B.S.F. or B.Sc.F. Bachelor of Science in Forestry Bachelor of Science in Forestry: Forest Pathology and Disease Management 4

Question 1

Chestnut blight, caused by Cryphonectria parasitica, kills American chestnut by producing which mechanism?

Accepted Answer

Oxalic acid that lowers canker pH, killing cambial tissue while sparing roots

Answer

Cryphonectria parasitica produces oxalic acid within cankers, creating a low-pH environment that kills cambial tissue but cannot penetrate below the soil line, allowing root sprouting.

Question 2

Which approach is the basis of the hypovirulence strategy for biological control of chestnut blight?

Accepted Answer

Introducing CHV1 hypovirus into virulent fungal strains to reduce their pathogenicity

Answer

CHV1 (Cryphonectria hypovirus 1) infects virulent Cryphonectria strains and reduces their virulence, allowing infected cankers to heal—a strategy that has succeeded in Europe but faces somatic incompatibility barriers in North America.

Question 3

In forest pathology surveys, a 'periodic detection survey' differs from an 'intensive delimiting survey' primarily in that it:

Accepted Answer

Covers large areas to detect new or spreading pests, while delimiting defines the exact boundaries of a known infestation

Answer

Detection surveys cast a wide net to find new infestations across large landscapes, while delimiting surveys intensively map the precise extent of a known infestation to guide management response.

Question 4

Which fungal structure allows Armillaria species to spread through soil and infect new host roots at a distance from the original inoculum source?

Accepted Answer

Rhizomorphs

Answer

Rhizomorphs are melanized, root-like mycelial strands that allow Armillaria to actively grow through soil and contact healthy roots, enabling spread far from the original infected stump.

Question 5

What is the epidemiological significance of asymptomatic carriers in forest disease spread, as seen with Phytophthora ramorum?

Accepted Answer

Some hosts like bay laurel can be heavily infected and produce massive quantities of spores without showing severe symptoms, fueling regional epidemics

Answer

California bay laurel is a highly productive sporulating host for Phytophthora ramorum that shows minimal disease symptoms, making it a major driver of the sudden oak death epidemic.

B.S.F. or B.Sc.F. Bachelor of Science in Forestry Practice Test

B.S.F. or B.Sc.F. Bachelor of Science in Forestry Practice Test

B.S.F. or B.Sc.F. Bachelor of Science in Forestry Bachelor of Science in Forestry: Forest Pathology and Disease Management 4