ISA Certified Arboriculture Certification Comprehensive
EXAM LATEST VERSION 2026-2027 QUESTIONS AND
ANSWERS
What type of alternative pesticide has the potential side effect of phytotoxic injury if used
during dry periods?
(A) Insect growth regulator
(B) Microbial
(C) Insecticidal soap
(D) Horticultural oil - answer>>Some plants may suffer phytotoxic injury due to the use of
horticultural oils in dry times.
The answer is (D)
When valuing the cost of a tree, when is it most appropriate to use the CTLA trunk formula
method?
(A) The tree is below a specific height
(B) Smaller sized trunks
(C) Larger sized trunks
(D) Excessive number of branches - answer>>The CTLA trunk formula method is based on the
size of the tree and is best suited for those which are too large to have comparisons of
replacement.
The answer is (C)
What type of ordinance would stipulate the requirements of trees that fall within two pieces of
property?
(A) Right-of-way
,(B) Permits
(C) List of acceptable species
(D) Tree preservation order - answer>>There are a number of ordinances that affect the proper
handling, placement or maintenance of trees. If there is a question involving property lines and
obligations, it is an issue of right-ofway.
The answer is (A)
If a threshold temperature is established as 50o , what is the degree day unit recorded for a day
with a temperature of 30o?
(A) 0o
(B) 20o
(C) -20o
(D) -30o - answer>>When calculating the degree day unit, a negative number is recorded as
zero.
The answer is (A)
What is not considered a benefit of trees in an urban setting for environmental advantages?
(A) Improved air quality
(B) Increased runoff for better flow of drainage
(C) Cooling of the air
(D) Better habitats for wildlife - answer>>Trees have a number of benefits which may be
environmental, social, economic or aesthetic. Some of the environmental advantages include
better quality and cooler air, better habitat for local wildlife, reduction in greenhouse effects,
and decreased stormwater runoff creating a more efficient drainage system.
The answer is (B)
,The value of green infrastructure ____________ over time.
(A) Increases
(B) Decreases
(C) Stays stagnant
(D) Has a slight increase and then a gradual decline - answer>>Green infrastructure as it grows
properly will increase in value over time by increasing in size or significance.
The answer is (A)
A tree is measured to have a drip line to drip line distance of 66 ft. Using a canopy cover
estimation of the tree as a circle, how many trees would it take to cover one acre?
(A) 5
(B) 9
(C) 13
(D) 22 - answer>>A method for calculating canopy cover includes estimating the cover of a tree
as a circle with a diameter measured from the drip line on one end to the other. To then
calculate the cover, use the equation for the area of a circle: A = pie r(2) = pie 33(2) = 3419.5(2)
squared feet.
Then you can divide the square feet of one tree into that of an acre which is 43,560
acres/3419.5 = 12.73 Trees. Round up to 13 trees.
The answer is (C)
What is the commonly accepted reasonable maximum amount of a single plant family within an
overall tree population?
(A) 10%
(B) 30%
(C) 50%
, (D) 60% - answer>>Diversity among tree populations is important for the balance of aesthetics
and defense. It is often recommended to maintain the following maximums within populations:
• 30% of a single plant family
• 20% of a single genus
• 10% of a single species
The answer is (B)
What is not a common subcomponent of an urban forest management plan?
(A) Risk management plan
(B) Planting plan
(C) Tree inventory
(D) Emergency response - answer>>The urban forest management plan identifies and
documents procedures necessary for the proper maintenance of the inventory. It may include:
• Planting plan • Preservation plan • Emergency response • Operations • Removal plan
The tree inventory identifies the type and locations but is not a part of the management plan.
The answer is (C)
According to ANSI A300, what is the acceptable situation to remove healthy fonds from a palm
tree?
(A) Too long
(B) Needed for clearance
(C) Non-diseased yellowing fonds
(D) Too short - answer>>Pruning is covered in Section 1 of the ANSI A300 and fonds are in part
9. Section 9.2 indicates that "Healthy fonds shall not be removed except when necessary for
clearance."
