Exam 1 Flashcards
Disease Triangle
In order for infection to occur you must have a susceptible host, a virulent pathogen, and the right environment
Disease Cycle (monocyclic)
- Pathogen infects
- Pathogen grows and reproduces
- Pathogen makes propagules
- Propagules dispersed to new host
Plant disease
A disorder of structure or function in a plant, affects physiology and morphology, caused by a pathogen
Fungi
have hyphae that produce spores
Protists
Fungal-like, have hyphae and spores but are in a different kingdom
Bacteria
Require a host, do not have a cell wall
Nematodes
soil-borne diseases, worm-like
Signs
structure of casual pathogen, can be big or small
Symptoms
abnormality of plant, includes chlorosis, necrosis, cankers, galls, wilting, blights
Koch’s Postulates
- microbe must be correlated with the disease, constant association with symptomatic host
- microbe must be isolated from host and grown in pure culture
- pure culture inoculated into healthy susceptible host must reproduce disease
- microbe must be recoverable from experiment host
Koch’s Postulates (simple)
find microbe + disease, isolate, re-infect, recover
Modes of infection
Direct penetration, Penetration through natural openings, Penetration through natural wounds
Direct penetration
pathogen (fungi) makes injury
Penetration (natural openings)
pathogen (bacteria) enters through stomata, lenticel, or hydathodes
Penetration (natural wounds)
pathogen enters via wounds caused by insects/wind/humans, through natural cracks between main and lateral roots
Survival outside of host
using survival structures; on/in soil, seeds, vegetative propagative organs, insects, perennial plants
Dissemination
via winds, rain splashing/runoff, insects, flooding, contaminated seeds/transplants, animals, tools
Monocyclic
one infestation per season
Polycyclic
disperses progeny repeatedly throughout season
Myxomycetes
slime molds, protist disease
Plasmodiophoromycetes
survive winter as resting spores in the soil, disrupt by adding lime and increasing soil pH, protists
Oomycetes
type of plasmodiophoromycete, Fungal-like protists