IOWA COMMERCIAL PESTICIDE APPLICATORS EXAM 2025/2026
QUESTIONS WITH ANSWERS GRADED A+
✔✔C5:Differentiate between the twelve aquatic herbicides- names, what they control,
best use scenarios, and limitations - 1, 2, & 3 - ✔✔1) 2,4-D (Navigate, Weedar 64,
Weedone 638, and others) not as effective on underwater plants as it is on terrestrial
plants, primarily limited to treatment of plants with aerial parts (rooted floating plants &
cattails, bulrushes, & many broadleaf species), liquid ester formulations toxic to fish; 2)
Bispyribac-sodium (Tradewind) used in controlling submersed, floating & emergent
weeds in water bodies with limited or no outflow, can be applied both as a surface
application and subsurface application, no restrictions for drinking or swimming or
fishing but should not be used for irrigating or ornamental crops until less than 1ppb; 3)
Carfentrazone (Stingray) limited use for control of floating and emergent weeds,
generally used in combination with another aquatic herbicide for foliar application
because it is very short-lived, no restrictions on swimming or fishing but should not be
used for drinking or livestock for one day or irrigation for 14 days (when more than 20%
of surface is treated)
✔✔C5:Differentiate between the twelve aquatic herbicides - 4, 5, & 6 - ✔✔4) Diquat
(Reward, Weedtrine D, and others) has been a standard for submersed flowering weed
control (with Aquathol) also some activity on duckweed & cattails), should not be
applied to turbid water (easily adsorbed), often used in a tank mix with copper chelates
and Aquathol; 5) Endothal (Aquathol, Cascade, Hydrothol, Teton), two salts - amine salt
[Cascade, Hydrothol 191] and potassium salt [Aquathol, Teton] Hydrothol controls both
algae and submersed flowering plants while Aquathol is used strictly for submersed
flowering plants (and pondweeds that are rooted floaters), both compounds are contact
materials and only kill plant tissues they contact, control is usually rapid with drop down
within a week, Fish are extremely sensitive to Hydrothol but not as sensitive to
Aquathol, both salts are subject to rapid microbial degradation (persist for only 15 to 16
days) restrictions: 7 to 25 days for irrigation on food crops, domestic uses, & livestock
watering; 6) Flumioxazin (Clipper) broad-spectrum contact herbicide used to control
submersed, floating & emergent weeds, should have limited or no outflow (no flowing
water), can be applied as a surface & subsurface application, is most effective against
early-growth weeds, no restrictions for swimming or fishing but should not be used for
irrigation for at least 5 days
✔✔C5:Differentiate between the twelve aquatic herbicides - 7, 8, & 9 - ✔✔7) Fluridone
(Avast, Sonar, Whitecap) broad-spectrum systemic, good for complete eradication of
vegetation (primarily for submersed flowering plants, some duckweed, partial
emergents, no algae); only registered herbicide that can control weeds for more than
one year (should be applied early, works slow, dissolved O2 fairly safe), can't be used
as a spot treatment, plants can uptake chemical shoreline trees can be damaged; no
restrictions on swimming or fishing, should not be used within a quarter mile of potable
intake, don't use for irrigation for 7 to 30 days after, depending on crop; 8) Glyphosate
(Aquapro, Rodeo, Shore-Klear; others) the primary herbicide for the control of rooted
floating and emergent plants, spray aerial parts, won't work on submersed plants, will
, provide reasonably long-term control of perennial plants (spatterdock, cattail, willow);
needs surfactant, rapidly inactivated by soil particles, in general slow acting; only
restriction may not be used within a half mile of a potable water intake; 9) Imazamox
(Clearcast) a systemic herbicide that is effective in controlling many floating and
emergent aquatic weeds as well as some submergent, surfactant may be used; no
restrictions for livestock watering, swimming, fishing, domestic use, but there are
specific restrictions for irrigation and near potable water intakes
✔✔C5:Differentiate between the twelve aquatic herbicides - 10, 11, & 12 - ✔✔10)
Imazapyr (Habitat, Lineage, Polaris) a systemic herbicide for the control of most
emerged and floating plants in and around water; should use a surfactant, slow acting,
may not show symptoms or die for several days or weeks; no restrictions for
recreational purposes or consumption by livestock, don't use for irrigation until 120 days
after application, should not be applied within a half mile upstream of a potable water
intake (unless intake turned off for a minimum of 48 hours after application; 11)
Penoxsulam (Galleon) a systemic herbicide that can be used to selectively control
certain submersed, floating, and emergent vegetation, control is highly dependent on
contact time, for some weeds or circumstances, split or multiple applications are
necessary for optimum performance; no restrictions for potable use or by livestock,
pets, or other animals, or for swimming or fishing, check label for limitations on irrigation
use;
12) Triclopyr (Renovate) systemic herbicide used to control certain submersed and
emergent plants in and adjacent to aquatic sites with minimal outflow, apply when plants
are actively growing and leaves are fully developed; use a surfactant, for submersed
plants use a drop hose or add a sinking agent, no restrictions for recreational purposes
(swimming and fishing) or livestock consumption, don't use for irrigation for 120 days.
