Pathogens

Question 1

Seed pathogen

Answer 1

D. sapinea

Question 2

Xylem pathogen

Answer 2

X. fastidiosa

Question 3

flower pathogen

Answer 3

U. virens

Question 4

fruit pathogen

Answer 4

A. tenuis

Question 5

fruit pathogen

Answer 5

B. cinerea

Question 6

leaf pathogen

Answer 6

P. triticina

Question 7

root and root crop pathogen

Answer 7

Phytophthora sp.

Question 8

stem pathogen

Answer 8

S. sclerotiorum

Question 9

viroid pathogen

Answer 9

Potato spindle tuber viroid (PSTVd)

Question 10

characteristics of D. sapinea

Answer 10

Infection - seed cone blight
Colonization - by growing and spreading through infected needles
Spread - tree to tree esp. in wet conditions
Symptoms - 4Ds - Damping off and root
rot of seedlings
- Decay
- Discoloration
- Death of seedling

Question 11

characteristics of X. fastidiosa

Answer 11

Spread - plant to plant through vectors
Ability - block the xylem vessels
Control Strategies - Insecticide for vector
- Removal and
destruction of infected plants
- Quarantine
Alternative Strategies - Breed resistant
plant varieties
- Utilizing bio.
control agents

Question 12

characteristics of U. virens

Answer 12

Inhibits - pollen germination and tube elongation
Invade - both pistil and stamen

• Digests integuments
• Not a systemic pathogen

Question 13

Characteristics of A. tenuis

Answer 13

• major mycotoxin

Causes - fruit rot (black spots)
- blights
Location - moist warm environment
Infection - Wound, natural openings, insect damage
Spread - fruit to fruit through spores

Question 14

Characteristics of B. cinerea

Answer 14

Causes - grey mold on fruits
Spread - wind, water, insects through spores
Location - worldwide esp. moist warm environment
Infection - Wound, senescence, stressed by environmental factors

Question 15

Characteristics of P. triticina

Answer 15

Primary Host - common wheat, durum wheat, cultivated and wild emmer wheat, etc.

Alternative host - meadow rue
Life cycle - Asexual and sexual stage
Infection - stomata
Spread - only through its hosts; due to it struggling to infect other plants

Question 16

Characteristics of Phytophthora sp.

Answer 16

Requirements - warm and moist soil
Hosts - potato, tomato, etc.
Causes - root rot, blight, leather rot, etc.
Life cycle - direct and indirect germination
- sexual and asexual stage

Question 17

Characteristics of S. sclerotiorum

Answer 17

Hosts - lettuce, cabbage, sunflower, etc.
Infection - nodes; watery lesions (brown)
- lesions expand (grey-white)
causing plants to become
bleached and break

Question 18

Characteristics of Potato spindle tuber viroid

Answer 18

Hosts - potato, tomato, etc.
Control - cannot be controlled by chemical and biological means
Spread - through vectors or pollen
Found - leaves and tubers of potato plants