PCA WEEDS EVALUATION EXAM 2026 QUESTIONS AND
SOLUTIONS SCORED A+
✔✔Describe how different types of vegetative propagules spread. - ✔✔When weeds
with vegetative propagules are fragmented, they can be spread to different fields or
parts of the field.
✔✔Describe how to map a field in relationship to weed management considerations. -
✔✔A field should be mapped to show what weeds are present, where the weeds are
present, how many weeds are present, and if there are any factors that will influence the
choice of management (water sources, sensitive sites, etc)
✔✔List information necessary to document a field's weed history - ✔✔Cropping history,
weeds prevalent, areas of high weed pressure
✔✔Absolute sampling - ✔✔Sampling to count every individual in a given area
✔✔Relative sampling - ✔✔Sampling to give an estimate of a total population by
sampling a proportion of a population in a given area
✔✔Random sampling patterns - ✔✔Every sample unit has an equal chance of selection
✔✔Stratified sampling patterns - ✔✔Partitions the habitat into subunits that may vary in
character, each subunit is then independently sampled
✔✔Systematic sampling patterns - ✔✔Each sample unit is chosen systematically from a
randomly selected starting point, such as every 50th plant or every 5 feet.
✔✔Identify essential times during which monitoring should be done for annual weeds -
✔✔Winter annuals during fall and winter, summer annuals during spring and summer
✔✔Identify essential times during which monitoring should be done for perennial weeds
- ✔✔At all times aware that some species are dormant during some seasons
✔✔Define biological control - ✔✔Use of organism or byproducts of living organisms to
suppress or kill pests
✔✔Describe and give an example of biological weed control using arthropods. - ✔✔-
Gall forming mite (Aceria chondrillae) on rush skeletonweed
-Tetranychus lintearius to control gorse
-Cinnabar moth (Tyria jacobaea) on tansy ragwort
-Ragwort seed fly (Botanophila seneciella) on tansy ragwort
-Ragwort flea beetle (Longistarsus jacobaeae) on tansy ragwort
-Klamath weed beetle (Chrysolina quadrigemina) on Klamath weed/St. Johnswort
,✔✔Describe and give an example of biological weed control using pathogens. - ✔✔-
Xanthamonas campestris pv. poannua to control unwanted grass species
-Phyllocoptes fructiphilus to kill multiflora rose
-Puccinia carduorum to control musk thistle
✔✔Describe and give an example of biological weed control using grazing animals. -
✔✔-Young stages of Yellow starthistle
-Grass carp
✔✔Identify the factors that would limit the use of biological control for weeds. -
✔✔Agent may attack non-target species, need species with high specificity to the target
weed, some agents may not exist for pest weeds, program is expensive and takes a
long time, unexpected factors such as environment or other predators of control agent
✔✔Describe the impact of seedbed preparation on weeds. - ✔✔Secondary tillage can
eliminate existing vegetation, apply fertilizer only where crops will be planted, remove
weeds as seedling crops as emerging, dislodging small weeds
✔✔Describe the impact of irrigation method on weeds. - ✔✔Different weeds will grow in
different irrigation methods (drip vs sprinkler vs flood). Managing the irrigation method to
provide adequate water to crop but reduce water to weeds (drip) can help reduce weed
populations
✔✔Describe the impact of irrigation timing on weeds. - ✔✔Preplant irrigation to remove
germinated weeds. Not irrigating after cultivation to allow weeds to dry out and die.
✔✔Describe the impact of time of seeding on weeds. - ✔✔Time seeding to outcompete
weeds to reduce weed pressure. Do not seed if weeds have emerged.
✔✔Describe the impact of soil nutrition on weeds. - ✔✔If soil nutrients are directed to
other spots than where the crops will uptake them, then the weeds will take up nutrients
and try to out-compete the crop being grown
✔✔Describe the impact of seed/plant spacing on weeds. - ✔✔If there is not enough
room for weeds to receive light or water, crops will out-compete weeds
✔✔Describe the impact of crop variety on weeds. - ✔✔Select for varieties that grow
quickly and develop canopies to shade out weeds to reduce susceptibility to weed
competition
✔✔Describe the impact of crop rotation on weeds. - ✔✔Allows for diverse methods to
manage weeds. Diversification of crops grown reduces and prevents the proliferation of
weed species acclimated to a monoculture
, ✔✔Describe the impact of pre-irrigation on weeds. - ✔✔Pre-irrigation can germinate
weed seed present and allow for easy cultivation before planting.
