Louisiana Commercial Arborist Exam
Practice Questions And Correct Answers
(Verified Answers) Plus Rationales Q&A
1. A mature live oak (Quercus virginiana) in a Louisiana commercial landscape
exhibits sparse, chlorotic foliage with interveinal yellowing and marginal necrosis on
newer leaves. Soil pH is 7.8, and the tree is in a frequently irrigated lawn. Which of the
following is the most likely primary cause?
A. Manganese deficiency induced by high soil pH
B. Nitrogen deficiency from lawn competition
C. Iron deficiency induced by high soil pH
D. Magnesium deficiency from leaching
Answer: C. Iron deficiency induced by high soil pH
Rationale: High soil pH (7.8) in Louisiana's calcareous soils commonly induces iron
deficiency in live oaks, causing interveinal chlorosis on new growth. Manganese deficiency
also occurs at high pH but typically shows more uniform chlorosis; nitrogen deficiency
affects older leaves first; magnesium deficiency causes interveinal chlorosis on older
leaves. The pattern on newer leaves and high pH strongly point to iron.
2. During a tree risk assessment, a commercial arborist uses a resistograph on a
leaning water oak (Quercus nigra) and finds a sound wall thickness of 2 inches on a
20-inch diameter trunk. According to current ANSI A300 (Part 9) and ISA BMPs,
what is the most appropriate interpretation?
A. The tree is safe because the sound wall exceeds 1 inch minimum.
B. The tree has a high likelihood of failure due to insufficient sound wood.
C. The tree requires immediate removal regardless of other factors.
D. The tree should be cabled and retained with annual inspections.
Answer: B. The tree has a high likelihood of failure due to insufficient sound wood.
Rationale: ANSI A300 Part 9 and ISA BMPs indicate that for a 20-inch diameter tree, a
sound wall of only 2 inches (10% of radius) is below the typically recommended 30% sound
wood threshold, indicating a high likelihood of failure. Option A is incorrect because 1
inch is not the standard for this size; C is too absolute without considering site and targets;
D is not supported without further analysis.
Page 1 of 80
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,3. An arborist is pruning a large, mature pecan tree (Carya illinoinensis) in July in
Baton Rouge. Which of the following pruning cuts is most consistent with ANSI A300
standards for maintaining tree health?
A. Removing a large lower limb with a flush cut to the trunk to prevent decay.
B. Making a reduction cut on a lateral branch that is at least one-third the diameter of the
parent branch.
C. Using the three-cut method to remove a heavy limb, leaving the branch collar intact.
D. Topping the central leader to reduce height and risk of storm damage.
Answer: C. Using the three-cut method to remove a heavy limb, leaving the branch
collar intact.
Rationale: ANSI A300 standards require the three-cut method for heavy limbs to prevent
tearing, and leaving the branch collar intact promotes proper wound closure. Flush cuts
(A) remove the collar and increase decay; reduction cuts (B) should be made on laterals at
least one-third to one-half the diameter, but the phrasing 'at least one-third' is acceptable,
yet C is the most clearly correct standard practice. Topping (D) is a harmful practice
discouraged by ANSI A300.
4. A commercial arborist is diagnosing a declining maple tree in a Louisiana parking
lot. The tree shows dieback, small leaves, and a thin canopy. Soil compaction is
suspected. Which of the following diagnostic methods would best confirm the extent of
compaction?
A. Using a penetrometer to measure soil resistance at various depths.
B. Performing a soil pH test.
C. Collecting soil samples for nutrient analysis.
D. Conducting a foliar tissue analysis.
Answer: A. Using a penetrometer to measure soil resistance at various depths.
Rationale: A penetrometer directly measures soil resistance, indicating compaction layers
that restrict root growth and water infiltration. Soil pH (B) and nutrient analysis (C) assess
fertility but not physical compaction; foliar analysis (D) reflects nutrient status but not soil
structure. Penetrometer testing is the standard field method to confirm compaction.
Page 3 of 80
, 5. An arborist is planning to remove a large, dead pine tree near a power line in
Louisiana. According to OSHA and ANSI Z133 standards, which of the following is
required before beginning the removal?
A. Ensuring all workers wear approved head, eye, and foot protection.
B. Notifying the utility company and ensuring lines are de-energized or insulated.
C. Using a bucket truck to access the tree for cutting.
D. Applying a wound dressing to the final cut.
Answer: B. Notifying the utility company and ensuring lines are de-energized or
insulated.
Rationale: ANSI Z133 and OSHA require that any tree work within 10 feet of energized
lines be performed only after the utility has de-energized or insulated the lines, or by a
qualified line-clearance arborist. PPE (A) is required but not sufficient; bucket truck (C) is
a method, not a prerequisite; wound dressing (D) is not standard for removals.
6. A client requests that a large crape myrtle (Lagerstroemia indica) be pruned to
'knuckle' it back severely every year to promote larger blooms. What is the best
professional response based on current arboricultural science?
A. Agree, because severe pruning increases flower size and is standard practice.
B. Explain that this practice, known as 'crape murder,' can lead to weak growth and
long-term decline.
C. Recommend topping the tree to reduce height and improve bloom density.
D. Suggest applying a high-nitrogen fertilizer to offset the stress.
Answer: B. Explain that this practice, known as 'crape murder,' can lead to weak
growth and long-term decline.
Rationale: Severe annual pruning of crape myrtle, often called 'crape murder,' stimulates
excessive epicormic growth, weakens branch structure, and can lead to decline. Option A is
incorrect because while bloom size may increase, it is not sustainable. Topping (C) is also
harmful; fertilizer (D) does not address the pruning damage.
