Iowa Commercial Pesticide Applicator
Category 1A
What is the greatest hazard when applying most herbicides? - Answer-Injury to nontarget plants
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
Why are Basagran, Blazer, Buctril, Poast Plus, and Fusilade 2000 only applied postemergence? - Answer-
They have little or no soil activity
Are Roundup and Gramoxone Extra selective or nonselective herbicides? - Answer-Nonselective
Are Blazer, Basagran, Buctril, and Gramoxone Extra contact herbicides or translocated herbicides? -
Answer-Contact herbicides
Define translocated herbicides - Answer-Herbicides which move in the phloem of plants
Do translocated herbicides move up, down, or both ways in plants? - Answer-Because translocated
herbicides move within the phloem, they can move both up and down a plant.
Are Roundup, 2,4-D, Fusilade 2000, Poast Plus, Clarity, and Banvil contact herbicides or translocted
herbicides? - Answer-Translocated herbicides
Category 1A
What is the greatest hazard when applying most herbicides? - Answer-Injury to nontarget plants
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
Why are Basagran, Blazer, Buctril, Poast Plus, and Fusilade 2000 only applied postemergence? - Answer-
They have little or no soil activity
Are Roundup and Gramoxone Extra selective or nonselective herbicides? - Answer-Nonselective
Are Blazer, Basagran, Buctril, and Gramoxone Extra contact herbicides or translocated herbicides? -
Answer-Contact herbicides
Define translocated herbicides - Answer-Herbicides which move in the phloem of plants
Do translocated herbicides move up, down, or both ways in plants? - Answer-Because translocated
herbicides move within the phloem, they can move both up and down a plant.
Are Roundup, 2,4-D, Fusilade 2000, Poast Plus, Clarity, and Banvil contact herbicides or translocted
herbicides? - Answer-Translocated herbicides
