In a replicated field trial comparing two insecticides for aphid control, the
researcher observes a significant treatment effect but also notes high variability
in untreated plots. Which design element most directly addresses this issue to
strengthen causal inference?
A. Increasing the number of untreated control plots
B. Using a randomized complete block design with blocking by initial
aphid density
C. Applying a pre-treatment insecticide to all plots
D. Reducing the plot size to minimize edge effects
Correct Answer: B - Using a randomized complete block design
with blocking by initial aphid density
RATIONALE
Blocking by initial aphid density accounts for pre-existing variability,
reducing experimental error and strengthening causal inference.
Increasing control plots (A) may not reduce variability; pre-treatment
(C) confounds results; smaller plots (D) may increase edge effects.
Question 2
A researcher applies a soil insecticide in a demonstration plot adjacent to a
wetland. Which pesticide characteristic most increases the risk of off-site
movement via runoff?
A. High soil organic carbon sorption coefficient (Koc)
B. Low water solubility
C. High persistence and moderate water solubility
D. High vapor pressure
Correct Answer: C - High persistence and moderate water
solubility
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, RATIONALE
High persistence allows the pesticide to remain available for runoff,
while moderate water solubility facilitates transport in runoff water.
High Koc (A) and low solubility (B) reduce runoff risk; high vapor
pressure (D) increases volatilization, not runoff.
Question 3
Which of the following best describes the primary purpose of a 'demonstration'
trial as opposed to a 'research' trial in Category 10 pest control?
A. Demonstration trials are conducted under controlled laboratory
conditions to test hypotheses.
B. Demonstration trials are designed to show practical efficacy to
stakeholders, often without replication.
C. Research trials are always larger in scale and use commercial
equipment.
D. Demonstration trials require EPA experimental use permits, while
research trials do not.
Correct Answer: B - Demonstration trials are designed to show
practical efficacy to stakeholders, often without replication.
RATIONALE
Demonstration trials aim to visually show pest control results to
growers or the public, typically with limited replication. Research
trials (A, C) focus on hypothesis testing and statistical rigor. Both may
require permits (D), so that is not a distinguishing factor.
Question 4
A graduate student plans to test a new biopesticide on a small plot. The
pesticide is not registered for the target pest. What is the most appropriate
regulatory step before application?
A. Apply for an Experimental Use Permit (EUP) from EPA.
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, B. Obtain a Virginia pesticide dealer license.
C. Notify the local extension agent only.
D. Use the pesticide under a Section 18 emergency exemption.
Correct Answer: A - Apply for an Experimental Use Permit
(EUP) from EPA.
RATIONALE
An EUP is required for experimental use of unregistered pesticides or
unregistered uses. A dealer license (B) is for sales; notifying extension
(C) is insufficient; Section 18 (D) is for emergency exemptions, not
routine research.
Question 5
In resistance management, which strategy is most effective for delaying
resistance to a single-site insecticide?
A. Applying the insecticide at the highest labeled rate every week
B. Rotating with insecticides from different mode-of-action groups
C. Using the same insecticide but increasing frequency
D. Mixing the insecticide with a synergist that inhibits detoxification
enzymes
Correct Answer: B - Rotating with insecticides from different
mode-of-action groups
RATIONALE
Rotating modes of action reduces selection pressure for resistance to
any one chemical. High rates/frequency (A, C) accelerate resistance;
synergists (D) may help but do not address the core issue of repeated
exposure to the same mode of action.
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