Page 4 of 80
Practice Questions And Correct Answers
(Verified Answers) Plus Rationales Q&A
1. A mature live oak (Quercus virginiana) in a Louisiana commercial landscape
exhibits sparse, chlorotic foliage with interveinal yellowing and marginal necrosis on
newer leaves. Soil pH is 7.8, and the tree is in a frequently irrigated lawn. Which of the
following is the most likely primary cause?
A. Manganese deficiency induced by high soil pH
B. Nitrogen deficiency from lawn competition
C. Iron deficiency induced by high soil pH
D. Magnesium deficiency from leaching
Answer: C. Iron deficiency induced by high soil pH
Rationale: High soil pH (7.8) in Louisiana's calcareous soils commonly induces iron
deficiency in live oaks, causing interveinal chlorosis on new growth. Manganese deficiency
also occurs at high pH but typically shows more uniform chlorosis; nitrogen deficiency
affects older leaves first; magnesium deficiency causes interveinal chlorosis on older
leaves. The pattern on newer leaves and high pH strongly point to iron.
2. During a tree risk assessment, a commercial arborist uses a resistograph on a
leaning water oak (Quercus nigra) and finds a sound wall thickness of 2 inches on a
20-inch diameter trunk. According to current ANSI A300 (Part 9) and ISA BMPs,
what is the most appropriate interpretation?
A. The tree is safe because the sound wall exceeds 1 inch minimum.
B. The tree has a high likelihood of failure due to insufficient sound wood.
C. The tree requires immediate removal regardless of other factors.
D. The tree should be cabled and retained with annual inspections.
Answer: B. The tree has a high likelihood of failure due to insufficient sound wood.
Rationale: ANSI A300 Part 9 and ISA BMPs indicate that for a 20-inch diameter tree, a
sound wall of only 2 inches (10% of radius) is below the typically recommended 30% sound
wood threshold, indicating a high likelihood of failure. Option A is incorrect because 1
inch is not the standard for this size; C is too absolute without considering site and targets;
D is not supported without further analysis.
Page 1 of 80
,Page 2 of 80
,3. An arborist is pruning a large, mature pecan tree (Carya illinoinensis) in July in
Baton Rouge. Which of the following pruning cuts is most consistent with ANSI A300
standards for maintaining tree health?
A. Removing a large lower limb with a flush cut to the trunk to prevent decay.
B. Making a reduction cut on a lateral branch that is at least one-third the diameter of the
parent branch.
C. Using the three-cut method to remove a heavy limb, leaving the branch collar intact.
D. Topping the central leader to reduce height and risk of storm damage.
Answer: C. Using the three-cut method to remove a heavy limb, leaving the branch
collar intact.
Rationale: ANSI A300 standards require the three-cut method for heavy limbs to prevent
tearing, and leaving the branch collar intact promotes proper wound closure. Flush cuts
(A) remove the collar and increase decay; reduction cuts (B) should be made on laterals at
least one-third to one-half the diameter, but the phrasing 'at least one-third' is acceptable,
yet C is the most clearly correct standard practice. Topping (D) is a harmful practice
discouraged by ANSI A300.
4. A commercial arborist is diagnosing a declining maple tree in a Louisiana parking
lot. The tree shows dieback, small leaves, and a thin canopy. Soil compaction is
suspected. Which of the following diagnostic methods would best confirm the extent of
compaction?
A. Using a penetrometer to measure soil resistance at various depths.
B. Performing a soil pH test.
C. Collecting soil samples for nutrient analysis.
D. Conducting a foliar tissue analysis.
Answer: A. Using a penetrometer to measure soil resistance at various depths.
Rationale: A penetrometer directly measures soil resistance, indicating compaction layers
that restrict root growth and water infiltration. Soil pH (B) and nutrient analysis (C) assess
fertility but not physical compaction; foliar analysis (D) reflects nutrient status but not soil
structure. Penetrometer testing is the standard field method to confirm compaction.
Page 3 of 80
, 5. An arborist is planning to remove a large, dead pine tree near a power line in
Louisiana. According to OSHA and ANSI Z133 standards, which of the following is
required before beginning the removal?
A. Ensuring all workers wear approved head, eye, and foot protection.
B. Notifying the utility company and ensuring lines are de-energized or insulated.
C. Using a bucket truck to access the tree for cutting.
D. Applying a wound dressing to the final cut.
Answer: B. Notifying the utility company and ensuring lines are de-energized or
insulated.
Rationale: ANSI Z133 and OSHA require that any tree work within 10 feet of energized
lines be performed only after the utility has de-energized or insulated the lines, or by a
qualified line-clearance arborist. PPE (A) is required but not sufficient; bucket truck (C) is
a method, not a prerequisite; wound dressing (D) is not standard for removals.
6. A client requests that a large crape myrtle (Lagerstroemia indica) be pruned to
'knuckle' it back severely every year to promote larger blooms. What is the best
professional response based on current arboricultural science?
A. Agree, because severe pruning increases flower size and is standard practice.
B. Explain that this practice, known as 'crape murder,' can lead to weak growth and
long-term decline.
C. Recommend topping the tree to reduce height and improve bloom density.
D. Suggest applying a high-nitrogen fertilizer to offset the stress.
Answer: B. Explain that this practice, known as 'crape murder,' can lead to weak
growth and long-term decline.
Rationale: Severe annual pruning of crape myrtle, often called 'crape murder,' stimulates
excessive epicormic growth, weakens branch structure, and can lead to decline. Option A is
incorrect because while bloom size may increase, it is not sustainable. Topping (C) is also
harmful; fertilizer (D) does not address the pruning damage.
Page 4 of 80
