ILLINOIS FIELD CROPS APPLICATOR 2025/2026 QUESTIONS
WITH ANSWERS GRADED A+
✔✔describe the appearance of alfalfa weevil larvae and adults - ✔✔1. larvae-shiny
black head
curved body green with white stripe
skelotonize have fields look white frosted
2. adults-light brown with darker brown stripe along center of back-chew on stems
✔✔what kind of damage does alfalfa weevil cause? - ✔✔1. larvae skeletonize leaves,
causing fields to appear frosted.
2. adults feather the leaves and chew on stems
3. economic thresholds: -at first cutting >3 larvae per stem and 20% of the tips
skeletonized
-later cuttings:feeding on 50% of crowns and no regrowth for 3-6 days
✔✔describe the appearance of potato leafhopper - ✔✔green wedge shaped about 1/8
inch long
✔✔what kind of damage does potato leafhopper cause - ✔✔1. yellowish leaflets
2. dark brown triangular leaflet tips
✔✔when is alfalfa most suceptible to potato leafhopper damage, and as a
consequence, when is scouting for this pest most critical? - ✔✔1. scout when alfalfa is
regrowing after cutting
2. tender, regrowing alfalfa is most susceptible
✔✔describe the appearance of older armyworm larvae and the damagethey cause on
wheat - ✔✔1. appearance-1 1/2 inches long, and brown/green with two orange stripes
on each side
2. damage-seedlings get chewed to the ground
-move in mass and seek out food and can destroy corn plants
✔✔what are the economic thresholds for grasshoppers? - ✔✔non-crop areas:15-20
nymphs per square yard
corn:> 7 per square yard
soybean:5-10% pod feeding
✔✔sheath - ✔✔enloses the bud shoot and is connected to the leaf blade at the collar
the sheath of most grass plants is split and overlapping
✔✔ligule - ✔✔located on the inner side of the leaf blade and appears as an extension of
the sheath at its intersection with the blade. ligules are hairlike or membranous and very
in length and shape
, ✔✔auricle - ✔✔may or not be present, very in length. long auricle may cross one
another and clasp the stem, as in quackgrass.
✔✔leaf blade hairs - ✔✔absent, hairy, hairy at base
✔✔there are four main characteristics that are used to identify broadleaf weed
seedlings - ✔✔1.cotyledons: the food source for the seedling(shape and size vary:
opposite)
2.true leaves: those produced after the cotyledons(shape and color vary greatle)
3. arrangement of true leaves: alternate, opposite, or whorled
4. leaf petiole(leafstalk): attaches leaf to stem(vary in length and hairness or may be
absent)
✔✔name 3 types of overwintering, vegative, reproductive structures (propagules) -
✔✔rhizomes, stolons, budding roots, bulbs
✔✔weeds affect crop production by - ✔✔competing with crops for water, nutrients, and
sunlight, and space.
reducing:yield , crop quality, and harvest efficiency
✔✔epp - ✔✔early preplant, applied 2 or more weeks prior to planting
✔✔ppi - ✔✔preplant incorporated, applied and mechanically incorporated prior to
planting
✔✔pre - ✔✔preplant, applied prior to crop planting. or, preemergence, applied after
planting but before crop and weeks emergence
✔✔post - ✔✔postemergence, applied after crop and weed emergence
✔✔when are weeds the most susceptible to herbicides applied postemergence? - ✔✔1.
annuals-seedling
2. biennials-seedling, or rosette
3. perennial-seedling, or bud to bloom, fall regrowth
✔✔all soil applied herbicides need to move into the soil, which can be accomplished by
- ✔✔mechanical methods or rain
most weed seeds germinate in the top 2 inch of soil
✔✔ An Integrated Pest Management program is based upon - ✔✔1.Scouting for pests-
understanding pest biology 2.Environmental information-growth stages of field crops
3.technology to prevent unacceptable thresholds of pest damage by most econmomical
means-economic threshold of insects, diseases or weeds
WITH ANSWERS GRADED A+
✔✔describe the appearance of alfalfa weevil larvae and adults - ✔✔1. larvae-shiny
black head
curved body green with white stripe
skelotonize have fields look white frosted
2. adults-light brown with darker brown stripe along center of back-chew on stems
✔✔what kind of damage does alfalfa weevil cause? - ✔✔1. larvae skeletonize leaves,
causing fields to appear frosted.
