Certified Arborist Test Tree Diagnosis and Treatment 1

Question 1

Which symptom pattern most reliably distinguishes oak wilt from other causes of rapid crown decline in red oaks?

Accepted Answer

Rapid wilting and bronzing of leaves beginning at the leaf margins and progressing from branch tips toward the trunk, often killing the tree within a single growing season

Answer

Interveinal chlorosis beginning on the oldest leaves and progressing inward over several seasons

Answer

Scattered branch dieback concentrated in the upper canopy with heavy fungal fruiting bodies on the bark

Answer

Gradual thinning of the canopy over three or more years with eventual trunk decay

Question 2

An arborist observes sunken, discolored bark lesions on a stressed honeylocust with an amber, gum-like exudate at the margins. The inner bark beneath the lesion is brown and water-soaked. What is the most likely diagnosis?

Accepted Answer

Cytospora canker, a stress-related fungal canker that invades weakened or wounded tissue

Answer

Bacterial wetwood, which causes fermentation gases to force liquid through bark fissures

Answer

Hypoxylon canker, which produces a silvery-gray crust of fungal stromata on the bark surface

Answer

Armillaria root rot, identified by white mycelial fans beneath the bark at the root collar

Question 3

What is the primary mode of transmission for fire blight (Erwinia amylovora) from tree to tree, and which tissue type shows the pathognomonic 'shepherd's crook' symptom?

Accepted Answer

Pollinating insects carry the bacterium to blossoms during wet spring weather; shepherd's crook forms on infected shoot tips

Answer

Soil-borne root contact transmits the bacterium; shepherd's crook forms on large structural roots

Answer

Windborne spores spread during dry conditions; shepherd's crook appears on the trunk

Answer

Bark beetle galleries inoculate the xylem; shepherd's crook forms on water sprouts

Question 4

A mature sugar maple shows progressive dieback of branches in the upper crown combined with heavy seed production, early fall coloration, and epicormic sprouting along the lower trunk. These signs together are consistent with which condition?

Accepted Answer

Maple decline syndrome, a multi-factorial stress condition often linked to soil compaction, drought, and foliar diseases acting together

Answer

Verticillium wilt, distinguished by the characteristic green-brown streaking visible in cross-sections of affected branches

Answer

Asian longhorned beetle infestation, identified by the round exit holes and frass-filled galleries in the sapwood

Answer

Hypoxylon canker, which preferentially attacks the upper crown first in sugar maple

Question 5

Phytophthora root rot is frequently misdiagnosed as drought stress in landscape trees. Which combination of diagnostic observations most reliably differentiates Phytophthora infection from simple moisture deficit?

Accepted Answer

Wilting that does not recover after irrigation, discolored (reddish-brown) inner bark at the root collar, and decline symptoms that worsen in chronically wet or poorly drained soils

Answer

Yellowing of leaves beginning at the shoot tips with brown necrotic margins, and wilting that recovers fully after a single deep watering

Answer

White mycelial fans visible under the bark at the root collar accompanied by honey-colored mushrooms at the base of the tree

Answer

Bark splitting and sunken cankers on major scaffold branches combined with oozing liquid from trunk lenticels

Question 6

When evaluating a tree for potential Armillaria root rot, which combination of field signs provides the strongest confirmatory evidence?

Accepted Answer

White, fan-shaped mycelial mats beneath the bark at the root collar, dark rhizomorphs under the soil surface, and honey-colored mushrooms clustered at the base in autumn

Answer

Round emergence holes approximately 3/8 inch in diameter in the bark and sawdust-like frass in bark crevices

Answer

Resinous pitch tubes on the lower trunk with blue-stained sapwood visible in bark peel-backs

Answer

Galls or swollen tissue at the root crown with a crumbly, tumor-like internal structure