UCONN EXTENSION MASTER GARDENER DIAGNOSTIC FINAL
EXAM COMPLETE EXAM QUESTIONS AND VERIFIED
ANSWERS | 2026–2027 LATEST UPDATE | GUARANTEED
PASS | DETAILED RATIONALES | FULL STUDY GUIDE | EXAM
PREP | PRACTICE TEST | CERTIFICATION PREPARATION
1. A homeowner reports that their tomato plants have developed dark, sunken lesions on the
stems near the soil line, with white to pinkish fungal growth appearing under wet conditions. The
plants are wilting despite adequate soil moisture. What is the most probable diagnosis?
A. Early blight
B. Septoria leaf spot
C. Southern blight
D. Fusarium wilt
Correct Answer: C. Southern blight
Rationale: Southern blight, caused by the fungus Sclerotium rolfsii, is characterized by stem lesions
near the soil line, wilting, and distinctive white to pinkish mycelial growth. Early blight (A) typically
shows concentric ring lesions on leaves, not stem-base rot. Septoria leaf spot (B) primarily affects
leaves with small, dark spots. Fusarium wilt (D) causes vascular discoloration and general yellowing
without the characteristic mycelial growth. [Return to Study Guide]
2. Which of the following cultural practices is the most effective, non-chemical strategy for
managing Japanese beetle (Popillia japonica) grubs in a home lawn?
A. Applying synthetic pyrethroids to the turf surface in early summer
B. Introducing beneficial nematodes (Heterorhabditis bacteriophora) in late summer
C. Decreasing mowing height to 1.5 inches to desiccate the soil
D. Applying a high-nitrogen fertilizer in early spring to encourage root growth
Correct Answer: B. Introducing beneficial nematodes (Heterorhabditis bacteriophora) in late
summer
Rationale: Beneficial nematodes are an effective biological control for grubs, as they actively seek out
and infect the larvae. Late summer (August-September) is the optimal time for application when
grubs are small and actively feeding. Option A is a chemical strategy, not a non-chemical one. Option
C could stress the lawn and is not directly effective against grubs. Option D does not control grubs
and may even exacerbate disease issues with excessive growth. [Return to Study Guide]
3. A client has a mature oak tree that is showing signs of dieback in the upper canopy. You notice
that the tree was planted too deeply several years ago, with mulch piled against the trunk. This
condition is most directly associated with which plant health problem?
A. Vascular wilt
B. Girdling roots
C. Phytophthora root rot
D. Bacterial leaf scorch
Correct Answer: B. Girdling roots
,Rationale: Deep planting and excessive mulch against the trunk create an environment that
encourages stem-girdling roots. These roots encircle the trunk's base, restricting the flow of water
and nutrients, leading to dieback. Vascular wilt (A) is caused by pathogens. Phytophthora root rot (C)
is a soil-borne disease often favored by poor drainage. Bacterial leaf scorch (D) is a systemic infection
causing marginal leaf necrosis. [Return to Study Guide]
4. According to Integrated Pest Management (IPM) principles, what is the first step a Master
Gardener should recommend when a client reports a pest problem?
A. Apply a broad-spectrum insecticide to prevent further damage
B. Remove and destroy all affected plant material immediately
C. Correctly identify the pest and assess the level of infestation
D. Implement a biological control agent, such as a predator insect
Correct Answer: C. Correctly identify the pest and assess the level of infestation
Rationale: Correct identification is the cornerstone of IPM. Without knowing what the pest is and if its
population has reached an economically or aesthetically damaging level (the action threshold), it is
impossible to select an effective and appropriate management strategy. Options A, B, and D are
actions that may be taken later but are not the first step. [Return to Study Guide]
5. Which of the following describes the primary characteristic that differentiates a true bulb from a
corm?
