CERTIFIED ARBORIST EXAM QUESTIONS
FORM REAL EXAMS LATEST 2025-2026 UPDATE
WITH 150 QUESTIONS & 100% CORRECT
DETAILED ANSWERS GRADED A+ (BRAND
NEW!!)
Q1. A mature oak shows canopy dieback, epicormic shoots, and fungal conks at the base. The
most likely condition is:
A. Nutrient deficiency
B. Root rot caused by Armillaria
C. Drought stress only
D. Leaf miner infestation
Correct answer: B
Armillaria root rot commonly causes decay at the base, reduced water uptake, dieback, and
stress-induced epicormic growth.
Q2. Which pruning cut minimizes risk of decay best in mature trees?
A. Flush cut
B. Heading cut
C. Collar cut outside branch bark ridge
D. Stub cut
Correct answer: C
Proper collar cuts preserve the branch protection zone, reducing decay entry.
Q3. A tree in compacted urban soil most commonly suffers from:
A. Excess potassium
B. Oxygen deficiency in root zone
C. Overproduction of chlorophyll
D. Increased mycorrhiza activity
Correct answer: B
Soil compaction reduces pore space and oxygen availability to roots.
Q4. Which pest is most associated with ash tree mortality?
A. Emerald ash borer
B. Bark beetle
C. Gypsy moth
D. Leafhopper
,Correct answer: A
Emerald ash borer larvae disrupt vascular tissue, killing ash trees.
Q5. CODIT theory in arboriculture refers to:
A. Chemical oxygen demand in trees
B. Compartmentalization of decay in trees
C. Cutting of dead internal tissue
D. Carbon oxidation decay index test
Correct answer: B
CODIT explains how trees isolate decay through internal barriers.
Q6. A tree leaning suddenly after a storm most likely indicates:
A. Leaf imbalance
B. Root plate failure
C. Excess fertilization
D. Natural phototropism
Correct answer: B
Sudden leaning suggests structural root failure or soil/root plate movement.
Q7. Which fertilizer ratio promotes root establishment in transplanting?
A. High nitrogen
B. High phosphorus
C. High potassium only
D. No fertilizer needed ever
Correct answer: B
Phosphorus supports root development in young/transplanted trees.
Q8. What is the main risk of topping a mature tree?
A. Increased fruit production
B. Rapid structural improvement
C. Weak epicormic growth and decay
D. Enhanced root growth
Correct answer: C
Topping causes stress, weak regrowth, and decay entry points.
,Q9. The best time to prune most deciduous trees is:
A. Peak summer heat
B. Dormant season
C. Flowering stage
D. Heavy rain season
Correct answer: B
Dormant pruning reduces stress and disease transmission risk.
Q10. Which organism is a vascular wilt pathogen?
A. Verticillium
B. Aphids
C. Scale insects
D. Caterpillars
Correct answer: A
Verticillium blocks xylem vessels causing wilting and decline.
Q11. A common symptom of overwatering trees is:
A. Leaf scorch
B. Root hypoxia and chlorosis
C. Increased flowering
D. Bark thickening
Correct answer: B
Excess water reduces oxygen, damaging roots and causing chlorosis.
Q12. Which tool is safest for large limb removal at height?
A. Handsaw only
B. Chainsaw with harness and training
C. Hatchet
D. Pruning shears
Correct answer: B
Chainsaws are used with proper PPE and training for aerial work.
Q13. The main function of tree cambium is:
A. Water storage
B. Photosynthesis
C. Secondary growth
D. Leaf production
, Correct answer: C
Cambium produces new xylem and phloem for trunk growth.
Q14. Which soil condition most reduces root growth?
A. Loose sandy soil
B. High aeration
C. Compaction
D. Organic mulch
Correct answer: C
Compacted soils restrict root expansion and oxygen flow.
Q15. What is the primary benefit of mulch?
A. Increases soil salinity
B. Conserves moisture and regulates temperature
C. Stops all pests
D. Eliminates need for irrigation
Correct answer: B
Mulch improves soil moisture retention and temperature stability.
Q16. A girdling root causes:
A. Increased growth
B. Improved stability
C. Restricted vascular flow
D. Enhanced nutrient uptake
Correct answer: C
Girdling roots constrict trunk vascular tissue, causing decline.
Q17. Which insect is a bark-boring pest?
A. Aphid
B. Bark beetle
C. Caterpillar
D. Spider mite
Correct answer: B
Bark beetles tunnel under bark disrupting cambium.