✔✔Describe the impact of synthetic mulches on weeds. - ✔✔Synthetic mulches such as
plastic can block sunlight from reaching weed seeds and preventing germination.
✔✔Describe the impact of organic mulches on weeds. - ✔✔Prevent germination of
weed seeds by keeping the shallow layer dry and giving the crop seed a head start
✔✔Describe the impact of sanitation methods on weeds. - ✔✔Sanitation of equipment
and irrigation water (screens) can reduce the amount of weed seed moved to different
parts of the field or different fields
✔✔List and describe common cultivation/tillage methods. - ✔✔Rolling cultivators, plant
hoe, V-sweep, cultivator knife, bed knives, shovels, vegetable knives, Alabama sweeps,
chisel plow sweeps, cultivator sweeps
✔✔Describe how weeds are affected by depth of tillage. - ✔✔Small weed seed won't
germinate if buried deep but larger seed will. Vegetative propagation will not re-emerge
if buried deep enough but it is difficult.
✔✔Describe how weeds are affected by timing of tillage. - ✔✔Dormant seed will be
more likely to not emerge if tillage is done during dormancy. Freshly emerged seed
should be tilled immediately to eliminate the weed. Vegetative propagation needs to be
tilled/removed before periods of rapid growth.
✔✔Describe how weeds are affected by no-tillage. - ✔✔No-tillage can promote weed
growth unless no-tillage is used with different methods of control such as mulches.
✔✔Describe cultivation techniques used in perennial crops. - ✔✔Mechanical cultivation
used for seedbed preparation and then hand cultivation used in rows after perennial
crop growth.
✔✔Compare the advantages and disadvantages of different cultivation methods. -
✔✔Hand cultivation: can be closer to the crop but expensive to pay for labor and room
for human error
Mechanical cultivation: inexpensive, but time consuming and often needs a crew to
hand cultivate behind the equipment
✔✔Identify the proper timing for cultivation and hand weeding. - ✔✔When weeds have
just emerged
SOLUTIONS SCORED A+
✔✔Describe how different types of vegetative propagules spread. - ✔✔When weeds
with vegetative propagules are fragmented, they can be spread to different fields or
parts of the field.
✔✔Describe how to map a field in relationship to weed management considerations. -
✔✔A field should be mapped to show what weeds are present, where the weeds are
present, how many weeds are present, and if there are any factors that will influence the
choice of management (water sources, sensitive sites, etc)
✔✔List information necessary to document a field's weed history - ✔✔Cropping history,
weeds prevalent, areas of high weed pressure
✔✔Absolute sampling - ✔✔Sampling to count every individual in a given area
✔✔Relative sampling - ✔✔Sampling to give an estimate of a total population by
sampling a proportion of a population in a given area
✔✔Random sampling patterns - ✔✔Every sample unit has an equal chance of selection
✔✔Stratified sampling patterns - ✔✔Partitions the habitat into subunits that may vary in
character, each subunit is then independently sampled
✔✔Systematic sampling patterns - ✔✔Each sample unit is chosen systematically from a
randomly selected starting point, such as every 50th plant or every 5 feet.