A. True bulbs have a basal plate, while corms do not.
B. True bulbs are composed of modified leaves (scales), while corms are a swollen stem base.
C. Corms produce offsets, while true bulbs produce bulblets.
D. True bulbs require a period of vernalization, while corms do not.
Correct Answer: B. True bulbs are composed of modified leaves (scales), while corms are a swollen
stem base.
Rationale: This is a fundamental taxonomic distinction. A true bulb, like a tulip or onion, has layers of
fleshy scales that are modified leaves. A corm, like a crocus or gladiolus, is a solid, swollen
underground stem. Both have basal plates and can produce offsets, so A and C are not differentiating
characteristics. The need for vernalization varies by species, not by the type of storage organ. [Return
to Study Guide]
6. A rose bush exhibits stunted growth, and the leaves have a distinctive, yellow-green mosaic
pattern. The plant is not responding to a balanced fertilizer application. Which of the following is
the most likely cause?
A. Rose rust
B. Black spot
C. Rose rosette disease
D. Downy mildew
Correct Answer: C. Rose rosette disease
Rationale: Rose rosette disease is a viral-like disease that causes rapid, elongated shoots, witches'
brooms, distorted foliage, and a yellow mosaic or mottling on leaves. It is often fatal. Rose rust (A)
produces orange pustules, black spot (B) produces circular black spots, and downy mildew (D) causes
purplish-red patches and downy growth on leaves, not a mosaic pattern. [Return to Study Guide]
, 7. A homeowner requests a list of "deer-resistant" plants for a woodland garden. Which of the
following criteria should be the primary basis for your recommendations?
A. General preference of deer as indicated in university extension guides
B. Plants with strong fragrances or prickly textures
C. A combination of these factors as deer preferences are highly regional and situational
D. Plants known to be toxic to deer, such as daffodils
Correct Answer: C. A combination of these factors as deer preferences are highly regional and
situational
Rationale: Deer feeding habits vary significantly by region, season, and the availability of other food
sources. No plant is truly "deer-proof." The most reliable recommendations are based on a
combination of local university extension data, known physical deterrents (fragrance, texture), and
toxicity, acknowledging that hungry deer will eat almost anything. This reflects the professional
understanding of deer management. [Return to Study Guide]
8. When interpreting a soil test report, you find that the pH is 7.8 and the iron (Fe) level is
adequate. A client's rhododendrons are showing interveinal chlorosis in the newest leaves. What is
the most likely problem?
A. An iron deficiency caused by low soil pH
B. An iron deficiency caused by high soil pH, locking up the available iron
C. A nitrogen deficiency due to the high pH
D. A magnesium deficiency caused by a pH imbalance
Correct Answer: B. An iron deficiency caused by high soil pH, locking up the available iron
Rationale: While the soil test reports adequate total iron, it is not available to the plant at a high pH.
Rhododendrons and other acid-loving plants require a low pH for iron uptake. The symptom of
interveinal chlorosis on new leaves is classic for iron chlorosis. The problem is not a lack of iron in the
soil but its unavailability due to the high pH. [Return to Study Guide]
9. What is the primary purpose of performing a "tug test" or "pull test" when evaluating the
rooting of a new plant cutting?
A. To determine if the cutting has started to photosynthesize
B. To check for callus formation at the wound site
C. To assess the strength of the root system without causing significant damage
D. To ensure the rooting medium has not become contaminated
Correct Answer: C. To assess the strength of the root system without causing significant damage
Rationale: The "tug test" is a gentle method to feel for resistance, indicating that roots have formed.
This is done in a propagation setting to avoid constantly pulling the cutting out of the medium, which
would disrupt the delicate new roots and potentially kill the plant. It is not a test for photosynthesis,
callus, or contamination. [Return to Study Guide]
10. In the management of turfgrass diseases, using a preventive fungicide application is most
appropriate for which type of disease?
