Certified Arborist Test Tree Diagnosis and Treatment 3

Question 1

What are the key diagnostic features that distinguish bacterial leaf scorch (BLS) from drought stress or other leaf scorch conditions in oaks and elms?

Accepted Answer

BLS causes marginal leaf browning that progresses inward with a distinct yellow or reddish band separating living and dead tissue, appears in mid to late summer, and recurs annually with greater severity

Answer

Bacterial leaf scorch (caused by Xylella fastidiosa) characteristically shows marginal browning advancing inward with a distinct yellow or reddish margin between dead and living tissue, appearing progressively in mid-late summer, worsening annually, and confirmed by ELISA or PCR laboratory testing.

Question 2

What are the primary differences between contact insecticides and systemic insecticides in arboricultural treatments, and when is each type preferred?

Accepted Answer

Contact insecticides kill insects directly upon contact but have no plant-protective residue; systemic insecticides are absorbed and translocated within the plant, providing internal protection against feeding insects

Answer

Contact insecticides act on direct contact and have limited residual protection, best suited for exposed pest populations accessible to spray coverage. Systemic insecticides are absorbed into plant tissue and distributed via the vascular system, protecting against insects that feed on or within plant tissue regardless of spray coverage.

Question 3

How does the integrated pest management (IPM) approach differ from traditional pest management, and what are the four core IPM tactics?

Accepted Answer

IPM is a decision-making framework that uses monitoring and economic/aesthetic thresholds to select the least disruptive effective combination of cultural, biological, mechanical, and chemical tactics

Answer

IPM is a science-based decision framework that combines monitoring (to identify pests and assess population levels), threshold-based decision making, and multiple management tactics — cultural, biological, mechanical/physical, and chemical — selecting the least-risk approach that achieves acceptable control.

Question 4

What is phytophthora root rot, what conditions favor it, and how should affected trees be managed?

Accepted Answer

A soilborne water mold disease favored by saturated, poorly drained soils — managed by improving drainage, reducing irrigation, and applying phosphonate fungicides

Answer

Phytophthora root and collar rot, caused by Phytophthora species (water molds, not true fungi), thrives in saturated, poorly drained soils. It attacks fine roots and root collars, causing progressive dieback and wilting. Management centers on drainage improvement, irrigation reduction, root collar exposure, and phosphonate applications.

Question 5

What are the symptoms of emerald ash borer (EAB) infestation, and at what stage of infestation are symptoms typically first visible?

Accepted Answer

Symptoms (canopy dieback, D-shaped exit holes, serpentine galleries, bark splitting, epicormic sprouting) typically appear 1-3 years after initial infestation, when larval populations are significant enough to disrupt vascular transport

Answer

EAB infestations typically go undetected for 1-3 years because early larval damage is below economic and visible thresholds — by the time canopy dieback, D-shaped exit holes, bark splitting, and epicormic sprouts are visible, infestation is usually well-established and significant population density exists.

Certified Arborist Test Practice Test

Certified Arborist Test Practice Test

Certified Arborist Test Tree Diagnosis and Treatment 3