Page 1 of 103
NYC Horticulturist Exam Questions with Correct
Answers and explanations LATEST THIS YEAR -JUST
RELEASED
NYC Horticulturist Exam
SUMMARIZED EXAM COVERAGE
The NYC Horticulturist Exam (including the Yonkers Horticulturist II open-competitive examination) tests
knowledge of horticultural principles and practices for public sector landscaping roles. Key domains
include: educating and interacting with the public on horticultural topics; familiarity with a wide range of
plant species including trees, shrubs, perennials, annuals, and aquatic plants; principles and practices of
planting, cultivating, pruning, propagating, and maintaining landscapes; pest and disease identification
and control; soil science and fertility management; irrigation systems and water conservation; and
seasonal landscape maintenance including snow/ice control.
1. You are conducting a public workshop on rose care. A participant asks about small black spots with
fringed margins on the leaves. What is the most likely disease and its cause?
A) Rust caused by fungal spores
B) Black spot caused by Diplocarpon rosae
C) Powdery mildew caused by dry conditions
D) Botrytis blight caused by excess humidity
Answer: B
Rationale: Black spot (Diplocarpon rosae) produces circular black spots with fringed or feathery margins
on rose leaves, leading to defoliation.
, Page 2 of 103
2. What is the ideal soil pH range for most turfgrasses grown in New York State?
A) 4.5–5.0
B) 5.5–6.0
C) 6.0–7.0
D) 7.5–8.0
Answer: C
Rationale: Most turfgrasses perform best in slightly acidic to neutral soils (6.0–7.0), which optimizes
nutrient availability for root uptake.
3. Which of the following plants is considered invasive in New York State and should not be
recommended for public plantings?
A) Red Maple (Acer rubrum)
B) Sugar Maple (Acer saccharum)
C) Japanese Barberry (Berberis thunbergii)
D) Eastern Redbud (Cercis canadensis)
Answer: C
, Page 3 of 103
Rationale: Japanese Barberry is invasive in New York, spreading aggressively into woodlands and
displacing native vegetation.
4. A park manager reports that a mature maple tree has leaves wilting and yellowing on only one side of
the tree. What is the most likely diagnosis?
A) Drought stress affecting the entire canopy
B) Verticillium wilt, a vascular disease causing unilateral symptoms
C) Anthracnose affecting all leaves equally
D) Iron deficiency due to high soil pH
Answer: B
Rationale: Verticillium wilt causes uneven wilting, often affecting one side of the tree due to vascular
infection.
5. You are designing a water-wise garden for a public park in New York. Which irrigation method is most
efficient for reducing water loss?
A) Overhead sprinklers operating at midday
B) Flood irrigation applied weekly
, Page 4 of 103
C) Drip irrigation delivering water directly to the root zone
D) Hand watering with a hose daily
Answer: C
Rationale: Drip irrigation delivers water directly to the root zone, reducing evaporation and runoff.
6. A resident brings a plant sample with yellowing between the leaf veins but the veins themselves
remain green. What nutrient deficiency is most likely?
A) Nitrogen deficiency
B) Phosphorus deficiency
C) Potassium deficiency
D) Iron deficiency
Answer: D
Rationale: Interveinal chlorosis is a classic sign of iron deficiency, especially common in alkaline soils.
7. Which pest is known for tunneling inside the trunks and branches of ash trees, causing dieback and
tree mortality?
NYC Horticulturist Exam Questions with Correct
Answers and explanations LATEST THIS YEAR -JUST
RELEASED
NYC Horticulturist Exam
SUMMARIZED EXAM COVERAGE
The NYC Horticulturist Exam (including the Yonkers Horticulturist II open-competitive examination) tests
knowledge of horticultural principles and practices for public sector landscaping roles. Key domains
include: educating and interacting with the public on horticultural topics; familiarity with a wide range of
plant species including trees, shrubs, perennials, annuals, and aquatic plants; principles and practices of
planting, cultivating, pruning, propagating, and maintaining landscapes; pest and disease identification
and control; soil science and fertility management; irrigation systems and water conservation; and
seasonal landscape maintenance including snow/ice control.
1. You are conducting a public workshop on rose care. A participant asks about small black spots with
fringed margins on the leaves. What is the most likely disease and its cause?
A) Rust caused by fungal spores
B) Black spot caused by Diplocarpon rosae
C) Powdery mildew caused by dry conditions
D) Botrytis blight caused by excess humidity
Answer: B
Rationale: Black spot (Diplocarpon rosae) produces circular black spots with fringed or feathery margins
on rose leaves, leading to defoliation.
, Page 2 of 103
2. What is the ideal soil pH range for most turfgrasses grown in New York State?
A) 4.5–5.0
B) 5.5–6.0
C) 6.0–7.0
D) 7.5–8.0
Answer: C
Rationale: Most turfgrasses perform best in slightly acidic to neutral soils (6.0–7.0), which optimizes
nutrient availability for root uptake.
3. Which of the following plants is considered invasive in New York State and should not be
recommended for public plantings?
A) Red Maple (Acer rubrum)
B) Sugar Maple (Acer saccharum)
C) Japanese Barberry (Berberis thunbergii)
D) Eastern Redbud (Cercis canadensis)
Answer: C
, Page 3 of 103
Rationale: Japanese Barberry is invasive in New York, spreading aggressively into woodlands and
displacing native vegetation.
4. A park manager reports that a mature maple tree has leaves wilting and yellowing on only one side of
the tree. What is the most likely diagnosis?
A) Drought stress affecting the entire canopy
B) Verticillium wilt, a vascular disease causing unilateral symptoms
C) Anthracnose affecting all leaves equally
D) Iron deficiency due to high soil pH
Answer: B
Rationale: Verticillium wilt causes uneven wilting, often affecting one side of the tree due to vascular
infection.
5. You are designing a water-wise garden for a public park in New York. Which irrigation method is most
efficient for reducing water loss?
A) Overhead sprinklers operating at midday
B) Flood irrigation applied weekly
, Page 4 of 103
C) Drip irrigation delivering water directly to the root zone
D) Hand watering with a hose daily
Answer: C
Rationale: Drip irrigation delivers water directly to the root zone, reducing evaporation and runoff.
6. A resident brings a plant sample with yellowing between the leaf veins but the veins themselves
remain green. What nutrient deficiency is most likely?
A) Nitrogen deficiency
B) Phosphorus deficiency
C) Potassium deficiency
D) Iron deficiency
Answer: D
Rationale: Interveinal chlorosis is a classic sign of iron deficiency, especially common in alkaline soils.
7. Which pest is known for tunneling inside the trunks and branches of ash trees, causing dieback and
tree mortality?