2. adults feather the leaves and chew on stems
3. economic thresholds: -at first cutting >3 larvae per stem and 20% of the tips
skeletonized
-later cuttings:feeding on 50% of crowns and no regrowth for 3-6 days
✔✔describe the appearance of potato leafhopper - ✔✔green wedge shaped about 1/8
inch long
✔✔what kind of damage does potato leafhopper cause - ✔✔1. yellowish leaflets
2. dark brown triangular leaflet tips
✔✔when is alfalfa most suceptible to potato leafhopper damage, and as a
consequence, when is scouting for this pest most critical? - ✔✔1. scout when alfalfa is
regrowing after cutting
2. tender, regrowing alfalfa is most susceptible
✔✔describe the appearance of older armyworm larvae and the damagethey cause on
wheat - ✔✔1. appearance-1 1/2 inches long, and brown/green with two orange stripes
on each side
2. damage-seedlings get chewed to the ground
-move in mass and seek out food and can destroy corn plants
✔✔what are the economic thresholds for grasshoppers? - ✔✔non-crop areas:15-20
nymphs per square yard
corn:> 7 per square yard
soybean:5-10% pod feeding
✔✔sheath - ✔✔enloses the bud shoot and is connected to the leaf blade at the collar
the sheath of most grass plants is split and overlapping
✔✔ligule - ✔✔located on the inner side of the leaf blade and appears as an extension of
the sheath at its intersection with the blade. ligules are hairlike or membranous and very
in length and shape
, ✔✔auricle - ✔✔may or not be present, very in length. long auricle may cross one
another and clasp the stem, as in quackgrass.
✔✔leaf blade hairs - ✔✔absent, hairy, hairy at base
✔✔there are four main characteristics that are used to identify broadleaf weed
seedlings - ✔✔1.cotyledons: the food source for the seedling(shape and size vary:
opposite)
2.true leaves: those produced after the cotyledons(shape and color vary greatle)
3. arrangement of true leaves: alternate, opposite, or whorled
4. leaf petiole(leafstalk): attaches leaf to stem(vary in length and hairness or may be
absent)
✔✔name 3 types of overwintering, vegative, reproductive structures (propagules) -
✔✔rhizomes, stolons, budding roots, bulbs
✔✔weeds affect crop production by - ✔✔competing with crops for water, nutrients, and
sunlight, and space.
reducing:yield , crop quality, and harvest efficiency
✔✔epp - ✔✔early preplant, applied 2 or more weeks prior to planting
✔✔ppi - ✔✔preplant incorporated, applied and mechanically incorporated prior to
planting
✔✔pre - ✔✔preplant, applied prior to crop planting. or, preemergence, applied after
planting but before crop and weeks emergence
✔✔post - ✔✔postemergence, applied after crop and weed emergence
✔✔when are weeds the most susceptible to herbicides applied postemergence? - ✔✔1.
annuals-seedling
2. biennials-seedling, or rosette
3. perennial-seedling, or bud to bloom, fall regrowth
✔✔all soil applied herbicides need to move into the soil, which can be accomplished by
- ✔✔mechanical methods or rain
most weed seeds germinate in the top 2 inch of soil
✔✔ An Integrated Pest Management program is based upon - ✔✔1.Scouting for pests-
understanding pest biology 2.Environmental information-growth stages of field crops
3.technology to prevent unacceptable thresholds of pest damage by most econmomical
means-economic threshold of insects, diseases or weeds
