Certified Arborist Test Tree Diagnosis and Treatment 2

Question 1

What is the primary symptom pattern that differentiates verticillium wilt from other causes of canopy dieback in susceptible tree species?

Accepted Answer

Sudden wilting and dieback of individual branches ('flagging') while adjacent branches remain healthy, often with green streaking in the sapwood

Answer

Verticillium wilt (caused by Verticillium dahliae or V. albo-atrum) characteristically causes sudden wilting and death of individual branches while adjacent branches appear healthy. Diagnostic confirmation involves the characteristic green, brown, or black streaking in the outer sapwood of affected branches.

Question 2

What are the diagnostic symptoms of anthracnose on sycamore, and how is it distinguished from more serious diseases?

Accepted Answer

Blotchy brown leaf spots following vein patterns, shoot blight in spring, and twig dieback — primarily a cosmetic problem in most years

Answer

Sycamore anthracnose (Apiognomonia veneta) causes brown blotches that follow leaf veins, premature spring defoliation, twig dieback, and shoot blight. While alarming in appearance, it is primarily cosmetic in healthy trees — severe multiple-year defoliation can deplete vigor but rarely kills established sycamores.

Question 3

What is the significance of 'yellownecked caterpillar' and similar defoliating insects in tree health, and when does defoliation become a threat to tree survival?

Accepted Answer

Single-year complete defoliation rarely kills healthy trees, but repeated defoliation over consecutive years depletes NSC reserves and can lead to mortality, particularly combined with drought or other stresses

Answer

A single defoliation event depletes non-structural carbohydrate reserves but rarely kills a healthy tree — it refoliates from stored reserves. Repeated defoliation over multiple consecutive years progressively depletes NSC beyond recovery thresholds, particularly when combined with drought or root stress, leading to decline and mortality.

Question 4

What are the symptoms and transmission mechanism of Dutch elm disease, and what management strategies are available?

Accepted Answer

A vascular wilt caused by Ophiostoma novo-ulmi transmitted by bark beetles, causing yellowing and wilting flagging in the crown — managed through sanitation, fungicide injection, and pheromone traps

Answer

Dutch elm disease is caused by the fungus Ophiostoma novo-ulmi (and O. ulmi), transmitted by elm bark beetles that carry spores from infected to healthy trees. Symptoms include yellowing and wilting flagging branches with brown streaking in the sapwood. Management includes removing infected wood promptly, fungicide trunk injections, and insecticide treatment to reduce beetle vectoring.

Question 5

What is the purpose of a tree health assessment using canopy transparency, and what does it measure?

Accepted Answer

An estimate of overall crown density and vitality by evaluating the proportion of sky visible through the live crown compared to a full, healthy crown of the same species

Answer

Canopy transparency — the percentage of sky visible through the live crown — is a standardized forest health monitoring metric that inversely correlates with crown density. Increased transparency indicates reduced foliage density from defoliation, dieback, or branch mortality, and is used to assess tree vitality and decline.

Certified Arborist Test Practice Test

Certified Arborist Test Practice Test

Certified Arborist Test Tree Diagnosis and Treatment 2