IOWA HERBICIDE RIGHT OF WAY CATEGORY 6
EXAM STUDY GUIDE 2026 QUESTIONS WITH
SOLUTIONS GRADED A+
◉ Which procedures will help reduce herbicide drift?
A. Increasing spray pressure
B. Reducing spray pressure
C. Hanging nozzles to a type which emits larger droplets
D. Reducing height of boom
E. Both B and C. Answer: Both B and C
◉ Phenoxy herbicides are widely used along roadsides because:
A. They are effective on a wide variety of broadleaf and woody species
B. They rarely damage plants in adjacent areas
C. They are high in human toxicity
D. They do not damage grasses
E. Both A and D. Answer: They do not damage grasses
◉ Which of the following nonselective herbicides has the longest period
of control, when used at a given site:
A. Bromacil
,B. Dichlobenil
C. Prometon
D. Tebuthiuron. Answer: Dichlobenil
◉ When is the best time to treat many perennials developing from an
established root system? Answer: During early flowering
◉ In order to avoid injury to nearby desirable trees; persistent,
nonselective herbicides such as Hyvar should be applied:
A. Only in the fall
B. Outside the drip line of the desirable trees
C. At least 10 feet from the desirable trees
D. Outside an area equal to twice the height of the desirable trees
E. A minimum of 1/2 mile from the desirable trees. Answer: Outside an
area equal to twice the height of the desirable trees
◉ Basal bark treatment is not recommended for wood species larger
than 6" in diameter because:
A. The bark prevents penetration of the herbicide and reduces
effectiveness
B. The cost is prohibitive
C. There is a high risk of drift
D. None of the above. Answer: The bark prevents penetration of the
herbicide and reduces effectiveness
, ◉ A major disadvantage of the phenoxy-herbicides is:
A. They are non-selective herbicides
B. They can damage desirable plants at very low rates, making them
susceptible to drift damage
C. They are highly toxic to wildlife
D. They persist in the soil for several years. Answer: They can damage
desirable plants at very low rates, making them susceptible to drift
damage
◉ Krenite is different from most brush herbicides because:
A. It can be applied either to the foliage or the soil
B. Little effect is seen the year of application
C. Both A and B
D. None of the above. Answer: Little effect is seen the year of
application
◉ Which of the following formulations do not dissolve in water?
A. Wettable powders
B. Soluble powders
C. Emulsifiable concentrate
D. All of the above dissolve in water. Answer: Wettable powders
EXAM STUDY GUIDE 2026 QUESTIONS WITH
SOLUTIONS GRADED A+
◉ Which procedures will help reduce herbicide drift?
A. Increasing spray pressure
B. Reducing spray pressure
C. Hanging nozzles to a type which emits larger droplets
D. Reducing height of boom
E. Both B and C. Answer: Both B and C
◉ Phenoxy herbicides are widely used along roadsides because:
A. They are effective on a wide variety of broadleaf and woody species
B. They rarely damage plants in adjacent areas
C. They are high in human toxicity
D. They do not damage grasses
E. Both A and D. Answer: They do not damage grasses
◉ Which of the following nonselective herbicides has the longest period
of control, when used at a given site:
A. Bromacil
,B. Dichlobenil
C. Prometon
D. Tebuthiuron. Answer: Dichlobenil
◉ When is the best time to treat many perennials developing from an
established root system? Answer: During early flowering
◉ In order to avoid injury to nearby desirable trees; persistent,
nonselective herbicides such as Hyvar should be applied:
A. Only in the fall
B. Outside the drip line of the desirable trees
C. At least 10 feet from the desirable trees
D. Outside an area equal to twice the height of the desirable trees
E. A minimum of 1/2 mile from the desirable trees. Answer: Outside an
area equal to twice the height of the desirable trees
◉ Basal bark treatment is not recommended for wood species larger
than 6" in diameter because:
A. The bark prevents penetration of the herbicide and reduces
effectiveness
B. The cost is prohibitive
C. There is a high risk of drift
D. None of the above. Answer: The bark prevents penetration of the
herbicide and reduces effectiveness
, ◉ A major disadvantage of the phenoxy-herbicides is:
A. They are non-selective herbicides
B. They can damage desirable plants at very low rates, making them
susceptible to drift damage
C. They are highly toxic to wildlife
D. They persist in the soil for several years. Answer: They can damage
desirable plants at very low rates, making them susceptible to drift
damage
◉ Krenite is different from most brush herbicides because:
A. It can be applied either to the foliage or the soil
B. Little effect is seen the year of application
C. Both A and B
D. None of the above. Answer: Little effect is seen the year of
application
◉ Which of the following formulations do not dissolve in water?
A. Wettable powders
B. Soluble powders
C. Emulsifiable concentrate
D. All of the above dissolve in water. Answer: Wettable powders