A. A disease that is easily controlled by a curative application
B. A disease that is difficult to control after symptoms appear, like dollar spot
C. A disease caused by a virus
D. A disease that is seasonal and consistently predictable, like spring dead spot
EXAM COMPLETE EXAM QUESTIONS AND VERIFIED
ANSWERS | 2026–2027 LATEST UPDATE | GUARANTEED
PASS | DETAILED RATIONALES | FULL STUDY GUIDE | EXAM
PREP | PRACTICE TEST | CERTIFICATION PREPARATION
1. A homeowner reports that their tomato plants have developed dark, sunken lesions on the
stems near the soil line, with white to pinkish fungal growth appearing under wet conditions. The
plants are wilting despite adequate soil moisture. What is the most probable diagnosis?
A. Early blight
B. Septoria leaf spot
C. Southern blight
D. Fusarium wilt
Correct Answer: C. Southern blight
Rationale: Southern blight, caused by the fungus Sclerotium rolfsii, is characterized by stem lesions
near the soil line, wilting, and distinctive white to pinkish mycelial growth. Early blight (A) typically
shows concentric ring lesions on leaves, not stem-base rot. Septoria leaf spot (B) primarily affects
leaves with small, dark spots. Fusarium wilt (D) causes vascular discoloration and general yellowing
without the characteristic mycelial growth. [Return to Study Guide]
2. Which of the following cultural practices is the most effective, non-chemical strategy for
managing Japanese beetle (Popillia japonica) grubs in a home lawn?
A. Applying synthetic pyrethroids to the turf surface in early summer
B. Introducing beneficial nematodes (Heterorhabditis bacteriophora) in late summer
C. Decreasing mowing height to 1.5 inches to desiccate the soil
D. Applying a high-nitrogen fertilizer in early spring to encourage root growth
Correct Answer: B. Introducing beneficial nematodes (Heterorhabditis bacteriophora) in late
summer
Rationale: Beneficial nematodes are an effective biological control for grubs, as they actively seek out
and infect the larvae. Late summer (August-September) is the optimal time for application when
grubs are small and actively feeding. Option A is a chemical strategy, not a non-chemical one. Option
C could stress the lawn and is not directly effective against grubs. Option D does not control grubs
and may even exacerbate disease issues with excessive growth. [Return to Study Guide]
3. A client has a mature oak tree that is showing signs of dieback in the upper canopy. You notice
that the tree was planted too deeply several years ago, with mulch piled against the trunk. This
condition is most directly associated with which plant health problem?
A. Vascular wilt
B. Girdling roots
C. Phytophthora root rot
D. Bacterial leaf scorch
Correct Answer: B. Girdling roots
,Rationale: Deep planting and excessive mulch against the trunk create an environment that
encourages stem-girdling roots. These roots encircle the trunk's base, restricting the flow of water
and nutrients, leading to dieback. Vascular wilt (A) is caused by pathogens. Phytophthora root rot (C)
is a soil-borne disease often favored by poor drainage. Bacterial leaf scorch (D) is a systemic infection
causing marginal leaf necrosis. [Return to Study Guide]
4. According to Integrated Pest Management (IPM) principles, what is the first step a Master
Gardener should recommend when a client reports a pest problem?
A. Apply a broad-spectrum insecticide to prevent further damage
B. Remove and destroy all affected plant material immediately
C. Correctly identify the pest and assess the level of infestation
D. Implement a biological control agent, such as a predator insect
Correct Answer: C. Correctly identify the pest and assess the level of infestation
Rationale: Correct identification is the cornerstone of IPM. Without knowing what the pest is and if its
population has reached an economically or aesthetically damaging level (the action threshold), it is
impossible to select an effective and appropriate management strategy. Options A, B, and D are
actions that may be taken later but are not the first step. [Return to Study Guide]
5. Which of the following describes the primary characteristic that differentiates a true bulb from a
corm?
