IOWA APPLICATOR 11F EXAMINATION TEST
PAPER 2026 QUESTIONS WITH CORRECT
ANSWERS
● 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
PAPER 2026 QUESTIONS WITH CORRECT
ANSWERS
● 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
