IOWA COMMERCIAL PESTICIDE APPLICATOR
CATEGORY 1A ACTUAL EXAM PAPER 2026
QUESTIONS WITH ANSWERS GRADED A+
◉ Name some herbicides which are very effective against germinating
weeds but less effective on established weeds. Answer: Frontier, Lasso,
and Dual
◉ What soil conditions reduce the activity of many herbicides and
require increased rates for adequate weed control? Answer: Higher
levels of soil organic matter or clay
◉ Two herbicides which are more active on soils with a pH above 7.5
and can injure soybeans. Answer: Sencor and Lexone
◉ Where are high pH soils most common in Iowa? Answer: Next to
limestone and gravel roads
◉ Two herbicides that are more persistent and likely to carryover
residues. Answer: Atrazine and chlorimuron
, ◉ What factors can increase chances of herbicide carryover? Answer:
Dry weather, high rates, late application, and in the case of some
herbicides, high soil pH
◉ Can additive injury occur when applying Sencor/Lexone on soybeans
in fields with atrazine carryover residues? Answer: Yes
◉ What do preemergence herbicides rely on to move the herbicide into
the weed seed germination zone (top 1/2-1 inch) of soil? Answer:
Rainfall or irrigation
◉ What tillage tools will improve weed control when rainfall does not
occur soon after herbicide application, and weeds begin emerging?
Answer: Rotary Hoe and Harrow
◉ Name 3 herbicides which must be incorporated to prevent evaporation
loss. Answer: Sultan+, Eradicane, Eradicane Extra
◉ Define photodecomposition. Answer: Chemical breakdown caused by
exposure to light
◉ Name two herbicides that must be incorporated to prevent
photodecomposition. Answer: Treflan, Sonalan
CATEGORY 1A ACTUAL EXAM PAPER 2026
QUESTIONS WITH ANSWERS GRADED A+
◉ Name some herbicides which are very effective against germinating
weeds but less effective on established weeds. Answer: Frontier, Lasso,
and Dual
◉ What soil conditions reduce the activity of many herbicides and
require increased rates for adequate weed control? Answer: Higher
levels of soil organic matter or clay
◉ Two herbicides which are more active on soils with a pH above 7.5
and can injure soybeans. Answer: Sencor and Lexone
◉ Where are high pH soils most common in Iowa? Answer: Next to
limestone and gravel roads
◉ Two herbicides that are more persistent and likely to carryover
residues. Answer: Atrazine and chlorimuron
, ◉ What factors can increase chances of herbicide carryover? Answer:
Dry weather, high rates, late application, and in the case of some
herbicides, high soil pH
◉ Can additive injury occur when applying Sencor/Lexone on soybeans
in fields with atrazine carryover residues? Answer: Yes
◉ What do preemergence herbicides rely on to move the herbicide into
the weed seed germination zone (top 1/2-1 inch) of soil? Answer:
Rainfall or irrigation
◉ What tillage tools will improve weed control when rainfall does not
occur soon after herbicide application, and weeds begin emerging?
Answer: Rotary Hoe and Harrow
◉ Name 3 herbicides which must be incorporated to prevent evaporation
loss. Answer: Sultan+, Eradicane, Eradicane Extra
◉ Define photodecomposition. Answer: Chemical breakdown caused by
exposure to light
◉ Name two herbicides that must be incorporated to prevent
photodecomposition. Answer: Treflan, Sonalan
