CPH Plant Diseases and Pathology

Question 1

Powdery mildew on ornamental plants is caused by which type of organism?

Accepted Answer

Fungus

Answer

Bacterium

Answer

Virus

Answer

Nematode

Question 2

Fire blight, which causes a characteristic 'shepherd's crook' wilting of shoot tips on apple and pear trees, is caused by which pathogen?

Accepted Answer

Erwinia amylovora (bacterium)

Answer

Botryosphaeria obtusa (fungus)

Answer

Apple mosaic virus

Answer

Phytophthora cactorum (oomycete)

Question 3

Dutch elm disease is caused by which type of pathogen, and is primarily spread by which vector?

Accepted Answer

Fungus spread by bark beetles

Answer

Bacterium spread by aphids

Answer

Virus spread by leafhoppers

Answer

Oomycete spread by water splash

Question 4

Which of the following best describes a 'biotroph' in plant pathology?

Accepted Answer

A pathogen that requires living host tissue to complete its life cycle

Answer

A pathogen that kills host tissue before extracting nutrients

Answer

A pathogen that only colonizes dead plant material

Answer

A pathogen capable of surviving indefinitely in the soil

Question 5

Verticillium wilt causes yellowing and wilting of foliage primarily by:

Accepted Answer

Colonizing and blocking the xylem vessels, restricting water flow

Answer

Producing toxins that destroy chlorophyll in leaf cells

Answer

Attacking root cortex cells, preventing mineral uptake

Answer

Injecting proteases that digest cell walls throughout the plant

Question 6

Which of the following symptoms is most characteristic of iron (Fe) deficiency chlorosis?

Accepted Answer

Interveinal yellowing beginning on young upper leaves

Answer

Interveinal yellowing beginning on older lower leaves

Answer

Uniform yellowing of all leaves simultaneously

Answer

Purpling of older leaf margins and tips

Question 7

The disease triangle concept in plant pathology states that disease development requires:

Accepted Answer

A susceptible host, a virulent pathogen, and a favorable environment

Answer

Heat, humidity, and a nutrient-deficient soil

Answer

A vector, a wound site, and prolonged wetness

Answer

Soil compaction, poor drainage, and a weakened host