ISA Arborist Certification Practice Exams Part 1
Exam 2025–2026 Accurate Real Exam Questions
and Verified Correct Answers JUST RELEASED
What statement below is true regarding how a tree's growth rate and photosynthesis rate
will react to the amount of available resources?
(A) The growth rate will be limited before the photosynthesis rate
(B) The photosynthesis rate will be limited before the growth rate
(C) The photosynthesis rate and growth rate become hindered equally with limited
resources
(D) The photosynthesis rate will not be hindered by limited resources - answer>>>A
What single resource has the most detrimental effect on a tree's ability to perform
photosynthesis if limited?
(A) Light
(B) Water
(C) CO2
(D) None of the above - answer>>>D
What extract listed below is not an allelochemical classified as a natural insecticide?
(A) Nicotine
(B) Lignin
(C) Rotenone
(D) Neem - answer>>>B
A tree is identified as being in the mortality spiral when what has occurred?
(A) The tree has begun to see detrimental stress factors
,(B) The tree has seen an isolated but severely detrimental stress factor
(C) Cumulative stress factors have yielded a situation where very few actions can save the
tree
(D) Any combination of stress factors has occurred over time - answer>>>C
The foundational element of an appropriate response process (ARP) is which of the
following?
(A) Monitoring
(B) Immediate action
(C) Establish thresholds
(D) Readily available resources - answer>>>A
What is not a characteristic of any organism classified as a pest?
(A) Threatens health or appearance of plants
(B) May also contribute to the surrounding landscape
(C) Provides competition to the local landscape
(D) Diminishes safety or enjoyment of an area - answer>>>B
Key stressors are identified by what criteria?
(A) Universally detrimental site conditions
(B) Retroactive analysis of stress
(C) Identifying local pests and conditions which may be detrimental (D) Species specific
historical stressors - answer>>>C
Key plants can be identified by which of the following criteria?
(A) Client specific indications(B) Specific species(C) Susceptibility to specific pests (D) All
the above - answer>>>D
,For a threshold temperature of 50°, determine the average degree day unit value for
ooo temperatures over a 3-day span of 85 , 76 , and 82 .
(A) 22° (B) 26° (C) 31° (D) 45° - answer>>>C
What statement regarding landscapes with a monoculture of plantings is true?
(A) They are more susceptible to pest problems
(B) They are less susceptible to pest problems
(C) They are equally as susceptible to pest problems
(D) No correlation exists - answer>>>A
What is not one of the three options available for plant health care professionals to
manage pests?
(A) Manage (B) Eradicate (C) Suppress (D) Prevent - answer>>>A
What is not a means of biological control for pest populations?
(A) Predators (B) Pathogens (C) Parasites (D) Miticides - answer>>>D
After application of pesticides, it is found that the original threat has died off, but a new
contingency of mites has developed as a threat. This development is classified as which of
the following?
(A) Pest insurgence
(B) Pest resurgence
(C) Primary outbreak
(D) Secondary outbreak - answer>>>D
, 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>>>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>>>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>>>A
If a threshold temperature is established as 50°, what is the degree day unit recorded for
a day with a temperature of 30°?
(A) 0° (B) 20° (C) -20° (D) -30° - answer>>>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
Exam 2025–2026 Accurate Real Exam Questions
and Verified Correct Answers JUST RELEASED
What statement below is true regarding how a tree's growth rate and photosynthesis rate
will react to the amount of available resources?
(A) The growth rate will be limited before the photosynthesis rate
(B) The photosynthesis rate will be limited before the growth rate
(C) The photosynthesis rate and growth rate become hindered equally with limited
resources
(D) The photosynthesis rate will not be hindered by limited resources - answer>>>A
What single resource has the most detrimental effect on a tree's ability to perform
photosynthesis if limited?
(A) Light
(B) Water
(C) CO2
(D) None of the above - answer>>>D
What extract listed below is not an allelochemical classified as a natural insecticide?
(A) Nicotine
(B) Lignin
(C) Rotenone
(D) Neem - answer>>>B
A tree is identified as being in the mortality spiral when what has occurred?
(A) The tree has begun to see detrimental stress factors
,(B) The tree has seen an isolated but severely detrimental stress factor
(C) Cumulative stress factors have yielded a situation where very few actions can save the
tree
(D) Any combination of stress factors has occurred over time - answer>>>C
The foundational element of an appropriate response process (ARP) is which of the
following?
(A) Monitoring
(B) Immediate action
(C) Establish thresholds
(D) Readily available resources - answer>>>A
What is not a characteristic of any organism classified as a pest?
(A) Threatens health or appearance of plants
(B) May also contribute to the surrounding landscape
(C) Provides competition to the local landscape
(D) Diminishes safety or enjoyment of an area - answer>>>B
Key stressors are identified by what criteria?
(A) Universally detrimental site conditions
(B) Retroactive analysis of stress
(C) Identifying local pests and conditions which may be detrimental (D) Species specific
historical stressors - answer>>>C
Key plants can be identified by which of the following criteria?
(A) Client specific indications(B) Specific species(C) Susceptibility to specific pests (D) All
the above - answer>>>D
,For a threshold temperature of 50°, determine the average degree day unit value for
ooo temperatures over a 3-day span of 85 , 76 , and 82 .
(A) 22° (B) 26° (C) 31° (D) 45° - answer>>>C
What statement regarding landscapes with a monoculture of plantings is true?
(A) They are more susceptible to pest problems
(B) They are less susceptible to pest problems
(C) They are equally as susceptible to pest problems
(D) No correlation exists - answer>>>A
What is not one of the three options available for plant health care professionals to
manage pests?
(A) Manage (B) Eradicate (C) Suppress (D) Prevent - answer>>>A
What is not a means of biological control for pest populations?
(A) Predators (B) Pathogens (C) Parasites (D) Miticides - answer>>>D
After application of pesticides, it is found that the original threat has died off, but a new
contingency of mites has developed as a threat. This development is classified as which of
the following?
(A) Pest insurgence
(B) Pest resurgence
(C) Primary outbreak
(D) Secondary outbreak - answer>>>D
, 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>>>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>>>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>>>A
If a threshold temperature is established as 50°, what is the degree day unit recorded for
a day with a temperature of 30°?
(A) 0° (B) 20° (C) -20° (D) -30° - answer>>>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
