, Question 1
A nursery manager observes that a population of two-spotted spider mites has
developed resistance to abamectin after three consecutive applications. Which
strategy best delays resistance while maintaining effective control?
A. Switch to a different mode of action (IRAC group) with a short
residual, such as bifenazate.
B. Increase the application rate of abamectin and add a surfactant.
C. Rotate abamectin with another GABA-gated chloride channel blocker
like fipronil.
D. Apply abamectin more frequently at lower rates to reduce selection
pressure.
Correct Answer: A - Switch to a different mode of action (IRAC
group) with a short residual, such as bifenazate.
RATIONALE
Rotating to a different IRAC group (e.g., bifenazate, group 25) is the
cornerstone of resistance management. Increasing rate or frequency of
the same MoA intensifies selection, and using another GABA blocker
(fipronil) does not diversify MoA.
Question 2
Which factor most directly increases the risk of groundwater contamination
from a soil-applied pesticide in an ornamental nursery?
A. High organic matter content in the soil
B. Shallow water table and sandy soil
C. Presence of a claypan layer below the root zone
D. Alkaline soil pH greater than 7.5
Correct Answer: B - Shallow water table and sandy soil
Page 2
, RATIONALE
Sandy soils have low sorption capacity and high permeability, while a
shallow water table reduces the distance to groundwater. High organic
matter and claypan layers reduce leaching; pH affects degradation but
is less directly linked to groundwater contamination.
Question 3
A landscaper needs to control bagworms on arborvitae. The larvae are in early
instars and the plants are near a pond. Which insecticide is both effective and
least likely to harm aquatic organisms?
A. Carbaryl
B. Bacillus thuringiensis var. kurstaki
C. Permethrin
D. Malathion
Correct Answer: B - Bacillus thuringiensis var. kurstaki
RATIONALE
Bacillus thuringiensis var. kurstaki is highly specific to lepidopteran
larvae and has minimal aquatic toxicity. Carbaryl, permethrin, and
malathion are broad-spectrum and toxic to aquatic invertebrates and
fish.
Question 4
Which statement correctly describes the legal requirement for pesticide
applicators in Virginia regarding the posting of treated ornamental sites?
A. Posting is required only for turf applications on school grounds.
B. Posting is required for all outdoor ornamental applications on
residential properties.
C. Posting is required for applications on non-residential properties if the
label requires it.
D. Posting is never required for ornamental pest control.
Page 3
, Correct Answer: C - Posting is required for applications on
non-residential properties if the label requires it.
RATIONALE
Virginia regulations require posting when the pesticide label mandates
it, typically for non-residential sites. Residential posting may be
required by local ordinances but is not a universal state requirement.
Option C accurately reflects the conditional legal standard.
Question 5
A plant diagnostician observes white, powdery growth on the upper leaf
surface of begonias, along with distortion of new growth. Which
environmental condition most favors the disease?
A. High humidity and moderate temperatures (60-80°F)
B. Low humidity and high temperatures (>90°F)
C. Free water on leaves for extended periods
D. Cool temperatures (<50°F) and dry conditions
Correct Answer: A - High humidity and moderate temperatures
(60-80°F)
RATIONALE
Powdery mildew fungi thrive in high humidity but do not require free
water; moderate temperatures favor infection. Free water and extreme
temperatures are less conducive. Distortion of new growth is a
common symptom.
Question 6
Which of the following best explains why repeated applications of a single-site
fungicide can lead to a rapid buildup of resistant pathogen populations?
A. Single-site fungicides are more prone to leaching.
B. Fungal pathogens have short life cycles and high reproductive rates.
C. Single-site fungicides induce mutations in the target gene.
Page 4
A nursery manager observes that a population of two-spotted spider mites has
developed resistance to abamectin after three consecutive applications. Which
strategy best delays resistance while maintaining effective control?
A. Switch to a different mode of action (IRAC group) with a short
residual, such as bifenazate.
B. Increase the application rate of abamectin and add a surfactant.
C. Rotate abamectin with another GABA-gated chloride channel blocker
like fipronil.
D. Apply abamectin more frequently at lower rates to reduce selection
pressure.
Correct Answer: A - Switch to a different mode of action (IRAC
group) with a short residual, such as bifenazate.
RATIONALE
Rotating to a different IRAC group (e.g., bifenazate, group 25) is the
cornerstone of resistance management. Increasing rate or frequency of
the same MoA intensifies selection, and using another GABA blocker
(fipronil) does not diversify MoA.
Question 2
Which factor most directly increases the risk of groundwater contamination
from a soil-applied pesticide in an ornamental nursery?
A. High organic matter content in the soil
B. Shallow water table and sandy soil
C. Presence of a claypan layer below the root zone
D. Alkaline soil pH greater than 7.5
Correct Answer: B - Shallow water table and sandy soil
Page 2
, RATIONALE
Sandy soils have low sorption capacity and high permeability, while a
shallow water table reduces the distance to groundwater. High organic
matter and claypan layers reduce leaching; pH affects degradation but
is less directly linked to groundwater contamination.
Question 3
A landscaper needs to control bagworms on arborvitae. The larvae are in early
instars and the plants are near a pond. Which insecticide is both effective and
least likely to harm aquatic organisms?
A. Carbaryl
B. Bacillus thuringiensis var. kurstaki
C. Permethrin
D. Malathion
Correct Answer: B - Bacillus thuringiensis var. kurstaki
RATIONALE
Bacillus thuringiensis var. kurstaki is highly specific to lepidopteran
larvae and has minimal aquatic toxicity. Carbaryl, permethrin, and
malathion are broad-spectrum and toxic to aquatic invertebrates and
fish.
Question 4
Which statement correctly describes the legal requirement for pesticide
applicators in Virginia regarding the posting of treated ornamental sites?
A. Posting is required only for turf applications on school grounds.
B. Posting is required for all outdoor ornamental applications on
residential properties.
C. Posting is required for applications on non-residential properties if the
label requires it.
D. Posting is never required for ornamental pest control.
Page 3
, Correct Answer: C - Posting is required for applications on
non-residential properties if the label requires it.
RATIONALE
Virginia regulations require posting when the pesticide label mandates
it, typically for non-residential sites. Residential posting may be
required by local ordinances but is not a universal state requirement.
Option C accurately reflects the conditional legal standard.
Question 5
A plant diagnostician observes white, powdery growth on the upper leaf
surface of begonias, along with distortion of new growth. Which
environmental condition most favors the disease?
A. High humidity and moderate temperatures (60-80°F)
B. Low humidity and high temperatures (>90°F)
C. Free water on leaves for extended periods
D. Cool temperatures (<50°F) and dry conditions
Correct Answer: A - High humidity and moderate temperatures
(60-80°F)
RATIONALE
Powdery mildew fungi thrive in high humidity but do not require free
water; moderate temperatures favor infection. Free water and extreme
temperatures are less conducive. Distortion of new growth is a
common symptom.
Question 6
Which of the following best explains why repeated applications of a single-site
fungicide can lead to a rapid buildup of resistant pathogen populations?
A. Single-site fungicides are more prone to leaching.
B. Fungal pathogens have short life cycles and high reproductive rates.
C. Single-site fungicides induce mutations in the target gene.
Page 4
