unit 9: basic weed scouting. unit 9 objectives: – knowledge of basic scouting procedures –...
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Unit 9: Basic Weed Scouting
Unit 9 Objectives:– Knowledge of basic scouting procedures– Understanding of proper scouting times – Using field weed surveys– Basic weed ID
Unit 9: Basic Weed Scouting
Early season weed scouting– Done within 2 wks of planting after emergence
Also can determine:– Need for hoeing– Preemergence & preplant herbicides– Need for post emergence herbicides
– ID and record weed species
Unit 9: Basic Weed Scouting
– Determine severity of weed infestation Count number of weeds/10’ of row for heavy
infestations, weeds/100’ of row for light infestations Sample area <5 ac Record weed height & growth stage
– Also note soil conditions Can help indicate herbicide effectiveness
– Too dry, not enough moisture for chemical uptake– Too wet, herbicide may have leached through root zone
Unit 9: Basic Weed Scouting
– Identify weeds as early as possible for most effective control
Weed mapping– Complete a detailed weed map of each field by
mid-May– Will help you monitor changes in weed population
throughout the year, & from year to year– Include:
Perennial weed locations
Unit 9: Basic Weed Scouting
Annual weed locations & infestation levels Mark distinguishing features
Final weed survey– Timing: late July to mid-August– Add to, or complete another weed map– Don’t generalize observations from areas near
waterways, poorly drained areas, next to borders– Rank species from most commonly to least
commonly found
Unit 9: Basic Weed Scouting
Economic Threshold guidelines– Weeds and crop compete for the same resources:
Soil Fertility Sunlight Water
– Problems other than yield losses: Clogging, damaging harvest equipment Loss of cash rented ground to “neater” farmers
Unit 9: Basic Weed Scouting
– Weed infestations the first 4-6 wks, then treatment = no economic losses
– No weeds first 4-6 wks, then weed infestation = minimal yield losses, but increased weed seed production
– Similar weeds typically cause economic losses in similar crops
Grass weeds to grass type crops Corn weeds to corn type crops Broadleaf weeds to broadleaf type crops (soybeans)
Unit 9: Basic Weed Scouting
Giant Foxtail– Blade is densely hairy– Ligule has fringe hairs– Found through the Midwest
Unit 9: Basic Weed Scouting
Yellow foxtail– Sheath is flattened, smooth with split,
overlapping, smooth margins– Blade is smooth with long hairs– Ligule has fringe hairs
Unit 9: Basic Weed Scouting
Green Foxtail– Sheath – round to slightly flat w/ split, overlapping
hairy margins– Blade is smooth to rough w/ rough margins– Ligule is a fringe of hairs– Continuous hairy collar
Unit 9: Basic Weed Scouting
Fall Panicum– Sheath – slightly flat, smooth w/ split, overlapping
membranous margins– Blade is smooth w/ prominent mid-vein– Ligule is a fringe of hairs– Continuous collar
Unit 9: Basic Weed Scouting
Shattercane– Sheath – rounded and smooth w/ split,
overlapping thin, membranous margin– Blade – flat w/ sparsely placed hairs on upper
surface– Ligule – long, membranous, rounded w/ jagged
ciliated margin
Unit 9: Basic Weed Scouting
Yellow Nutsedge– Leaves – triangular, taper to a point, greenish
yellow– Very distinctive
Unit 9: Basic Weed Scouting
Quackgrass– Sheath – rounded w/ sparse, short hairs, can be
smooth & split, overlapping margins– Blade – flat, rough to smooth– Ligule – short, membranous, truncate in shape
Unit 9: Basic Weed Scouting
Burcucumber– Hypcotyl – green & rough– Cotyledons – oblong to spoon shaped– True leaves – alternate, pentagon shaped
somewhat hairy– Petioles – long & greed– Fruit – barbed, prickly bristles
Unit 9: Basic Weed Scouting
Common Cocklebur– Hypcotyl – smooth, fleshy, purple tinge near soil– Cotyledons – fleshy, shiny, long and thin shaped– True leaves – opposite (first pair), alternate later
Serrated leaves Oval in shape Rough to hairy surface
– Petioles – long, hairy, can be purple spotted
Unit 9: Basic Weed Scouting
Jimsonweed– Hypcotyl – fleshy, purple tinged, smooth– Cotyledons – smooth, narrow, short petioles– True leaves – alternate, large, smooth, pointed
