10 free, exam-style ISA Certified Arborist (ISA-CA) practice questions with answers and
explanations. No signup required. Work through them below, then take the
full free ISA-CA practice test to study every exam domain.
These 10 free ISA-CA questions are organized by exam domain, so you can see how each part of the ISA Certified Arborist blueprint is tested. Reveal the answer and explanation under each question.
Domain 1: Tree Biology 7% of exam
Question 1
An arborist removes a large branch and the resulting wound shows rapid decay spread vertically but limited spread radially. Based on the CODIT model, which wall is likely functioning well and which is functioning poorly?
- Wall 1 is functioning poorly; Wall 2 is functioning well
- Wall 2 is functioning poorly; Wall 3 is functioning well
- Wall 3 is functioning poorly; Wall 4 is functioning well
- Wall 4 is functioning poorly; Wall 1 is functioning well
Show answer & explanation
Correct answer: A - Wall 1 is functioning poorly; Wall 2 is functioning well
Domain 2: Soil Science 6% of exam
Question 2
The 10-20-30 rule for urban tree species diversity recommends that a community plant:
- 10 trees per block, 20 per street, and 30 per neighborhood
- No more than 10% of one species, 20% of one genus, and 30% of one family
- 10 native species for every 20 non-native and 30 cultivar selections
- Trees spaced 10, 20, or 30 feet apart depending on mature size
Show answer & explanation
Correct answer: B - No more than 10% of one species, 20% of one genus, and 30% of one family
Domain 3: Water Management 5% of exam
Question 3
An arborist is examining a pin oak growing in an alkaline soil with a pH of 7.8. The tree shows interveinal chlorosis on its newest leaves. The MOST appropriate recommendation is to:
- Apply a high-nitrogen fertilizer to promote green foliage
- Address the iron availability issue, potentially through soil acidification, chelated iron applications, or trunk injection
- Prune the affected branches to remove the yellowed leaves
- Increase watering to flush salts from the root zone
Show answer & explanation
Correct answer: B - Address the iron availability issue, potentially through soil acidification, chelated iron applications, or trunk injection
Domain 4: Tree Nutrition and Fertilization 5% of exam
Question 4
Before planting a B&B tree, an arborist finds that the root flare is buried 4 inches below the top of the root ball. The arborist should:
- Plant the root ball as-is with the top even with the soil grade
- Remove excess soil from the top of the root ball to expose the root flare before setting the planting depth
- Add extra soil on top after planting to protect the exposed roots
- Dig the hole 4 inches deeper to accommodate the extra soil on the root ball
Show answer & explanation
Correct answer: B - Remove excess soil from the top of the root ball to expose the root flare before setting the planting depth
Domain 5: Tree Selection and Installation 8% of exam
Question 5
The key distinction between reduction and topping is that reduction:
- Removes branches at random heights regardless of lateral branch size
- Makes cuts back to lateral branches large enough to sustain growth, while topping cuts to stubs or inadequate laterals
- Is only performed on conifers, while topping is for hardwoods
- Always removes more of the canopy than topping
Show answer & explanation
Correct answer: B - Makes cuts back to lateral branches large enough to sustain growth, while topping cuts to stubs or inadequate laterals
Domain 6: Pruning 12% of exam
Question 6
An arborist inspects a mature maple showing branch dieback, sparse foliage, and mushrooms growing from the root flare. The mushrooms are a _______ and the dieback is a _______.
- Symptom; sign
- Sign; symptom
- Symptom; symptom
- Sign; sign
Show answer & explanation
Correct answer: B - Sign; symptom
Domain 7: Diagnosis and Treatment 14% of exam
Question 7
A homeowner notices their oak tree declining 4 years after a new driveway was installed near the tree. The arborist should recognize that:
- The driveway cannot be the cause since it was installed years ago
- Delayed decline from root damage during driveway construction is a common pattern, as effects can take 3 to 7 years to appear
- The tree is declining due to old age, not the driveway
- Only diseases cause delayed onset symptoms
Show answer & explanation
Correct answer: B - Delayed decline from root damage during driveway construction is a common pattern, as effects can take 3 to 7 years to appear
Domain 8: Trees and Construction 5% of exam
Question 8
A tree with a high likelihood of failure but no targets in its fall zone would receive a risk rating of:
- Extreme, because the tree is likely to fail
- Low, because even though failure is likely, there is no target to be harmed
- High, because all trees with defects are high risk
- Moderate, as a default for any defective tree
Show answer & explanation
Correct answer: B - Low, because even though failure is likely, there is no target to be harmed
Domain 9: Urban Forestry 8% of exam
Question 9
The 10-foot minimum approach distance to energized electrical conductors for unqualified arborists applies to the arborist's:
- Body only - tools and ropes can be closer
- Body, tools, ropes, rigging equipment, and any tree parts being cut or lowered
- Body only during active cutting
- Nothing - it is only a recommendation, not a requirement
Show answer & explanation
Correct answer: B - Body, tools, ropes, rigging equipment, and any tree parts being cut or lowered
More ISA-CA practice questions
Question 10
Using the CTLA trunk formula, the appraised value of a tree is calculated as:
- Species + Size + Condition + Location
- Basic Tree Cost × Species % × Condition % × Location %
- Trunk diameter × height × species factor
- (Species + Condition) × (Size + Location) ÷ 2
Show answer & explanation
Correct answer: B - Basic Tree Cost × Species % × Condition % × Location %