✔✔Identify essential times during which monitoring should be done for annual weeds -
✔✔Winter annuals during fall and winter, summer annuals during spring and summer
✔✔Identify essential times during which monitoring should be done for perennial weeds
- ✔✔At all times aware that some species are dormant during some seasons
✔✔Define biological control - ✔✔Use of organism or byproducts of living organisms to
suppress or kill pests
✔✔Describe and give an example of biological weed control using arthropods. - ✔✔-
Gall forming mite (Aceria chondrillae) on rush skeletonweed
-Tetranychus lintearius to control gorse
-Cinnabar moth (Tyria jacobaea) on tansy ragwort
-Ragwort seed fly (Botanophila seneciella) on tansy ragwort
-Ragwort flea beetle (Longistarsus jacobaeae) on tansy ragwort
-Klamath weed beetle (Chrysolina quadrigemina) on Klamath weed/St. Johnswort
,✔✔Describe and give an example of biological weed control using pathogens. - ✔✔-
Xanthamonas campestris pv. poannua to control unwanted grass species
-Phyllocoptes fructiphilus to kill multiflora rose
-Puccinia carduorum to control musk thistle
✔✔Describe and give an example of biological weed control using grazing animals. -
✔✔-Young stages of Yellow starthistle
-Grass carp
✔✔Identify the factors that would limit the use of biological control for weeds. -
✔✔Agent may attack non-target species, need species with high specificity to the target
weed, some agents may not exist for pest weeds, program is expensive and takes a
long time, unexpected factors such as environment or other predators of control agent
✔✔Describe the impact of seedbed preparation on weeds. - ✔✔Secondary tillage can
eliminate existing vegetation, apply fertilizer only where crops will be planted, remove
weeds as seedling crops as emerging, dislodging small weeds
✔✔Describe the impact of irrigation method on weeds. - ✔✔Different weeds will grow in
different irrigation methods (drip vs sprinkler vs flood). Managing the irrigation method to
provide adequate water to crop but reduce water to weeds (drip) can help reduce weed
populations
✔✔Describe the impact of irrigation timing on weeds. - ✔✔Preplant irrigation to remove
germinated weeds. Not irrigating after cultivation to allow weeds to dry out and die.
✔✔Describe the impact of time of seeding on weeds. - ✔✔Time seeding to outcompete
weeds to reduce weed pressure. Do not seed if weeds have emerged.
✔✔Describe the impact of soil nutrition on weeds. - ✔✔If soil nutrients are directed to
other spots than where the crops will uptake them, then the weeds will take up nutrients
and try to out-compete the crop being grown
✔✔Describe the impact of seed/plant spacing on weeds. - ✔✔If there is not enough
room for weeds to receive light or water, crops will out-compete weeds
✔✔Describe the impact of crop variety on weeds. - ✔✔Select for varieties that grow
quickly and develop canopies to shade out weeds to reduce susceptibility to weed
competition
✔✔Describe the impact of crop rotation on weeds. - ✔✔Allows for diverse methods to
manage weeds. Diversification of crops grown reduces and prevents the proliferation of
weed species acclimated to a monoculture
, ✔✔Describe the impact of pre-irrigation on weeds. - ✔✔Pre-irrigation can germinate
weed seed present and allow for easy cultivation before planting.
✔✔Describe the impact of synthetic mulches on weeds. - ✔✔Synthetic mulches such as
plastic can block sunlight from reaching weed seeds and preventing germination.
✔✔Describe the impact of organic mulches on weeds. - ✔✔Prevent germination of
weed seeds by keeping the shallow layer dry and giving the crop seed a head start
✔✔Describe the impact of sanitation methods on weeds. - ✔✔Sanitation of equipment
and irrigation water (screens) can reduce the amount of weed seed moved to different
parts of the field or different fields
✔✔List and describe common cultivation/tillage methods. - ✔✔Rolling cultivators, plant
hoe, V-sweep, cultivator knife, bed knives, shovels, vegetable knives, Alabama sweeps,
chisel plow sweeps, cultivator sweeps
✔✔Describe how weeds are affected by depth of tillage. - ✔✔Small weed seed won't
germinate if buried deep but larger seed will. Vegetative propagation will not re-emerge
if buried deep enough but it is difficult.
✔✔Describe how weeds are affected by timing of tillage. - ✔✔Dormant seed will be
more likely to not emerge if tillage is done during dormancy. Freshly emerged seed
should be tilled immediately to eliminate the weed. Vegetative propagation needs to be
tilled/removed before periods of rapid growth.
✔✔Describe how weeds are affected by no-tillage. - ✔✔No-tillage can promote weed
growth unless no-tillage is used with different methods of control such as mulches.
✔✔Describe cultivation techniques used in perennial crops. - ✔✔Mechanical cultivation
used for seedbed preparation and then hand cultivation used in rows after perennial
crop growth.
✔✔Compare the advantages and disadvantages of different cultivation methods. -
✔✔Hand cultivation: can be closer to the crop but expensive to pay for labor and room
for human error
Mechanical cultivation: inexpensive, but time consuming and often needs a crew to
hand cultivate behind the equipment
✔✔Identify the proper timing for cultivation and hand weeding. - ✔✔When weeds have
just emerged