apex, toothed margins– Petioles – long, pale green to purple, may have
short hairs
Unit 9: Basic Weed Scouting
Common Lambquarters– Hypcotyl – purple, smooth– Cotyledons – fleshy, long, oval, dull color– True leaves – seem paired at first, become
alternate Pale green Oval shape Irregular toothed margins
– Petioles – long, pale green
Unit 9: Basic Weed Scouting
Ivyleaf Morningglory– Hypcotyl – dull green to purple, crease along both
sides– Cotyledons – shiny, smooth, deeply indented
base– True leaves – alternate, hairy, three lobed leaves– Petioles – long, hairy, green to reddish tint
Unit 9: Basic Weed Scouting
Pitted Morningglory– Hypcotyl – smooth, somewhat purple– Cotyledons – smooth, butterfly shaped, deeply
indented lobes, pointed– True leaves – alternate, smooth, heart shaped,
maybe purple margins– Petioles – long and pale green to purple
Unit 9: Basic Weed Scouting
Tall Morningglory– Hypcotyl – dull green to purple, smooth– Cotyledons – shiny, smooth, deeply indented
base– True leaves – alternate, hairy broadly heart
shaped, pointed apex– Petioles – long, hairy, dull green to reddish tint
Unit 9: Basic Weed Scouting
Eastern Black Nightshade– Hypcotyl – reddish to purple– Cotyledons – pointed tip w/ sparse hairs– True leaves – alternate, oval, wavy tooth margins
Underside – red to purple
– Petioles – red, purple, green, sparse hairs
Unit 9: Basic Weed Scouting
Smooth Pigweed– Hypcotyl – reddish purple– Cotyledons – oblong, purple tinge, rough to
smooth– True leaves – alternate, oval, notched or pointed
apex, pale green to reddish– Petioles – long, may be hairy– Root – long, red taproot
Unit 9: Basic Weed Scouting
Common Ragweed– Hypcotyl – purplish, rigid, rough– Cotyledons – club-shaped, rounded apex, smooth
surface– True leaves – opposite, irregular lobed– Petioles – grooved, widen to V-shaped stem
Unit 9: Basic Weed Scouting
Giant Ragweed– Hypcotyl – smooth, shiny, can be purple blotched– Cotyledons – spatulate, rounded apex gradually
narrowing to base, smooth, shiny– True leaves – opposite, oval, pointed w/ serrated
margins, rough short-haired surface– Petioles – concave above, winged toward stem,
rough hairy surface
Unit 9: Basic Weed Scouting
Smartweed– Hypcotyl – smooth, tinged dark purple– Cotyledons – smooth, fleshy, elongated, shiny w/
hairy margins– True leaves – alternate and elongated, shiny, may
be spotted purple, hairy margins– Petioles – short, arise from swollen joints
Unit 9: Basic Weed Scouting
Waterhemp– Hypcotyl – reddish purple– Cotyledons – oblong, purple tinge– True leaves – alternate, narrow oval to elongated,
pale greed to reddish, smooth– Petioles - long
Unit 9: Basic Weed Scouting
Velvetleaf– Hypcotyl – velvety, soft short hairs– Cotyledons – heart shaped, rounded apex, fuzzy
surface– True leaves – alternate, heart shaped, rounded
apex, serrated margin, velvety surface– Petioles – round, covered w/ soft hairs
Unit 9: Basic Weed Scouting
Field Bindweed (perennial)– Hypcotyl – smooth– Cotyledons – kidney shaped– True leaves – alternate, spade shaped, smooth– Petioles - smooth
Unit 9: Basic Weed Scouting
Hedge Bindweed (perennial)– Hypcotyl – smooth– Cotyledons – kidney shaped– True leaves – alternate, larger than field
bindweed, arrowhead shaped– Petioles - smooth
Unit 9: Basic Weed Scouting
Hemp Dogbane (perennial)– Hypcotyl – red above ground– Cotyledons – elongated, smooth– True leaves – opposite, elliptic, thick, shiny, white
midvein– Petioles – short, smooth, “milklike” sap
Unit 9: Basic Weed Scouting
Common Milkweed (perennial)– Hypcotyl – pale green to purple– Cotyledons – elliptical, thick, covered w/ short
hairs– True leaves – opposite, thick, dull, velvety,
elliptical, pointed– Petioles – ridged, “milklike” sap
Unit 9: Basic Weed Scouting
Honeyvine Milkweed (perennial)– Hypcotyl – green to slightly pink, smooth– Cotyledons – shiny, oblong, rounded apex,
narrows into long petiole– True leaves – opposite, oblong to heart shaped,
pointed apex, dull green to bluish tint– Petioles – long, sparsely hair covered
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