A. True bulbs have a basal plate, while corms do not.
B. True bulbs are composed of modified leaves (scales), while corms are a swollen stem base.
C. Corms produce offsets, while true bulbs produce bulblets.
D. True bulbs require a period of vernalization, while corms do not.
Correct Answer: B. True bulbs are composed of modified leaves (scales), while corms are a swollen
stem base.
Rationale: This is a fundamental taxonomic distinction. A true bulb, like a tulip or onion, has layers of
fleshy scales that are modified leaves. A corm, like a crocus or gladiolus, is a solid, swollen
underground stem. Both have basal plates and can produce offsets, so A and C are not differentiating
characteristics. The need for vernalization varies by species, not by the type of storage organ. [Return
to Study Guide]
6. A rose bush exhibits stunted growth, and the leaves have a distinctive, yellow-green mosaic
pattern. The plant is not responding to a balanced fertilizer application. Which of the following is
the most likely cause?
A. Rose rust
B. Black spot
C. Rose rosette disease
D. Downy mildew
Correct Answer: C. Rose rosette disease
Rationale: Rose rosette disease is a viral-like disease that causes rapid, elongated shoots, witches'
brooms, distorted foliage, and a yellow mosaic or mottling on leaves. It is often fatal. Rose rust (A)
produces orange pustules, black spot (B) produces circular black spots, and downy mildew (D) causes
purplish-red patches and downy growth on leaves, not a mosaic pattern. [Return to Study Guide]
, 7. A homeowner requests a list of "deer-resistant" plants for a woodland garden. Which of the
following criteria should be the primary basis for your recommendations?
A. General preference of deer as indicated in university extension guides
B. Plants with strong fragrances or prickly textures
C. A combination of these factors as deer preferences are highly regional and situational
D. Plants known to be toxic to deer, such as daffodils
Correct Answer: C. A combination of these factors as deer preferences are highly regional and
situational
Rationale: Deer feeding habits vary significantly by region, season, and the availability of other food
sources. No plant is truly "deer-proof." The most reliable recommendations are based on a
combination of local university extension data, known physical deterrents (fragrance, texture), and
toxicity, acknowledging that hungry deer will eat almost anything. This reflects the professional
understanding of deer management. [Return to Study Guide]
8. When interpreting a soil test report, you find that the pH is 7.8 and the iron (Fe) level is
adequate. A client's rhododendrons are showing interveinal chlorosis in the newest leaves. What is
the most likely problem?
A. An iron deficiency caused by low soil pH
B. An iron deficiency caused by high soil pH, locking up the available iron
C. A nitrogen deficiency due to the high pH
D. A magnesium deficiency caused by a pH imbalance
Correct Answer: B. An iron deficiency caused by high soil pH, locking up the available iron
Rationale: While the soil test reports adequate total iron, it is not available to the plant at a high pH.
Rhododendrons and other acid-loving plants require a low pH for iron uptake. The symptom of
interveinal chlorosis on new leaves is classic for iron chlorosis. The problem is not a lack of iron in the
soil but its unavailability due to the high pH. [Return to Study Guide]
9. What is the primary purpose of performing a "tug test" or "pull test" when evaluating the
rooting of a new plant cutting?
A. To determine if the cutting has started to photosynthesize
B. To check for callus formation at the wound site
C. To assess the strength of the root system without causing significant damage
D. To ensure the rooting medium has not become contaminated
Correct Answer: C. To assess the strength of the root system without causing significant damage
Rationale: The "tug test" is a gentle method to feel for resistance, indicating that roots have formed.
This is done in a propagation setting to avoid constantly pulling the cutting out of the medium, which
would disrupt the delicate new roots and potentially kill the plant. It is not a test for photosynthesis,
callus, or contamination. [Return to Study Guide]
10. In the management of turfgrass diseases, using a preventive fungicide application is most
appropriate for which type of disease?
A. A disease that is easily controlled by a curative application
B. A disease that is difficult to control after symptoms appear, like dollar spot
C. A disease caused by a virus
D. A disease that is seasonal and consistently predictable, like spring dead spot
