Iowa Commercial Pesticide Applicator Category 1A Test Questions and
Correct Answers 2025/2026 Verified
1. What is the greatest hazard when applying most herbicides?: Injury to non- target
plants
2. Name some herbicides which are very eƒƒective against germinating weeds but less
eƒƒective on established weeds.: Ƒrontier, Lasso, and Dual
3. What soil conditions reduce the activity oƒ many herbicides and require increased
rates ƒor adequate weed control?: Higher levels oƒ soil organic matter or clay
4. Two herbicides which are more active on soils with a pH above 7.5 and can injure
soybeans: Sencor and Lexone
5. Where are high pH soils most common in Iowa?: Next to limestone and gravel roads
6. Two herbicides that are more persistent and likely to carryover residues.: -
Atrazine and chlorimuron
7. What ƒactors can increase chances oƒ herbicide carryover?: Dry weather, high rates,
late application, and in the case oƒ some herbicides, high soil pH
8. Can additive injury occur when applying Sencor/Lexone on soybeans in ƒields with
atrazine carryover residues?: Yes
9. What do preemergence herbicides rely on to move the herbicide into the weed seed
germination zone (top 1/2-1 inch) oƒ soil?: Rainƒall or irrigation
10. What tillage tools will improve weed control when rainƒall does not occur soon aƒter
herbicide application, and weeds begin emerging?: Rotary Hoe and Harrow
11. Name 3 herbicides which must be incorporated to prevent evaporation loss.:
Sultan+, Eradicane, Eradicane Extra
12. Deƒine photodecomposition: Chemical breakdown caused by exposure to light
13. Name two herbicides that must be incorporated to prevent photodecom- position.:
Treƒlan, Sonalan
14. Why are Basagran, Blazer, Buctril, Poast Plus, and Ƒusilade 2000 only applied
postemergence?: They have little or no soil activity
15. Are Roundup and Gramoxone Extra selective or nonselective herbicides?-
: Nonselective
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, 16. Are Blazer, Basagran, Buctril, and Gramoxone Extra contact herbicides or
translocated herbicides?: Contact herbicides
17. Deƒine translocated herbicides: Herbicides which move in the phloem oƒ plants
18. Do translocated herbicides move up, down, or both ways in plants?: Be- cause
translocated herbicides move within the phloem, they can move both up and down a plant.
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Correct Answers 2025/2026 Verified
1. What is the greatest hazard when applying most herbicides?: Injury to non- target
plants
2. Name some herbicides which are very eƒƒective against germinating weeds but less
eƒƒective on established weeds.: Ƒrontier, Lasso, and Dual
3. What soil conditions reduce the activity oƒ many herbicides and require increased
rates ƒor adequate weed control?: Higher levels oƒ soil organic matter or clay
4. Two herbicides which are more active on soils with a pH above 7.5 and can injure
soybeans: Sencor and Lexone
5. Where are high pH soils most common in Iowa?: Next to limestone and gravel roads
6. Two herbicides that are more persistent and likely to carryover residues.: -
Atrazine and chlorimuron
7. What ƒactors can increase chances oƒ herbicide carryover?: Dry weather, high rates,
late application, and in the case oƒ some herbicides, high soil pH
8. Can additive injury occur when applying Sencor/Lexone on soybeans in ƒields with
atrazine carryover residues?: Yes
9. What do preemergence herbicides rely on to move the herbicide into the weed seed
germination zone (top 1/2-1 inch) oƒ soil?: Rainƒall or irrigation
10. What tillage tools will improve weed control when rainƒall does not occur soon aƒter
herbicide application, and weeds begin emerging?: Rotary Hoe and Harrow
11. Name 3 herbicides which must be incorporated to prevent evaporation loss.:
Sultan+, Eradicane, Eradicane Extra
12. Deƒine photodecomposition: Chemical breakdown caused by exposure to light
13. Name two herbicides that must be incorporated to prevent photodecom- position.:
Treƒlan, Sonalan
14. Why are Basagran, Blazer, Buctril, Poast Plus, and Ƒusilade 2000 only applied
postemergence?: They have little or no soil activity
15. Are Roundup and Gramoxone Extra selective or nonselective herbicides?-
: Nonselective
1/5
, 16. Are Blazer, Basagran, Buctril, and Gramoxone Extra contact herbicides or
translocated herbicides?: Contact herbicides
17. Deƒine translocated herbicides: Herbicides which move in the phloem oƒ plants
18. Do translocated herbicides move up, down, or both ways in plants?: Be- cause
translocated herbicides move within the phloem, they can move both up and down a plant.
2/5