✔✔C5:Describe the potential toxicity that aquatic herbicides can have on nontarget
species such as invertebrates, fish, and other vertebrate animals - ✔✔There can be
direct and indirect effects, Invertebrates: decaying plants may reduce the dissolved
oxygen, destruction of habitat, there's usually fewer species but more individuals, don't
over apply or apply incorrectly, high reproductive potential helps inverts bounce back;
Vertebrates other than fish: probably few problems if used at recommended rates and
applied properly, hogs can be adversely affected if they drink water that has been
treated with rotenone; Fish: most herbicides are nontoxic to fish when applied at
recommended rates, several can be toxic, the two chemicals most toxic to fish are
Hydrothol 191 and 2,4-D ester liquid, largemouth bass and bluegill are less sensitive to
copper than trout, which can be killed at very low concentrations, copper applied directly
over nesting fish may cause some mortality of eggs or fingerlings; adjuvants,
surfactants, and wetting agents can cause problems.
✔✔C5:Describe bioaccumulation and its relationship to aquatic herbicides -
✔✔Bioaccumulation is the accumulation of a pesticide against a gradient, the presence
of small amounts of aquatic herbicide in fish is a normal event, related to the
concentration of residue in water, if bioaccumulation was occurring fish would contain
QUESTIONS WITH ANSWERS GRADED A+
✔✔C5:Differentiate between the twelve aquatic herbicides- names, what they control,
best use scenarios, and limitations - 1, 2, & 3 - ✔✔1) 2,4-D (Navigate, Weedar 64,
Weedone 638, and others) not as effective on underwater plants as it is on terrestrial
plants, primarily limited to treatment of plants with aerial parts (rooted floating plants &
cattails, bulrushes, & many broadleaf species), liquid ester formulations toxic to fish; 2)
Bispyribac-sodium (Tradewind) used in controlling submersed, floating & emergent
weeds in water bodies with limited or no outflow, can be applied both as a surface
application and subsurface application, no restrictions for drinking or swimming or
fishing but should not be used for irrigating or ornamental crops until less than 1ppb; 3)
Carfentrazone (Stingray) limited use for control of floating and emergent weeds,
generally used in combination with another aquatic herbicide for foliar application
because it is very short-lived, no restrictions on swimming or fishing but should not be
used for drinking or livestock for one day or irrigation for 14 days (when more than 20%
of surface is treated)
✔✔C5:Differentiate between the twelve aquatic herbicides - 4, 5, & 6 - ✔✔4) Diquat
(Reward, Weedtrine D, and others) has been a standard for submersed flowering weed
control (with Aquathol) also some activity on duckweed & cattails), should not be
applied to turbid water (easily adsorbed), often used in a tank mix with copper chelates
and Aquathol; 5) Endothal (Aquathol, Cascade, Hydrothol, Teton), two salts - amine salt
[Cascade, Hydrothol 191] and potassium salt [Aquathol, Teton] Hydrothol controls both
algae and submersed flowering plants while Aquathol is used strictly for submersed
flowering plants (and pondweeds that are rooted floaters), both compounds are contact
materials and only kill plant tissues they contact, control is usually rapid with drop down
within a week, Fish are extremely sensitive to Hydrothol but not as sensitive to
Aquathol, both salts are subject to rapid microbial degradation (persist for only 15 to 16
days) restrictions: 7 to 25 days for irrigation on food crops, domestic uses, & livestock
watering; 6) Flumioxazin (Clipper) broad-spectrum contact herbicide used to control
submersed, floating & emergent weeds, should have limited or no outflow (no flowing
water), can be applied as a surface & subsurface application, is most effective against
early-growth weeds, no restrictions for swimming or fishing but should not be used for
irrigation for at least 5 days
✔✔C5:Differentiate between the twelve aquatic herbicides - 7, 8, & 9 - ✔✔7) Fluridone
(Avast, Sonar, Whitecap) broad-spectrum systemic, good for complete eradication of
