B.S.F. or B.Sc.F. Bachelor of Science in Forestry Bachelor of Science in Forestry: Forest Pathology and Disease Management 2 — Questions and Answers
Question 1: Which fungal pathogen causes white pine blister rust, a significant disease of five-needled pines in North America?
- Cronartium ribicola (Correct answer)
- Heterobasidion annosum
- Armillaria mellea
- Phytophthora cinnamomi
Correct answer: Cronartium ribicola
Cronartium ribicola is the introduced rust fungus responsible for white pine blister rust, which requires Ribes species as an alternate host.
Question 2: What is the primary mode of spread for Phytophthora ramorum, the pathogen causing sudden oak death?
- Wind-dispersed basidiospores
- Zoospores through water movement and infected plant material (Correct answer)
- Bark beetle vectors
- Airborne conidia during dry conditions
Correct answer: Zoospores through water movement and infected plant material
Phytophthora ramorum spreads primarily via zoospores transported by water runoff, rain splash, and movement of infected nursery stock.
Question 3: In forest disease management, what does the term 'disease triangle' refer to?
- Three stages of fungal fruiting body development
- The interaction of susceptible host, virulent pathogen, and favorable environment (Correct answer)
- A triangular monitoring plot used in disease surveys
- Three categories of root disease pathogens
Correct answer: The interaction of susceptible host, virulent pathogen, and favorable environment
The disease triangle illustrates that disease occurs only when a susceptible host, virulent pathogen, and favorable environment all overlap simultaneously.
Question 4: Which of the following best describes the role of Ribes eradication as a management strategy for white pine blister rust?
- It kills the rust fungus directly by removing its overwintering structure
- It disrupts the fungal life cycle by eliminating the required alternate host (Correct answer)
- It prevents bark beetle vectors from reproducing
- It reduces soil inoculum levels of Cronartium ribicola
Correct answer: It disrupts the fungal life cycle by eliminating the required alternate host
Removing Ribes shrubs disrupts the obligate two-host life cycle of Cronartium ribicola, preventing spore production that would infect pines.
Question 5: Fusiform rust, caused by Cronartium quercuum f.sp. fusiforme, primarily affects which tree species in the southeastern United States?
- Loblolly and slash pines (Correct answer)
- Eastern white pine and sugar maple
- Douglas-fir and western hemlock
- Northern red oak and American beech
Correct answer: Loblolly and slash pines
Fusiform rust is the most economically damaging disease of loblolly and slash pines in southeastern pine plantations.
Question 6: What is the function of a 'sentinel tree network' in forest disease management?
- Trees genetically engineered to resist all fungal pathogens
- A network of native trees planted in foreign countries to detect exotic pests before they arrive (Correct answer)
- Trees treated with systemic fungicides to create disease-free buffer zones
- Automated sensors attached to trees to measure water potential
Correct answer: A network of native trees planted in foreign countries to detect exotic pests before they arrive
Sentinel tree networks plant native species in botanical gardens abroad where new pests are present, providing early warning of threats before they reach North America.
Question 7: Which symptom is most characteristic of Verticillium wilt in forest trees?
- Fruiting bodies erupting through the bark in concentric rings
- Asymmetric crown dieback with green streaking in sapwood (Correct answer)
- Resin-soaked wood throughout the entire bole
- Witches' broom formation at branch tips
Correct answer: Asymmetric crown dieback with green streaking in sapwood
Verticillium wilt causes asymmetric shoot and crown dieback, and cross-sections of infected branches reveal distinctive green or brown streaking in the vascular tissue.
B.S.F. or B.Sc.F. Bachelor of Science in Forestry Bachelor of Science in Forestry: Forest Pathology and Disease Management 2
Which fungal pathogen causes white pine blister rust, a significant disease of five-needled pines in North America?