PCA: Weeds Exam Study Guide2+Questions and
Answers Verified 100% Correct | Pass Assured
Dicot - ANSWER have two seed leaves inside the seed coat. They are usually rounded
and fat, because they contain the endosperm to feed the embryo plant
Monocot - ANSWER An angiosperm that has only one seed leaf.
reproductive capability of weeds - ANSWER weeds often form persistent seedbanks and
can reproduce at a young age. rhizomes or other vegetative structures, these plants can
form thick, single-species stands.
Describe the mechanisms by which weed seeds are disseminated. - ANSWER Wind,
water, animal + human: poop, clothing/fur, accidental planting, transport, soil
movement,
Describe how the following factors contribute to regulating the seed bank and seed
longevity:
Cultural - ANSWER Mulching
Describe and give an example of biological weed control using:
a. arthropods;
b. pathogens;
c. grazing animals. - ANSWER Arthropods- cochineal attacking prickly pear cactus.
Pathogens- Using rust to control orange wattle
Grazing animals- Goats eating weeds to prevent reseeding and fires.
, Soil solarization - ANSWER Not only kill pathogens, but can cook/destroy weed seeds to
a certain depth.
Weed control: steaming - ANSWER The use of high temperature water onto weeds
Describe some preventative measures that can be used to manage weeds: Quarantine -
ANSWER Hold livestock that may be infested with seed in a single location until they are
shorn or until weed seeds have had the chance to pass through their digestive system.
Feed out infested fodder in a feed lot type situation only and introduce clean fodder to
stock.
Mode of Action - ANSWER The mechanisms by which herbicides kill plants
amides (propanil) - ANSWER MoA- inhibition of their photosynthesis and CO2 fixation
bipyridiliums (paraquat, diquat) - ANSWER MoA- inhibiting photosynthesis
dinitroanilines (trifluralin, pendimethalin); - ANSWER MoA- inhibition of cell mitosis
diphenylethers (oxyfluorfen); - ANSWER MoA- rupturing of the cell membrane. Soil and
foliar applied with limited movement in the soil
glycine (glyphosate); - ANSWER MoA- binds to and blocks the activity of the enzyme
enolpyruvylshikimate-3-phosphate synthase
phenoxy carboxylic acids (auxinic herbicides, 2,4-D); - ANSWER MoA- plant growth
hormone auxin, which results in uncontrolled growth and eventually death. selective
herbicide which kills many terrestrial and aquatic broadleaf weeds
Answers Verified 100% Correct | Pass Assured
Dicot - ANSWER have two seed leaves inside the seed coat. They are usually rounded
and fat, because they contain the endosperm to feed the embryo plant
Monocot - ANSWER An angiosperm that has only one seed leaf.
reproductive capability of weeds - ANSWER weeds often form persistent seedbanks and
can reproduce at a young age. rhizomes or other vegetative structures, these plants can
form thick, single-species stands.
Describe the mechanisms by which weed seeds are disseminated. - ANSWER Wind,
water, animal + human: poop, clothing/fur, accidental planting, transport, soil
movement,
Describe how the following factors contribute to regulating the seed bank and seed
longevity:
Cultural - ANSWER Mulching
Describe and give an example of biological weed control using:
a. arthropods;
b. pathogens;
c. grazing animals. - ANSWER Arthropods- cochineal attacking prickly pear cactus.
Pathogens- Using rust to control orange wattle
Grazing animals- Goats eating weeds to prevent reseeding and fires.
, Soil solarization - ANSWER Not only kill pathogens, but can cook/destroy weed seeds to
a certain depth.
Weed control: steaming - ANSWER The use of high temperature water onto weeds
Describe some preventative measures that can be used to manage weeds: Quarantine -
ANSWER Hold livestock that may be infested with seed in a single location until they are
shorn or until weed seeds have had the chance to pass through their digestive system.
Feed out infested fodder in a feed lot type situation only and introduce clean fodder to
stock.
Mode of Action - ANSWER The mechanisms by which herbicides kill plants
amides (propanil) - ANSWER MoA- inhibition of their photosynthesis and CO2 fixation
bipyridiliums (paraquat, diquat) - ANSWER MoA- inhibiting photosynthesis
dinitroanilines (trifluralin, pendimethalin); - ANSWER MoA- inhibition of cell mitosis
diphenylethers (oxyfluorfen); - ANSWER MoA- rupturing of the cell membrane. Soil and
foliar applied with limited movement in the soil
glycine (glyphosate); - ANSWER MoA- binds to and blocks the activity of the enzyme
enolpyruvylshikimate-3-phosphate synthase
phenoxy carboxylic acids (auxinic herbicides, 2,4-D); - ANSWER MoA- plant growth
hormone auxin, which results in uncontrolled growth and eventually death. selective
herbicide which kills many terrestrial and aquatic broadleaf weeds