FORM REAL EXAMS LATEST 2025-2026 UPDATE
WITH 150 QUESTIONS & 100% CORRECT
DETAILED ANSWERS GRADED A+ (BRAND
NEW!!)
Q1. A mature oak shows canopy dieback, epicormic shoots, and fungal conks at the base. The
most likely condition is:
A. Nutrient deficiency
B. Root rot caused by Armillaria
C. Drought stress only
D. Leaf miner infestation
Correct answer: B
Armillaria root rot commonly causes decay at the base, reduced water uptake, dieback, and
stress-induced epicormic growth.
Q2. Which pruning cut minimizes risk of decay best in mature trees?
A. Flush cut
B. Heading cut
C. Collar cut outside branch bark ridge
D. Stub cut
Correct answer: C
Proper collar cuts preserve the branch protection zone, reducing decay entry.
Q3. A tree in compacted urban soil most commonly suffers from:
A. Excess potassium
B. Oxygen deficiency in root zone
C. Overproduction of chlorophyll
D. Increased mycorrhiza activity
Correct answer: B
Soil compaction reduces pore space and oxygen availability to roots.
Q4. Which pest is most associated with ash tree mortality?
A. Emerald ash borer
B. Bark beetle
C. Gypsy moth
D. Leafhopper
,Correct answer: A
Emerald ash borer larvae disrupt vascular tissue, killing ash trees.
Q5. CODIT theory in arboriculture refers to:
A. Chemical oxygen demand in trees
B. Compartmentalization of decay in trees
C. Cutting of dead internal tissue
D. Carbon oxidation decay index test
Correct answer: B
CODIT explains how trees isolate decay through internal barriers.
Q6. A tree leaning suddenly after a storm most likely indicates:
A. Leaf imbalance
B. Root plate failure
C. Excess fertilization
D. Natural phototropism
Correct answer: B
Sudden leaning suggests structural root failure or soil/root plate movement.
Q7. Which fertilizer ratio promotes root establishment in transplanting?
A. High nitrogen
B. High phosphorus
C. High potassium only
D. No fertilizer needed ever
Correct answer: B
Phosphorus supports root development in young/transplanted trees.
Q8. What is the main risk of topping a mature tree?
A. Increased fruit production
B. Rapid structural improvement
C. Weak epicormic growth and decay
D. Enhanced root growth
Correct answer: C
Topping causes stress, weak regrowth, and decay entry points.
,Q9. The best time to prune most deciduous trees is:
A. Peak summer heat
B. Dormant season
C. Flowering stage
D. Heavy rain season
Correct answer: B
Dormant pruning reduces stress and disease transmission risk.
Q10. Which organism is a vascular wilt pathogen?
A. Verticillium
B. Aphids
C. Scale insects
D. Caterpillars
Correct answer: A
Verticillium blocks xylem vessels causing wilting and decline.
Q11. A common symptom of overwatering trees is:
A. Leaf scorch
B. Root hypoxia and chlorosis
C. Increased flowering
D. Bark thickening
Correct answer: B
Excess water reduces oxygen, damaging roots and causing chlorosis.
Q12. Which tool is safest for large limb removal at height?
A. Handsaw only
B. Chainsaw with harness and training
C. Hatchet
D. Pruning shears
Correct answer: B
Chainsaws are used with proper PPE and training for aerial work.
Q13. The main function of tree cambium is:
A. Water storage
B. Photosynthesis
C. Secondary growth
D. Leaf production
, Correct answer: C
Cambium produces new xylem and phloem for trunk growth.
Q14. Which soil condition most reduces root growth?
A. Loose sandy soil
B. High aeration
C. Compaction
D. Organic mulch
Correct answer: C
Compacted soils restrict root expansion and oxygen flow.
Q15. What is the primary benefit of mulch?
A. Increases soil salinity
B. Conserves moisture and regulates temperature
C. Stops all pests
D. Eliminates need for irrigation
Correct answer: B
Mulch improves soil moisture retention and temperature stability.
Q16. A girdling root causes:
A. Increased growth
B. Improved stability
C. Restricted vascular flow
D. Enhanced nutrient uptake
Correct answer: C
Girdling roots constrict trunk vascular tissue, causing decline.
Q17. Which insect is a bark-boring pest?
A. Aphid
B. Bark beetle
C. Caterpillar
D. Spider mite
Correct answer: B
Bark beetles tunnel under bark disrupting cambium.