vegetation (primarily for submersed flowering plants, some duckweed, partial
emergents, no algae); only registered herbicide that can control weeds for more than
one year (should be applied early, works slow, dissolved O2 fairly safe), can't be used
as a spot treatment, plants can uptake chemical shoreline trees can be damaged; no
restrictions on swimming or fishing, should not be used within a quarter mile of potable
intake, don't use for irrigation for 7 to 30 days after, depending on crop; 8) Glyphosate
(Aquapro, Rodeo, Shore-Klear; others) the primary herbicide for the control of rooted
floating and emergent plants, spray aerial parts, won't work on submersed plants, will
, provide reasonably long-term control of perennial plants (spatterdock, cattail, willow);
needs surfactant, rapidly inactivated by soil particles, in general slow acting; only
restriction may not be used within a half mile of a potable water intake; 9) Imazamox
(Clearcast) a systemic herbicide that is effective in controlling many floating and
emergent aquatic weeds as well as some submergent, surfactant may be used; no
restrictions for livestock watering, swimming, fishing, domestic use, but there are
specific restrictions for irrigation and near potable water intakes
✔✔C5:Differentiate between the twelve aquatic herbicides - 10, 11, & 12 - ✔✔10)
Imazapyr (Habitat, Lineage, Polaris) a systemic herbicide for the control of most
emerged and floating plants in and around water; should use a surfactant, slow acting,
may not show symptoms or die for several days or weeks; no restrictions for
recreational purposes or consumption by livestock, don't use for irrigation until 120 days
after application, should not be applied within a half mile upstream of a potable water
intake (unless intake turned off for a minimum of 48 hours after application; 11)
Penoxsulam (Galleon) a systemic herbicide that can be used to selectively control
certain submersed, floating, and emergent vegetation, control is highly dependent on
contact time, for some weeds or circumstances, split or multiple applications are
necessary for optimum performance; no restrictions for potable use or by livestock,
pets, or other animals, or for swimming or fishing, check label for limitations on irrigation
use;
12) Triclopyr (Renovate) systemic herbicide used to control certain submersed and
emergent plants in and adjacent to aquatic sites with minimal outflow, apply when plants
are actively growing and leaves are fully developed; use a surfactant, for submersed
plants use a drop hose or add a sinking agent, no restrictions for recreational purposes
(swimming and fishing) or livestock consumption, don't use for irrigation for 120 days.
✔✔C5:Describe the potential toxicity that aquatic herbicides can have on nontarget
species such as invertebrates, fish, and other vertebrate animals - ✔✔There can be
direct and indirect effects, Invertebrates: decaying plants may reduce the dissolved
oxygen, destruction of habitat, there's usually fewer species but more individuals, don't
over apply or apply incorrectly, high reproductive potential helps inverts bounce back;
Vertebrates other than fish: probably few problems if used at recommended rates and
applied properly, hogs can be adversely affected if they drink water that has been
treated with rotenone; Fish: most herbicides are nontoxic to fish when applied at
recommended rates, several can be toxic, the two chemicals most toxic to fish are
Hydrothol 191 and 2,4-D ester liquid, largemouth bass and bluegill are less sensitive to
copper than trout, which can be killed at very low concentrations, copper applied directly
over nesting fish may cause some mortality of eggs or fingerlings; adjuvants,
surfactants, and wetting agents can cause problems.
✔✔C5:Describe bioaccumulation and its relationship to aquatic herbicides -
✔✔Bioaccumulation is the accumulation of a pesticide against a gradient, the presence
of small amounts of aquatic herbicide in fish is a normal event, related to the
concentration of residue in water, if bioaccumulation was occurring fish would contain