The answer is (B)
EXAM LATEST VERSION 2026-2027 QUESTIONS AND
ANSWERS
What type of alternative pesticide has the potential side effect of phytotoxic injury if used
during dry periods?
(A) Insect growth regulator
(B) Microbial
(C) Insecticidal soap
(D) Horticultural oil - answer>>Some plants may suffer phytotoxic injury due to the use of
horticultural oils in dry times.
The answer is (D)
When valuing the cost of a tree, when is it most appropriate to use the CTLA trunk formula
method?
(A) The tree is below a specific height
(B) Smaller sized trunks
(C) Larger sized trunks
(D) Excessive number of branches - answer>>The CTLA trunk formula method is based on the
size of the tree and is best suited for those which are too large to have comparisons of
replacement.
The answer is (C)
What type of ordinance would stipulate the requirements of trees that fall within two pieces of
property?
(A) Right-of-way
,(B) Permits
(C) List of acceptable species
(D) Tree preservation order - answer>>There are a number of ordinances that affect the proper
handling, placement or maintenance of trees. If there is a question involving property lines and
obligations, it is an issue of right-ofway.
The answer is (A)
If a threshold temperature is established as 50o , what is the degree day unit recorded for a day
with a temperature of 30o?
(A) 0o
(B) 20o
(C) -20o
(D) -30o - answer>>When calculating the degree day unit, a negative number is recorded as
zero.
The answer is (A)
What is not considered a benefit of trees in an urban setting for environmental advantages?
(A) Improved air quality
(B) Increased runoff for better flow of drainage
(C) Cooling of the air
(D) Better habitats for wildlife - answer>>Trees have a number of benefits which may be
environmental, social, economic or aesthetic. Some of the environmental advantages include
better quality and cooler air, better habitat for local wildlife, reduction in greenhouse effects,
and decreased stormwater runoff creating a more efficient drainage system.
The answer is (B)
,The value of green infrastructure ____________ over time.
(A) Increases
(B) Decreases
(C) Stays stagnant
(D) Has a slight increase and then a gradual decline - answer>>Green infrastructure as it grows
properly will increase in value over time by increasing in size or significance.
The answer is (A)
A tree is measured to have a drip line to drip line distance of 66 ft. Using a canopy cover
estimation of the tree as a circle, how many trees would it take to cover one acre?
(A) 5
(B) 9
(C) 13
(D) 22 - answer>>A method for calculating canopy cover includes estimating the cover of a tree
as a circle with a diameter measured from the drip line on one end to the other. To then
calculate the cover, use the equation for the area of a circle: A = pie r(2) = pie 33(2) = 3419.5(2)
squared feet.
Then you can divide the square feet of one tree into that of an acre which is 43,560
acres/3419.5 = 12.73 Trees. Round up to 13 trees.
The answer is (C)
What is the commonly accepted reasonable maximum amount of a single plant family within an
overall tree population?
(A) 10%
(B) 30%
(C) 50%
, (D) 60% - answer>>Diversity among tree populations is important for the balance of aesthetics
and defense. It is often recommended to maintain the following maximums within populations:
• 30% of a single plant family
• 20% of a single genus
• 10% of a single species
The answer is (B)
What is not a common subcomponent of an urban forest management plan?
(A) Risk management plan
(B) Planting plan
(C) Tree inventory
(D) Emergency response - answer>>The urban forest management plan identifies and
documents procedures necessary for the proper maintenance of the inventory. It may include:
• Planting plan • Preservation plan • Emergency response • Operations • Removal plan
The tree inventory identifies the type and locations but is not a part of the management plan.
The answer is (C)
According to ANSI A300, what is the acceptable situation to remove healthy fonds from a palm
tree?
(A) Too long
(B) Needed for clearance
(C) Non-diseased yellowing fonds
(D) Too short - answer>>Pruning is covered in Section 1 of the ANSI A300 and fonds are in part
9. Section 9.2 indicates that "Healthy fonds shall not be removed except when necessary for
clearance."
The answer is (B)
