Lecture 2

Question 1

What is a plant disease?

Answer 1

abnormality in a physiological process that reduces the economic or aesthetic value

Question 2

What is the difference of injury and disease?

Answer 2

there is a persistent (or semi) irritation and are generally progressive

Question 3

What are the major plant pathogen groups?

Answer 3

fungi, bacteria, phytoplasmas, nematodes, viruses, parasitic plants, algae

Question 4

What is a saprophyte

Answer 4

acquires nutrients from dead material

Question 5

What is a facultative parasite?

Answer 5

when conditions favorable, mostly saprophyte. occasionally functions as a parasite

Question 6

Facultative means

Answer 6

mostly exists in the opposite

Question 7

What is a facultative saprophyte

Answer 7

mostly parasite when conditions favorable. occasionally a saprophyte

Question 8

What is a parasite?

Answer 8

lives in or on a living organism

Question 9

Define Biotrophic

Answer 9

completes entire life cycle in a living host (obligate parasite)

Question 10

Define Necrotrophic

Answer 10

a pathogen that kills host cells using toxins or enzymes and then obtains its energy (facultative)

Question 11

Hemibiotrophic:

Answer 11

first obtains nutrients from living cells then switches to Necrotrophic phase

Question 12

What is in the plant disease triangle?

Answer 12

susceptible host, virulent pathogen, disease-favorable environment

Question 13

Define Infection court

Answer 13

a site in or on a host plant where infection can occur

Question 14

Examples of natural openings

Answer 14

stomata, root cap, nectar or pollen tube

Question 15

Examples of forced openings

Answer 15

aposortium fungals, stylet nematodes, vector viruses

Question 16

Steps of the disease cycle

Answer 16

penetration, infection/colonization, reproduction, survival, dispersal, deposition. Dispersal of secondary inoculumn goes straight to deposition

Question 17

Deposition versus penetration step

Answer 17

deposition gets on the plant, penetration gets in the plant

Question 18

Infection and colonization step

Answer 18

pathogen obtains nutrients from the host plant by spreading through intercellular membranes.

Question 19

Reproduction step

Answer 19

pathogen produces new infectious units like spores, cells, virons

Question 20

Two types of infectious units

Answer 20

binary fusion- direct development
variety development- asexual, sexual, and spore types

Question 21

survival step

Answer 21

persistence of the pathogen when the preferred host plant is absent

Question 22

Places to overwinter

Answer 22

in dead fruit, in cankers, sclerotia, infected seeds, mycelium

Question 23

Dispersal step

Answer 23

movement of inoculum from plant to plant

Question 24

dispersal strategies

Answer 24

flooding, rain, insects, wind, seed contamination, sharp/wounding objects