as plant pathogens, only flagellate protozoa are associated with plant disease.
Koshes postulates (4)
- Suspected pathogen must be consistent.
- Must be isolated and noted.
- Disease must be produced on a healthy plant with isolated oragnism.
- The same pathogen must be isolated from the inoculated plant.
hyphae
microscopic filaments which have defined cell walls.
mycelium
alot of hyphae.
septate
hyphae that are divided by crosswalls or sepa
nonseptate
hyphae without septa
haustorium
special absorbing organs; may be simple knob, long tube, or variously branched.
sclerotium
dense compacted aggregate of mycelium
appresium
swollen tip of hypa or germ tube that facilitates attachment and penetration of host.
infection peg
arises from appresium and goes into the cell wall and cuticle.
spores
sepcialized propagated units produced by fungi.
intracellular
penetrates into host cells, absorbs food directly from host protoplasm
intercellular
penetrate between cells, absorb food as it diffuses out of cells.
external mycelia
live on plant surface.
correct term for food source
food substrate
asexual spores
one or more types per species
sexual spores
one type per species
the normal chromosome content of most fungi is?
haploid
Plasmogamy
fusion of cells bringing two sexually compatible haploid nuclei into one cell.
Karyogamy
nuclear fusion, forming a diploid nucleus.
dikaryotic
having 2 haploid nuclei per cell.
teleomorph
perfect stage, sexual spores only.
anamorph
asexual spores only, imperfect stage.
holomorph
spores in all stages, sexual and asexual
